Heart defects, for everyone

Arrhythmias

2012-01-13T21:25:00.000-06:00

Pediatric or adolescentarrhythmias come in all different kinds, and it depends on where in the heartthe arrhythmia is located (top, middle or bottom of the heart).

It is very fortunate when thecardiologist knows what kind of arrhythmia it is without further testing,although often an ECG or a Holter Monitor will allow the doctor to evaluate therhythm.

Adolescents often come intoan echo lab with symptoms of tachycardia, syncopal episodes, bradycardia, heartblock, chest pain and various other patterns that may or may not be apparentdirectly.

Exercise stress testing is anappropriate procedure used in order to stimulate the arrhythmia. This is also avaluable tool that evaluates exercise tolerance and the presence of ischemia (lackof oxygen to the heart muscle) and other symptoms that are not present at rest.

Electrophysiology may be amethod that is used in the event of life threatening situations.

There are times when animplantable defibrillator may be needed to control arrhythmias, but often drugtherapy is sufficient. Pacemakers are usually used depending on the location ofthe arrhythmia, especially if there is a significant malfunction of the heart’sconduction system.

More aggressive treatment(electrophysiology, ablation, and pacemakers) are usually reserved for patientsthat do not respond to drug therapy.

Sinus Arrhythmia

This is common in childrenand adolescents, and is characterized by a normal sinus rhythm that isirregular. It is not dangerous or necessarily abnormal.

Tachycardia

This is the most common causeof arrhythmia in a fetus or young adult and is often due to a “short circuit”in the wiring of the heart such as a bundle branch block, or may be caused bysuch abnormalities as cardiomyopathy or other structural defects in the heart.

Wolff-Parkinson-White Syndrome (WFW)

Essentially a short circuitin the wiring of the top part of the heart, or the atria which causespre-excitation of the ventricles before the normal impulse is supposed to getto the ventricles. This is more common in patients with such abnormalities asEbstein’s malformation or transpositions.

Irregular tachycardia, atrialfibrillation, syncope, palpitations are more common developments, and the riskof sudden death is higher. Ablation (zapping the short circuit with acatheter), or drug therapy is the most common treatments.

Atrial Conduction Abnormalities

These are essentially “shortcircuits” in the top part of the heart that lead to such arrhythmias as atrialfibrillation, atrial flutter and nodal problems (those areas of the heart thatconduct bio-electric impulses from one part of the heart to another, or the SAand AV nodes).

Some nodal problems arereferred to as “sick sinus syndrome”. Drug therapy and ablation are commonsolutions to these types of problems and have a high success rate.

Some arrhythmias areinherited and are associated with various cardiomyopathies, or primary diseasesof the musculature of the heart or its electrical system, e.g. hypertrophiccardiomyopathy and/or the disorders described above.

Echocardiography

There are often stories inthe newspaper of young adults who are athletes that die during strenuousexercise. Various arrhythmias can be the cause, and are important to diagnosewith a pediatric cardiologist, and often result in a treadmill stress test.

However, the most common cause of sudden deathduring exercise that I am aware of are two congenital defects, “anomalouscoronary arteries” and “IHSS” (or idiopathic hypertrophic sub-aortic stenosis).

What the heck does thatmean? For parents and those who are nottechnologists, that means that the arteries that feed the heart muscle(coronary arteries) are not connected up properly, or that there is anintrinsic, inherited disease of the heart muscle that is enlarged and ispreventing blood from exiting the heart when it is pumping at a high rate.These defects are discussed in other posts, but my experience is that they arethe most common causes of sudden death upon heavy exertion.

My rule of thumb as anechocardiographer is to check for these (and any other defects) in any youngpatient.

Ken Heiden RDCS, RVT

“Congenital Heart Defects,Simplified”

www.HeartDefectsSimplified.com

Heart defects, for everyone: 3 D Echocardiography

2011-12-30T23:33:00.000-06:00

Heart defects, for everyone: 3 D Echocardiography, HeartDefectsSimplified.com

3 D Echocardiography

2011-12-30T18:36:00.000-06:00

3D echo is in the process of revolutionizing pediatric echocardiography. It is like the difference between looking at a crude snapshot of an infant's heart in the womb, as opposed to a 3D movie of that same infant's heart.

Many cities have 3D images of babies on their billboards advertising their hospitals, as if you have taken a picture of that baby in real time. This is a far cry from how we used to look at babies in the womb, grainy hard to see, black and white slices of a baby.

With typical 2D cardiac imaging, you are looking at a several millimeter slice of the heart, one looped image at a time, whereas with 3D, it as if you have inserted a video camera into the womb and are looking at the fetus's heart as if you are holding it in your hand and watching it function.

This is made possible by the advancement from piezoelectric to composite transducers, not to mention the advancement in computer technology in the last few years. These new composite materials significantly improve bandwidth, sensitivity and resolution, and the newest technologies allow for much faster computer enhancement of image quality and manipulation.

This is a very important advancement in pediatric cardiology. For instance, many of these defects are very hard to visualize in a 2D format, but when utilized in a 3D format, they become much more understandable. Further, modern technology allows you to manipulate the image in any way you want, to see the heart in numerous views.

Endocardial cushion defects (AV canal) is a perfect example. Unless you have actually seen this defect with a real heart, this might be an easy defect to misdiagnose. Is there a cleft mitral valve? Is it partial or complete? Is there a VSD and or an ASD? Where are the bridging leaflets? Exactly how do the shunts occur? Is there a malaligned outflow tract?

In conclusion, 3D echocardiography in many ways is quantifiable, reproducible and comparable to MRI in many of the measurements used in cardiology. Volumes and ejection fractions are two examples. This is increasingly becoming an invaluable technique in invasive procedures (such as the closure of ASD's).

YouTube Video

2011-12-25T10:38:00.001-06:00

Please check out our new You Tube video called "Congenital Heart Defects Simplified". This routes you to our website that is a complete didactic registry review for the pediatric registry test. The purchase price of $99.95 includes the book "Congenital Heart Defects, Simplified", and an online test test that provides 30 SDMS CME's

The blog, of course is free, and is an invaluable addendum to the book for anyone who is interested in this field.

Furthermore, you can follow us on Facebook, "Pediatric EchoSonographers", an online forum for all who wish to communicate with other sonographers in the field, or anyone wishing to know more about heart defects, such as nurses, parents, or even pediatric cardiologists and their patients.

Ken Heiden RDCS, RVT

Cardiomyopathies Part Three Restrictive

2011-12-14T12:43:00.001-06:00

Restrictive Cardiomyopathies ( Part Three)

This type of cardiomyopathy is defined as the “stiffness” of the ventricle that disallows a significant increase in volume of the ventricle but causes the pressure to rise to abnormally high levels.

These can be categorized in two ways: reduced systolic volumes and reduced diastolic volumes.

These are the rarest types of cardiomyopathies (3% of all cardiomyopathies) but the prognosis is very grave with half of all children dying in the first 2 years without transplantation. However, survival rates after transplantation is very good. Most children require transplantation within 4 years.

Cardiac failure usually occurs rapidly as a result of increased pulmonary vascular resistance and increased pulmonary hypertension. Symptoms include chest pain, ischemia, and syncope and ECG changes.

There are numerous causes for this disease and is often familial (3 of ten children). Genetic mutations of varying types are the most common cause of this disorder. Myocardial disorders caused by endocardial fibrosis, fibroelastosis, and endomyocardial diseases, parasitic infections, and other acquired factors are common. Infiltrative and storage diseases of the endocardium are also contributing factors.

Loffler’s endocarditis and Anderson-Fabry disease may be examples of this. Sarcoidosis is yet another contributing factor.

Onset is quick, and prognosis is poor, with over half of children of adolescents dead within a year.

Imaging techniques include MRI, CT and sonography. Findings usually include ventricular dilatation without hypertrophy. Be watchful of thrombosis.

This disease causes significant ventricular non-compliance which causes a significant rise in ventricular filling pressures that reduces cardiac output.

This defect is often confused with other symptomatic problems such as asthma and chest infections which may delay diagnosis.

Echocardiography generally reveals significant increases in bi-atrial size, severe diastolic dysfunction, and increased end diastolic pressures and pulmonary hypertension.

Transplantation is the recommended solution, but prophylactic treatment is necessary until that time.

Segmental Approach to Echocardiography

2011-12-07T19:08:00.000-06:00

The Segmental Approach as a Framework for Evaluation

Of Congenital Heart Defects

In General

Heart defects are the most common birth defect in children, occurring in approximately 8 of every 1000 live births. Every year, between thirty-five and forty thousand children are born in the United States with congenital heart defects.

Over the years, more than 30 complex congenital heart defects have been identified and named, as well as numerous abnormalities of a less severe nature. Because 1 or more of these defects or abnormalities may arise in conjunction with any of the others, congenital heart defects occur across a very broad spectrum. This has led to an often-bewildering number of individual definitions, classifications and subclassifications.

Until the 1980s, the nomenclature used to define and describe congenital heart defects was primarily derived from the study of embryology. Specific defects were determined to be present because of genetic errors that occurred during embryologic development. For example, a failure of the endocardial cushions to form properly resulted in AV canal, a common defect in the middle portion of the heart. Or, at a different stage of embryologic development, the incomplete formation of the ventricular septum resulted in ventricular septal defect (VSD). The study of embryology is still a useful tool for understanding heart defects, particularly with respect to terminology. However, during the 1980s a simplified segmental approach was developed supplementing embryology in the evaluation and classification of heart defects

In the segmental approach, the focus is upon the structural components or segments of the heart and the connections between them.

Using this framework, the cardiovascular system is divided into sections. Each section is evaluated sequentially following the flow of blood into the heart (systemic and pulmonary venous return), through the heart (atrioventricular valves and ventricles) and out the great vessels (semilunar valves and great arteries). The objective of the segmental approach is to accurately describe, document and assess anomalies within and between the structures of the heart without resorting to obscure terminology or complicated classifications based on embryology.

Three Step Evaluation of Cardiovascular Anatomy

For purposes of analysis, the cardiovascular system may be divided into 3 sections.

· The atria and venous connections (atrial arrangement)

· The “ventricular mass” (ventricular arrangement)

· Arterial outflow portion (arrangement of the great arteries)

Atrial Situs

The first step in an evaluation using the segmental approach consists of determining atrial situs. Situs refers to the location or position of the atria in relation to nearby anatomy. Left-sided structures and right-sided structures have different morphology. Typically, atrial situs corresponds to abdominal situs.

· The term “atrial situs solitus” describes a normal atrial arrangement.

· Where the atria are transposed, the term “situs inversus” is used.

· “Situs ambiguous” (situs ambiguus) describes everything in between, but in most cases, the atrial arrangement will be either morphologically right-sided or left-sided.

It may not always be easy to distinguish the right atrium from the left. Venous connections are not a reliable anatomic guide. For example, the pulmonary veins may be abnormally connected to the extent that they do not drain into the left atrium at all, or may do so only partially (total and partial anomalous pulmonary return). Right and left atrial morphology may be more reliably determined by examining the atrial appendages. The right atrial appendage is a broad-based triangular shaped structure. The left is narrow, tubular or finger-like in appearance. Transesophageal echo (TEE) provides the best views of the atrial appendages.

Atrial-ventricular Connections and Ventricular Morphology

The second step in a segmental analysis involves assessing the ventricular mass and the connections between the ventricles and atria. This requires an evaluation of the cardiac crux. The cardiac crux is the area where the walls of the atria and ventricles intersect and the atrioventricular valves are positioned on the ventricular septum. Embryologic development is particularly significant in this region, giving rise to a wide range of anatomic variation.

· It is particularly important to distinguish right ventricular morphology from left ventricular morphology and to establish whether there are 2 discrete ventricles divided by an intact ventricular septum or 1 functional ventricle paired with a rudimentary hypoplastic ventricle. True single ventricle syndromes are rare.

· Atrioventricular valve anatomy is a useful guide in ventricle differentiation. However, the atrioventricular connection may vary. It may be biventricular (atria connect to both ventricles), univentricular (atria connect to 1 ventricle) or common (atria connect to both ventricles through a single multileaflet valve structure).

Ventriculo-arterial Connections and Great Artery Arrangement

The final step in a segmental evaluation examines the morphology of the great arteries and their connections to the ventricular mass. Abnormalities in the origins of the great arteries, known as conotruncal anomalies, are predominately of 3 types.

· Transposed connections occur when the main pulmonary artery arises from the left ventricle, and the aorta arises from the right ventricle.

· Where both great arteries are connected to a single ventricle (almost always the right ventricle), a double outlet connection is present.

· A single outlet connection occurs when only 1 artery (aortic) arises from the ventricular mass or the great arteries are fused into a single truncal (aortic) artery with the pulmonary artery or arteries branching from it.

Nomenclature

In the segmental approach, both normal and abnormal structural relationships are defined using simple descriptive language that avoids terminology derived from embryology. Commonly used terms in segmental analysis include:

· Segments: The anatomical structures into which the cardiovascular system is divided for purposes of evaluation. Segments include the systemic and pulmonary veins, atria, ventricles, and great arteries.

· Connections: Describes the anatomical sequence of structures. Connections include venous to atria (veno-atrial), atria to ventricles (atrial-ventriclar) and ventricles to great arteries (ventriculo-arterial).

· Concordant: Describes a normal sequential relationship between the heart’s chambers, valves and great vessels. The term “appropriate” is often used interchangeably with concordant especially in relation to connections.

· Discordant: Refers to an abnormal sequential relationship between chambers, valves and great vessels

· Commitment: Describes the degree of abnormality of flow through valves into ventricles and great vessels. For example, a valve which overrides a large ventricular septal defect (VSD) is committed to more than 1 ventricle. Commitment is assigned based on the “50% rule.” If more than 50% of a valve overrides a VSD, it is said to be committed.

· Ambiguous: Term used where precise identification of a ventricle or other structure cannot be determined

· Inlet/outlet anomalies: Anomalies of structures and flow into the ventricles (inlet) or out of the ventricles into the great arteries (outlet)

Conclusion

The segmental approach is a logical and practical guide for conceptualizing heart dynamics and analyzing complex congenital heart defects. It eliminates the notion that pediatric echocardiographers have to memorize details about complicated abnormalities, their characteristic lesions and possible subclassifications. It is not intended to be a step-by-step protocol for the performance of an echocardiographic examination. Echocardiographers do not need to diagnose congenital heart disease in order to conduct a study. That is the province of the pediatric cardiologist. The segmental approach provides the echocardiographer with a framework for performing an informed, accurate and complete evaluation.

Heart defects, for everyone: Comgenital Heart Defects: A Fundamental Framework

2011-12-05T21:34:00.000-06:00

Heart defects, for everyone: Comgenital Heart Defects: A Fundamental Framework

2011-12-05T21:33:00.000-06:00

Heart defects, for everyone: Comgenital Heart Defects: A Fundamental Framework

Comgenital Heart Defects: A Fundamental Framework

2011-12-05T21:23:00.002-06:00

The Segmental Approach as a Framework for Evaluation

Of Congenital Heart Defects

In General

In the segmental approach, the focus is upon the structural components or segments of the heart and the connections between them.

Three Step Evaluation of Cardiovascular Anatomy

For purposes of analysis, the cardiovascular system may be divided into 3 sections.

· The atria and venous connections (atrial arrangement)

· The “ventricular mass” (ventricular arrangement)

· Arterial outflow portion (arrangement of the great arteries)

Atrial Situs

· The term “atrial situs solitus” describes a normal atrial arrangement.

· Where the atria are transposed, the term “situs inversus” is used.

· “Situs ambiguous” (situs ambiguus) describes everything in between, but in most cases, the atrial arrangement will be either morphologically right-sided or left-sided.

It may not always be easy to distinguish the right atrium from the left. Venous connections are not a reliable anatomic guide. For example, the pulmonary veins may be abnormally connected to the extent that they do not drain into the left atrium at all, or may do so only partially (total and partial anomalous pulmonary return). Right and left atrial morphology may be more reliably determined by examining the atrial appendages. The right atrial appendage is a broad-based triangular shaped structure. The left is narrow, tubular or finger-like in appearance. Trans esophageal echo (TEE) provides the best views of the atrial appendages.

Atrial-ventricular Connections and Ventricular Morphology

Ventriculo-arterial Connections and Great Artery Arrangement

· Transposed connections occur when the main pulmonary artery arises from the left ventricle, and the aorta arises from the right ventricle.

· Where both great arteries are connected to a single ventricle (almost always the right ventricle), a double outlet connection is present.

Nomenclature

· Connections: Describes the anatomical sequence of structures. Connections include venous to atria (veno-atrial), atria to ventricles (atrial-ventricular) and ventricles to great arteries (ventriculo-arterial).

· Discordant: Refers to an abnormal sequential relationship between chambers, valves and great vessels

· Ambiguous: Term used where precise identification of a ventricle or other structure cannot be determined

· Inlet/outlet anomalies: Anomalies of structures and flow into the ventricles (inlet) or out of the ventricles into the great arteries (outlet)

Conclusion

The segmental approach is a logical and practical guide for conceptualizing heart dynamics and analyzing complex congenital heart defects. It eliminates the notion that pediatric echocardiographers have to memorize details about complicated abnormalities, their characteristic lesions and possible sub classifications. It is not intended to be a step-by-step protocol for the performance of an echocardiographic examination. Echocardiographers do not need to diagnose congenital heart disease in order to conduct a study. That is the province of the pediatric cardiologist. The segmental approach provides the echocardiographer with a framework for performing an informed, accurate and complete evaluation.

Cardiomyopathies Part two:Dilated

2011-11-29T19:34:00.001-06:00

Dilated cardiomyopthies are somewhat common in children and account for .73 cases per 100,000 in the general population. It is a typically inherited disorder, and is often associated with neuro-muscular disorders such as Duchene and muscular dystrophy

Myocarditis is an important aspect of this disease, and are usually viral, but may also be bacterial, fungal, protozoal or parasitic. In other words, this disease may be inherited or acquired.

This disease presents as a dilated, balloon looking or globular heart with atrial enlargement. In the beginning, most patients present with high pulmonary pressures and low cardiac output. Infants usually present poor feeding, and failure to thrive. As the disease progresses, the child will experience dyspnea, tachycardia and peripheral edema.

The ECG is often normal, but the X-ray is frequently abnormal, reflecting and enlarged heart.

Echocardiography
Evaluate the size of the structures of the heart, the ejection fraction, diastolic function, the presence of thrombus, regurgitation of the valves and pulmonary pressures. Always check for any VSD or ASD, or any outflow obstructions.

Management of this disease is typically prophylactic in order to prevent thrombus, arrhythmias, and efforts to increase systolic function, for instance beta blockers and digitalis. In the the most extreme cases, ventricular assist devices may be necessary. End stage disease may require may require transplantation.

Cardiomyopathies part one:Hypertrophic

2011-11-28T04:51:00.003-06:00

Cardiomyopathies in the neonate are a diverse group diseases that are strictly defined as "a myocardial disorder in which the heart muscle is structurally and functionally abnormal, in the absence of coronary artery disease, hypertension, valvular disease, and congenital defects sufficient to cause the abnormality".

There are four major types: hypertrophic, dilated, restrictive and arrhythmogenic right ventricular. There are other variants that are unclassified, but in some circumstances, differing types of cardiomyopathies can co-exist, such as hypertrophic and dilated types.

Most hypertrophic cardiomyopathies are genetic disorders with familial connections and can further be sub classified according to type, such as protein diseases (three fifths of this population) that are chromosomal disorders that affect the development of the myocardium. Examples of these would be sarcomeric protein diseases, glycogen and lysosomal storage diseases and disorders of fatty acid metabolism.

Syndromes such as Noonan's, LEOPARD, and Friedreich's ataxia are other variants. For example, Noonan's and LEOPARD children are characterized by short stature, dysmorphic faces, skeletal abnormalities and webbed necks. In these children, pulmonary stenosis is a common finding.

These genetic types cause disarray and fibrosis of the myocardium. Systolic and diastolic dysfunction are a major consequence of hypertrophic diseases as well as LVOT obstruction and arrhythmias.

Most individuals are asymptomatic until they become adolescents; early n life they may present with cardiac failure, ECG abnormalities, shortness of breath and failure to thrive. In older children the most common symptoms are dyspnea and chest pain.

Myocarditis (or an inflammation of the myocardium) can play an important role in the development of this disease. Viruses are the most likely cause of myocarditis but it may also be bacterial, fungal, protozoal or parasitic, as well as an autoimmune response.

Echocardiography

Look for left ventricular hypertrophy (LVH) and/or dilatation. The hypertrophy may be asymmetric so pay close attention to possible obstructions of the left ventricular outflow tract (LVOT). Diastolic function is assessed using the usual techniques such as tissue Doppler and/or strain gauge. Arrhythmias are common, especially with exertion, therefore stress testing is a useful diagnostic tool.

Treatment is typically prophylactic. In cases where there is significant obstruction of the LVOT, a surgical myectomy may be performed. The prevention of arrhythmias that could result in sudden death are an important aspect of treatment. Some patients may require an implantable defibrillator. Hypertrophic diseases are often familial, therefore other members of the family should be assessed if they are thought to be at risk.

Ken Heiden RDCS, RVT

Bibliography: "Paediatric Cardiology", 3'd edition by Robert Anderson MD

Cardiomyopathies Part Four: Arrhythmogenic Right Ventricle

2011-11-27T06:08:00.004-06:00

Cardiomyopathies cover a lot of territory, from dilated to hypertrophic. Think of the heart as having a wiring system, just like your house. Everything works on electricity; it is just bioelectric which is much slower. The impulses travel from cell to cell as opposed to a wire. Further, there are two nodes that these impulses must travel through, the SA and AV nodes

Whenever there is a disease of the heart, there also can be malfunctions of this wiring system, creating "short circuits" in that wiring that lead to arrhythmia problems.

For instance, if the heart is overly dilated and the muscle fiber is stretched to its' maximum, this may disrupt conduction through the muscle fibers. If the heart is overtly muscular as a result of volume of pressure difficulties, the same may occur.

They are strictly defined in terms of ventricular morphology, and consist of four major types: Dilated, hypertrophic, restrictive and arrhythmogenic (RV cardiomyopathies). There are other types, but these are the most recognizable variants.

Arrhythmogenic RV cardiomyopathy is characterized by a myocardial disease in which the muscular portions (myocardium) are replaced by fibrous tissue and fat, and can be regional or expand to other areas of the heart.

Prevalence is about 3% of all cardiomyopathies.

It usually begins asymptotically, and progresses to symptomatic electrical abnormalities due to fibro-fatty infiltration of the myocardium, especially on the right side. Eventually, this can cause bi-ventricular failure.

Sudden cardiac death can occur at any stage of this disease.

This is typically an inherited disease. In its' early stages, it usually infiltrates the RV, infundibulum, apex and RVOT, and then may progress to the left ventricular region. The first symptoms are often sudden cardiac death all the way to puberty, but patients may also experience syncopal episodes in the months preceding their death.

There really is no test for this abnormality aside from EKG findings such as inverted T waves and RBBB. Signal averaged EKG is often valuable in the detection of this disease. EKG abnormalities seem to be the best approach to detecting this disease, such as distinctive ventricular arrhythmias.

Echo findings include the exclusion of partial anomalous venous return and Ebstein's. Look for RV dilatation and hypokenesia, aneurisms, regional wall motion variations and hyertrabeculation.

Treatment involves the use of beta blockers and treatments for cardiac failure. Some patients may require transplantation. High risk patients should be offered defibrillators. Prophylaxis however, is the primary treatment as of this writing.

Conus, What is It?

2011-11-12T08:27:00.002-06:00

As you go to conferences, you will hear more and more about the conus and its' importance. The conus is simply the pyramidal structure that is the right ventricular outflow tract (RVOT). The AV valve apparatus and the semi-lunar valve structure (conotruncal apparatus), is essentially the skeleton of the heart that is a fibromuscular structure that forms the valves of the heart.

The entire AV, conotruncal apparatus forms together, and it is a fibromuscular structure that essentially attaches to the muscular parts of the heart (ventricles and atria) in varying degrees. Everything grows from the outside of the heart towards the center, and many defects occur when everything does not meet up in the center of the heart or the crux of the heart.

The Conus

It is essentially the RVOT, or the infundibulum and is much longer and a pyramidal structure that is primarily fibrous in nature, whereas the LVOT is a shorter, primarily muscular structure.. The fibrous structures merge into the muscular parts of the heart in varying ways, as described above.

If the conus fails to develop properly, it can lead to numerous right sided heart defects, from tetralogy of fallot, to pulmonary atresia.

The RVOT is perpendicular to the LVOT, and it is important to image these structures appropriately.

Concordance, Discordance and transpositon; what does it mean?

2011-10-15T20:03:00.002-05:00

Concordance refers to chambers and valves that are properly aligned, or a normally aligned heart. The left atrium (LA) drains blood properly into the left ventricle (LV) and out the aorta (AO) , and the right atrium (RA) drains properly into the right ventricle (RV) and out the pulmonary artery (PA). Also, the great veins drain normally, the cavae (SVC, IVC drain into the RA), and the pulmonary veins (PV) drain into the LA.

Discordance refers to chambers or valves that are malaligned. The RA may drain into the LV, or the LA may drain into the RV. The atria may be "switched", or the ventricles may be "switched". The cono-truncal apparatus may also be switched. The AV valve apparatus may be malformed.

Transposition is similar to discordance but usually refers to the ventricles and the cono-truncal apparatus. The LV pumps blood out the pulmonary artery and the RV pumps blood out of the PA.

Remember one important rule: The AV valves (mitral and tricuspid valves) almost always attach to their appropriate ventricles (MV to LV, TV to RV), and the cono-truncal valves attach to their appropriate arteries (aortic valve or AOV to LV, and pulmonic valve or PV to RV).

Anything can happen in the heart! Hence the "segmental approach to pediatric cardiology". Cardiologists gave up trying to compartmentalize every defect; now they divide the heart into sections, and describe each section independently.

Describe the atria, the ventricles, the cono-truncal apparatus, the AV valve apparatus and the veins all separately. Describe them as concordant (normally aligned), discordant (abnormally aligned) or transposed. Describe the blood flow and its direction, and document all gradients.

As an echo tech, this is how you describe the heart, rather than trying to name a defect. It is up to the cardiologist to actually name the defect.

Ken Heiden RDCS, RVT

www.HeartDefectsSimplified.com

Overriding Aorta, the infundibulum (conus), and tetralolgy of fallot

2011-09-15T00:39:00.000-05:00

The so called cardiac skeleton is a fibromuscular structure that holds in place all of the structures of the heart, especially the atrioventricular valves (mitral and tricuspid valves) and the semilunar valve (aortic an pulmonic valve) apparatus. It is a structure that is very fibrous in certain areas and more muscular in others.

In effect,these are fibrous structures that blend into the muscular areas of the heart in varying ways. For example, the right ventricular outflow tract (RVOT) may also be described as the infundibulum or the conus that is a funnel shaped, primarily fibrous portion that is much longer or elongated than the left ventricular outflow tract (LVOT), which is a much shorter structure and is primarily muscular in nature. Each has fibromuscular components.

The RVOT and the LVOT are perpendicular to each other, and also connect to the AV valves via the fibromuscular cardiac skeleton.

It is important to remember that the infundibulum is an elongated, funnel shaped structure that makes up the RVOT, and is much longer than the LVOT. This becomes important in many cases of pulmonary stenosis or other abnormalities such as tetralogy of falot.

If the infundibulum (or conus) becomes malformed, this in effect, causes the aorta to move to the right, thus overriding the interventricular septum. The overriding aorta is really a product of the malformed conus.

This is an important aspect of tetralogy of falot. As an echocardiographer, it is your responsibility to determine the extent to which the aorta overrides the interventricular septum, if at all.

Remember that tetralolgy of falot consists of four defects: right ventricular hypertrophy, varying types of pulmonary stenosis or absent pulmonary valve, overriding aorta and a large VSD (ventricular septal defect).

Also, which way does the VSD shunt go: right-to-left, left-to-right or bidirectional.

The point of this article is to make you aware of the infundibulum (or conus) and it's importance.

Thank You
Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

A Note About Anomalous Pulmonary Veins

2011-09-12T20:40:00.001-05:00

Development of venous circulation of the heart tends to be skimmed over by many, even by the foremost in the field, while everyone concentrates on the left or right sided functions of the heart.

The early fetal heart is encircled by four veins, the vena cava on the right side, the cardinal vein to the left, the inomminate vein superiorly which connects the vena cava and the cardinal vein, and the sinus venosus or ductus venosus which connects the cardinal vein and vena cava inferiorly. This all tends to drain into the primitive heart in masse before any of the structures such as the septum's are fully formed.

While all of this is going on, the lungs are just "buds" and are starting to sprout pulmonary veins that begin to grow outward towards the left atrium, which has formed "buds" which will eventually merge with these growing pulmonary veins.

The sinus venosus or ductus venosus is a confluent structure that tends to drain all venous flow into the right sided structures of the heart before the fully formed "sections", or septum's that separate each section of the heart are completed.

As the heart develops and remodels itself into a four chambered, four valved, fully functioning structure, these extraneous veins will begin to disintegrate, that is the cardinal vein and the ductus, and the inomminate vein (which will later become the right subclavian, right carotid junction), leaving only the vena cava to drain into the right atrium.

If any of these primary veins persist and do not disintegrate or do not fully form, it is possible that one or more of the developing pulmonary veins may attach themselves to this "confluence" that drains into the right atrium rather than attaching to the developing buds of the left atrium.

Hence, incoming pulmonary venous flow will be diverted either fully or partially into the right side of the heart rather than the left side of the heart.

One, two or more of the pulmonary veins may drain into the right side of the heart through this "confluence".

This defect is known as either "partial anomalous pulmonary veins, or complete anomalous pulmonary veins.

AV Canal or Endocrdial Cushion Defects

2011-06-30T22:47:00.000-05:00

This is such a confusing defect for so many people, and if you go to web sites on the subject, you might just find pages and pages of the most minute details on this particular defect. Let me try to simplify this for you.

The heart develops four chambers, four valves, and eight blood vessels that run in and out of the heart (in its first few weeks of growth.. What is really important as far as AV canal goes, is the development of the four chambers, the AV valve (mitral and tricuspid) valve apparatus, the truncus arteriosis (aorta and pulmonary artery) apparatus and the atrial septum and the ventricular septum.

The "crux" of the heart is the center of the heart where all of these structures meet in the first few weeks of development

Under normal circumstances, the inter-atrial septum is a muscular structure that grows inferiorly from the base of the heart in the first few weeks of development until it attaches to the the AV valve structure, forming two complete atria.The muscular inter-ventricular septum grows superiorly from the apex of the heart until it attaches the the AV structure and form two complete ventricles.

The AV and truncus portions of the heart are primarily fibrous in nature, but are fibro-muscular where they meet the septum portions.

An AV Canal or Endocardial Cushion Defect can most simply described as the following:

A failure of the crux of the heart to fully form, leaving a large primum ASD or atrial septal defect and
large VSD or ventricular septal defect at the crux of the heart.

Typically, the AV valves do not fully form and merge into one fused type of valve, often a five leaflet
type of "single" AV valve that drains into both ventricles.

The tricuspid valve is often hypoplastic but not atretic. Tricuspid valve atreisia is another defect.

The mitral valve may "over-ride" the inter-ventricular septum in that the papillary muscles and the
chordae may attach to the right ventricle instead of the the left ventricle, or they may attach to the left ventricle in the normal fashion.

An AV Canal is best described as a large ":hole in the middle of the heatt", generally with complete
mixing of blood in the heart and is typically not life threatening.

A "Partial AV Canal" is best described as a bi-leaflet mitral valve with one extra leaflet-a tri-leaflet .
mitral valve.

Mwechosolutions.com
heartdefectssimplified.com

Fetal Circulation

2010-07-12T17:48:00.000-05:00

The heart is the first organ to become fully functional and is delivering oxygenated blood flow to the fetus within the first few weeks of life.

(Please see my posts on embryology and morphology to fully understand this subject)

Since the fetus does not breathe nor eat and therefore cannot produce its own oxygen and nutrient supply, it depends upon the mother for these essential functions. The placenta is the intermediate organ between the mother and the fetus that provides both nutrients and oxygenated blood flow to the fetus, as well as disposes of de-oxygenated blood flow returning from the fetus.

It is important to remember that the fetal lungs do not function until after birth; the placenta provides these vital functions. The growing fetus does not require fully oxygenated blood flow in its growing state, for example SaO2 levels of 99%. Instead, it can survive quite well on SaO2 levels that are in the 70-85% range and do quite well. This is why fetuses with complex congenital heart defects most often survive until birth.

Once born, and the fetus must depend upon its own circulatory supply, do complex congenital heart defects become critically important.

Fetal circulation is a bit complex and difficult to understand. The physiologic rule that all arterial blood flows away from the heart, and all venous blood flows to the heart gets a little backwards in this case.

The placenta provides three vessels to the fetus that make up the umbilical cord: one umbilical vein, and two umbilical arteries. The placenta collects highly oxygenated blood from the mother and transfers this blood flow to the fetus via the umbilical vein, drains into the vena caval circulation and returns to the fetal heart via the right atrium and right ventricle.

This highly oxygenated blood enters the right heart and is diverted away from the fetal lungs through the two naturally occurring holes between the right and left heart, the PFO (patent foramen ovale), and the PDA (patent ductus arteriosis). These normally occurring fetal right-to-left shunts direct blood flow to the left side of the heart where it is delivered primarily to the upper portion of the fetus, the head and upper body. These are the most important structures at this level of development, especially the brain.

As blood flows through the rest of the circulatory system it tends to de-satuarate as it travels to more inferior structures, such as the kidneys and the lower extremities.

The umbilical arteries attach to the internal illiac arteries in the fetus, and serve to carry more de-saturated blood flow from the fetus back to the placenta, where it will be cleaned and re-saturated for return to the placenta.

I realize that the umbilical vein carries oxygenated blood to the fetus, and the umbilical arteries carry de-oxygentated fetal blood flow back to the placenta. This can be quite confusing, but this is the way fetal circulation happens.

The area of the PFO and the surrounding structure or the right atrium is a "folded" type of crest that naturally causes blood to flow from the right atrium into the left atrium until after birth when this structure should naturally close.

If a neonate reaches normal gestation of 40 weeks, the PDA tends to be "programmed" to close at this point. Premature neonates tend to have a PDA that stays open. This will cause (after birth) blood to flood the right side of the heart and hence deteriorate SaO2 levels.

Very often the PDA will need to be closed surgically with a minimally invasive procedure that ligates this opening. This procedure is often done bedside, and corrects the problem of over-circulation of the lungs.

Ken Heiden (RDCS)
HeartDefectsSimplified.com

Atrial Septal Defects

2010-07-01T13:12:00.001-05:00

Atrial septal defects, or a hole between the two atriums are among the most common of congenital heart defects and the most easily repairable of all defects. This defect s one of the most common reasons that an echocardiographer will image a neonate, as well as looking for a PDA, or patent foramen ovale (a hole between the aorta and pulmonary artery).

(Please see my posts on embryology). These two defects are naturally occurring holes that every neonate is born with. Since the fetus obtains most of their nutrients and oxygenated blood flow through the arterial and venous connections via the placenta and the mother, these defects are necessary to deliver blood flow that is destined for the lungs in the fetus, to the left ventricular circulation. In other words, the fetus does not breathe, therefore, blood flow to the lungs is not necessary.

Once born and the neonate begins to breathe, and these two holes should close naturally providing the neonate is of full gestation ( 40 weeks). Closure usually happens with in a few days. If the neonate is premature, closure tends to persist until the neonate reaches 40 weeks. The body seem to be programmed to this 40 week schedule.

In the neonate with persistent opening of these defects, blood will flow left-to-right across the defect and create a volume overload of the right heart, and thus the lungs. This tends to create a situation in which there is diminished oxygen transfer between the lungs and the capillary beds that supply oxygen rich blood to the rest of the body.

About one in ten neonates with any other congenital heart defect will have an atrial septal defect, and surprisingly, autopsy results indicate that up to one of every three adults may have an open PFO. The foramen ovale tends to be a defect that can be passive, in other words it will open when there tends to be a pressure difference between the right and left atriums.

Under normal circumstances, the pressure in the left and right atriums tend to be equal, approximately 5-10 mmHg. In the presence of other cardiac defects, such as a valsalva maneuver, CHF, or any other defect that may compromise flow, the defect may temporarily open.

It has been my experience that many young adults who suffer a stroke, often have a temporarily open PFO. This is often revealed while doing a TEE, or trans-esophageal echocardiogram. This means that for whatever reason, a blood clot that has developed in the venous system, passed through the PFO, entered the arterial blood flow, and progressed to the brain to cause a stroke.

There are typically three types of atrial septal defects:

Sinus Venosis Defects:
This defect occurs at the roof of the atrium, and may allow one or more of the left pulmonary veins to drain directly into the right atrium. The inter-atrial septum for the most part is a muscular structure at it's base and roof, while the foramen tends to be flexible structure that may or not be patent. Coronary sinus defects occur also at this level. This means that the coronary sinus, the venous return from the coronary veins, drains into this structure.

Primum ASD, or Ostium Primum Defect:
This defect occurs at the inferior portion of the inter-atrial septum and is highly associated with AV canal defects, or endocardial cushion defects (see my posts on this subjects). This defect tends to happen when the crux of the heart fails to fully develop. The AV valves do not fully form as well as the inferior portions of the atrial septum, and the superior portions of the interventricular septum fail to completely attach appropriately.

Patent Foramen Ovale or PFO:
As stated before, this opening between the atriums is a common occurrence in neonates as well as adults. The most common presentation physiologically in this person would be dyspnea upon exertion. This defect is typically asymptomatic and may never be discovered even into adulthood, unless there is some other symptom that develops, such as a stroke in a young adult.

Echocardiography:
Contrast echocardiography, or TEE with contrast is the best way to evaluate this defect. This defect can often be found with echocardiography alone, but it is not the most accurate way to evaluate this defect, since this defect may occur spontaneously, e.g. with respiratory or with valsalva maneuvers.

Always evaluate the interatrial septum in multiple views. These defects are not typically heard with a stethoscope or with physical examination, and X-ray evaluation may be non-specific, or at best show an enlarged right heart.

Always rule out a sinus venosis defect by evaluating the pulmonary venous inflow, and rule out a primum defect by evaluating for an AV canal (or endocardial cushion defect).

Prognosis and Repair
These types of defects are well tolerated and may never present symptoms. Right ventricular overload is usually well tolerated by the body, and pulmonary hypertension typically occurs late in adulthood. Unless the shunt is large, symptoms tend to be minimal throughout adulthood. A CVA, or a stroke in a younger patient is often the only way that these defects may be found.

Spontaneous closure of these simple shunts often occurs during adolescence. Very often, VSD's, ASD's and PFO's are often followed until this time, unless the patient begins to exhibit right ventricular enlargement, pulmonary hypertension or congestive heart failure, or chronic respiratory problems.

If repair is needed, it typically involves the placement of a "rivet" type of device that closes the PFO that is minimally invasive, or a surgical procedure that sutures the shunt closed (primum or venosis types of shunts). Mortality and complications are extremely low for all of these procedures.

Long term results are excellent, and complications are rare.

Ken Heiden RDCS
HeartDefectsSimplified.com

Stress Testing or Exercise Performance for patients with Congenital Heart Disease

2010-06-28T18:45:00.001-05:00

Children with known heart defects, or patients with suspected heart defects typically are the primary recipients of stress tests. There are numerous reasons why this may be done, including the evaluation of heart rhythms, ischemia (whether the heart muscle is receiving enough oxygen), or if the patient can produce symptoms during exercise, the extent of exercise capacity, and aerobic capacity at peak exercise.

It is often important to evaluate children who have had a cardiac surgery in order to compare these patients with those who are normal. Patients with minimal cardiac defects often have exercise tolerance that is comparable to their peers, but those patients with significant cardiac defects will seldom compare to their normal piers.

Aerobic capacity in patients with compromised hearts is an important determinant when evaluating these children for possible surgical intervention. For instance, patients with a tetralogy of fallot or significant pulmonary regurgitation or other pulmonary problems will exhibit significant pulmonary distress during exercise.

Measuring blood pressure during exercise is also important. Normally, systolic blood pressure should increase during exercise, and diastolic blood pressure should decrease. Abnormal blood pressure responses during exercise may indicate a significant cardiac defect. If systolic blood pressure is blunted or decreases during exercise, this may indicate such defects as a significant left ventricular outflow obstruction, pulmonary hypertension or anomalies of the coronary arteries. (See my posts on these subjects).

Echocardiography
This non-invasive test should be routinely done on any child suspected of a congenital heart defect. As an echocardiographer, it has been my experience that many pubescents who die as a result of strenuous exercise often have at least one of two primary defects: IHSS, or idiopathic hypertrophic sub-aortic stenosis (a deformation of the outflow tract of the left ventricle), or anomalous coronary arteries (a defect in the arteries that feed the heart muscle).

Most congenital heart defects should be found with this procedure alone, and is typically done on many infants and adolescents.Stress echocardiography is also an important tool in the evaluation of myocardial ischemia. This test involves exercising the patient in conjunction with standard echocardiography. Nuclear perfusion imaging is another exercise related test that evaluates myocardial perfusion. this test involves the injection of a radioisotope via and intravenous connection, and an X ray device that can evaluate the oxygen content of the heart.

Conclusion
In the end, exercise testing may aid the pediatric cardiologist in their effort to evaluate whether surgical intervention may be required, or in the cases of those who have had repairs, how well these patients are responding to their surgery. Furthermore, it is important to evaluate whether arrhythmias or ischemia develop during exercise. Additionally, physicians wish to know how high blood pressures become with peak exercise, and whether there is any exercise induced asthma.

Ken Heiden RDCS
HeartDefectsSimplified.com

Prostaglandins and Indomethacin treatments for PDA

2010-06-26T12:20:00.001-05:00

Chemical treatment for the patent ductus arteriosis (PDA) are some of the most common reasons that an echocardiographer will be called to the NICU to do an echocardiogram. These neonates are often severely premature and may or may not have a complex congenital defect.

Very often, the echocardiographer will be imaging these patients that are simply premature without a significant congenital abnormality, and they will primarily be evaluating the PDA and the direction of the shunt. When patients are born prematurely and they have an open PDA, this causes an inordinate amount of blood flow to be directed to the pulmonary circuit via the open PDA (left-to-right shunt). This results in pulmonary overflow and will result in pulmonary distress and wildly fluctuating SaO2 levels.

Indomethacin (or Indomyacin) is used when there is pulmonary overflow and the neonatologist wishes to close the PDA. Prostaglandins are used when the neonatologist wishes to keep the PDA open, often in the presence of complex defects in which pulmonary flow is severely compromised and the PDA may be the only shunt keeping the neonate alive.

Keep in mind that the PDA is a normal shunting process, and the body is programmed to close this shunt at 40 weeks of gestation. Neonates born prematurely (say 30 weeks or so) often continue to have a patent ductus. Indomethacin treatments may be done in an effort to close this shunt. This therapy is not always successful and as a result, the echocardiographer may be called back several times to evaluate the patency of the duct.

If chemical treatment is not successful, then a PDA ligation may be necessary. An untreated patent ductus is highly associated with patient morbidity and the inability of the patient to compensate for this pulmonary overcirculation must usually be treated.

Prostaglandin treatments are done in many cases of complex congenital defects where it is imperative that the PDA kept open in order to provide adequate blood flow to (especially) the pulmonary circuit, while the patient is waiting for surgical intervention. This is especially true when there is significant obstruction is the pulmonary circuit, such as Ebstein's malformation of the tricuspid valve, pulmonary atresia, tetralogy of fallot, D-transpositions or certain types of truncus arteriosis.

Echocardiography
Echocardiography is a routine procedure in most institutions to evaluate the patency of an arterial duct (PDA) prior to intervention, and to rule out any other cardiac defects. Early detection of these types of defects contribute significantly to positive patient outcomes. Clinical outcomes are significantly impacted of the magnitude of the shunt, and include such secondary problems such as left ventricular failure, renal insufficiency, pulmonary edema, hemorrhage and myocardial ischemia.

First, rule-out other significant cardiac defects. If the PDA is what you are concentrating on, determine whether the shunt is left-to-right, right-to-left or bi-directional. If the shunt is right-to-left or bi-directional, then this indicates severely high pulmonary pressures and is a development that the neonatologist must be made aware of. PDA shunts are best evaluated in the parasternal short axis views or the suprasternal short axis views.

Measure the size of the PDA and the magnitude of the shunt (measure the gradient across the PDA). Determine the direction of the shunt. Rule out any other cardiac defects. Most importantly, measure right ventricular systolic pressure (pulmonary pressures) adequately. (see my post on "Measuring RVSP"). It is critically important that the neonatologist or pediatric cardiologist know accurately what the pulmonary pressures are.

Pulmonary Hypertension
Persistent pulmonary hypertension in the neonate is the failure of the neonate's lungs to accomplish a reduction in pulmonary vascular resistance to incoming pulmonary blood flow that leads to the inability of the lungs to fully oxygenate pulmonary blood flow.

Pressures in the lungs must be substantially lower than that of the systemic circulation in order for proper flow and oxygenation of the systemic blood flow to occur. (see my posts on the "Normal Heart" and Morphology" sections).

To summarize, blood flow in the body is dependent upon pressure and volume differences between the pulmonary and systemic circulations. Venous and pulmonary circulations contain a large volume of blood, but low pressures (venous pressures average between 5 and 20 mmHg).

Arterial volumes are low, but the pressures are very high (systemic blood pressure as measured with a BP cuff e.g. 120 mmHg). It is this difference in pressure that allows blood to move form a high pressure environment to a low pressure environment and back again. This difference in pressure and volume also dictates how efficiently oxygen and CO2 is transferred back and forth between the two systems.

As pulmonary pressures increase, this decreases ability of the body to transfer oxygen and CO2 across the capillary beds of the lungs and the tissues of the body.

Pulmonary hypertension must be addressed by the neonatologist or pediatric cardiologist in order to prevent long term lung damage. If the cause is an open PDA, then it will be ligated or corrected chemically. If there are significant congenital defects, then palliative procedures will be used until the neonate is ready for surgery. The primary treatment is oxygen therapy in order to alleviate hyoxaemia (low SaO2 levels).

The goal of chemical treatments is to reduce pulmonary pressures while maintaining systemic pressures until the neonate is able to undergo surgical treatment. Surgical interventions are usually done when the neonate achieves appropriate maturity to undergo these interventions.

Ken Heiden RDCS
HeartDefectsSimplified.com

Down Syndrome (Trisomy 21) and Other Chromosomal Disorders

2010-06-17T12:04:00.010-05:00

Down Syndrome is a chromosomal defect in which there is an extra chromosome inserted into the DNA other than the normal 46 chromosomes.

Of children born with a cardiac defect, about one in twenty have trisomy 21. This is highly associated with congenital heart disease, particularly atrioventricular heart defects (AV canal or endocardial cushion defects). These children tend to have below average intelligence and have other defects associated with this syndrome such as duodenal and anal atresia and Hirschprungs's disease (enlargement or obstruction of the colon).

Please see my previous posts on "endocardial cushion defects", or "AV canal", "embryology" and "morphology".

AV canal is the most commonly associated defect with Down syndrome. This defect is a failure of the heart to completely form at the crux, or center of the heart. As a result, there are malformed mitral an tricuspid valves with an associated membranous VSD (ventricular septal defect) and an ASD (atrial septal defect).

Where there is one defect (especially left-sided) there may be others. Always rule out other defects such as bicuspid aortic valve, ASD's, VSD's, PDA's, and coarctation of the aorta.

Trisomy 18 (Edward's Syndrome)
This defect occurs in about one of every 3500 births and is very often fatal to the newborn due to the extensive nature of the defects. Extra cardiac defects include mental retardation, clenched fists, crossed legs, low birth weight and small skull development. Cardiac defects include persistent PDA, VSD or ASD's.

Trisomy 13 (Patau's Syndrome)
This defect occurs in about one of every 7000 births and is typically fatal to the neonate. Extra-cardiac defects include cleft palate, brain malformations and polydactyly ( an extra digit, typically the thumb of little finger). Cardiac defects include atrial malformations, VSD's, ASD.s, and AV canal.

Apert's Syndrome
This is a genetic disorder resulting from premature closure of the cranial sutures between the bones of the skull. It is characterized by malformations of the skull and facial features and usually involves "webbing" and/or fusion of the bony structures of the hands and feet. Cardiac malformations include ASD's and VSD's.

Cri du chat
A chromosomal disorder characterized by a distinctive cat-like cry and abnormalities of the skull and face. Associated cardiac abnormalities include VSD's, PDA, ASD, AV canal and tetralogy of fallot.

DiGeorge Syndrome
A chromosomal disorder (deletion of chromosome 22), resulting in the absence of the thymus and parathyroid glands. Presentations include deformed palate, recurrent infections, neuro-muscular disorders, kidney malfunctions and mental deficiencies. Associated heart defects include VSD, PDA, interrupted aortic arch, Tetralogy of Fallot and Truncus Arteriosis.

Ken Heiden, RDCS
Please visit CongenitalHeartDefectsSimplified.com for more information.

Echosonographers: Are you terrified to learn congenital heart defects?

2010-04-28T19:44:00.014-05:00

There is no doubt that this is an intimidating subject; There are some sonographers I have talked to in the past who have actually told me that they would rather quit their jobs than to start doing pediatric echos!

The problem is that adult congenital heart defect patients who have had surgeries going back to the 70's are now beginning to show up in adult echo labs. Sooner or later, sonographers will have to learn this subject and at least be competent enough to provide a basic echocardiogram that is readable for a pediatric cardiologist.

There are currently about a million adults in the USA alone who have had pediatric heart surgery.

This has spawned a new industry in the medical field that has led to a fusion of adult and pediatric echocardiography. There are clinics popping up everywhere that treat these patients and have on staff both adult and pediatric cardiologists. The primary reason that these people are showing up is that many of these defect repairs are not permanent, and many people are now suffering from problems such as congestive heart failure and now need further treatment.

As a sonographer in one of these institutions, it is up to you to be able to not only image these surgical corrections and perform a competent echocardiogram, but to identify the original defect.

Many of these patients only know that they had a defect repaired early in childhood, but have no idea what their original defect was or what kind of surgery they had. On the other hand, some of these patient are quite sophisticated and have extensive knowledge about congenital heart defects.

A significant number of these patients no longer go to a Children's Hospital and may show up in your adult lab. In the end, if you are a sonographer of any kind, it will be in your best interest to start learning this subject now.

Fortunately, there is an easier way to learn this complicated subject. This blog is an extremely good beginning. Start by reading my posts on embryology and morphology. It is extremely important that the sonographer understand how and why these defects develop. (use the search tool on the right to access these posts easily).

Secondly, read my posts on "the segmental approach to pediatric cardiology". The segmental approach divides the heart into sections, and then requires the sonographer to evaluate and describe each section in detail.

The sections are: the atrial mass, the ventricular mass, the atrioventricular valve apparatus (or AV connections), the truncal mass (or ventriculo-arterial connections), and the veno-atrial connections (vena cavae and the pulmonary veins).

It is important to approach the heart in this way. Keep in mind that the heart is composed of four chambers, four valves and eight blood vessels that run in and out of the heart.

During fetal development, anything may happen to these connections, and many of these defects overlap with each other. To this day, there is much controversy on how to classify and name these defects with all of their sub-classifications and permutations.

This is especially true when you cross borders and continents, for example, Europe and Canada to the USA, as well as Asia.

Finally, read the post on "how to do a pediatric echo"

The worst way to approach this subject is to try to memorize each defect (there are at least 30 major defects and many sub-defects). As an echocardiographer, it is up to you to describe the various connections involved in each defect rather than to try to name the defect. It is up to the pediatric cardiologist to actually name the defect.

For instance, the echocardiographer may write in the worksheet something like " concordant atrioventricular connections, discordant ventriculo-atrial connections and concordant veno-atrial connections".

In other words, a D-transposition of the great vessels. It is up to the reading cardiologist to make the definitive diagnosis and name the actual defect.

In summary, it is a good idea for the sonographer to fully read the posts on this blog. Further, it is a good idea to read the book "Congenital Heart Defects, Simplified", and keep this book with you whenever you scan. This book is 105 pages long, and itemizes each defect in a two page format with diagrams (including surgical repairs) on the right, and bullet point descriptions on the left. It is a durable spiral bound book that allows easy and quick access to any defect you may encounter.

This book starts at the very beginning and describes the normal heart, and progresses to the most complex and difficult defects. Everything is in alphabetical order and most of the information one may need is included in the two page format.

The appendix is especially valuable, and includes subjects such as a summation of the surgical repairs (in alphabetical order), typical functions and values, scanning protocols, imaging tips, a worksheet and a complete glossary.

This blog nicely augments all of the information found in the book, and provides the most up-to-date information available.

I use as my primary resource the book "Paediatric Cardiology" (British spelling), by Robert Anderson M.D. et al, one of the most respected cardiologists in both the USA and Europe. This 1400 page book (third edition) was published in 2010 by Elsevier Publishing, and is the go to book for todays pediatric cardiologists.

My book "Congenital Heart Defects, Simplified" is a home study course that includes a 300 question registry review, a test available and graded in an online format, excellent for students and experienced sonographers alike. 30 SDMS CME's are awarded for completion of this course.

Please use the link on the right of this blog, or go to "HeartDefectsSimplified.com".

To contact me, go to the contact section of the website.

Thank You

Ken Heiden RDCS, RVT

Hypoplasia of the Right Ventricle (Pulmonary Atresia with Intact Ventricular Septum) or PA-IVS

2010-04-21T21:00:00.003-05:00

It is advisable to read my posts on embryology, morphology and the segmental approach to pediatric cardiology, as well as my post on univentricular heart in order to fully understand how and why these defects form.

A hypoplastic (severely small) right ventricle can occur in numerous settings such as a univentricular heart in which there is a dominant left ventricle or LV) where there is a double inlet left ventricle, a malformed or atretic tricuspid valve (TV), or critical stenosis of the pulmonary valve with an intact ventricular septum.

Severe right ventricular hypertrophy (RVH) is common. This is due to the inability of the RV to adequately pump blood into the pulmonary circuit as a result of the outflow obstruction. This causes the RV to become hypertrophic which obliterates the right ventricular cavity.

This particular defect is best described as a pulmonary atresia (absence of the pulmonic valve) with intact ventricular septum (PA-IVS), and concordant atrioventricular connections (the AV valves or mitral and tricuspid valves are normally attached to their concordant ventricles), however the tricuspid valve is typically abnormal.

The defining factor in this defect is the presence of an intact ventricular septum.

This is an uncommon defect and accounts for about 3% of all congenital heart defects, but is the third most common cause of cyanotic lesions; D-TGA and tetralogy of fallot are the most common cyanotic lesions, in that order. PA-IVS occurs in about 5 of every 100,000 births.

The tricuspid valve is typically abnormal and may be stenosed, hypoplastic, regurgitant or may show characteristics of Ebstein's malformation (see my post on Ebstein's malformation). In the presence of severe tricuspid regurgitation, the pulmonic valve may not be stenosed, but may be unable to open due to insufficient pressure in the RV to open the valve. In this case, pulmonary atresia is physiologic rather than anatomic.

Anomalous coronary arteries are frequently found in this defect and may lead to myocardial ischemia.

Pulmonary circulation is usually dependent on the presence of a patent ductus arteriosis (PDA). and the shunt is left-to-right. If there is an ASD, the shunt will be right-to-left. Cyanosis is fairly immediate after birth and it is critical to keep the PDA open using chemical therapy.

Echocardiography
Echocardiography is the diagnostic method of choice. As explained in previous posts, use the segmental approach to evaluate the heart. Evaluate the atria and the AV connections. Evaluate the ventriculo-arterial connections and rule out a transposition. Determine if there is a VSD, ASD and a PDA.

Evaluate right ventricular size, the presence of tricuspid regurgitation and the presence of a pulmonic valve. Measure the size of the pulmonary arteries and their branches, and determine the source of pulmonary blood flow.

Finally, evaluate the coronary arteries, the left ventricle, the aortic valve and the various connections on the left side of the heart.

Surgical Intervention

A balloon atrial septostomy will be done shortly after birth in order to create a right-to-left shunt across the ASD so that pulmonary circulation can be increased.

The PDA must be kept open and is done via chemical therapy.

A Blalock-Taussig shut will be attached from the right subclavian artery to the right pulmonary artery in order to create increased pulmonary flow (see my post on this subject).

A transjunctional patch may be used that opens the right ventricular outflow tract (RVOT) and a pulmonary homograft valve may be used.

Typically, a Fontan procedure is done in order to separate pulmonary and systemic blood flow ( see my post on this procedure). A Fontan procedure is a staged procedure that essentially connects the inferior and superior vena cavae to the pulmonary arteries, thus enhancing pulmonary venous flow while separating the pulmonary venous circuit from the systemic arterial circuit.

If possible, a balloon valvotomy is done across the pulmonic valve via a minimally invasive catheterization procedure.

Outcomes
Survival is difficult to determine due to the rarity of this defect, however some studies report survival of 80-90% after 14 years of age. Most mortality occurs within the first few months after repair. Coronary artery malformations tend to increase mortality. After the Fontan procedure, complications include tricuspid regurgitation, fatigue, exercise intolerance, coronary artery problems and pulmonary outflow obstructions.

Univentricular Heart (Single Ventricle Syndromes)

2010-04-20T19:20:00.007-05:00

It is advisable to read my posts on the segmental approach to pediatric cardiology, embryology and morphology in order to gain a solid understanding of how and why these defects develop.

The term "univentricular heart" is somewhat misleading in that a true single ventricle is rare; typically there is one dominant ventricle and one hypoplastic ventricle. This defect is especially complicated in that it overlaps with so many other associated cardiac defects.

The best way to approach any congenital heart defect is to use the "segmental approach to pediatric heart defects" (see my post on this subject). Simply defined, you should divide the heart into sections and describe each of these defects separately.

Are there two atria or is there one atrium? Are there two ventricles? Describe the AV valves (the atrioventricular junction or the mitral and tricuspid valves) and how do they connect to the atria and ventricles? Describe the ventriculo-arterial junction (how do the ventricles attach to truncal vessels via the aorta and the pulmonary artery). Finally, describe the venous connections (the pulmonary veins and vena caval connections).

A univentricular heart may be best described as a defect that encompasses two complete atria that provide venous inflow into a dominant ventricle (either right or left) via a malformed AV connection, where a biventricular surgical repair is not feasible. In other words, this describes a "double inlet ventricle".

There are typically two atria, two ventricles (one of which is typically hypoplastic), and varying types of atrioventricular or AV connections. It is the AV connection that tends to provide the definitive diagnosis.

Atrioventricular Valvular Formation (AV valves)
There are several things that may happen to the AV valves as they form. Normally, there is one mitral and one tricuspid valve that provide inflow into separate ventricles.

There may be one atretic (absent) AV valve and one functional AV valve. If the tricuspid valve is atretic, this is usually described as "tricuspid atresia". If there is an atretic mitral valve, then this typically falls into the category of "hypoplastic left heart syndrome".

There may be a common AV valve that provides inflow into a ventricle with a large membranous VSD (ventricular septal defect) and a large primum ASD. This is described as an "endocardial cushion defect, or AV canal".

There could be a functional AV valve that overrides the ventricular septum wherein the papillary muscles are located in both ventricles, and one hypoplastic valve.

An" imperforate" valve refers to a situation in which there is a severely hypoplastic valve in which one of the atria is connected via this hypoplastic valve to a ventricle that may be functional or non-functional, and is defined by the presence of papillary muscles that attach to this AV structure.

As you can see, this is a complex and difficult defect to identify.

Echocardiography
The best approach (as explained previously) is to divide the heart into sections and describe each section of the heart separately. It is up to the cardiologist to name the defect specifically, but the job of the echocardiographer to describe the various abnormalities of the heart segmentally.

It is important to describe the double inlet aspect and to differentiate it from a common AV connection (AV canal). This is done by identifying whether there is a VSD and an ASD.

Try to identify which is the dominant ventricle (RV or LV), and which is the hypoplastic ventricle. In rare cases, there may be no hypoplastic ventricle; This is a true single ventricle type of syndrome.

Next, look at the truncal vessels and how they connect to the single ventricle. Is the pulmonic or aortic valve stenotic? Are any of the truncal vessels hypoplastic?Are they transposed?

Finally, look at the venous connections and make sure the vena cava are connected to the right atrium, and the pulmonary veins are connected to the left atrium.

If there are any stenotic valves, try to determine any gradients and try to evaluate the area of the stenotic valve.

MRI has now become important in the evaluation of any defect that echocardiography cannot identify; the drawback is that the neonate must be sedated and must remain still for up to an hour. Further, MRI can not evaluate physiologic blood flow.

Surgical Management (Glenn shunt, Hemi-Fontan and the Complete Fontan)
There are three goals for initial surgical palliation in order to prepare the neonate for further repair:
1) Establish adequate but low pressure flow through the pulmonary circuit.
2) Optimize systemic outflow for those with outflow obstructions.
3) Ensure adequate venous return through both atria.

The eventual goal of surgical repair is to separate pulmonary and venous outflow, and is usually done with staged procedures, culminating in the Fontan Procedure.

In patients with excessive pulmonary flow, pulmonary banding will be done. In patients with inadequate pulmonary flow, a Blalock-Taussig shunt will be used. (see my posts on this subject for complete descriptions).

If there is aortic obstruction, the "Damus-Kaye-Stansel" procedure is the most effective way to alleviate this type of variant. The pulmonary artery is divided and attached to the aorta in such a way as to augment aortic flow.

An atrial septostomy may be used in order to improve mixing of venous and systemic blood flow.

Once the neonate is stabilized, the Fontan procedure will be utilized.

Stage One
Blalock-Taussig (BT) shunt: usually performed within the first few days after birth, and establishes a systemic-to-pulmonary artery shunt between the brachiocephalic artery or the right subclavian artery, to the right pulmonary artery via (usually) a tubed homograft or synthetic graft.

Glenn Procedure or Hemi-Fontan: usually performed at 4-6 months after birth as a bridge to Fontan completion. The BT shunt and pulmonary artery band is usually removed. The superior vena cava is then attached to right pulmonary artery, creating a systemic venous-to-pulmonary connection.

Fontan Completion: Usually performed at 2-3 years of age; the inferior vena cava is connected to the right pulmonary artery via a tunnel like patch within the right atrium (Lateral Tunnel Fontan), or by creating a conduit for IVC flow outside the right atrium (Extracardiac Fontan).

This essentially separates the pulmonic and systemic flow patterns and allows the body to adapt gradually to the varying flows, and prevents over-circulation and under-circulation to the lungs.

Ken Heiden RDCS
HeartDefectsSimplified.com

Hypoplastic Left Heart Syndrome (HLHS), or Hypoplasia of the Left Heart

2010-04-17T12:24:00.006-05:00

It is advisable to read my posts concerning embryology, morphology and the segmental approach to pediatric cardiology in order to gain a solid understanding of how and why these defects develop.

Hypoplastic left heart syndrome (HLHS) is best described as a syndrome that features hypoplasia of the left ventricle, atresia (absence of) the mitral valve, atresia or hypoplasia of the aortic valve and/or the aorta, a VSD (ventricular septal defect), an ASD (atrial septal defect) and a PDA (patent ductus arteriosis). In this scenario, the right heart is typically dominant and provides most of the systemic circulation.

As with all defects, there can be numerous variations; the aorta may be in concordance with the right ventricle (which is more of a double outlet right ventricle), there may be a coarcted aorta or an interrupted aortic arch, or the hypoplastic left ventricle may communicate more with the pulmonary artery, which will look like pulmonary atresia.

HLHS has an incidence of about 3 in every 10,000 births or about 8% of all congenital heart defects, and is the leading cause of death in neonates, whether prenatal or postnatal. This defect is often discovered via fetal echocardiography before the 24th week, and often leads to termination of the pregnancy.

Prior to the 1980's there was no treatment for this defect, but since then as surgical intervention has improved, surgical outcomes have become quite good.

There are typically concordant atrioventricular and ventriculo-arterial connections, with an ASD that is left-to-right, a VSD, and a PDA that is right-to-left. The PDA may be the only way that the systemic circulation is provided.

The left ventricle is typically severely hypoplastic as well as the aortic valve and the aortic trunk. The mitral valve is typically severely stenosed or atretic with significant obstruction of the left ventricular outflow tract (LVOT).

This means that incoming pulmonary venous flow must pass through the ASD in a left-to right fashion, be pumped out the pulmonary artery and through a right-to-left PDA in order to supply the systemic circulation. To further complicate the situation, coarctation of the aorta (CoA) is common.

Post Natal Palliative Treatments
As discussed previously, prenatal echocardiography typically identifies this lesion prior to birth, and prepares the the delivery team to stabilize the neonate after birth. Prostaglandin therapy is the rule; this drug allows the shunts to stay open, thus keeping systemic circulation viable.

There is complete mixing of the pulmonary and systemic circulation, and equalization of pressures across the heart chambers. This leads to right ventricular volume overload, significant pulmonary hypertension (PHTN), and systemic SaO2 levels of around 80%.

The gaol of pre-surgical intervention is to balance pulmonary and systemic flow so that pulmonary over-circulation will not damage the lungs.

Echocardiography
Pre-operative evaluation is highly dependent on an echocardiogram. It is especially important to image all abnormal structures adequately, paying particular attention to the presence of the ASD, VSD, PDA, and direction of blood flow therein. The PDA is especially important since this defect determines systemic flow.

Evaluate the aortic valve and the aortic arch carefully and determine if there are any abnormal branches. Evaluate the pulmonary veins and make sure they drain into the left atrium.

Coronary artery defects may be present. Evaluate the origins of the coronary arteries, if possible. Evaluate all of the valves and determine the level of stenosis and regurgitation.

Surgical Intervention
Complete repair of this defect is a multi-staged procedure. and involves the Norwood procedure and the Fontan procedure. The first procedure, the Norwood procedure is usually done as soon as the neonate is stabilized. The goal of surgical intervention is to eventually separate pulmonary circulation from systemic circulation.

The Norwood procedure is the surgery of choice for initial palliation, and attempts to fulfill three goals: The left-to-right ASD must be kept open in order to accommodate pulmonary venous inflow; systemic outflow must be maximized in order to perfuse all distal tissues and pulmonary outflow to the lungs must be maintained in such a way that the lungs are not damaged.

The Norwood procedure begins with a Blalock-Taussig shunt that establishes a systemic-to-pulmonary connection between the right brachiocephalic artery and the right pulmonary artery, typically with a tubed homograft or a graft made of synthetic material.

A Sano modification may be used to establish pulmonary circulation instead of the Blalock-Taussig shunt, by utilizing a synthetic conduit between the right ventricle and the pulmonary artery.

The aorta is reconstructed by excising the distal pulmonary artery inferior to its branches and using a homograft to attach the pulmonary trunk to the aortic trunk. This is called a "neo-aorta" and creates a type of truncus arteriosis that isolates the pulmonary artery branches from the systemic truncal arterial flow.

A variation of this procedure keeps the pulmonary artery branches attached to the neo-aorta, but "bands" the pulmonary branches so that pulmonary inflow volume and pressures are reduced (see my post on pulmonary artery band), and the placement of a stent across the PDA which increases systemic arterial flow. This is known as a "Hybrid Palliation".

The second and third stages of this repair involve the Fontan procedure (discussed in detail in previous posts "the Fontan Procedure" or the "Glenn Shunt") and is typically done within the first to third years of life.

The first stage of the Fontan procedure disconnects the Blalock-Taussig shunt and attaches the superior vena cava to the right pulmonary artery. The second stage of the Fontan procedure attaches the inferior vena cava to the right pulmonary artery by placing a tunnel-like connection within the right atrium (lateral Tunnel Fontan), or by creating a conduit for IVS flow outside the atrium (Extra cardiac Fontan procedure).

Cardiac Transplantation
This is an important option for neonates that have exhausted all other avenues of repair, and post surgical outcomes are very good, better than 70% after four years. HLHA remains the most common reason for heart transplantation. The lack of viable organs that can be used for transplantation is the primary limitation for this procedure.

Mortality rates for transplantation vs. reconstruction are very similar, and the use of one procedure over another is highly individualistic. Transplantation should be limited to patients for whom reconstruction is not possible or has failed. This option includes patients that have right ventricular failure, severe tricuspid regurgitation, or patients with immunosupression disorders.

Conclusion
Patients who are discharged after the first palliation procedure may require further balloon angioplasty or surgical revision. Patients who go on to the next steps are at very low risk of mortality, and long term survival rates exceed 95%. Progressive dilitation of the neo-aorta and its valve may occur and may sometimes require replacement of the neo-aortic valve.

Ken Heiden RDCS
HeartDefectsSimplified.com

Vascular Ring and Related Aortic Arch Conditions

2010-04-11T15:00:00.010-05:00

Please see my posts on embryology, morphology and the systematic approach to imaging for a complete description of how and why congenital heart defects form.

Vascular ring describes defects that encompass the aortic arch and its branches, the pulmonary artery and its branches, and how they relate to the esophagus and the trachea.

This defect is described loosely as any part of the malformed aorta, the pulmonary artery or any branches that encircle the esophagus and or trachea.

During embryological development, there is typically a double aortic arch with is branches that typically encircle the esophagus and trachea.

As the fetus develops, the right-sided branches will disintegrate, leaving only the left-sided aorta and its appropriate branches; innonomate, left carotid and left subclavian branches.

Under normal circumstances, a left-sided aorta will have the following normal branches in order: The innonomate (or brachiocephalic) artery that will further branch into the right subclavian artery and the right common carotid artery; the left common carotid artery, and the left subclavian artery are the next two branches from the aorta.

The "double aortic arch" or "persistent right aortic arch" may persist, and present varying anomalous connections of the innonomate, left and right subclavian arteries and the carotid arteries, any of which may encircle the esophagus or trachea. If the left-sided aorta disintegrates, this will leave a right-sided aorta with its branches or a "right aortic arch" defect.

A double aortic arch and right aortic arch are the most common presentations of these defects (in that order).

The incidence of this defect is difficult to determine, since there is a significant population that does not present with symptoms. Right aortic arch is an anomaly that sometimes occurs in association with other defects such as tetralogy of fallot.

Clinical manifestations of this defect vary with the severity of encirclement of the trachea and esophagus, and present most commonly as an airway obstruction, and later in life as esophageal obstructions. Common symptoms would be wheezing, cough, stridor or feeding difficulties.

Respiratory problems are exacerbated with exertion and are often positional, and there are often respiratory infections that may mimic asthma. Esophageal problems develop later in life as the infant begins to take solid food, and present with symptoms such a choking or dysphagia.

Echocardiography
The diagnosis is typically made by echocardiography, X-ray, CT or MRI. Echocardiography is particularly important in that it can differentiate between right and left aortic arch, double aortic arch and its varying branches, and also can present doppler so that direction of blood flow may be determined, as well as any other related defects.

CT and MRI is particularly valuable in that it provides a complete evaluation anatomically, and allows the surgeon to provide a clear postoperative strategy. Echocardiography is well suited for evaluating the origins of arterial connections, while CT can image these arteries more distally as well as presenting 3-D imaging. Contrast imaging is often used with these techniques.

Surgical Intervention
Surgery may may not be required depending on the severity of the defect. and whether the defect is symptomatic. Additionally, children sometimes outgrow this defect. If there is significant esophageal/tracheal compromise, then surgery is usually done.

If there is a double aortic arch, the non-dominant arch will be excised and removed, and any aberrant arterial branches will be excised and attached to their more normal positions.

A right aortic arch may or may not be treated surgically, depending on the surgeon. Any structures that impinge upon the esophagus or the trachea will be repaired.

Pulmonary Arterial Sling
This is a malformation of the left pulmonary artery. In this defect, the left pulmonary artery arises abnormally from the left pulmonary arterial trunk and develops in such a way as to impinge upon the left branch of the trachea. The left pulmonary artery is often hypoplastic, and stenosis of the left pulmonary artery is common, as well as left lung complications.

This defect is commonly associated (in at least 1/3 of cases) with other left-sided defects such as ASD, VSD, tetralogy of fallot, coarctation of the aorta and persistent left superior vena cava. Symptoms are similar to that of vascular ring (wheezing, coughing and stridor).

Echocardiography will show an aberrant origin of the left pulmonary artery. CT and MRI provide the definitive diagnosis.

Outcomes
Surgical outcomes for this surgery are excellent with postoperative complications close to zero.

Ken Heiden RDCS
HeartDefectsSimplified.com

Atrioventricular Septal Defects (Endocardial Cushion Defects or AV Canal)

2010-04-08T20:14:00.005-05:00

Please read my posts concerning embryology, morphology and the segmental approach to pediatric cardiology in order to gain a complete understanding of how and why these defects develop.

Atrioventricular septal defects (or AV Canal) could be described as a failure of the fibrous skeleton of the heart or the apparatus of the heart that contains the atrioventricular valves (mitral and tricuspid valves) and the truncal valves (aortic and pulmonic valves), to fuse appropriately to the muscular portions of the heart which include the atria, ventricles and the atrial and ventricular septums, which in turn form the "crux" or the center of the heart. This malformation essentially creates a "hole" in the center of the heart.

The crux of the heart could also be described as the "atrioventricular junction".

The so called "fibrous skeleton" is really not a contiguous fibrous structure. Parts of it are entirely fibrous, other parts are fibro-muscular, and another part is fibro-fatty.

The valves of the heart attach to the muscular portions of the heart in varying ways.

For instance, the aortic valve attachment is almost completely fibrous, whereas the infundibulum (RVOT of right ventricular outflow tract) is a conically shaped fibro-muscular segment that connects the right ventricle to the pulmonary artery.

The AV valves (mitral and tricuspid valves) connect to the ventricles and the atria via both fibrous and fibro-muscular attachments.

The fibro-fatty layer follows the atrioventricular groove and serves to insulate the electrical conduction systems of the atria from the ventricles.

The segment that houses the mitral and tricuspid valves are also known as the "endocardial cushions", while the segment that houses the aortic and pulmonic valves are also known as the "conus cushions".

The hallmark of an atrioventricular septal defect is a primum ASD, a membranous VSD, and a single overriding (or merged) AV valve that has (typically) five leaflets. The right side of this structure has two of the tricuspid valve leaflets while the left side has one of the mitral valve leaflets, with two leaflets at the center called "bridging leaflets" that override the ventricular septum.

Shunting can occur across this defect in varying ways and may be right-to left, left-to-right, or most commonly bi-directional since there tends to be equalization of pressures throughout the heart.

Shunting is also dependent on how the bridging leaflets attach. If they are situated superiorly towards the atrial septum, then most of the shunting occurs at the ventricular level. If the bridging leaflets are situated inferiorly towards the ventricular septum, then most of the shunting will occur at the atrial level. If they "float" then shunting occurs at both the atrial and ventricular levels.

A final variant occurs when the bridging leaflets close the septal defect so that there is minimal or no shunting across the common atrioventricular junction.

There are numerous types of variants of the common AV valve associated with this defect and are really not that relevant as it concerns the sonographer. This is the job of the surgeon. Suffice it to say that the five leaflets may attach themselves to each other in several different ways, along with their attachments to the atria and ventricles.

The papillary muscles are often abnormal. For instance, a "parachute mitral valve" could be described as hypoplasia of one or more of the papillary muscles and their attachments that creates a funnel type of inlet across the already abnormal mitral valve.

To further complicate this situation, the bridging leaflets may attach themselves in such a way that one or the other ventricles become dominant. For instance, if the common valve is situated in such a way that most of the atrial inflow enters one of the ventricles more than the other ventricle, then this is known as a "double inlet syndrome", most commonly a "double inlet right ventricle".

A "partial AV canal" might be described as a defect that involves a common AV junction in which there is a trileaflet tricuspid valve and a trileaflet mitral valve ( a bileaflet mitral valve with a cleft that essentially makes this a trileaflet valve).

The atrial shunt tends to be left-to-right, and the ventricular shunt tends to be bi-directional. This causes volume overload in both sides of the heart and pressure overload of the right side of the heart (pulmonary hypertension or PHTN).

Echocardiography
Evaluate the heart in all of the standard views and determine that there is a common AV junction. Determine the direction and size of both the atrial and ventricular shunts.

Look for outflow obstructions across the RVOT or LVOT. These obstructions may occur as a result of the way the bridging leaflets are attached to their atrioventricular and ventriculo-arterial components. This may best be determined by looking for "ventricular imbalance". If one ventricle tends to be hypoplastic, then it is likely due to an outflow obstruction.

If there is bi-directional shunting at the ventricular level, this indicates severe pulmonary hypertension since pressures have equalized across the chambers of the heart.

The four chamber and subcostal views are best views used to determine whether there is a common AV junction, and which way and how large the shunts are.

Look for any valvular regurgitation. Valvular stenosis is difficult to determine in this lesion since there is so much mixing of right and left flow, and true gradients are hard to determine.

As outlined previously, there are numerous variations to this defect, but it is most commonly presented as a common, five leaflet, overriding AV valve with a primum ASD, and a large membranous VSD with bi-directional shunting and pulmonary hypertension.

Be sure to evaluate the pressure gradient across the VSD. This pressure gradient tends to be small, since the VSD is large and pressures tend to equalize throughout the heart. Subtract this pressure gradient from the systolic blood pressure, and this will give you the pulmonary artery systolic pressure. (see my post on "evaluating right ventricular systolic pressure").

This defect is highly associated with Down Syndrome. For the sonographer, remember the axiom that "where there is one left-sided defect, always look for others". Always check for ASD's, VSD's, coarctation of the aorta, right sided aorta, interruptions of the aorta and any outflow obstructions.

Surgical Repair
Surgery is always required to correct an AV canal defect, and is usually done within the first year of life.

The goal of this repair is to close the septal defects so that pulmonary congestion is minimized, and to reconstruct the common AV valve. Since there are so many permutations in which the common AV valve may present, there are numerous ways in which the common valve may be repaired and is highly individualistic.

The ASD and VSD are repaired with synthetic patches. The common AV valve is sutured together in such a way as to create a separate inflows for the right and left sides, and the septums are attached appropriately.

Any outflow obstructions are repaired, as well as other extraneous defects such as a coarctation of the aorta or a PDA (patent ductus arteriosis). The object of valvular repair is to do it in such a way as to limit post-surgical regurgitation or stenosis of the newly created AV valves

Outcomes
Surgical outcomes are highly dependent upon the severity of the defect, the level of shunting, and the severity of pulmonary hypertension. Surgical techniques have improved over the last 40 years or so and long term survival is very good, about 80-90%.

Ken Heiden RDCS
HeartDefectsSimplified.com

Pulmonary Stenosis

2010-03-28T13:48:00.004-05:00

This one of the most common congenital defects and is characterized by obstruction of the outflow portion of the right ventricle.

Pulmonary stenosis may be classified as subvalvular, valvular or supravalvular. All types may vary in terms of severity from mild, moderate and severe.

The incidence of pulmonary stenosis in the general population is approximately 0.4% to 0.6% (or about 6 of every 1000 births) and comprises about 10% of all congenital heart defects.

This defect may occur in isolation, or in conjunction with other complex defects. It is the second most common defect (with PDA or patent ductus arteriosus, ASD or atrial septal defect and VSD or ventricular septal defect being the most common). This blog post will concentrate on isolated pulmonary stenosis.

Valvular Stenosis
Valvular stenosis is the fusion of the three leaflets of the pulmonic valve and may be mild, moderate or severe. This fusion tends to be uniform across the three leaflets, and in its severe form the narrowing may leave only a pinhole opening at the center.

The stenosed valve may have up to 4 leaflets but it is typically bicuspid or tricuspid. A "tethered" valve refers to a stenotic valve that during systole takes on a dome like appearance. A "dysplastic" valve means that the leaflets are thickened.

When the valve is moderately or severely stenotic there is often right ventricular hypertrophy and an ASD is common. Pulmonary stenosis and right ventricular hypertrophy are hallmarks of tetralogy of fallot, therefore this defect should always be ruled out when attempting to identify isolated pulmonary stenosis.

Subvalvular Stenosis
The infundibulum is the conically shaped muscular part of the RVOT (right ventricular outflow tract) that lies just inferior to the pulmonic valve. Subvalvular stenosis is rare and usually occurs in conjunction with right ventricular hypertrophy and a VSD (ventricular septal defect). As the right ventricle hypertrophies, so does the infundibulum. Subvalvular stenosis means that the diameter of the RVOT is reduced and may be described as mild, moderate or severe.

Supravalvular Stenosis
Stenosis of the pulmonary arterial tree is common, and complicates other defects such as tetralogy of fallot or transpositions, or may coexist with stenosis of the pulmonic valve and a VSD. Branch stenosis (or stenosis of one or both pulmonary arteries) is very common.

Congenital stenosis of the pulmonary trunk involves thickening of the musculature therein, whereas branch stenosis tends to be a temporary situation in which the pulmonary branches ( left and/or right pulmonary arteries) constrict as a natural way to prevent volume overload of the lungs in the presence of left-to-right shunts, such as a VSD, ASD or especially a large PDA.

Critical pulmonary stenosis is a cyanotic event and is life-threatening; the shunts (PDA, ASD) will right-to-left whereas the PDA will be left-to-right in an effort by the body to saturate the lungs.

Echocardiography
The gold standard for evaluation of pulmonic stenosis at all levels is echocardiography. The sonographer should determine whether the stenosis is subvalvular, valvular or supravalvular. Is there a VSD, ASD or PDA? Branch stenosis is the most commonly found lesion in the presence of a shunt.

Try to determine the severity of the lesion by using color, pulsed and continuous doppler. Evaluate the gradient across the lesion. Any gradient greater than 16 mmHg is considered abnormal and a gradient of 64 mmHg is considered severe. If the defect is surgically repaired, follow-up echos are usually done.

In the case of branch stenosis, if the underlying shunt (ASD, VSD or especially PDA) is repaired, then the pulmonary artery/arteries will eventually dilate and return to normal as pulmonary flow is normalized.

Be careful to rule out additional abnormalities such as tetralogy of fallot, and transpositions.

Surgical Repair
The procedure of choice for valvular stenosis is balloon septostomy, a minimally invasive procedure that introduces a catheter across the valve, a balloon is inflated and pulled back across the valve, thus opening the stenosis. Neonates or infants that present moderate to severe stenosis or duct dependent pulmonary circulation should be treated immediately. This procedure provides excellent long term results with the primary complication being pulmonic regurgitation.

Valvotomy, or surgical repair of the valve may also be done, however severe regurgitation of the pulmonic valve may result and in these cases leads to eventual right ventricular failure. A follow-up procedure may involve replacing the valve.

Supravalvular pulmonary stenosis usually involves augmentation of the pulmonary artery with patch angioplasty or in cases that involve more than one segment of the pulmonary tree, a transannular patch may be used.

Subvalvular stenosis may be repaired by excising the obstructive tissue in the infundibulum. If further augmentation of the RVOT is required, a patch may be used.

Ken Heiden, RDCS
HeartDefectsSimplified.com

"Congenital Heart Defects, Simplified" by Ken Heiden RDCS (AE, PE), RVT

2010-03-26T19:04:00.006-05:00

"Congenital Heart Defects, Simplified" is a heavy duty spiral bound, well-organized and easy-to-read book for the busy sonographer who needs to access information immediately in a busy clinical setting. It is also and excellent guide for medical and nursing students seeking to understand congenital heart defects easily and efficiently.

The book includes full descriptions of the 30 most common congenital heart defects, ranging from familiar defects like pulmonary stenosis and aortic coarctation to more uncommon ones, such as truncus arteriosis.

Each defect is explained in a two-page spread with bullet-point descriptions on the right-hand page and full-color illustrations (that include surgical repairs) on the left. The 90 full-color illustrations will further enhance your understanding of this complex subject area. The book is indexed in alphabetical order so that the sonographer can find information quickly and easily.

The "Basic Concepts" section of the book starts at the very beginning of this subject and explains the normal heart, essential concepts, basic embryology and common shunts.

The "Appendixes" section of the book is a valuable resource that includes a synopsis of the surgical repairs (in alphabetical order), normal functions and values, scanning protocols for sonographers, imaging tips, an echocardiogram worksheet and a complete glossary of terms.

Since the 1960's, more and more adults who have had heart repairs as children are now showing up in adult labs to have echocardiograms. It is increasingly important that sonographers are aware of congenital defects and repairs in order to properly assess this new and increasing population of patients.

This blog is an excellent resource that builds upon the information found in the book and makes this complex subject so much more understandable for the busy clinician as well as parents of children who have congenital defects.

Many pediatric cardiologists have purchased the book; the full-color illustrations and easy-to-read format provides an excellent resource for their patients and parents alike.

Additionally, this is a home study course that provides an online, 300 question registry review for 30 SDMS CME's.

To find out more about this excellent book, just click on the link to the right of this page or go to www.HeartDefectsSimplified.com

Ken Heiden RDCS

Truncus Arteriosis (Common Arterial Trunk)

2010-03-25T07:20:00.009-05:00

(Click on image to enlarge)

Truncus Arteriosis is a rare congenital defect that affects approximately 3 in every 10,000 births and accounts for approximately 1% of all congenital heart abnormalities.

It is advisable to read my previous posts on embryology, morphology and the segmental approach to pediatric cardiology in order to gain a solid understanding of how and why congenital heart defects form.

To summarize embryologic development, it is best to divide the growing heart into sections: the atria, ventricles, atrioventricular valves, the venoatrial connections and the formation of the arterial trunk.

The arterial trunk begins as a single tube that emerges from the ventricular mass and begins twist or spiral in a rightward direction also known as “d-looping”. At the same time, this tube will septate or separate itself into two tubes that under normal circumstances will eventually attach itself as two separate arteries (the pulmonary artery and the aorta) to their appropriate ventricles.

Bear in mind that in the normal heart, the semilunar valves (aortic and pulmonic valves) almost always follow their respective arteries, and the AV valves (mitral and tricuspid) almost always follow their respective ventricles.

Truncus arteriosis occurs when the common arterial trunk fails to septate, and attaches itself to the ventricular mass as a single outflow artery. Furthermore, there is a malformation of the interventricular septum at the level of the attachment that leads (most often) to a large VSD (ventricular septal defect).

The aortic and pulmonic valves are “merged” to become a single multi leaflet semilunar valve that along with this single outflow arterial trunk overrides the ventricular septum. The AV valves are usually normal and are in concordance with their respective atrioventricular connections.

There are several types of truncus arteriosis that are defined based upon how the right and left pulmonary arteries are attached to the common arterial trunk.

Type I

This is the most common variant. The common arterial trunk gives rise to a short pulmonary segment that will then branch into the right and left pulmonary arteries.

Type II and III

In these variations (respectively), the pulmonary arteries arise directly from the common arterial trunk just distal to its base, directly from the base of the common trunk or in some other posterior-lateral configuration.

Type IV

This is a special classification that is really a type of tetralogy of fallot (see my previous post regarding this defect). Here, there is a solitary common arterial trunk with atresia of the main pulmonary artery. The right and left pulmonary arteries are typically fed by the PDA (patent ductus arteriosis).

Other types of congenital defects are commonly associated with truncus arteriosis including right aortic arch, interrupted aortic arch, anomalous coronary arteries and severe regurgitation of the truncal valve. If there is an interrupted aortic arch, the distal portion (descending thoracic aorta) will be fed by a PDA.

Other defects such as anomalous pulmonary venous return should also be considered.

Echocardiography
Keep in mind that it is not up to the sonographer to name the particular defect, this should be done by the reading cardiologist. It is however, the responsibility of the sonographer to accurately describe the various anatomical aspects of the heart and to completely evaluate their connections to each other.

This is best done by applying the "segmental approach" as outlined in previous posts.

The sonographer should describe the atria and their particular venoatrial connections. Describe the ventricle(s) and their particular atrioventricular connections. Lastly, describe the truncal arteries (or artery) and their particular ventriculo-arterial connections.

In the case of truncus arteriosis, evaluate the truncal origin, the size of the VSD, regurgitation and/or stenosis of the truncal valve and the direction of any shunting.

Evaluate the aorta completely and locate the origin of the pulmonary arteries. Is there a right aortic arch or is there an interrupted aortic arch? Is there a PDA?

Finally, evaluate the coronary arteries and determine where they originate.

Surgical Repair
The goal of surgical repair is to establish separate pulmonary and systemic circulations as early as possible before pulmonary overcirculation causes permanent damage to the lungs.

The pulmonary arteries are detached from the common trunk leaving the common trunk as the first portion of the aorta (neo-aorta). The aorta is then repaired as needed.

The VSD is repaired using a dacron or pericardial patch, and is connected in such a way as to redirect left ventricular outflow exclusively to the aorta.

Repair of the pulmonary portion of trunk is usually done using the "Rastelli Procedure". This technique uses a valved conduit or a homograft that is anastomosed to the right ventricle, effectively creating a new right ventricular outflow tract and trunk. The pulmonary arteries are then attached to the new pulmonary trunk.

The availability of homografts may be limited. One modification involves attaching the pulmonary arteries directly to the right ventricle without the use of a conduit. The advantage of this procedure is that it avoids long term complications such as pulmonic valve and pulmonic trunk stenosis.

Other modifications may include procedures such as a conduit that uses of a bovine jugular venous graft with a trileaflet valve.

When there is an interrupted aortic arch, the PDA is removed. The proximal and distal ends of the aorta are then reattached and the aorta is reconstructed as necessary. The pulmonary arteries are attached to the right ventricle using one of the procedures outlined above.

Modern surgical repair of truncus arteriosis is very successful and mortality rates are under 20% however, long term complications are common.

Regurgitation of the homograft may vary from mild to severe. Stenosis of the conduit is common after the first few years and the conduit often needs to be replaced. The use of a transcatheter angioplasty with stent implantation usually prolongs the life of the conduit and is the procedure of choice.

Ken Heiden RDCS
HeartDefectsSimplified.com

Pulmonary Atresia with Major Aortopulmonary Collateral Arteries (MAPCA's), or Tetralogy of Fallot with Pulmonary Atresia

2010-03-18T16:39:00.004-05:00

In the normal heart, desaturated blood returning from the body enters the right heart via the vena cavae and is pumped out of the right ventricle into the pulmonary artery and to the lungs where blood picks up oxygen. Fully saturated blood then returns to the left heart via the pulmonary veins and is pumped out of the left ventricle into the aorta to feed all areas of the body. (See my post on the normal heart).

When there is severe stenosis (blockage), or atresia (absence) of the pulmonary arterial trunk and there is little or no blood flow to the lungs, then the body must someway find a way to perfuse the lungs . As a result, the body develops arterial collaterals that branch out from the aorta and integrate themselves with the pulmonary circulation (bronchopulmonary plexus) in order to perfuse the lungs with an adequate blood supply.

This alternate blood supply to the lungs is termed "major aortopulmonary collateral arteries" or (MAPCA's). This type of circulatory pattern is often found in tetralogy of fallot with severe obstruction of the pulmonary trunk, or pulmonary atresia with or without a ventricular septal defect (VSD).

Blockage of the pulmonary trunk may be subvalvular, valvular or supravalvular; As discussed previously in my post on tetralogy of fallot, a subvalvular defect typically involves hypertrophy (muscular thickening) of the infundibulum of the right ventricular outflow tract. Hypertrophy of the infundibulum may be mild, moderate, severe or it may obliterate the the base of the pulmonary trunk altogether.

At the valvular level, the pulmonic valve may be severely stenosed, bicuspid or missing altogether. A supravalvular obstruction typically involves the distal pulmonary artery and one or both of its branches.

The most typical pattern is that the muscular outlet septum fuses at the origin of the right ventricular outflow tract (RVOT) or the base of the infundibulum, resulting in pulmonary atresia and a severely hypoplastic pulmonary artery.

Often, a patent ductus arteriosis (PDA) may be the only way that the lungs become perfused. This PDA may only provide a portion of the flow necessary for the lungs. In cases like this, MAPCA's will develop to perfuse the other portions of the lungs that are not receiving adequate blood flow.

In cases where the PDA and MAPCA's occur concurrently, some parts of the lungs will be either perfused adequately and other parts of the lungs will be perfused inadequately or the lungs may be be completely perfused adequately. Some neonates may not be diagnosed with this conditon

These types of pulmonary lesions that involve MAPCA's are increasingly being described as "tetralogy of fallot with pulmonary atresia", although this anomaly may also be described as "Pulmonary Atresia with or without a Ventricular Septal Defect".

Another variation of this defect may involve a fistula, or a veno-arterial connection between the aorta and pulmonary artery, called an "aortopulmonary window" or AP window. This may also assist pulmonary flow.

As I have outlined in many of my previous posts, almost anything can happen to a pediatric heart as it develops.

Echocardiography
For the reasons outlined above, any defect is best described segmentally (see my post on the "Systematic Approach to Pediatric Echocardiography"). In other words, describe all defects by dividing the heart into sections; the atria, the ventricles, the AV (atrioventricular valvular) connections, the ventriculo-arterial connections (LV and RV to the great arteries), and the pulmonary systemic and pulmonary venous return as they attach to the atria.

For the echocardiographer, it is best to left up to the reading cardiologist to name the particular defect. It is not up to the pediatric sonographer to name the defect, but to accurately describe the various parts of the heart as they connect to each other. For example, the sonographer may include in the worksheet such statements such as "? tetralogy, or ?pulmonary atresia, etc.

Echocardiography is not a very good way to diagnose MAPCA's. This is best done with MRI when this diagnosis is suspected. It is best for the echocardiographer to evaluate the size of the aorta and compared it to the size of the pulmonary artery.

Evaluate for an imperforate pulmonic valve. Evaluate whether the stenosis is subvalvular, valvular or supravalvular. Use color to differentiate this diagnosis. Evaluate the semilunar valves carefully. Are they tricuspid, bicuspid or stenotic?

Evaluate the aortic trunk carefully, and differentiate it from the pulmonary trunk. It is possible that one or two of the pulmonary arteries may originate from the aortic trunk (Truncus Arteriosis defects). Always look for a patent RVOT.

Evaluate the coronary arteries carefully and make sure that they are not anomalous.

Palliative and Surgical Repair
Palliative repair is sometimes necessary in order to prepare the neonate for a complete repair of this defect. Early intervention may required to improve pulmonary circulation and prevent right ventricular dilitation and failure. This may involve the placement of a Blalock-Taussig shunt (discussed previously in a post) in order to increase pulmonary circulation.

Every surgery is completely dependent on the particular circumstances of each patient.

For a complete surgical repair, the MAPCA's may be detached and ligated, or may be surgically integrated into the pulmonary circulation.

The VSD and/or ASD (atrial septal defect) will be closed. The stenotic pulmonary artery may be repaired with a transannular patch that opens the pulmonary artery, but sacrifices the pulmonic valve.

A Rastelli procedure may be done, which is a procedure that replaces the pulmonary trunk with an aortic or pulmonary homograft. These types of conduits are now the preferred approach, as opposed to a patch repair which results in severe pulmonic regurgitation. This regurgitation will eventually lead to right ventricular dilitation as a result of volume overload and eventual failure, typically within 20 years or so.

Outcomes
The majority of patients with this kind of defect require multiple surgical interventions. Pulmonary atresia is associated with a greater mortality rate, as opposed to syndromes with pulmonary stenosis (tetralogy of fallot).

Whether there are staged procedures, or primary surgical interventions does not significantly improve survivability.

After 20 years, survival rates are approximately 60%.

Ken Heiden
HeartDefectsSimplified.com

Typical Functions and Values for a Full-Term Neonate

2010-03-14T16:34:00.003-05:00

Keep in Mind that these functions and values vary depending on the age of the patient. Premature neonates will have smaller values, while the infant or child will have a larger heart, thus sizes will be a bit larger. Neonates have much faster heart rates than older children, as well as heart size that is a little larger. The neonate has blood pressures that are much lower than that of a child.

All values are variable dependent on body mass.

(double click image to enlarge)

Tetralogy of Fallot (TET)

2010-03-09T19:50:00.010-06:00

Tetra, as in tetralogy, is latin for "four", or four defects. Hence the title of this defect. Tetralogy of Fallot encompasses four defects; overriding aorta, pulmonary stenosis, right ventricular hypertrophy and a VSD.

This is one of the more common defects in congenital heart disease and affects about 3.5 % of all infants born with congenital heart defects, or about one in every 3500 births.

It is a complex cyanotic abnormality resulting from a failure of the interventricular outlet septum (LVOT or left ventricular outflow tract) and the pulmonary outflow infundibulum (RVOT or right ventricular outflow tract) to form normally and attach properly to their respective great artery truncal vessels. Further, as a result of the infundibular malformation, there is (typically) sub-pulmonic stenosis.

As a result, there is large VSD, an overriding aorta, right ventricular hypertrophy and pulmonary stenosis. This malformation at the crux of the heart may cause the aorta to override minimally (most left ventricular outflow proceeds out the aorta), or the aorta may be so malaligned to the right that most right ventricular outflow proceeds out the aorta and the pulmonary artery.

There are varying degrees to which the aorta may override the interventricular septum, in other words how "committed" the aorta is to one ventricle or the other. The aorta may override but be primarily committed to the left ventricle, or it may be doubly committed to both ventricles, or it may be primarily committed to the right ventricle. The level of commitment to the right ventricle varies between 5 to 100%.

If the aorta is primarily committed to the right ventricle then this would sound like a "double outlet right ventricle" (see my post on this subject), and in reality it is! If the aorta overrides to the point that it is totally committed to the right ventricle, then it can technically be a double outlet right ventricle, There is no reason that a double outlet right ventricle can not coexist with a tetralogy of fallot,

The difference is the malformation at the level of the infundibulum and the LVOT.

Typically, there is sub-pulmonic stenosis or hypertrophy at the level of infundibulum, but there may also be pulmonic valve stenosis as a result of a bicuspid pulmonic valve or a congenitally stenotic pulmonic valve, or a supravalvular stenosis of the main pulmonary artery or one of its branches.

Right ventricular hypertrophy occurs when the right ventricle can not pump blood out easily as a result of the pulmonary stenosis; this causes the right ventricle to "thicken" or hypertrophy.

The degree of cyanosis in the neonate depends much more upon the amount of pulmonary stenosis present rather than the percentage amount that the aorta overrides the ventricular septum If there is significant pulmonary stenosis, this reduces blood flow to the lungs hence enhancing cyanosis.

As the aorta is more committed to the right ventricle, this reduces systemic blood flow and mixing of the systemic and venous circuits, but the size of the VSD encourages equalization of the pressures and SaO2 levels of both ventricles.

Echocardiography
It is important for the sonographer to evaluate the degree to that the aorta overrides, the size of the VSD and the level of pulmonary stenosis, and whether this stenosis is sub-pulmonary, pulmonic at the level of the valve, or supravalvular (superior to the valve).

Measure the size of the VSD. Is it right-to-left, left-to-right or bidirectional? Determine to what degree the aorta overrides the ventricular septum. Is the aorta more committed to the left ventricle or to the right ventricle?

Finally determine what type of pulmonary stenosis is present. Is it sub-pulmonary, at the level of the pulmonic valve, or is it supra-valvular? How much stenosis is present? Measure the pressure gradient across the stenosis. Also, measure the size of the pulmonary artery and its branches. Are they hypoplastic?

Keep in mind that there may complete atresia of the pulmonary artery (this will be discussed in another post).

Look for anomalous coronary arteries, as this will be an important surgical consideration.

A right aortic arch may be common in this defect. Document this, and determine which branches are the brachiocephalic, carotid and subclavian arteries.

Major Aortocopulmonary Arteries (MAPAC's)
In the presence of severe pulmonic obstruction, the body tries to perfuse the lungs somehow. As a result, collateral arteries will begin to branch out from the aorta and integrate themselves into the lungs, thus providing blood flow in the pulmonary circuit.

This will be further discussed in a future post. If there is a severe lesion in the outflow portion of the pulmonary tract, then MAPCA"s should be suspected. This defect can not really be detected by echocardiography but rather by MRI.

Surgical Repair
Surgical repair is required in this defect. In the past, 2 to 4 years before permanent corrective surgery would be performed, a palliative (temporary) shunt procedure was done in order to establish a systemic arterial to pulmonary artery connection that increases blood flow to the pulmonary circulation.

Several types of shunts were typically used.:
Blalock-Taussig shunt (classic): involves the anastamosis of the right subclavian artery to the right pulmonary artery.
Blalock-Taussig shunt (modified): presently the preferred procedure that uses a homograft or synthetic tube to attach the right subclavian artery to the right pulmonary artery.
Potts shunt: the descending aorta is attached to the left pulmonary artery via a "hole" or an anastamosis.
Waterston shunt: the ascending aorta is attached to the right pulmonary artery via a "hole" or an anastamosis.

Presently, complete single-stage surgical repair at approximately 6 months of age is the preferred approach. However, severely cyanotic neonates may still require palliative shunting. In these patients, the modified Blalock-Taussig shunt is the preferred approach, although some institutions may use balloon dilation and stenting of the infundibulum. This may be done in prior to, or in addition to a complete repair.

Complete repair generally involves the following:
1) If a palliative shunt was used, it will be detached and removed.
2) The VSD outflow malformation is closed with an autograft (pericardium), or a knitted Dacron or Teflon patch.
3) If an ASD (atrial septal defect) is present, it will be closed.
4) If there is a PDA (patent ductus arteriosis) present, it will be closed.
5) Pulmonary stenosis is relieved by resection of the obstructive tissue in the infundibulum. If the pulmonary valve is involved or if there is supravalvular involvement then a valvotomy and/or a transannular patch will be used.

The object of surgery is to normalize right ventricular pressures, open the stenotic pulmonary artery, close the shunts and save the pulmonic valve if possible. Unfortunately, a patch repair tends to sacrifice the pulmonic valve.

If the pulmonic valve can not be saved, or if a pulmonary conduit is not used, then there will be severe pulmonic regurgitation. This is well tolerated by the heart for up to 20 years, but eventually it will result in chronic right ventricular dilitation and eventual failure. This condition may require at some point the implantation of a prosthetic pulmonic valve or a valved conduit.

Outcomes
Survival for this surgery is excellent, with over 90% of patients still alive after 30 years. Reintervention may be necessary in about 15-20% of patients later in adulthood. This typically involves resection of additional infundibular stenosis, or the above stated repair of the pulmonic valve and or its outflow tract.

Ken Heiden RDCS
HeartDefectsSimplified.com

Common Shunts

2010-03-06T18:28:00.001-06:00

A shunt is defined as any communication between the right and left heart. A fistula is defined as any communication between and artery and a vein. One or more shunts will be present in almost all complex defects.

For the echocardiographer, evaluation of a common shunt, PDA (patent ductus arteriosis), PFO (patent ductus arteriosis or) or VSD (ventricular septal defect) will be one of the most likely reasons a neonate is scanned.

The PDA and a PFO are two shunts that occur naturally in every normally developing fetus. The reason is that the fetus does not breathe, therefore the right ventricle of the heart is essentially dormant until after birth.

Embryologically, all blood returning to the right side of the heart via the cavae is diverted to the left side of the heart through the naturally occurring PDA and PFO and mixed with left sided blood. Prior to birth, all shunts should be right to left.

Following birth the lungs begin to function and the baby is breathing, Flow should alter to become left to right until these shunts close naturally within two to four days.

These shunts are programed genetically to close shortly after full gestation (40 weeks), but they tend to persist if the neonate is premature. Unfortunately, these open shunts flood the right side of the heart and the lungs with abnormally large amounts of blood flow which compromises the exchange of oxygen levels in the blood at the pulmonary capillary level.

The lungs are the last organs to develop and as a result any stress on the lungs makes it difficult for the neonate. Premature neonates (preemies), especially severely premature neonates are especially susceptible to any blood volume overload on the right (pulmonary) side of the heart.

As a result of this volume overload, most preemies will exhibit pulmonary hypertension (increased blood pressure of the pulmonary artery and its branches).

Keep in mind that blood flow occurs in the body as a result of low pressures on the right side (pulmonary side) and high pressures on the left side (systemic side). Simple physics. Flow always travels from a high pressure environment to a low pressure environment. As pressure on the right side is increased, flow is compromised especially through the pulmonary capillary beds, which in turn compromises proper oxygenation of the blood that enters the systemic circulation.

If the echocardiographer encounters any shunt that is right to left in a neonate, this is a serious condition whether it is a PFO, PDA, VSD or a shunt associated with a complex lesion. Right to left shunting indicates that pressure on the right side is higher than the left, indicating the presence of severe pulmonary hypertension.

PDA (Patent Ductus Arteriosis)
A naturally occurring shunt between the aorta and the pulmonary artery, that should close shortly after birth.

PFO (Patent Foramen Ovale)
The foramen is the center portion of the interatrial septum. It is a naturally occurring shunt between the left and right atria that should close shortly after birth.

VSD (Ventricular Septal Defect)
An abnormal communication between the left and right ventricle. VSD's are very common and may go unnoticed until well into adulthood. Unless they are very large, they often eventually close by puberty. Childhood murmurs are often VSD's. If they persist, then a minimally invasive catheterization type procedure is utilized using a "rivet" type of device that is introduced into the ventricles and "clamps" the hole shut.

"Peri-membranous" or "membranous" VSD's are located just below the AV valves (mitral and tricuspid valves). These types of VSD's are highly associated with AV canal or endocardial cushion defects.

Muscular VSD's can occur in any other part of the muscular part of the interventricular septum. The echocardiographer should keep in mind that there may be one or many VSD's. Multiple VSD's are often referred to as "swiss cheese VSD's".

An outflow VSD is located in the right or left ventricular outflow tract of one or both ventricles. A supracristal VSD is located in the right ventricular outflow tract (RVOT), while a left ventricular outflow tract VSD may be referred to as just an "outflow VSD".

ASD (Atrial Septal Defect)
An abnormal communication between the atria of the right and left heart. ASD's should close shortly after birth, however they often persist well into adulthood. They are a common cause of stroke young in adults. If a blood clot travels through the venous system, passes the ASD, it may very well go to the brain. The echocardiographer should always interrogate the interatrial septum (especially in adults) thoroughly to rule out an ASD.

A patent foramen ovale (PFO or secundum ASD) was described above and is one of the most common reasons that an echo may be done.

A sinus venosis ASD is located superiorly (at the roof of the atrium) and is commonly associated with total and partial anomalous venous return.

A primum ASD is located inferiorly (at the base of the interatrial septum) near the AV valves and is commonly associated with AV canal defects or endocardial cushion defects.

Fistula (Aortopulmonary Defect or AP Window)
A fistula is any communication between an artery and a vein. For the heart, it is a defect that is located superiorly to the semilunar valves and allows blood flow to communicate between the aorta and the pulmonary artery.

Echocardiography
The echocardiographer should always be careful to evaluate all structures of the heart using color in multiple views. These are defects that can easily be missed. The atrial and ventricular septums should be carefully interrogated in the parasternal long and short axis views, the apical views and especially in the subcostal views.

For the neonate, the subcostal views are often the best way to evaluate congenital heart disease since there are no structures in the way. The echocardiographer can literally point the probe in any direction and image almost all of the structures.

Ken Heiden RDCS
HeartDefectsSimplified.com

"Double Switch" Procedure for Complex Transpositions (Jatene Procedure)

2010-03-05T17:48:00.003-06:00

The Double Switch procedure refers to a surgical procedure that corrects D-transpositions (or complex transpositions).

(please see my posts on D-transpositions and double outlet right ventricle as well as embryology for information on the formation of these defects).

A complex transposition of the great arteries means that the aorta is attached to the right ventricle, and the pulmonary artery is attached to the left ventricle. In other words, the great arteries are switched.

Cavae flow with low Sao2 returns to the right ventricle, but is pumped back out into the body via the transposed aorta without returning to the lungs for re-oxygenation. Meanwhile, pulmonary venous flow returns to the left ventricle, but is pumped back into the lungs via the transposed pulmonary artery without oxygenating the body.

Blood flow is in "parallel". Oxygenated blood flow never mixes with de-oxygenated blood flow unless there is a shunt of some kind, a PDA, PFO or VSD

The object of the procedure is to excise the aorta and the pulmonary artery from their respective outflow apparatus while leaving the trunks of both arteries intact.

The coronary arteries are detached from the aortic trunk along with a "button" of tissue at their origins that will be used to reattach these arteries.

The pulmonary artery trunk and the infundibulum which are attached to the left ventricle become the "neo-aorta". The aorta and the coronary arteries are attached to this structure.

The pulmonary artery is then attached to the outflow apparatus of the right ventricle.

Blood flow is now "corrected" or in "series". De-oxygenated blood flow now mixes appropriately in the lungs, and oxygenated blood flow now mixes at the capillary level in the body.

Once again, please read my posts on embryology, morphology and transpositions to see color diagrams and complete explanations of these defects.

Ken Heiden RDCS
HeartDefectsSimplified.com

The Rastelli Procedure

2010-03-03T17:58:00.001-06:00

(click image to enlarge)

The Rastelli procedure is done when there is transposition of the great arteries pulmonary stenosis and a VSD. The object of the repair is to reroute left ventricular blood flow to the aorta, patch the VSD and then use a valved conduit to reroute right ventricular blood to the pulmonary artery

This procedure may be done in the case of many types of transposition, tuncus arteriosis, tetralogy of fallot and double outlet right ventricle.

1) An interventricular patch is placed across the VSD; this re-directs flow from the left ventricle to the aorta.
2) The PDA is excised.
3) The pulmonary trunk is divided, or ligated and a valved conduit (xenograph) is placed between the pulmonary arteries and the right ventricle.

The main drawback of this procedure is the need for replacement of the conduit later in life.

Embryology, the Basics

2010-03-02T19:54:00.001-06:00

(Click image to enlarge)

Embryology and morphology are the keys to understanding congenital heart defects. Many people make the mistake (as I did in the beginning) by trying to memorize each defect. Even if you can memorize each defect, this is further complicated by the fact that you would have to memorize every variation associated with each defect.

Over the years, there has been numerous controversies concerning the description of defects, essentially by trying to compartmentalize each defect into one universal description. There are just too many variables involved, too many variations of each defect in order to make this approach feasible.

The best approach is to use the "systematic approach to pediatric cardiology" (see my post on this subject).

Essentially, this means that as an echocardiographer, you divide the heart into five sections; the atria, the ventricles, the AV valves, the great arteries and their associated valves (aortic and pulmonic valves) and the great veins and their connections.

Embryologic formation
The heart begins as a single tube that septates (or begins to separate into two tubes) and begins to twist rightward onto itself, called "d" looping.

"D" refers to the Latin word dexter or "right". This tube will form an "S" shaped structure that will eventually form all the structures of the heart and begin pumping blood by the fourth week of life.

The superior (top) portion of the tube will start to balloon out and will begin to form the atria. Meanwhile, the inferior (bottom) portion of the tube will balloon out and begin to form the ventricles. The middle portion of this tube will form the AV valves (mitral and tricuspid valves), and this area will also form the truncal portion of the heart which will eventually become the aorta, pulmonary artery and its associated valves.

You may refer to these areas as the "truncus", "conus" and the "bulbus".

Truncus: will form the aorta and pulmonary artery and its valves.
Conus: will form the outflow tracts of the aortic and pulmonary valves, and the atria.
Bulbus: will form the ventricles.

Meanwhile, the great veins are an "H" shaped structure that drain the embryo. To the right are the cavae, and to the left is the cardinal vein. The innonomate vein drains into the cavae superiorly, and the ductus venosis drains inferiorly. As the fetus develops, the cardinal vein will disintegrate, leaving only the cavae and its associated subclavian veins.

The "balloon" shaped atria and ventricles begin to septate, or separate. The superior portion of the atria wil begin to grow a septum that moves inferiorly, and the inferior portion of the septum begins to grow superiorly until they meet in the middle. The ventricles do the same thing.

The AV valves are forming at the same time, as well as the truncal arteries and their valves. Ideally, everything meets in the middle of the heart or the "crux" and forms two atria, two ventricles, and appropriately attached valves and truncal arteries.

Anything may happen while these structures are forming.

The atria may form normally, or may be transposed, or may be isomeric; in other words there may be two right atria or two left atria.

The ventricles may form normally, or may be transposed, or one ventricle may be hypoplastic.

The AV valves may form normally, or one valve may override the ventricular septum, or there may be one "merged" completely overriding valve.

The truncal arteries may fail to twist properly and they may be transposed, In other words, the aorta (and aortic valve) may attach to the right ventricle, and the pulmonary artery (and pulmonic valve) may attach to the left ventricle.

Do not forget about all of the associated defects such as coarctation of the aorta, pulmonary or aortic stenosis, anomalous veins, mitral stenosis, shunts, cleft valves interrupted aortic arch, etc.

A good point to remember is that the aortic valve and the pulmonic valve tend to follow their respective arteries (aortic valve is almost always attached to the aorta and the pulmonic valve is almost always attached to the pulmonary artery), and the AV valves tend to follow their respective ventricles (the mitral valve is almost always attached to the left ventricle, and the tricuspid valve is almost always attached to the right ventricle).

Echocardiography
Embryology is a developing subject and to this day there is controversy on how to best describe these various anomalies and their associated defects. I tend to follow the model that Robert Anderson M.D. (author of "Paediatric Cardiology", third edition) and the Mayo Clinic subscribe to:

This is the "segmental" approach as described previously.

First, evaluate the atria. How are they attached to the ventricles?. How are the AV valves attached to the ventricles? How are the truncal arteries attached to the ventricles. And finally, how are the great veins attached to the atria?

It is not up to the echocardiographer to identify the particular defect by name. It is far better to describe the defects one-by-one, and leave it to the pediatric cardiologist to identify the lesion.

If you follow this approach, you will be far better off.

Another aspect to remember is that as an embryo, the lungs are non-functional, therefore cavae flow returns to the right atrium and is diverted to the left atrium via a PFO. Blood flow from the pulmonary artery is diverted to the aorta via the PDA. All shunts in the embryo are right-to-left.

Once the baby is born, the lungs become functional, and as a result, the shunts, PDA and PFO will become left-to-right, and will eventually close within a few days (see my post on "shunts").

Ken Heiden RDCS
HeartDefectsSimplified.com

Double Outlet Right Ventricle

2010-03-01T19:46:00.002-06:00

It is advisable to read my posts on morphology and embryology in order to best understand how these defects form and how best to describe them. (click on image to enlarge)

Double outlet ventricle is defined as a heart in which there are concordant atrioventricular connections (the atria are connected to the ventricles with intact AV valves) and there are two functioning ventricles, but the outflow tracts of the aorta and pulmonary artery arise from one ventricle. Double outlet right ventricle, in which both the pulmonary artery and the aorta arise from the right ventricle is the most common manifestation, however double outlet left ventricle may occur, but it is much rarer.

This purely morphologic method (describing each section of the heart separately) is the best way to approach this diagnosis since there are so many other variations that can occur. In fact, almost any other defect can occur in conjunction with double outlet syndromes, from pulmonic stenosis, coarctation of the aorta, mitral and aortic stenosis, overriding AV valve, septal defects and other valvular deformities, to interrupted aortic arch and anomalous venous return.

For the echocardiographer, use the systematic approach when imaging these defects (see my post on this subject). Divide the heart into five sections; the atria, ventricles, AV valves, truncal arteries and the semilunar valves, and the venous return and their connections.

Describe each section of the heart one at a time. By using this method, you will vastly improve your understanding of congenital heart disease and simplify your learning curve immensely.

Double Outlet Right Ventricle

There are three common types:

1) 1)Taussig- Bing types where there is a large VSD, with both great arteries arising from the right ventricle, and the aorta arises parallel and to the right of the pulmonary artery.

2) 2)There is a sub-aortic VSD, the aorta arises to the right of the pulmonary artery and there is infundibular (sub-pulmonic) stenosis and/or pulmonic stenosis. This is a variation of tetralogy of fallot.

3) 3) There is a sub-aortic VSD, the aorta arises to the right of the pulmonary artery but there is no pulmonary stenosis.

In the above examples, if there are bilateral infundibulums (two infundibulums rather than one) then the great arteries will be parallel to each other. If there is one infundibulum, then the arteries will arise spirally (somewhat perpendicular) to each other, but the aorta will be to the right of the pulmonary artery.

Infundibilum is defined as the elongated, conal type structure that makes up the right ventricular outflow tract inferior to the pulmonic valve.

When these hearts form, the universal feature is the incomplete formation of the left ventricular outflow tract (LVOT) and its appropriate attachment to the left ventricle, leaving a sub-aortic VSD. The aortic outflow then tends to arise from the right ventricle, and the structure will be rightward and posterior to the pulmonary artery (which has the appearance of a transposition).

There is much variability concerning the size of the VSD, its relationship to the great arteries, its particular location in the ventricle and the presence of other associated defects. Multiple VSD's are found on occasion. All of these variants relate to the amount of cyanosis present. As a result, it is important to document the pulmonary flow and any restrictions to this flow that may be present.

If pulmonary flow tends to be unrestricted, then this defect acts like a typical VSD. If pulmonary flow is restricted, this defect acts like tetralogy of fallot.

Surgical Repair

Surgical repair is variable and dependent on all of the other defects that may be present. Therefore, surgeries are divided into complex types and non-complex types.

Ballon septostomy (see my post: D-transposition of the great arteries) is often a palliative procedure. A balloon catheter is passed through the atrial septum, inflated, and then pulled back through the foramen, thus creating a large "hole" in the atriums. This allows immediate mixing of arterial and venous blood which immediately alleviates cyanosis.

Banding of the pulmonary trunk may also be required to alleviate pulmonary pressures.

Non complex surgeries typically involve the placement of a patch or intraventricular tunnel from the defect to the aorta that re-establishes left ventricular flow to the aorta, separates arterial and venous flow, and re-establishes right ventricular flow to the pulmonary artery.

Complex surgeries can be done many ways. Most ventricular defects can be repaired using the aforementioned patch procedure unless there is and associated LVOT or RVOT obstruction. Many surgeries have been tried over the years, but the surgery of choice is the arterial switch procedure or "Jatene procedure" (see D-transposition of the great arteries). The great arteries are "switched". The aorta is attached to the pulmonary trunk, and the pulmonary artery is attached to the aortic trunk. The coronary arteries are attached appropriately. This corrects the ventriculo-arterial deformation.

A "Rastelli Procedure" may be employed in the presence of severe pulmonary obstruction. Here, a valved conduit is placed between the right ventricle and the pulmonary artery, while the left ventricle to aortic connection is "baffled" or repaired.

Remember that complex defects involve other abnormalities such as a coarcted aorta. These defects are often corrected at this time or at a later date when the neonate is more stable.

Ken Heiden RDCS

HeartDefectsSimplified.com

Branch Stenosis and Pulmonary Artery Band

2010-02-26T19:18:00.004-06:00

Branch stenosis is probably one of the common defects that an echosonographer will encounter. It is typically a vasoconstrictive response in the pulmonary arteries that is an effort by the body to reduce pressure and or volume overload that will overfill the lungs with blood volume and pressure.

Lungs are the last organs to develop and as a result are especially vulnerable to pressure or volume problems after birth, particularly pulmonary hypertension. The pulmonary arteries and their branches naturally constrict in order to reduce blood volume and pressure into the lungs.

Branch stenosis will usually resolve over time once the underling cause of pulmonary hypertension resolves. In most cases, intervention is not required.

Most preemies tend to have pulmonary hypertension. As an echocardiographer, it is your responsibility to evaluate pulmonary artery pressure (PA pressure, or RVSP, right ventricular arterial pressure).

Measure the gradients across the right ventricular outflow tract (RVOT), the pulmonic valve (PV) and the right and left branches of the pulmonary arteries. any gradient more than 16 mmHg is considered abnormal.

Keep in mind that there may be a gradient across one pulmonary artery, but not necessarily the other. Measure the gradient across both arteries and record it.

Measuring Right Ventricular Systolic Pressure (RVSP)
Most premature neonates will have pulmonary hypertension (PHTN). Accurately measuring RVSP in order to assess the level of PHTN is extremely important. RVSP may be measured in 3 ways:

Measure the PDA pressure gradient: The PDA pressure gradient is the difference in pressure between the aorta and the pulmonary artery. Subtract the PDA pressure gradient from the systolic systemic blood pressure. The result will be the RVSP.
Measure the VSD pressure gradient: The VSD pressure gradient is the difference in pressure between the left ventricle and the right ventricle. Subtract the VSD pressure gradient from the systolic systemic blood pressure. The result will be the RVSP.
Measure the tricuspid regurgitation gradient: This gradient is the difference in pressure between the right ventricle and right atrium. Add 5mmHg to the gradient to compensate for central venous pressure (not 10mmHg as in adults). The result will be the RVSP.

Measuring Right Ventricular Systolic Pressure - Examples
Where blood pressure is 75/35mmHg, systolic systemic blood pressure (SBP) is 75 mmHg, and central venous pressure (CVP) is 5 mmHg:

PDA gradient (PDAg) = 50 mmHg. 75 mmHg (SBP) - 50 mmHg (PDAg) = 25 mmHg (RVSP)
VSD gradient (VSDg) = 50 mmHg. 75 mmHg(SBP) - 50 mmHg (VSDg) = 25 mmHg (RVSP)
Tricuspid regurgitation gradient (TRg) = 20 mmHg. 20 mmHg (TRg) + 5 mmHg (CVP) = 25 mmHg (RVSP)

Pulmonary Artery Band
An adjustable band is sutured into place across the pulmonary artery (PA), avoiding impairment of the pulmonary artery and the branches.
The sutures are tightened until pressure distal to the band are within ideal levels, usually 1/3 of systemic levels.

The band is usually removed when definitive repair of the underlying condition is performed or the pulmonary hypertension has been resolved.

Ken Heiden
HeartDefectsSimplified.com

Eisenmenger Syndrome

2010-02-26T17:37:00.002-06:00

It is highly advisable to read my posts on morphology in order to understand why these defects develop embryologically.

This is a defect that occurs when a shunt changes from left to right, to right to left. The definition excludes defects such as common atrium, single ventricle, anomalous veins and a truncus arteriosis.

The reason for this is that these congenital defects obligate mixing of systemic and pulmonary flow whereas Eisenmenger implies a long term shunt that has damaged the lungs to the point that surgery cannot be done to correct the malformation.

For instance, a VSD (ventricular septal defect), ASD (atrial septal defect) or an arterial defect (such as D-transposition) that has persisted for many years may damage the pulmonary vascular bed to a point that shunt reversal may occur.

Undetected shunts may persist well into adulthood. Large volumes of blood are delivered from the left side to the right side of the heart via these types of shunts, and any pressure problems will aggravate the situation.

Large shunts may go undiagnosed due to the fact that it may not present a murmur, and may only be detected later in life once irreparable damage has been done to the lungs. This continuous pressure and volume overload may eventually equalize pressures between the right and left sides of the heart until a reversal of blood flow occurs.

Remember, in the neonate, normal heart pressure is 1/3 on the right as it is on the left. The right side of the heart delivers blood flow into the lungs, and the pressure is about 25 mmHg. Left sided pressures are approximately 75 mmHg.

This pressure difference is what keeps blood moving in one direction throughout the circulatory system (flow occurs from a high pressure environment to a low pressure environment). If pressures equalize, then flow tends to stop and cyanosis occurs.

Lungs exist in a low pressure environment. If they are exposed to constant increases in pressure and volume, then an aggressive form of pulmonary vascular resistance will manifest, and eventually lead to right sided failure. Undetected shunts will eventually result in this right sided collapse, and hence Eisenmenger syndrome.

Eisenmenger syndrome may also be called "end stage pulmonary hypertension". Once these patients no longer respond to palliative procedures (such as pharmacological therapy), they may become candidates for heart-lung transplants.

Pulmonary banding may also be used. It is a procedure that alleviates pulmonary overcirculation by suturing an adjustable band across the pulmonary artery trunk. Sutures are tightened until pressures distal to the are within ideal levels.

Prior to transplantation, drug therapy seems to be the best approach. The drugs of choice are vasodilators and vasoconstrictive blockers that prevent damage to the lungs while preserving function.

Ken Heiden RDCS
HeartDefectsSimplified.com

Atrial Septostomy (Rashkind Procedure)

2010-02-24T16:37:00.003-06:00

Please read my post "D-transposition (Complex Transposition) of the Great Arteries", as well as my posts on morphology of pediatric heart to gain a better understanding of pediatric heart function and physiology.

This is a procedure that may be done on a fetus (intra-uterine), or a neonate that displays or will display severe cyanosis after birth. This procedure is considered if there is a severe pulmonary venous inflow obstruction such as hypoplastic left heart syndromes, or in the case of D-transposition (complex transposition), or in certain cases of severe pulmonary hypertension (PHTN).

If a fetus has a hypoplastic left heart or mitral stenosis, this procedure is done to reduce the stress on on the left atrium and therefore the entire pulmonary venous system.

In other words, if venous outflow from the lungs enters the left atrium and cannot get out of the left ventricle, it has to go somewhere, usually back into the lungs. This severely inhibits systemic outflow and also mixing of the blood at any capillary level.

The object of the repair is to open the atrial septum in order to decompress the left atrium and allow mixing of systemic and venous blood to occur so that SaO2 levels will increase and damage to the lungs will be minimized.

It is important to note that once pulmonary hypertension sets in, it is very difficult to reverse. Additionally, the lungs are the last organs to develop during gestation and it is very important to protect them from any damage.

If there is a D-transposition, then the atrial septostomy is the palliative procedure of choice (especially if there is no VSD) soon after birth. This procedure allows the neonate to stabilize so that further surgical repairs can be done.

In the case of children who exhibit severe right sided cardiac failure, Eisenengers syndrome or severe pulmonary hypertension may benefit from this procedure. Puncture of the atrial septum often relieve the symptoms of severe pulmonary hypertension.

Surgical Procedure
This is a minimally invasive, palliative procedure that introduces a balloon tipped catheter into into either the left or right atrium via the lateral chest wall. The catheter punctures the foramen at the atrial septal level, and then the ballon is inflated. It is then pulled back through the septum in order to create a hole that will allow mixing of the right and left circulations. This immediately reduces symptoms of cyanosis and allows the neonate (or fetus) to stabilize. This hole may or may not be permanent, and subsequent septostomies may be required.

Outcomes for this procedure are good, even when done intra-uterine. In the case of D-transpositions and other defects that severely limit left heart function, it is almost essential to stabilize the infant prior to further surgery, which often must be done within the first few weeks after birth.

Ken Heiden RDCS
HeartDefectsSimplified.com

L-Transposition (Congenitally Corrected Transposition) of the Great Arteries

2010-02-23T20:25:00.003-06:00

Note: it is highly advisable to read my posts on morphology and the segmental approach to congenital defects in order to better understand from an embryologic point of view why these defects form.

Transpositions are probably the most confusing of all of the defects, especially since there has been so much controversy and discussion within the medical field as to how best describe and classify them over the years.

First, let’s examine the terminology:

Morphologic: anatomically correct structure irrespective of its location.

Concordant: structures attached appropriately to each other.

Discordant: structures that are not appropriately attached to each other.

Atrioventricular: the junction between the atria and the ventricles.

Ventriculo-arterial: the junction between the ventricles and the great arteries

Venoatrial: the junction between the veins and the atria.

Blood flow in “parallel”: abnormal. The right sided or pulmonary circuit does not mix with the systemic circuit at pulmonary and capillary levels (with the exception of a shunt). This leads to cyanotic SaO2 levels.

Blood flow in “series”: normal. The right sided or pulmonary circuit mixes with systemic circuit at the pulmonary and capillary levels. SaO2 levels are generally normal (in the absence of other cardiac lesions).

For example; a concordant atrioventricular junction means that the morphologically correct atria are appropriately attached to their morphologically correct ventricles.

By using the systematic approach, it is possible to properly describe all of the variants in all types of transpositions (see my post concerning the systematic approach to congenital heart disease).

There are two categories of transpositions, D-types and L-types. D-types are discussed in a previous post.

L-transposition (congenitally corrected transposition) is a defect that is characterized by discordant atrioventricular connections and discordant ventriculo-arterial connections. In most cases the atria are in their normal positions.

Systemic venous blood empties into a morphologically correct right atrium via the vena cavae, through a mitral valve into a morphologic left ventricle and is ejected out through a morphologic pulmonic valve and pulmonary artery into the lungs.

Returning pulmonary venous flow empties into a morphologically correct left atrium, through the tricuspid valve and into a morphologic right ventricle and is ejected out through a morphologic aortic valve into the systemic circulation.

As a result of this double discordance, systemic and pulmonary blood flow is “corrected”. The right ventricle is now pumping systemic blood, and the left ventricle is pumping pulmonary blood.

The term “L” refers to the Latin levo or left, and denotes the position of the aortic valve relative to the pulmonary artery; the aorta is located anterior and to the left of the pulmonary artery.

This description does not entirely describe this defect and all of its variants, therefore the most appropriate way to describe all defects is to use the segmental approach, and describe the defects one by one.

A good tip to remember in all defects is that the AV valves (mitral and tricuspid) almost always follow their respective ventricles, and semi-lunar valves (aortic and pulmonic) almost always follow their respective arteries.

Coronary arteries typically arise from the aorta but may be anomalous. Ventricular septal defects are common as well as electrical conduction defects (heart block is common in this defect) . VSD's are present in half of these patients. It is important to evaluate for any outflow obstructions in the LVOT and RVOT. LVOT obstructions are especially common.

Tricuspid valve abnormalities are common. Look for overriding or straddling AV valves which may lead to double inlet syndromes.

Management
Surgical management of this defect is extremely difficult and probably not possible, although repairs have been attempted in the past. Very often, this defect is left alone.

Unfortunately, since the right ventricle is providing systemic arterial flow, the demand on this structure will eventually catch up and right heart failure may occur in early adulthood. Right heart failure is the primary concern of this defect and echocardiography is routinely used for adult patients in order to evaluate right heart function.

A "double switch procedure" involves the use of baffles to reroute vena cavae flow to the transposed right ventricle and to reroute pulmonary venous flow to the transposed left ventricle.

Meanwhile, the great arteries are excised and switched along with the coronary arteries (see D transposition of the great arteries, surgical repairs).

These surgeries are somewhat successful, but require a high level of maintenance over the years such as baffle repairs and valve replacements. Right ventricular failure later in life is common and progressive tricuspid regurgitation only aggravates this situation.

Surgical intervention can prolong life, but at this time there is there is no surgical procedure that does not require prolonged intervention.

Ken Heiden RDCS
HeartDefectsSimplified.com

D-Transposition of the great Arteries, Surgical Repair

2010-02-23T06:48:00.006-06:00

D-transpositions are cyanotic heart defects and must be dealt with immediately after birth.

Please read my previous post on D-transposition and my posts on morphology in order to adequately describe the way these defects develop embryologically and their physiologic effects and the appropriate definitions.

D-transposition of the great arteries most typically describe concordant atrioventricular connections and discordant ventriculo-arterial connections. Systemic venous blood flow (low SaO2) enters the right atrium, flows through a morphologic tricuspid valve into a morphologic right ventricle, and exits through a morphologic aortic valve and aorta into the systemic circulation.

A discordant ventriculo-arterial connection means that pulmonic blood flow leaves the lungs and enters a morphologic left atrium, flows through a morphologic mitral valve into a morphologic left ventricle and is ejected through a morphologic pulmonic valve and pulmonary artery back into the lungs. Since there is no or little mixing of systemic and pulmonic blood flow, both the systemic and pulmonic circuits are low SaO2, thus a cyanotic infant. Without these shunts, this defect is fatal.

First, let’s examine the terminology:

Morphologic: anatomically correct structure irrespective of its location.

Concordant: structures attached appropriately to each other.

Discordant: structures that are not appropriately attached to each other.

Atrioventircular: the junction between the atria and the ventricles.

Ventriculo-arterial: the junction between the ventricles and the great arteries

Venoatrial: the junction between the veins and the atria.

For example; a concordant atrioventricular junction means that the morphologically correct atria are appropriately attached to their morphologically correct ventricles.

In a D-transposition, blood flow is in "parallel" and mixing only occurs through the shunts.

The object of surgical repair is to reconnect right sided blood flow to the pulmonary artery, and to reconnect left sided blood flow to the aorta while maintaining continuity of the coronary arteries.

Surgical Repair

D-transposition of the great arteries (or complex transposition) is fatal unless surgery is done as soon as possible. A balloon septostomy is the first procedure that is typically performed. This minimally invasive procedure involves threading a catheter into the right atrium, through the atrial septum and into the left atrium. A balloon at the tip of the catheter is inflated and is pulled back through the foramen ovale, thus creating a hole in the atrial septum that allows pulmonary and systemic blood to mix.

This procedure has significantly increased survival since it was first used in 1966 and allows the neonate to stabilize before more extensive surgery is done.

Surgeries of the past

Before the advent of modern surgical techniques especially microsurgery, this defect was typically treated with an atrial “switch” or atrial redirection technique. The Mustard and the Senning procedures were done until the mid 1970’s when the first arterial switch procedure was done in 1975 by Jatene and colleagues. This procedure is now the surgery of choice and has been done successfully since the 1980's.

Both procedures involve the use of “baffles” that redirect atrial blood flow into their physiologically appropriate ventricles. After the surgery was complete, systemic venous blood flow returning to the right atrium would be redirected via the baffle into the left ventricle and ejected out the pulmonary artery and into the lungs. Meanwhile, pulmonary venous flow enters the left atrium and is redirected via the baffle into the right ventricle where it is ejected out the aorta into the systemic circulation.

The problem with this solution is that the right ventricle is acting as the systemic ventricle and eventually this burden on the right ventricle will cause it to fail, usually in early adulthood. The difference between these two procedures is that the Senning reroutes blood flow by enfolding the atrial walls and the Mustard uses pericardium for this purpose.

The echocardiographer should be aware of these procedures since these patients are coming to echo labs currently as adults.

The Arterial Switch procedure

This is the surgery of choice and is done as soon as possible after the neonate has been stabilized, typically within the first two weeks of life. The procedure involves the transection of the aorta and the pulmonary arteries leaving the trunks of the aorta and pulmonary arteries along with the infundibulum intact. The coronary arteries are removed along with a “button” of aortic tissue that will be used for later reattachment to the new or “neo aorta” (the old pulmonary trunk).

The arteries are now switched, attaching the aorta to the neo aorta, and attaching the pulmonary artery to the old aortic trunk. The coronary arteries are attached to neo aorta and any anomalous coronary artery problems would be corrected at this point. Any VSD’s or ASD’s will be corrected at this time.

Outcomes for these surgeries are very good with a survival rate of over 90% at age 27. The atrial switch procedure has the best outcomes with most patients experiencing a nearly normal quality of life.

The echocardiographer when evaluating these surgical repairs should be careful to evaluate bi-ventricular function, outflow tract obstructions, baffle obstructions and any regurgitant valves.

Ken Heiden RDCS

HeartDefectsSimplified.com

Bicuspid Aortic Valve

2010-02-12T19:05:00.001-06:00

Abnormalities of the left ventricular outflow tract (LVOT) can occur at the subvalvular, valvular and supravalvular level and are some of the most common defects. They occur in about 5% of all children that have congenital heat defects and are also highly associated with other left sided lesions such as ASD's, AV Canal (endocardial cushion defect), VSD's and coarctation of the aorta. It is important also to evaluate the LVOT, aortic valve and aorta in children who have Down Syndrome (Trisomy 21).

The normal aortic valve is tricuspid (trileaflet), has sinus of valsalva apparatus that open the two coronary artery systems (right and left coronary arteries), and one leaflet that does not open to any coronary artery. These leaflets are named the right coronary, left coronary and non coronary leaflets.

An abnormal aortic valve may be unileaflet, bileaflet, or trileaflet with one fused leaflet otherwise known as raphe. It is important for the echocardiographer to evaluate the aortic valve appropriately and allow the reading physician to properly diagnose the particular aortic valve abnormality. This is best done in the parasternal short axis view, which also allows one to properly image the origins of the coronary arteries.

Bicuspid aortic valves may be mildly, moderately or severely stenotic, and may not be noticed until well into adulthood. A truly bicuspid valve is rare, whereas "bicuspid" valves usually demonstrate a trileaflet pattern with one fused leaflet (or raphe). A trileaflet valve with calcification is considered "aortic stenosis".

For the echocardiographer, first determine whether this is a subvalvular, valvular or supravalvular lesion. If it is valvular, then determine whether it is unileaflet, bileaflet or trileaflet. Visualize the raphe (if present). Evaluate the coronary artery origins and make sure they are not anomalous (see previous post for "anomalous coronary arteries"). Use Doppler to evaluate the gradient across the valve, and use the continuity equation to determine the severity of the stenosis.

Mild: 16 mmHg to 30 mmHg
Moderate: 30 mmHg to 50 mmHg
Severe: >50 mmHg

Do not forget to evaluate other left sided defects; Remember the adage "where there is one left sided defect, look for others". Look for AV canal, ASD's, VSD's, coarctation of the aorta, subvalvular and supravalvular defects and any discordant atrioventrular defects.

Ken Heiden RDCS
HeartDefectsSimplified.com

D-Transposition (Complex Transposition) of the great Arteries

2010-01-14T01:18:00.011-06:00

click image to enlarge

Note: it is highly advisable to read my posts on morphology and the segmental approach to congenital defects in order to better understand from an embryologic point of view why these defects form.

Transpositions are the most confusing of the heart defects, and for many sonographers the hardest to understand. There are two types of transpositions: L- type (or corrected, typically non-cyanotic transpositions), and D-types which are usually cyanotic. This post will concentrate on the D- types.

There has been so much controversy and discussion within the medical field as to how best describe and classify this defect over the years.

For example; D-transpositions have typically been used to describe discordant or “switched” great arteries with respect to the ventricles, while describing the aorta as being in an anterior and rightward position to the pulmonary artery (hence the term “D” or dextra meaning “right” in Latin).

Unfortunately, this does not adequately describe all of the variants to this defect. As a result, the approach that is now favored is to describe the structures in a segmental fashion (see my previous blog on the "segmental approach").

In other words, it is best to describe the various four segments of the heart independent of each other: the arterial trunk and their attached valves as well as the great veins, the atria, the ventricles, and the atrioventricular valvular apparatus (AV valves, or mitral and tricuspid valves). It is best to describe each segment separately and then to describe their particular relationships to each other.

Embryologically, the trunk begins as a single tube that attaches itself via the conus to the primitive atrioventricular apparatus at the crux, or center of the heart. This tube begins to septate, or separate into two tubes that will eventually become the aorta and pulmonary artery. This primitive tube will twist rightward while the semilunar valves develop. Under normal circumstances, the aorta will attach to the left ventricle, and the pulmonary artery will attach to the right ventricle.

If this process fails to complete itself, then transposition may occur.

There are numerous sub-types to these defects that primarily involve transposition of the atria, further transposition of the ventricles that involves the aorta being attached to the right ventricle (RV), and the orientation of the infundibulum (right ventricular outflow tract) as it relates to the position of the aorta. That will not be discussed here. For the sonographer, determining transposition of the atria is not easy unless a TEE is done and does not really affect the essential circulatory patterns that will be discussed. Locate the infundibulum if possible, and be sure to identify the morphologic ventricles.

First, let’s examine the terminology:

Morphologic: anatomically correct structure irrespective of its location.

Concordant: structures attached appropriately to each other.

Discordant: structures that are not appropriately attached to each other.

Atrioventircular: the junction between the atria and the ventricles.

Ventriculo-arterial: the junction between the ventricles and the great arteries

Venoatrial: the junction between the veins and the atria.

For example; a concordant atrioventricular junction means that the morphologically correct atria are appropriately attached to their morphologically correct ventricles.

By using the systematic approach, it is possible to properly describe all of the variants in all types of transpositions.

D-transposition of the great arteries (D-TGA) usually refers to a defect in which there is concordant atrioventricular connections (the right atrium is appropriately attached to its' morphologic right ventricle with an intact tricuspid valve, and the left atrium is attached to its' morphologic left ventricle and an intact mitral valve), but there are discordant ventriculo-arterial connections.

This is not always true, but is typical of this defect. ("L" transpositions, or "corrected" transpositions will be discussed in another blog).

In other words, the atria and ventricles are normally situated but the aorta and pulmonary artery are "switched". The aorta arises from the right ventricle (usually with an intact infundibulum) and the pulmonary artery arises from the left ventricle. This configuration dramatically alters circulatory patterns in the body.

Keep in mind that the aortic and pulmonic valves typically follow their morphologically correct arteries, and the mitral and tricuspid valves typically follow their morphologically correct ventricles (the RV is the trabeculated ventricle).

Incoming systemic venous blood flow (low SaO2) from the vena cavae enters the right atrium, passes through the tricuspid valve to the right ventricle but is ejected through the aortic valve and aorta to feed the systemic circulation. Meanwhile, incoming pulmonary venous flow enters the left atrium, passes through the mitral valve to the left ventricle and is ejected back into the lungs via the pulmonary artery.

This means that there is no communication between the systemic and pulmonic circulations that allows intracardiac mixing of oxygenated and deoxygenated blood.

This defect is fatal unless the two circulatory patterns somehow mix.

In most cases, the requisite mixing occurs through one or more of the following associated defects:
PDA, the naturally occurring shunt between the aorta and pulmonary artery
ASD, the shunt between the right atrium and left atrium
VSD, a shunt between the right and left ventricles

It is imperative to the neonatologist that these shunts be kept open in order to preserve the life of the neonate until surgical intervention is done, usually within the first few weeks after birth. This can be done using drugs such as prostaglandins, which keep (especially) the PDA open.

For the sonographer, these tips will help you identify this lesion.
1) The aorta and pulmonary artery will arise parallel to one another, rather than perpendicularly. This is best visualized in the parasternal long axis view
2) Carefully evaluate coronary anatomy. Anomalous coronary arteries are common.
3) Evaluate the outflow tracts for obstructions
4) Carefully evaluate the PDA and/or ASD's or VSD's. VSD's are typical and may be maligned or override one or the other great arteries, thus creating an outflow obstruction. Muscular defects are common. VSD's and PDA's may provide the only intracardiac mixing fo pulmonary and systemic blood flow.
5) Carefully image the aortic arch. Is it right sided or left sided?
6) Anomalous coronary arteries are common. In 2/3 of patients, the coronary arteries originate normally from the two sinus' of valsalva, but their course through the ventricle may be aberrant. There is no predicting this configuration.

Do not confuse this defect with Tetralogy of Fallot, or Double Outlet Right Ventricle and L-transpositions.

Surgical repair of this defect is discussed in another post.

Ken Heiden RDCS
HeartDefectsSimiplified.com

The Systematic Approach to Pediatric Imaging for Sonographers

2010-01-12T07:28:00.012-06:00

There is no doubt about it, this is a tough specialty to break into. There are very few schools that teach pediatric ultrasound and most sonographers learn this specialty on the job, usually at a Children's Hospital or at a facility that has an NICU.

Before you continue with this particular blog, it would be very helpful to read my previous posts, four in total on embryology and morphology of the pediatric heart. Further, there is another post regarding the particular views that you need to become familiar with in order to complete an echocardiogram.

For the newcomer, don't panic the first time you begin imaging a complex defect. Even for the experienced sonographer, using a systematic approach to imaging will allow you to make a competent evaluation of just about any situation you may run into. Many sonographers make the mistake of trying to memorize every defect (and there are a lot of them). The systematic approach to imaging makes the process of diagnosis much more logical and far easier to understand.

What is the systematic approach to imaging?
Ask the nurse or neonatologist what they are looking for. Is the neonate premature or full term? Look at the SaO2 levels; do they fluctuate wildly or is the neonate cyanotic? If the SaO2 levels fluctuate then you are likely looking for a PDA. If the neonate is cyanotic then you are likely looking for a complex defect or severe pulmonary hypertension.

Have blood pressures been taken? If the arm pressures are significantly higher than ankle pressures then look for a coarctation of the aorta. If the SaO2 levels are significantly different between the upper and lower extremities then this will accomplish the same goal as blood pressures.

Quickly scan the neonate in several different views. You are really just looking to see if all of the structures of the heart are present and connected to each other appropriately. If everything is there and hooked up properly then you are just looking for ASD's, VSD's or a PDA.

The systematic approach involves dividing the heart into sections: The atria, the ventricles, the AV valve apparatus, the trunk (semi lunar valves and the great arteries) and the great veins (cavae and the pulmonary veins).

Look at these structures one at a time. Are there two atria? Are there two ventricles, or one primary ventricle (single ventricle syndromes). Which ventricle is the right ventricle and which one is the left ventricle. The right ventricle is the most trabeculated. If the ventricles are transposed then this is an L-transposition. Are the atria and ventricles attached properly?

Look at the AV valves carefully. Generally, three things happen to the AV valves, the annulus and the connecting apparatus (papillary muscles and their attachments). There may be two normal valves, or one valve may override the interventricular septum and the other may be hypoplastic (double inlet syndromes), or there may be a single overriding valve with multiple merged leaflets (AV canal, provided there are septal defects at the crux or center of the heart).

Furthermore, If the tricuspid valve is immature and does not completely form, then this is Ebstein's malformation. Mitral stenosis is possible, but rare. Cor triatriatum involves a membrane present in the left atrium that prevents blood draining the pulmonary veins from reaching the mitral valve and may be mistaken for mitral stenosis.

Evaluate the trunk. Does the aorta attach to the left ventricle and the pulmonary artery attach to the right ventricle? If they are transposed then this is a D- transposition. If the semilunar valves are not fully formed and separated, and the great arteries override the ventricles then this is a truncus arteriosis. If both of the semilunar valves originate from one ventricle, this is a double outlet syndrome.

Keep in mind that the semilunar valves tend to follow their respective ventricles (aortic valve attaches to the aorta, and the pulmonic valve attaches to the pulmonary artery), and the AV valves tend to follow their respective ventricles (mitral valve attaches to the left ventricle and the tricuspid valves attaches to the right ventricle).

It is also important to evaluate the coronary arteries. Do they arise from the aorta normally? Do one of the coronary arteries arise from the pulmonary artery? If there is an abnormality then this is anomalous coronary artery syndrome.

Finally, look at the great veins. Are the cavae attached to the right atrium and the pulmonary veins attached to the left atrium? If the pulmonary veins do not attach properly, then this is anomalous pulmonary veins (complete or partial).

If you take this approach you may not be able to name the defect, but you will at least be able to describe the various structures and their connections.

Once again, take the time to read the posts on this blog concerning embryology and morphology. If you have a good understanding of why the heart becomes malformed, then you are way ahead of the game.

Ken Heiden RDCS

HeartDefectsSimplified.com
mwechopeds@aol.com

CME'S: Do You Need Continuing Medical Education Credits for Echocardiography?

2010-01-04T14:32:00.002-06:00

30 CME's Available!

Everyone is always looking for ultrasound CME's whether you are a sonographer, or more recently a cardiologist who reads echocardiograms for an accredited laboratory.

As an ARDMS registered ultrasonographer, you are required to maintain 30 CME's every three years (triennium) or 10 CME's per year in order to fulfill your personal license requirements. This license requirement is especially important in order to maintain an ICAEL accreditation. Within the next two years, if your ultrasound laboratory is not ICAEL accredited, then you will not receive reimbursement from either private insurance or government programs. As it is, many private insurance companies now require pre-authorization for echocardiograms. If you are not ICAEL accredited, good luck.

Cardiologists who read echocardiograms are especially vulnerable to these new regulations since so many of them fulfill their CME requirements in invasive specialties (such as the cath lab or surgery). Cardiologists who read echos in any particular laboratory must now maintain at least 15 echosonography related CME's every three years in order to maintain ICAEL accreditation. Once again, these CME's must be related to the field of echosonography.

There are many ways to fulfill your CME requirements.

An example would be to join SDMS (Society for Diagnostic Medical Sonographers, SDMS.org). They offer CME's on their website providing that you are a member. The downside is that many of their CME's are general ultrasound. The American Society of Echocardiography (ASE.org) is another good resource.

The ICAEL requirements are causing many in the cardiology related fields to scramble, since licensing requirements have been lax for so many years now.

An excellent solution to this problem is to engage in an online interactive course in pediatric ultrasound using the tools available in this blog.

Simply log on to the link on this website "HeartDefectsSimplified.com", purchase the book "Congenital Heart Defects Simplified" and take a 300 question online review in order to receive 30 CME's. This is enough CME's to fulfill three years worth of educational requirements.

The cost is less than $200.00 US and is at least one fifth of what you would pay to attend a week long conference in order to obtain the same amount of CME's.

This open book test allows you to fulfill your CME requirements without leaving your house.

Congenital heart defects is the up and coming field in cardiology. There are now one million patients out there who have had congenital heart repairs, and as adults are now showing up in adult echo labs for routine echos.

It can only benefit you as a sonographer and a cardiologist to be aware of these defects and to be able to at least make a preliminary diagnosis.

The free test (for students) is currently available, and for those seeking SDMS CME's, this will be available Jan 31, 2010.

Once again, the website is HeartDefectsSimplified.com

Thanks

Ken Heiden RDCS

Cor Triatriatum

2009-11-13T17:15:00.002-06:00

Cor triatrium (triatrial heart, subdivided left atrium) is a defect that is characterized by a membrane in the left atrium that prevents incoming blood flow from the pulmonary veins to completely empty into the left ventricle. As a result of this obstructive membrane, pulmonary venous blood flow will drain into the left atrium and be diverted to the right atrium via an ASD.

This defect is the result of incomplete absorption of the common pulmonary vein during embryological development of the fetus.

Typically, the defect is located inferior to the pulmonary veins with an associated ASD that allows left sided atrial blood flow to be diverted to the right side of the heart. The membrane may completely or partially obstruct the left atrium and may resemble the defect of "anomalous pulmonary veins".

There is usually a VSD that allows the diverted blood flow to find it's way to the left side heart via this communication.

Echocardiography:
1) Evaluate the severity of any shunts.
2) Document all pulmonary venous inflow in order rule out anomalous pulmonary venous inflow.
3) The membranous portion may only block pulmonary venous inflow partially. Do not confuse this defect with "Partial Anomalous Venous Return". This defect tends to be an ASD.
4) Do not confuse this defect with mitral stenosis.

Surgical Repair
The obstructive membrane in the left atrium is excised and the ASD and VSD are repaired. The shunts are typically repaired with homographs.

Ken Heiden RDCS, RVT
heartdefectssimplified.com

Coarctation of the Aorta (CoA) and Interrupted Aortic Arch

2009-11-07T04:14:00.006-06:00

Coarctation of the aorta (CoA) describes a discreet narrowing of the aorta just proximal to the descending thoracic aorta at about the level of the left subclavian artery, in an area known as the "aortic shelf" which is near the insertion of the patent arterial duct (PDA or patent ductus arteriosus). This defect ranges in severity from mild to severe and may present few symptoms at birth.

CoA accounts for about 7% of children born with congenital heart defects with an overall incidence of approximately 1 in 12,000 of all live births.

CoA is typically detected in the newborn when blood pressures are done on all four limbs. Leg pressures will be significantly lower than arm pressures (a difference of greater than 10 mmHg). This narrowing of the aorta will result in lower blood pressures distal to the defect, and may be described as mild, moderate or severe. Any pressure gradient across the defect greater than 16 mmHg is considered abnormal.

CoA is best evaluated by echocardiography in the suprasternal position. The echocardiographer should always evaluate the thoracic aorta as carefully as possible. Position the probe with the notch facing towards the left shoulder. You should be able to image the entire thoracic aorta including the shelf area. Always use color doppler, pulsed wave and continuous wave doppler to evaluate the any abnormal gradient across the shelf. Any gradient larger than 16 mmHg is considered abnormal.

In the long axis subcostal view, the sonographer should evaluate the abdominal aorta and the inferior vena cava. If the aorta is pulsatile, there is probably not a coarctation proximally.

Where there is one left sided defect, there are often others. For example, always look for a CoA if an atrial septal defect (ASD), ventricular septal defect (VSD) or aortic valve abnormalities such as bicuspid aortic valve, stenotic and/or subvalvular stenosis are found. Right aortic arch and anomalies of the arch vessels e.g. the subclavian arteries may also exist.

Correctly evaluating the patent ductus arteriosis (PDA) is important. The ductal arch may be so large as to appear to be the aortic arch. It is important to not confuse the ductal arch with the aortic arch. The aortic arch will have three vessels that emerge from it: the brachiocephalic, left carotid and the left subclavian arteries. The ductus however, is one single vessel that connects the left pulmonary artery to the aorta.

If the PDA is very large, look for an interrupted aortic arch. Interrupted aortic arch is really the most severe form of CoA. This condition exists when the ascending aorta is separated from (discontinuous) with the descending thoracic aorta where the PDA provides the only connection between the two segments.

Surgical Repair
The preferred repair for both CoA (and interrupted aortic arch) involves the resection of the coarcted portion of the aorta. The two ends of the aorta are then sutured together in a procedure known as an "end-to-end anastamosis." If there is a PDA or a VSD, they will be closed.

A synthetic patch or a homograft may also be used to correct this defect, but this elevates the risk for aortic aneurism later in life as the aorta grows.

In the past, a portion of the left subclavian artery (LSA) would be excised and divided, and used for the repair. This type of homograft carries with it a low rate of rejection and recurrence of CoA, but the loss of the LSA will result in a loss of blood supply to the left arm.

A CoA may also be a "hidden" defect in the presence of a PDA. The surgical repair of a PDA is a minimally invasive procedure in which a catheter type of device is inserted into the thorax and the PDA is sutured shut. In some cases, CoA may develop post-operatively even if one was not present prior to ligation. Whenever a PDA ligation is done, a second echocardiogram should be done in order to rule this out.

Keep in mind the possibility of a right aortic arch. This is an aorta that instead of curving leftwards as it emerges from the heart, will develop in a rightward direction. If you cannot see the aorta with the notch on the probe pointed towards the left shoulder, try pointing the notch towards the right shoulder. This may facilitate this view.

In conclusion, the sonographer should always image and evaluate the aorta as completely as possible. The reading cardiologist will often send you back to look at the aorta more completely if this is not done properly the first time.

Ken Heiden
www.HeartDefectsSimplified.com

Branch Stenosis

2009-11-06T18:22:00.004-06:00

Branch Stenosis
Branch stenosis is an extremely common defect especially in premature neonates, but it is common in full term infants as well.

As an echocardiographer, you will see this condition in many of the neonates you examine. Branch stenosis usually happens as a result of pulmonary hypertension (PHTN), which occurs when there is volume or pressure overload of the right-sided circulation (right ventricle and the lungs). In a full term or premature neonate with a normal heart, the persistence of the normally occurring fetal shunts, the PDA and the PFO are usually the cause.

The PDA (patent ductus arteriosis) and PFO (patent foramen ovale) are normally occurring right to left shunts that are present in fetal circulation. Since the fetus does not breathe, all right-sided (pulmonary) flow is diverted to the left side of the heart prior to birth. After a normal birth, these shunts should become left to right.

The PFO is essentially an atrial septal defect that diverts blood flow from the right side of the heart prior to birth to the left side of the heart. The PDA diverts blood flow to the left side of the heart through a naturally occurring channel from the pulmonary artery to the aorta. Once an infant is born, these shunts will become left to right as the infant begins to use its lungs, and will stay open for a day or two until they naturally close.

Occasionally, these shunts remain open (patent) especially in a premature neonate with large shunts or a complex congenital defect.

Branch stenosis is typically a response by the body to reduce pulmonary pressure by using "vaso-constriction;" i.e., it is a physiologicic response in the branch pulmonary arteries to close down or constrict in an effort to reduce pressure distally. Branch stenosis will usually resolve in the first few days after birth if the underlying cause is resolved (the PDA and the PFO close).

Typically, it will be the PDA that does not close. If after several days, the PDA has not closed the neonatologist may perform a minimally invasive procedure that involves cutting a slit in the chest and using a catheter to suture the PDA. This significantly reduces volume overload in the pulmonary circulation and allows the neonatal heart to normalize circuation. Pulmonary stress is reduced, SaO2 levels increase, and the infant breathes easier.

A "Pulmonary Artery Band" is a minimally invasive device that is implanted onto the main pulmonary artery in order to alleviate high pulmonary pressures. This is a mesh type of device that wraps around the main pulmonary artery and is systematically closed untill pulmonary pressures are normalized. This device is often used in more complex defects, and can be removed at any time.

It is the job of the echocardiographer to evaluate pulmonary pressures accurately, and to determine if one or both of the pulmonary arteries, or even the main pulmonary artery, is involved. In addition, any complex defects must be ruled out.

For instructions on how to evaluate pulmonary pressures, especially right ventricular systolic pressure (RVSP), please see my previous blog on this subject, and consult my book "Congenital Heart Defects, Simplified."

Ken Heiden RDCS
http://www.HeartDefectsSimplified.com

Ebsteins Malformation of the Tricuspid Valve

2009-10-18T16:15:00.008-05:00

Ebsteins Malformation is a typically cyanotic deformation of the tricuspid valve in which one, two or the three leaflets of the valve fail to develop completely.

In the first few weeks of cardiac embryologic development, the three leaflets of the tricuspid valve including the tension apparatus (papillary muscles and the chordae) will emerge from the primordial spongy myocardium and move superiorly until they coapt with each other where they will form a sealed valvular unit.

Under normal circumstances, if the leaflets coapt, then the spongy myocardium will continue to trabeculate until the ventricle becomes more and more elastic, especially as the ventricle is in diastole or its filling stage. This is known as diastolic filling.

If the leaflets of the tricuspid valve fail to grow normally, and some or all leaflets continue to be attached to the myocardium, then right ventricular function becomes severely compromised.

The right ventricle will become "atrialized", in that the right ventricle is almost closed by the defect.

The severity of Ebstein's malformation will depend upon the degree of right ventricular outflow dysfunction and valvular insufficiency. There will usually be an ASD (atrial septal defect with right to left shunting). Cyanosis is common due to right ventricular failure.

The object of surgical repair will be to re-establish normal pulmonary flow.

Surgical Repair
If the valve leaflets are well developed, then repair of the valve structure is the preferred method. If the valve leaflets can not be repaired, then a prosthetic valve may be used.

In the past, a tricuspid valve "patch" would have been used to close the TV orifice and a Blalock-Taussig shunt (a connection between the brachiocephalic artery and the right pulmonary artery AKA "BT shunt") would be used. The purpose of a BT shunt is to increase pulmonary flow, and may be used as a palliative procedure before a more complex surgery is performed.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

The Arterial Trunk: Morphology of the Pediatric Heart: How to Identify the Various Structures of the Heart in the Presence of Congenital Heart Disease, for Echocardiographers. Part Four

2009-10-18T10:21:00.009-05:00

The Great Arteries
It is advisable that you read the first three installments of this series for important background information. As an echosonographer, the ability to identify the various structures of the heart is critical if you are going to provide adequate information to both the pediatric cardiologist as well as the pediatric surgeon.

Which atria connect to which ventricle? Which ventricles connect to each great artery? What types of venous connections are there? The best way to do an echo is to take each structure one at a time, identify that structure and determine where that structure begins and terminates.

Embryologically, the great arteries (pulmonary artery - PA, and the aorta - AO) begin as a common trunk that is attached to the ventricular mass with a "ring" of tissue that will later form the truncal cushions of the semilunar valves. This primordial trunk will begin to septate, or begin to form two separate arteries that twist rightward (d-looping) until the appropriate arteries merge with their respective ventricles.

If the venous connections are normal (inferior vena cava - IVC, superior vena cava - SVC and, the pulmonary veins), connecting to the appropriate atria, and the atria connect in a normal fashion to the appropriate ventricles, but the AO and PA are "switched" or transposed, this is a d-transposition of the great arteries.

If the venous connections are normal and connect to the heart appropriately, but the ventricles are transposed, this is known as an l-transposition, or "corrected transposition."

Four things may happen to the arterial trunk. These are known as "truncus arteriosis defects."

Truncus Arteriosis Defects
Where there are a two fully septated arteries that connect normally to the ventricular mass, this is a normal configuration.

There may be a "merged" PA and AO (common trunk) or a PA and AO that override a two ventricle structure with an incomplete ventricular septum (a large primum VSD). In this presentation, the semilunar valves also merge into a multi-leaflet common valve that may have two, three, four, or five leaflets. Most commonly, the valve is a four leaflet type of valve.

There may be a single truncal artery (typically of aortic morphology) where the pulmonary arteries arise distally from the aortic valve apparatus in the ascending or descending portion of the truncal artery with a large primum VSD.

There is a fourth type of configuration in which there is a common arterial trunk where the aortal portion is separated from the pulmonary artery, but connected by a PDA (patent ductus arteriosis) and a large primum VSD. This is known as a truncus arteriosis with an interrupted aortic arch.

Further adding to the mix, there may be a right sided aortic arch or left sided (normal) aortal aortic arch.

As an echosonographer, you must identify all of the structures of the heart: the atria, ventricles, venous connections and the type of truncal connections present. Further, you will need to identify the number of leaflets present in the semilunar valve apparatus, whether the arch is right or left sided, and where the pulmonary artery connections arise.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

The Ventricular Mass: Morphology of the Pediatric Heart: How to Identify the Various Structures of the Heart in the Presence of Congenital Heart Disease, for Echocardiographers. Part Three

2009-10-16T17:45:00.004-05:00

The Ventricular Mass
The ventricles are identified as a "mass", since in their embryologic development many things may happen to this structure. There may be two discrete ventricles divided by and intact septum, or there may be one dominant ventricle with one hypoplastic ventricle (typically a hypoplastic LV), or there may be a sinlgle ventricle (rare).

If you have read the previous blogs, you will see that the atria may develop seperately from the ventricles and be concordant, discordant or isomeric.

In other words, the left atrium may be attached to the left ventricle and the right atrium may be attached to the right ventricle (concordant),or the atria may be dicordant in that the RA is attached to the LV and the LA is attached to the RV, or they may be isomeric in that there may be two morphologic right or left atria attached in any way.

Typically, each atrioventricular valve, mitral valve (MV), tricuspid valve (TV) will follow its respective ventricle MV to left ventricle (LV), TV to right ventricle (RV) , and each semilunar valve will follow its respective great artery connection, aortic valve to aorta, pulmonic valve to pulmonary artery.

Embryolically, the ventricular mass is known as the "spongy myocardium". On the right side, the tricuspid valve, the papillary muscles and the chordae emerge from the spongy myocardium and grow superiorly until the three cusps of the tricuspid vave coapt into a fully functioning valve apparatus.

The spongy myocardium eventually develops into a trabeculaed structure that allows the ventricle to become more and more elastic. In other words, it becomes a structure that is more compliant during diastole (the ability to relax in diastole).

If the tricuspid valve leaflet apparatus fails to seperate from the "spongy myocardium", this results in a defect known as "Ebstein's Malformation."

A true univentricular heart is rare. This means that there is one ventricle. Typically, there is one dominant ventricle and one hypoplastic ventricle.

If there is a hypolplastic ventricle, then there is often an underdeveloped ventricle, AV valve and outflow valve (very often left ventricle, aorta, and mitral valve), otherwise known as a hypoplastic left heart syndrome (HLHS).

There may be a dominant ventricle with two inlet AV valves that drain into one ventricle. This is known as a "Double Inlet" defect. If there are two outlet valves with one dominant ventricle, this is known as a "Double Outlet" defect.

The 50% rule applies to all valves. If the particular valve crosses over any septum greater than 50%, then it overrides.

For instance, If the interventricular septum is to the left of both AV valves, the MV and TV, then this valve may be a double inlet defect in that both atria drain into one ventricle via the AV valves.

As an echocardiographer, it is important to visualize each structure in its entirety. The atria are not that easy to differentiate, but pay particular attention to the ventricles. The right ventricle is more trabeculated.

If the great arteries are parallel, then this may be a transposition. If the great arteries are perpindicular to each other, then the ventricles and the great arteries are probably normally related.

Evaluate the size of the ventricles. Which artery is connected to which ventricle? Where are the vena cava and pulmonary veins connected?

Take all of these into consideration as you evaluate the pediatric heart.

Ken Heiden, RDCS, RVT
www.HeartDefectsSimplified.com

The AV VAlves: Morphology of the Pediatric Heart: How to Identify the Various Structures of the Heart in the Presence of Congenital Heart Disease, for Echocardiographers. Part Two

2009-10-09T18:00:00.004-05:00

(See part one of this series for an appropriate introduction.)

As explained in part one, it is best to divide the heart into three sections- the atria, ventricular mass, and the outflow arteries. For the echocardiographer, it will alleviate much anxiety to evaluate the heart in this way, identifying each structure of the heart in a systematic and organized way.

As far as the atria and the ventricles are concerned, there may be concordance (the atria attach to their respective ventricles), there may be discordance (the atria do not attach to their respective ventricles) which means that either the ventricles or atria are transposed, or both are transposed.

There are also single atrium and single ventricle syndromes in which the morphology of these structures are either right or left oriented.

The morphology of the AV valves (mitral and tricuspid) are independent of the atrioventricular attachments and there are a variety of ways that the AV valves may present.

In a normal heart where there is a biventricular and biatrial arrangement or where there is discordance and transposition with biventricular arrangement, the AV valves will always follow their respective ventricles. In other words, anytime there are two ventricles and two AV valves, the tricuspid valve (TV)will always be attached to the right ventricle (RV) and the mitral valve will always be attached to the left ventricle (LV).

There are four typical configurations for the AV valves. All of these arrangements can be found with concordant, discordant, biventricular, mixed and double inlet types of connections of the atria and ventricles.

The first type is the concordant, or a normal configuration (described above). The second type is a two valve structure where one valve is imperforate or atretic. The third type is a common valve that overrides or straddles the ventricular septum and the fourth type is a single valve of right or left sided morphology that overrides or straddles the venticular septum.

A double inlet defect would be a two valve structure in which one of the valves straddle the ventricular septum and therefore both atria tend to drain into the dominant ventricle. Most often the dominant ventricle is the left ventricle.

A single valve may override the ventricular septum. This valve may be of right or left morphology. There is typically a biventricular arrangement; papillary muscles and the cords tend to attach to both ventricles rather than on just one side of the heart.

If there is a common valve, then it is not possible to determine if there is a right or left sided morphology to the valve structure. It is incorrect to consider the common valve as having mitral or tricuspid components. Even in the case of double inlet defects, it is best to describe the valves as just right sided and left sided as opposed to identifying them as a tricuspid or mitral valve.

A common valve configuration is really an endocardial cushion defect, absent the septal connections that seperate the right and left hearts. A true AVSD or atrioventricular septal defect with an overriding common valve is the hallmark of an endocardial cushion defect.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

The Atria: Morphology of the Pediatric Heart: How to Identify the Various Structures of the Heart in the Presence of Congenital Heart Disease, for Echocardiographers. Part One

2009-10-06T15:03:00.007-05:00

If you are an adult sonographer transitioning into the field of pediatric echosonography, you will quickly learn that knowing the didactics of various pediatric defects is just the tip of the iceberg. There are about 30 major defects and numerous less major defects, and all of these defects may occur in conjunction with each other e.g. double outlet right ventricle with d-transposition, or pulmonary atresia with or without ventricular septal defect.

Just adding to the confusion, pulmonary atresia with septal defect in certain circumstances may be be considered a severe type of tetralogy of fallot.

Do not panic! If you are new to this field I will try to give you some tips on how to make your ultrasound scan professional and readable to a pediatric cardiologist.

Your job is to identify each structure of the heart and determine flow dynamics. You do not diagnose the defect involved, but if you perform your job correctly, you will enable the cardiologist to diagnose the echocardiogram appropriately.

For the typical echocardiographer (unless you work at a childrens hospital), you will be evaluating PDA's (patent ductus arteriosis), ASD's (atrial septal defects), VSD's (ventricular septal defects), or pulmonary hypertension most of the time. When a complex defect occurs, take a systematic approach to the heart, and you will do just fine.

A systematic Approach to Imaging
Divide the heart into three sections. The atria and all of its venous connections; the "ventricular mass" or the ventricular section of the heart that may be one or two ventricles where one ventricle may be hypoplastic and one dominant; the arterial outflow portion which may consist of an independent aorta and pulmonary artery, or a common arterial trunk in which the aorta and pulmonary artery are merged, or an aortal trunk in which the pulmonary ateries derive from this structure.

Atriums
It is not easy to identify the right atrium from the left atrium via transthoracic echo. It is much easier with TEE (transesophageal echo). Do not assume that if the cavae flow into an atrium that it is the right atrium. By the same token, do not assume that if the pulmonary veins drain into an atrium it is the left atrium.

For example, in the case of total anomalous pulmonary venous return, the pulmonary veins drain into a "confluence", or large truncal vein that will drain into the right side of the heart at some point.

The right atrium is differentiated from the left based on the atrial appendage.

The right atrial appendage is a large "triangular" shaped structure with pectinate muscles that surround the orifice. The left atrial appendage is a smaller, tubular shaped structure.

The atria may be "concordant" with their particular ventricles (RA to RV, right atrium to right ventricle, LA to LV, left atrium to left ventricle), they may be a "mirror image" or transposed, or they may be "isomeric" which means that there are two right atria in one presentation, or two left atria in another presentation.

Most frequently, the RA and LA are positioned normally, and the AV valves and the RV and LV are positioned abnormally. It has been my experience that the AV valves tend to follow their respective ventricles (MV to LV, TV to RV.)

What Does All That Mean?
Typically, the RA and LA are positioned normally. Unless you do a TEE, as an echocardiographer it would be very difficult to tell the RA from the LA.

Pay more attention to the AV valves (mitral and tricuspid valves) and the ventricles.

There might be an absent TV valve, absent MV valve or an overriding single valve (endocardial cushion defect), along with any configurations of the ventricle: dominant LV (most frequently 80%), or a dominant RV, or rarely a true single ventricle.

Further, there may be a double inlet type of AV valve configuration, in which the AV valves drain into one ventricle.

As an echocardiographer, evaluate the pulmonary vein connections, the venae connections and document them. Determine whether there are two ventricles. If one is hypoplastic, try to determine which one is dominant. The LV is often dominant. The RV is a very coarsely trabeculated chamber.

Where is the outflow going? Determine which outflow artery is the aorta, and which one is the pulmonary artery. The aorta is typical in appearance and has the brachiocephalic, left carotid and left subclavian arteries that arise from it. The pulmonary artery has two large branches, the right and left pulmonary arteries that arise from it.

Do not confuse the "ductal arch" or the PDA with the aortica arch. The PDA is often so enlaged that it may look like the aortic arch. The ductal vessel is singular, and has no other arteries that arise from it.

It is important that you take a systematic approach to any echo scan. The normal heart has four chambers, four valves and eight blood vessels that run in and out of it. Evaluate each chamber and vessel, and do it in a coordinated approach.

Which is the right ventricle, and which is the left ventricle? Which outflow arteries are attached to which ventricle? Where do the cavae drain? Where do the pulmonary veins drain? Are there two outflow arteries (aorta and pulmonary artery)? Is there a PDA? Is there an ASD? Is there a VSD?

Take it one step at a time and you will do a very nice echocardiogram.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

How to Measure Right Ventricular Systolic Pressure (RVSP) for Echocardiographers

2009-10-04T16:32:00.005-05:00

As a pediatric echosonographer, pulmonary hypertension is one of the most common problems that you will encounter, especially in babies born prematurely.

Systemic hypertension occurs when blood pressure is abnormally high in the aorta and its branches (left sided circulation). This pressure is obtained with a blood pressure machine and a cuff. Pulmonary hypertension occurs when there is abnormally high blood pressure in the pulmonary artery and its branches (right sided circulation). This pressure must be obtained in a more indirect way.

Most premature neonates (born before the normal gestational age of 40 weeks) will have pulmonary hypertension (PHTN), since the lungs are the last organs of the body to fully develop. Any other congenital defects in which blood flow is abnormally shunted from the left side of the heart to the right side of the heart are contributing factors. Any time a significant amount of blood shunts to the right side of the heart, volume and or pressure problems occur.

As an echocariographer, it is extremely important that the right ventricle is evaluated completely, and its pressure is measured accurately. RVSP may be measured in three ways:

1) Measure the tricuspid regurgitation gradient. This gradient is the difference in pressure between the right ventricle and the right atrium. Add 5 mmHg to the gradient to compensate for central venous pressure (not 10 mmHg as in adults). The result is the RVSP.

2) Measure the PDA (patent ductus arteriosis) gradient. The PDA gradient is the difference in pressure between the aorta and the pulmonary artery. Subtract the PDA gradient from the systolic systemic blood pressure. The result is the RVSP.

3) Measure the VSD (ventricular septal defect) gradient. Note: this is only possible if there is a VSD present. The VSD gradient is the difference in pressure between the right and left ventricles. Subtract the VSD gradient from the systolic systemic pressure. The result is the RVSP.

Examples
Where the systemic blood pressure is 75/35 mmHg, systolic systemic blood pressure is 75 mmHg, and central venous pressure is assumed at 5 mmHg:

Tricuspid regurgitation gradient (TRg)= 20 mmHg
20 mmHg (TRg) + 5 mmHg (CVP) = 25 mmHg (RVSP)

VSD gradient (VSDg) = 50 mmHg
75 mmHg (SBP) - 50 mmHg (VSDg) = 25 mmHg (RVSP)

PDA gradient (PDAg) = 50 mmHg
75 mm Hg (SBP) - 50 mmHg (PDAg) = 25 mmHg (RVSP)

The best way to measure RVSP is to use the tricuspid regurgitation gradient. Keep in mind that it is important to get a good regurgitant envelope. This is very important and it can not be understated. A partial envelope or just a "valve click" will not do.

Be sure to Doppler tricuspid regurgitation in as many views as possible. Always use the highest gradient obtained and try to make the continuous wave curser as parallel to flw as possible. It is extremely important to provide the pediatric cardiologist or the neo-natologist with an accurate assessment of right ventricular pressures, as these can be life or death situations.

It is not always possible to measure (RVSP). If you can not do the measurement accurately, then specify this on the worksheet.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

Glenn Shunt, AKA Hemi-Fontan Procedure

2009-10-02T05:17:00.002-05:00

The Genn shunt, or Hemi-Fontan, is a procedue that is generally used in a serious cardiac defect in which there is complete mixing of blood as a result of a complete failure of the heart to seperate the right heart function from that of left heart function. This would include single ventricle syndromes (univentricular heart), and tricuspid atresia.

Under normal circunstances, the right heart is seperated from the left heart. The heart is really two pumps, the right heart and the left heart. (See "normal heart" in this blog). The right heart pumps blood into the lungs, and the left heart pumps blood into the body. These two circulations are seperated from each other by the interatrial and interventricular septums, and the only time that these circulations meet is at the level of the pulmonary and systemic capillary beds.

Pressure is low on the right side, and pressure is high on the left side.

This pressure "gradient" allows blood to flow through the body. For instance, most veins are visible on the skin. Veins carry blood back to the heart after it has been used by the body. Pressure is very low, about 5-10 mmHg.

Veins carry low oxygen blood flow, about 70% SaO2. Arteries carry high oxygen blood flow to the cells of the body with high pressure, about 120 mmHg and oxygen levels of 99% SaO2.

Arteries have pulses (high pressure), and veins are very compressible (low pressure).

In the congenital heart in which there is complete mixing of the right and left sides, this means that the cells of the body can not get enough oxygen as a result of complete mixing of right and left heart function. tyipcal SaO2 levels would be around 85%, rather than the normal 99%.

What is a GlennShunt, or Hemi-Fontan?
The object of this procedure is to seperate right heart function from left heart function. This allows pressures and oxygen levels to normalize.

The defect that would require a Glenn Shunt is characterized by a "single ventricle" or a severely hypoplastic right or left or right ventricle, in which there is a complete mixing of blood. This also leads to severe pulmonary hypertension, or too high pressure in the right-sided circulation.

When there is a single dominant ventricle with complete mixing, the first step is to excise the pulmonary artery. All blood flow to the body is now provided by the dominant ventricle. The SVC or superior vena cava, the great vein that drains blood from the upper portion of the body is now attached to the right pulmonary artery. This now provides venous flow to the lungs.

A Fontan completion requires that the IVC or inferior vena cava be attached to the right pulmonary artery. The Fontan completion now seperates right and left sided circulation. The reason that this procedure is done in stages is to reduce trauma to the lungs by gradually adapting the body to it's new circulation patterns.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

What are the Views for a Pediatric Echo, and why are Some Views Inverted?

2009-09-13T20:05:00.124-05:00

The scanning protocols for a pediatric echo are very similar to an adult echo except that you will be adding several views to the mix.

For a typical lab, the views are obtained in the following order:

Parasternal long axis view
Use 2- D to evaluate the left ventricle (LV), left atrium (LA) and the aorta (AO). Use M-mode, usually measuring the LV only (depending on lab protocol). Use color to evaluate the entire interventricular septum and the left atrium especially for pulmonary venous flow. Tilt the probe inferiorly to see the right ventricular inflow view and use color to evaluate these structures. Maneuver the probe anteriorly to view the right ventricular outflow tract (RVOT), pulmonary artery (PA) and the right and left pulmonary arteries (RPA, LPA). Use color to evaluate for regurgitation and a patent ductus arteriosis (PDA).

Parasternal short axis view
From apex to base in 2-D and with color,image the pulmonary artery with color and doppler, show the branches of the pulmonary artery and doppler each branch.
Image the aortic valve including the cusps, the right coronary artery and the left main coronary artery and document their origins. Follow up with color. Image the tricuspid valve, RA, RV, venae cavae and the interatrial septum. Use color on the septum to document any ASD.

4-Chamber Long axis view (inverted)
Image all chambers and valves carefully, scan again with color, and use doppler to document flow across the valves. Use color to evaluate the pulmonary veins, venae cavae, the interatrial and interventricular septums.
Note: it is generally not necessary to image the 2,3 and 5 chamber views unless your lab speciefies these views.

Long axis sub-xyphoid view (not inverted)
Evaluate the abdominal aorta and the inferior vena cava.

Long axis sub-xyphoid view (inverted)
This will yield a four chamber view. Sweep the heart using color to evaluate the pulmonary vein connections, the interatrial and interventricular septums, and the venae cavae connections. The LVOT and ascending AO should also be seen, as well as part of the aortic arch.

Short axis sub-xyphoid view (inverted)
Sweep the heart using both 2-D and color and evaluate the chambers, valves, septums, RVOT, pulmonary valve and the branches of the pulmonary artery. If you angulate properly, you should be able to visualize in the same axis, the LVOT, aortic valve, ascending and thoracic aorta, and the aortic arch. This is known as the "candy cane view".

Long axis suprasternal notch view (not inverted)
Image the aortic arch, aortic shelf (where the pulmonary artery and aorta intersect) and the thoracic aorta. Demonstate the first three branches of the aorta (brachiocephalic, left carotid and the left subclavian arteries). Use color and doppler to evaluate for coarctation of the aorta.

Short axis suprasternal notch view (not inverted)
Image the main pulmonary artery and its branches using 2-D, color and doppler. This the best view to evaluate for branch stenosis and a PDA.

Why are some views inverted?

Pediatric Cardiologists and surgeons when looking at an echo will be making critical decisions as to the management of the baby, therefore the heart should be presented in its "anatomically correct" positions. In other words, the atria are superior (top of the screen), the ventricles inferior (bottom of the screen), with the right side of the heart to the left of the screen, and the left side of the heart to the right side of the screen. The only exception is the parasternal long axis view.

Anything can happen to a pediatric heart as it develops. The ventricles and great arteries may be switched. There may only be one ventricle. Valves may be absent or the great veins may be mal-connected.

The M.D. needs to know with certainty where the right and left sides are, as well as superior and inferior. This allows he or she to make appropriate decisions concerning the heart and to read the echo appropriately.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

Anomalous Coronary Arteries

2009-09-09T20:27:00.005-05:00

Anomalous coronary arteries is a defect that is very rare, but it is the one defect that makes the news in every newspaper about once a year or so.

"Marine Dies in Grueling Basic Training". "Football Star Dies During Intense Workout". "Track Star Dead Following Heavy Training".

Two years ago, in Milwaukee, a young female died after dancing all night, and collapsed after a very strenuous night out.

These are the headlines that you see the next day, and everyone wonders how this can happen. What really caused this death in a very young person may not be followed up in the media, but post-autopsy results often diagnose anomalous coronary arteries.

Coronary arteries feed the heart muscle with oxygen rich blood and emerge from the aorta at two points just above the cusps of the aortic valve, the right and left coronary cusps. Most simply speaking, the right coronary artery feeds the right side of the heart, and the left coronary artery feeds the left side of the heart. The word "anomalous" means "that which is irregular or deviates from the normal". Hence, anomalous coronary arteries are a defect that results when these arteries arise from their point of origin abnormally.

There are three primary types of anomalous coronary arteries, some of which need to be surgically repaired and others that typically do not get repaired. These defects may not identified early in life, but eventually symptoms will occur. These may include angina, cardiomegally (enlarged heart), ECG abnormalities that may resemble a myocardial infarction (heart attack), or congestive heart failure (CHF).

Left Main Coronary Artery Arising from the Pulmonary Artery
This is the most common defect among anomalous coronary arteries and requires surgical intervention. Since the left coronary artery arises from the pulmonary artery, this means that the coronary artery is being fed de-oxygentated right sided blood with oxygen levels around 70% rather than 99% in a normal artery. The right coronary artery emerges properly from the aorta an has normal oxygen levels.

Without proper oxygenation in the left main coronary artery, the entire left side of the heart is essentially "starved" for adequate perfusion.

The goal of surgical repair is to re-establish a proper 2-coronary artery system. Ideally, the left main coronary artery is detached from the pulmonary artery and re-attached to the aorta. If this is not possible, then an artificial "tunnel" (aortopulmonary window) is excised between the aorta and the pulmonary artery through the right ventricular outflow tract and completed with a patch. This re-directs normal blood flow from the aorta into the left main coronary artery.

Left Main Coronary Artery Arising from the Right Coronary Artery
This a less serious defect in that there is fully saturated flow in the left main coronary artery. However, if the left main coronary artery courses between the aorta and pulmonary artery, this may result in the coronary artery being "trapped", or compressed during physical exertion.

All arteries pulse, or dialate and contract with every beat of the heart. During exertion, this pulse is exaggerated, and this causes the trapped coronary artery to close up as the aorta and pulmonary artery expand and contract. The resulting lack of perfusion to the left side of the heart may cause chest pain, angina or even sudden death.

If surgical repair is required, it will involve using either the mammary artery or an intra-aortic tunnel to create an enlarged path of flow for the left main coronary artery between the aorta and pulmonary artery.

Right Coronary Artery Arising from the Left Main Coronary Artery
This also known as "single coronary artery". The vessel is fully saturated with oxygen and there is usually no surgical intervention unless the right coronary artery is trapped between the aorta and the pulmonary artery.

Surgical intervention is uncommon but would follow the same procedure outlined above if needed.

Tips for Sonographers
The coronary arteries are best visualized in the parasternal short axis view at the level of the aortic valve. Here the non, right and left coronary cusps of the aortic valve are seen. The left main coronary artery is usually well visualized as it arises from its origin at the level of the left coronary cusp of the aortic valve.

The right coronary artery is often more difficult to see, but if you angulate the probe slightly superiorly and rotate a little clockwise, the vessel can be seen originating from the level of the right cusp of the aortic valve. If you angulate properly, you can usually see several millimeters of the right coronary artery.

Don't be afraid to work with these angles as you move the probe around, and remember that these adjustments are very slight. As with all babies, you do not have the same limitations visualizing the heart as you do with adults. The rib cages of babies are very cartilaginous and the bones have not ossified yet, so it is easy to view the heart from many different locations and angles.

Experiment! Make up your own views. Move that probe around and look at these structures from many different angles.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

Simple Shunts for Sonographers

2009-09-04T16:47:00.019-05:00

Click image to enlarge

Simple shunts are the most common congenital heart defects. They include ASD's (atrial septal defects), VSD's (ventricular septal defects) and a PDA (patent ductus arteriosis). A subcategory of ASD's include a PFO or a patent foramen ovale.

All children who are born into the world with normal hearts have two naturally occurring shunts, a PDA and a PFO. The reason for this is that the fetus does not breathe, and he/she derives all of its nutrients and oxygen from the mother. Therefore the right side of the heart is essentially non-functional. All blood returning to the right side of the heart in the fetus is shunted across the PDA and the PFO into the left side of the heart. In fetal development, these are normal and the shunts are right-to-left.

Further, normal SaO2 levels in the fetus is about 75%. This is why the fetus is able to survive almost any complex defect until birth.

At the point of birth, the lungs begin to function and these two shunts will revert to left-to-right as blood flow normalizes and pressures in the right and left hearts convert to post-natal levels. Pressure in the right side of the heart is about 1/3 that of the left side under normal circumstances.

In the neonate, right ventricular pressure is about 25mm/Hg and pressure in the left ventricle (systemic blood pressure) should be about 75 mm/Hg.

How to Image Shunts

Keep in mind that all views in pediatric echo are imaged in the inverted view with the exception of the parasternal long and short axis views, and the suprasternal notch views. The reason for this is that when the pediatric cardiologist is viewing the echo, he must know that the heart is represented in its anatomically correct position. That is, right side to the left of the screen, and left side to the right of the screen. Superior is to the top of the screen, and inferior is to the bottom of the screen.

This is important since almost anything can happen when the heart develops a defect. The right or left hearts may be inverted, or the great arteries or veins may be inverted as well. Hence, the reader needs to know where "right and left" actually are.

In the parasternal views, use color to scan the entire ventricular septum. In the apical views, do the same. VSD's can happen anywhere in the septum, so you must scan them in multiple views to make sure you can see them.

Scan the interatrial septum in every view possible. Sometimes you may not actually see the ASD until the end of the echo (in the subcostal views).

Use the short axis view and move superiorly one or two rib spaces to view the pulmonary artery and its branches. This is where you will see the PDA. The PDA is a natural postnatal communication between the aorta and the left pulmonary artery.

Under normal circumstances, shunts will close within a few days after birth. If they do not, this is where the echo is necessary. The problem with shunts is that if they persist, this will cause more blood to flood the right side, increasing blood volume into the lungs, and in turn, compromising the ability of the lungs to transfer oxygen adequately.

In the case of a PDA that will not close, this will be closed surgically in a minimally invasive procedure that involves just stitching the communication the aberrant communication between the pulmonary artery and the aorta. This is usually done at the bedside.

ASD's are a little different. They tend to persist, even into adulthood, in about 5 to 30% of all births. If they are large and do not close, the cardiologist will close it using a catheter procedure and a rivet type device called a "septal occluder".

Sometimes they watch them with serial echocardiograms over a period of years. Whether it is a VSD or ASD, they often close naturally over time, often by puberty.

As an echocardiographer, if the neonate is being monitored, look at the numbers! What is the blood pressure? What are the SaO2 levels? If the SaO2 fluctuates wildly between 85 and 100, then this tells you right away that there is a shunt. In other words, oxygenated and deoxygenated blood are mixing.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

Passing the Registry Exams, for Songraphers

2009-09-01T19:11:00.006-05:00

How to pass a multiple choice test

Writing a multiple choice test is no easy task, believe me I've done it. A good test will present questions that are relevant to the subject matter that you are trying to learn, and present answers that nudge you in the direction that you are studying

I hate trick questions, and I hate questions that are asked that are not really relevant to the subject you are trying to learn. These questions are often plucked out of nowhere in the text, and you are left asking "what is this question all about?"

Welcome to the world of online CME's.

The registry tests on the other hand are pretty well written. If you have studied the subject, you are likely to pass the test.

A good test presents a question, and then requires you to think carefully about the answer. Further, you learn from answer that you have chosen. If a test is well written, then you learn about the subject. A good test wants you to pass, not fail.

To write a good test, the question cannot be ambiguous in any way. The answer cannot be ambiguous either. If a test is well written, then you can make the following assumptions:

1) Two of the answers will be completely false.
2) One of the answers will be pretty close to true.
3) There will be one completely true answer.

There are so many people out there that are so terrified of tests that they completely fall apart during the exam, even though they may know the material.

Rule #1: Just decide that you are going to take the test twice and that you are going to fail the first time. During the first test, you are just there to study the test itself so that you can study the material and pass it the second time. This takes all the stress off, and you may actually enjoy the process.

I have taken several registry tests and always passed on the first try. When it came to the peds test (the hardest one of all), I employed this technique. Lo and behold, I was the most suprised person to find out I actually passed the exam!

Rule #2: As you go through the test, answer the questions you know and are sure about. Skip the questions you do not know. Finish all the questions that you know, and then go back and start answering the questions you do not know.

This takes a lot of stress off, and you are much more likely to pass the test. Remember that two of the answers are very false, one answer is almost true, and one is completely true. Usually, you can narrow it down to a 50/50 choice, which is much better than a one in four chance. Do not linger on a question that you do not know. This wastes valuable time.

Rule #3: If you are a student just coming out of school, you might consider taking the physics test first, since the material is still fresh in your mind. You will forget the physics fast. Believe me, it is true. 1/2 of all people who take these test fail the physics portion.

Rule#4: For the other tests, you might want to work in the field for awhile. The other tests require you to identify various lesions with video, and you should have experience looking at these lesions in real life.

In conclusion, I would suggest joining SDMS (Society of Diagnostic Medical Sonography). Their journal "JDMS" (Journal of Diagnostic Medical Sonography) is published quarterly, and twice a year they present an entire section on books from every aspect of ultrasound.

I would also highly recomend the Sidney Edelman seminars, especially for physics. These are three day seminars that are reasonably priced. I'm not pitching for him, but I went to his courses before every one of my exams, and I passed on the first try. They are very good.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

Pediatric Heart Structure and Function:The Basics

2009-08-31T14:56:00.002-05:00

(click image to enlarge)

The heart may seem like a complex structure, but in reality is just a simple pump. It pushes blood in one direction. That's all it really does. The heart is really two pumps, the right heart which pumps blood into the lungs, and the left heart which pumps blood into the body.

The atria (right atrium and left atrium) are the top structures of the heart and are like resevoirs and collect incoming blood. The ventricles (right and left ventricles) are the muscular bottom chambers that pump the blood and do all of the work.

The right atrium recieves desaturated blood (blood low in oxygen) from the body after it has been used via the vena cavae. This blood is ejected through the tricuspid valve into the right ventricle, and then pumped out the pulmonary valve and into the lungs via the pulmonary artery.

The left artrium recieves incoming saturated (blood rich in oxygen) from the lungs via the pulmonary veins. This blood is ejected through the mitral valve into the left ventricle, and then pumped out the aortic vave and into the rest of the body via the aorta.

The valves of the heart serve one purpose, and that is to keep blood moving in one direction only, and to prevent blood from regurgitating backwards. It works like you car engine. There are two intake valves that let blood into the heart (tricuspid and mitral valves), and two exhaust valves that let blood out of the heart (pulmonic and aortic valves).

The right and left heart are completely seperated from each other by a muscular layer of tissue called the septum (interatrial and interventricular septums). In the normal heart, the only areas where right-sided blood flow (venous blood) meets left-sided blood flow (arterial blood) is at the capillary level where oxygen transfer occurs.

All pumps operate on two simple principles, pressure and volume. The heart is no different. Pressure on the right side (venous circulation) is very low, typically 25 mm/Hg. Pressure on the left side (arterial circulation) is high, typically 70mm/Hg or higher. The latter pressure represents systemic systolic pressures or the pressures that are taken with a blood pressure cuff. (Keep in mind these are pediatric pressures, and not adult pressures).

Forgive me for being so simplistic in my explanations, but these concepts are critically important in the evaluation of pediatric heart disease. Most congenital heart defects are the result of "shunts", or an abnormal communication between the right and left sides of the circulatory system, or the result of defects in the formation of the valves.

The heart is composed of four chambers, four valves and eight blood vessels than run in and out of it. Anytime one part of the heart (or a blood vessel) communicates abnormally with another part of the heart, then "shunting" occurs. Valve problems keep blood from moving in a forward direction.

This is really what congenital heart defects are all about.

If the right side is "shunting" with the left side, or if blood flow is being impeded by valvular problems, then this significantly alters both the pressure and volume parameters of the pumping process, and alters the ability of the heart to transfer oxegenated blood to the body.

Anything can happen in a congenitally defective heart. The great vessels that run in and out of the heart may not be connected up properly. One or more valves may be defective. Various chambers of the heart may abnormally communicatewith one another. Or entire structures may be missing entirely.

Some congenital heart defects require extensive surgery, and others may only require "palliative" measures or minimal treatment.

As a parent, it is important that you understand these basic concepts so that you can understand what the doctors are talking about.

As a nurse, it is not only important that you have good working knowledge of this material so that you can treat the patient, but additionally provide a simplified instructional to the parents of these patients.

As a sonographer, your role is particulary important, since you are on the front line when these sometimes critically ill patients are born. It is up to you to properly image the heart and know what it is you are looking at so that the neonatologist and pediatric cardiologist can properly treat the patient.

Ken Heiden RDCS, RVT
www.HeartDefectsSimplified.com

Welcome to Heart defects, for everone

2009-08-28T17:01:00.004-05:00

This brand new blog is intended for anyone who is interested in congenital heart defects from sonographers who are new to the field as well as experienced technologists, nurses who work in this area of pediatrics, students and parents, or anyone who has a professional affiliation with a neonatal intensive care unit (NICU) or a pediatric facility who wish to know more about this emerging area of medicine.

This blog will be written by two people, Ken Heiden and Linda Wilson, and will address issues on two different levels. Ken Heiden will talk about issues that affect sonographers, nurses and other clinicians and Linda will discuss issues that affect parents.

In every instance, we will try to simplify this complex subject so that everyone from technologists, nurses and concerned parents will be able to comprehend this difficult field of medicine.

In the coming weeks, we will begin to post explanations for so many of these defects from common shunts such as ASD'S, VSD's and PDA's , and working our way through the more complex defects from a-z such as anomalous coronary arteries, double outlet right ventricle, single ventricle syndromes, tetralogy of fallot, transpositions and even the more obscure defects such as Apert syndrome to Marfan's.
Included will be discussions on the surgical repairs for these defects.

Ken Heiden has written a comprehensive, easy to read book on this subject and can be accessed at HeartDefectsSimplified.com.

I have used numerous resources to verify the information on my blog, but I would like to give particular thanks to the books outlined below:

References:
Anderson, Robert M.D., Paediatric Cardiology. 3d ed. Philadelphia, PA: Churchill Livingstone/Elsevier; 2010

Harland BK, Meridith, DS. National Certification Examination Review, Pediatric Echocardiography, 3rd ed. Plano, TX: Society of Diagnostic Medical Sonography; 2004

May LE. Pediatric Heart Surgery, A Ready reference for Professionals. Milwaukee, WI: Maxishare; 1999.

Reynolds, T. The Pediatric Echocardiographer's Pocket Reference. 3rd ed. Phoenix, AZ: Arizona Heart Institute; 2006

Snider AR, Serwer GA, Ritter SB. Echocardiography in Pediatric Heart Disease. 2nd ed. St. Louis, MO: CV Mosby Co.; 1997

Ken Heiden RDCS (AE, PE) RVT
www.HeartDefectsSimplified.com