Arrhythmias

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

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

Adolescents often come into an echo lab with symptoms of tachycardia, syncopal episodes, bradycardia, heart block, chest pain and various other patterns that may or may not be apparent directly.

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

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

There are times when an implantable defibrillator may be needed to control arrhythmias, but often drug therapy is sufficient. Pacemakers are usually used depending on the location of the arrhythmia, especially if there is a significant malfunction of the heart’s conduction system.

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

Sinus Arrhythmia

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

Tachycardia

This is the most common cause of 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 by such abnormalities as cardiomyopathy or other structural defects in the heart.

Wolff-Parkinson-White Syndrome (WFW)

Essentially a short circuit in the wiring of the top part of the heart, or the atria which causes pre-excitation of the ventricles before the normal impulse is supposed to get to the ventricles. This is more common in patients with such abnormalities as Ebstein’s malformation or transpositions.

Irregular tachycardia, atrial fibrillation, syncope, palpitations are more common developments, and the risk of sudden death is higher. Ablation (zapping the short circuit with a catheter), or drug therapy is the most common treatments.

Atrial Conduction Abnormalities

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

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

Some arrhythmias are inherited and are associated with various cardiomyopathies, or primary diseases of the musculature of the heart or its electrical system, e.g. hypertrophic cardiomyopathy and/or the disorders described above.

Echocardiography

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

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

What the heck does that mean?  For parents and those who are not technologists, that means that the arteries that feed the heart muscle (coronary arteries) are not connected up properly, or that there is an intrinsic, inherited disease of the heart muscle that is enlarged and is preventing 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 are the most common causes of sudden death upon heavy exertion.

My rule of thumb as an echocardiographer is to check for these (and any other defects) in any young patient.

Ken Heiden RDCS, RVT

“Congenital Heart Defects, Simplified”

www.HeartDefectsSimplified.com

Heart defects, for everyone: 3 D Echocardiography

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

3 D Echocardiography

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

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

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

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

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

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

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

Comgenital Heart Defects: A Fundamental Framework

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.  Trans esophageal 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-ventricular) 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 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

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.