4. Congenital Heart Disease II

What is the clinical presentation of aortic coartation?

A bicuspid aortic valve is present in 46% of cases. Approximately 45% of children with Turner syndrome have coarctation. The isolated aortic coarctation has a bimodal distribution. Clinical manifestations occur in about 65% of infants born with coarctation; they are uncommon between 1 and 30 years of age, and they develop again in patients surviving more than 40 years. (A) Neonates. When the ductus arteriosus is open, systemic hypertension is mild. During the first 2 weeks of life, closure of the ductus arteriosus may severely alter the circulatory system. A sudden acute left ventricular failure develops as systemic resistance and left ventricular pressure overload abruptly increase after closure of the ductus arteriosus. In the 'neonatal' type, collateral circulation is absent or inadequate. The severe hypoperfusion of the lower body is associated with acidosis and renal failure. A massive cardiomegaly is uniformly seen at chest X-ray. (B) Adults. Adult patients are asymptomatic and coarctation is discovered during a routine physical examination for athletic participation or employment. On physical examination, patients have (a) blood pressure discrepancies between the upper and lower extremities, (b) systolic murmur from the coarctation best heard posteriorly over the thoracic spine (interscapular and left infrascapular area), and (c) reduced lower extremity pulses to palpation. • Chest x-ray shows cardiac enlargement with so-called figure-3 configuration of the proximal descending thoracic aorta due to both prestenotic and poststenotic dilation. The upper curve is formed by the dilated aorta just above the coarctation, the central indentation by the coarctation itself, and the lower curve by the post-stenotic dilatation below the constricted segment. • Rib notching (unilateral or bilateral, second to ninth ribs) is present in 50% of cases but is rarely seen before the age of 10 years. Rib notching is noted as an erosion of the undersurface of a posterior rib, usually at its outer third.

What is the clinical presentation of patients with congenital aortic stenosis?

A child with congenital aortic stenosis is asymptomatic and is growing and developing normally but is discovered to have a systolic murmur during a routine physical examination. Symptomatic children have exertional dyspnea or typical angina pectoris with exercise. On auscultation, a systolic murmur click is present.

What is a foramen ovale? What is a patent foramen ovale?

A patent foramen ovale (PFO) is a slit-like defect in the interatrial septum formed by failure of postnatal fusion of the septum primum and septum secundum. The foramen ovale is a flap-like communication between the right and the left atria at the level of the fossa ovalis, which is present in the fetus and enables the venous blood to bypass the non-functioning fetal lung and go directly to the left side of the heart. The communication closes after birth, because of the complete fusion between the septum primum and septum secundum. If the communication persists beyond the age of one, it is called a patent foramen ovale. In that case, the septa are not sealed, but the communication is hemodynamically silent because pressures in the left atrium exceed pressures in the right atrium, and the flap-valve of the foramen ovale functionally shuts owing to shifting of the left-sided septum primum against the septum secundum.

What is anomalous origin of the coronary artery from the pulmonary artery?

Anomalous origin of coronary artery from the pulmonary artery is most frequently involves the left coronary artery and very rarely the right coronary artery. The anomalous origin of the left coronary artery results in the left ventricular myocardium being perfused by relatively desaturated blood under low pressure, leading to myocardial ischemia. Patients usually present in infancy with signs of left ventricular ischemia (exertional chest pain, syncope, sudden cardiac death, or acute myocardial infarction) or congestive heart failure. Patients with anomalous origin of the right coronary artery from the pulmonary artery generally remain asymptomatic until adulthood. This is because the oxygen demands of the right ventricle are lower than that of the left ventricle.

What happens to the heart in Eisenmenger syndrome?

CHDs with chronically increased pulmonary blood flow progressively evolve toward the development of generalized pulmonary vascular obstructive disease. Histopathological changes are most severe in the small muscular arteries and arterioles of the lung. • The first histopathological change is the circumferential thickening of the tunica media due to hyperplasia of smooth muscle cells. • This is followed by marked intimal thickening due to hyperplasia of smooth muscle cells in tunica intima leading to concentric or eccentric narrowing of the lumen. • The next stage is luminal thrombosis of the small arteries and arterioles. • Organization of the luminal thrombosis transforms the fully occluded vessel into a plexiform lesion, as endothelial cell proliferation forms multiple capillary-like channels that replace the luminal thrombus. This generalized pulmonary vascular obstructive disease ultimately increases pulmonary vascular resistance and sets the stage for pulmonary hypertension. When pressures in the right ventricle exceed pressures in the left ventricle the reversal of the initial left-to-right shunt into the right-to-left one occurs.

What is coarctation of the aorta?

Coarctation of the aorta is an obstruction in the descending aorta beyond the left subclavian artery at the insertion of the ductus arteriosus. Coarctation of the aorta is a common defect, accounting for 5% of patients with congenital heart disease. The condition is two to five times more common in males than in females. Generally, patients with coarctation of the aorta present early in life with congestive heart failure or later in life with arterial hypertension.

What are some complications of TOF?

Complications of long-term hypoxemia are secondary polycythemia, brain abscess, exercise intolerance, and cerebrovascular accidents. (A) Polycythemia. Polycythemia is the exaggeration of red cell production to maintain the oxygen carrying capacity of the blood. In polycythemia, there may be 8 to 9 million erythrocytes per cubic millimeter of blood (a normal range for adults is 4-6 million). The hematocrit may be as high as 70% (normal: 42-52%). (B) Stroke. Ischemic stroke secondary to arterial thrombosis is the most common neurological complications of uncorrected TOF. Stroke has been attributed to the increased blood viscosity due to polycythemia of cyanotic heart disease. (C) Brain abscess. Brain abscess is another frequent complication. Because of the right-to-left shunt, the venous blood bypasses the pulmonary circulation. Thus, bacteria in the bloodstream are not filtered through the pulmonary circulation, where they would normally be removed by phagocytosis. In the background of chronic ischemia, these bacteria easily seed the underperfused areas of the brain.

What is congenital aortic stenosis?

Congenital aortic stenosis may occur at the supravalvular, valvular or subvalvular levels. • Subaortic stenosis is caused by a thickened ring or collar of dense endocardial fibrous tissue below the level of the cusps • Valvular aortic stenosis refers to dysplastic valves that can be unicuspid, bicuspid, tricuspid, and quadricuspid. The unicuspid aortic valve, most frequently seen in critical VAS, has either an eccentric orifice with one patent commissure or a central orifice with no commissure. The bicuspid aortic valve is the most common congenital heart disease with a prevalence of approximately 2% of the population. The bicuspid valve has a single fused commissure and an eccentrically placed orifice. • Supravalvular aortic stenosis is a congenital aortic dysplasia with thickening and constriction of the ascending aortic wall. Supravalvar aortic stenosis is commonly associated with Williams syndrome which is a developmental disorder characterized by a distinctive, "elfin" facial appearance combined with supravalvular aortic stenosis, mental retardation and hypercalcemia. The Williams syndrome is caused by a microdeletion in the q11.23 region of chromosome 7. This deletion involves 26 to 27 genes, including the elastin gene.

What is dextrocardia?

Dextrocardia is a rare congenital disorder in which the major axis of the heart (from the base to the apex along the interventricular septum) points to the right. Dextrocardia by itself is asymptomatic and is discovered incidentally in adult life. It can be associated with normally located chest and abdominal viscera (situs solitus), or it can be accompanied by a reversal in the position of other organs (situs inversus totalis). In subjects with situs inversus the thoracic and abdominal viscera are mirror images of normal, the left lung has 3 lobes and the right lung has 2 lobes. The heart is right sided; the ascending aorta, aortic arch, and pulmonary trunk are in mirror image positions; and the aorta descends on the right. The larger lobe of the liver is on the left and the stomach and spleen are on the right. Individuals with situs inversus are phenotypically normal, and can lead normal healthy lives, without any complications related to their medical condition. Complex cardiac heart malformations are found more often with situs solitus than with situs inversus.

What is Ebstein anomaly?

Ebstein anomaly is characterized by apical displacement of the septal and posterior tricuspid valve leaflets. The tricuspid leaflets are dysplastic: they are displaced toward the apex of the right ventricle, are adherent to the ventricular septum, and may be redundant, contracted, or thickened. The part of the right ventricular wall proximal to the adherent valve leaflets is described as the atrialized portion of the right ventricle. The tricuspid valve is incompetent. The right atrium is enlarged. The dilated right atrium and the atrialized component of the right ventricle are of equal size. The functional right ventricle is shortened, containing only the apical trabecular part and the infundibulum. The hemodynamic consequences of Ebstein anomaly include tricuspid insufficiency combined with right- to-left shunting. The atrialized ventricular muscle and the remainder of the right ventricle contract simultaneously causing a backward flow of blood into the right atrium, accentuating the effects of tricuspid regurgitation. The right atrial pressure is higher than normal and right-to-left shunting through an atrial septal defect is usual. Ebstein anomaly is associated with a wide spectrum of clinical manifestations. The severe forms manifest clinically with cyanosis, and right-sided congestive heart failure, and are diagnosed during the first year of life. Patients with mild forms remain asymptomatic until late adolescence or early adult life.

What is Eisenmenger syndrome?

Eisenmenger syndrome (ES) refers to any untreated congenital cardiac defect with left-to-right shunt that leads to a net increase in pulmonary blood flow eventually leading to the development of pulmonary vascular obstructive disease and increased pulmonary vascular resistance. The increase in pulmonary vascular resistance results in a rise in pulmonary artery pressure. With the development of pulmonary artery hypertension, the increased right ventricular afterload increases pressures in the right heart and results in right ventricular dilation and right ventricular failure. In some patients this process continues until there is eventually shunt reversal with a right-to-left flow across the VSD. With right-to-left shunting, de-oxygenated blood returning to the right side of the heart, passes through a communication such as a VSD to the left side of the heart and is pumped to the body resulting in cyanosis. The phenomenon in which a left-to-right shunting progresses to shunt reversal is known as Eisenmenger syndrome. This condition is named after Victor Eisenmenger who first described this condition in 1897.. The most common forms of CHD that can lead to ES syndrome are VSD, ASD, AV canal defect, TA, and PDA. Approximately 50% of all patients with large unrepaired VSDs, and 10% of patients with large unrepaired ASDs are at risk of developing ES.

What is the clinical presentation of PFO?

In general patients with PFO are never identified clinically because they have no symptoms. PFO can result in ischemic stroke and migraine headache. (A) Paradoxical embolism. Right-to-left shunting at the atrial level has been implicated as a contributing factor to cryptogenic stroke (via paradoxical embolism). Cryptogenic stroke is a category of ischemic stroke for which no probable cause is found. (B) Migraine headaches with aura. PFO is also associated with migraine with aura. The mechanism of the migraine relationship to PFO remains unknown.

What is the pathology of coarctation of the aorta?

Pathophysiologic consequences involve two phenomena: (i) pressure overload in the heart and increase in the upper extremity blood pressure proximal to the coarctation, and (ii) hypoperfusion distal to the coarctation. Coarctation results in two common presentations. • The first is the neonatal presentation. Infants with severe coarctation become acutely ill as soon as the ductus arteriosus constricts or closes. Before the closure of ductus arteriosus, the lower extremity perfusion is maintained via ductus arteriosus. With closure of ductus arteriosus, the sudden increase in afterload is associated with congestive heart failure, circulatory shock, renal failure (oliguria or anuria) and metabolic acidosis. • The second presentation occurs in older children and adults. Coarctation of the aorta in this scenario results in upper extremity hypertension, leading to early coronary artery disease, aortic aneurysm, and cerebrovascular disease. The blood pressure in the upper body (i.e., above the coarctation) is 30 mm or 40 mm Hg higher than in the lower body (below the coarctation). Almost without exception, the obstructing indentation of the aorta is located opposite the entry of the ductus arteriosus. The infolding of the aortic wall is asymmetric and most marked on the posterior and lateral wall opposite the entry of the ductus arteriosus. The coarctation may be at, immediately above, or below the origin of the left subclavian artery. The coarctation of the aorta commonly becomes more obstructive as the child grows and is usually accompanied by increasing collateral flow involving the intercostal arteries and internal thoracic artery. Thus, because of extensive collateral circulation, it is possible to have severe obstruction of the aorta with only a small difference in blood pressure at rest between the arms and legs. The collateral vessels become larger and more tortuous with time, the intercostals ultimately eroding the undersurface of the ribs (rib notching). The interconnecting arteries of the collateral circulation are present at birth, enlarging to accommodate the need for increased flow as needed.

What is the clinical presentation of Eisenmenger syndrome?

Patients with ES seek medical attention because of progressive fatigue, dyspnea, and cyanosis. Laboratory studies reveal erythrocytosis (hemoglobin > 18 g/dL, normal: 12-18 g/dL) due to increased erythropoietin production in response to long-standing hypoxemia. Cardiac catheterization confirms the presence of severely increased pulmonary vascular resistance and pulmonary arterial hypertension [defined as a mean pulmonary arterial pressure greater than 25 mm Hg at rest (normal: 14 mm Hg). Chest X-ray reveal marked enlargement of the right ventricle with a massive dilatation of the pulmonary artery. With progressive right heart failure, tricuspid regurgitation, jugular venous distension, hepatomegaly, peripheral edema, and ascites occur. Eisenmenger syndrome is uniformly fatal. The usual life expectancy is 20-30 years.

What are the two types of coarctation of the aorta?

Preductal coarctation: narrowing occurring proximal to the ductus arteriosus. Preductal coarctation accounts for approximately 2% of all coarctations. They are seen most commonly in infants. • Postductal coarctation: narrowing occurring distal to the ductus arteriosus. This is the most common type of aortic coarctation and is seen in older children and adults.

What is a conotruncal defect?

TOF is a conotruncal defect resulting from deviation of the conotruncal septum. This displaced septum protrudes into the pulmonary outflow tract, often resulting in obstruction and hypoplasia of the downstream structures, including the pulmonary valve, and main pulmonary artery.This single morphologic defect results in a misalignment of ventriculoarterial septum with an overriding aorta causing a subsequent right ventricular outflow obstruction, ventricular septal defect, and right ventricular hypertrophy. The embryological term "conotruncus" correspond to the primitive cardiac outflow tract, i.e., the infundibulum of the right ventricle and truncus arteriosus, that later divides into the aorta and the pulmonary trunk.

What is tetralogy of Fallot?

Tetralogy of Fallot (TOF) is a cyanotic congenital heart malformation comprising four anatomical abnormalities: (a) infundibular pulmonary stenosis, (b) ventricular septal defect, (c) dextroposition of the aorta such that the aortic root overrides the crest of ventricular septum, and (d) right ventricular hypertrophy. TOF is the most common cyanotic heart defect. This defect accounts for approximately 5% of cases of congenital heart disease.

What is the clinical presentation of TOF?

The clinical presentation of the patient with TOF is dependent upon the degree of right ventricular outflow obstruction. Infants with severe obstruction present in the immediate newborn period with profound cyanosis. Infants with mild obstruction are asymptomatic initially. They will develop cyanosis and other clinical symptoms weeks or months after birth. (A) Cyanosis. Most patients present during the first month of life with a certain degree of cyanosis. In patients with less severe right ventricular outflow obstruction, cyanosis present months later in life. (B) Hypercyanotic ("tet") spells. Tet spells are a hallmark of TOF. A hypercyanotic spell is a paroxysmal hypoxic event characterized by severe reduction in pulmonary blood flow that could last minutes to several hours. Hypercyanotic spells can be triggered by a variety of different stimuli such as crying, feeding, or can occur spontaneously with no apparent cause. Clinically, tet spells are characterized by hyperpnea, irritability, and progressively severe cyanosis. Tet spells are due to acute and complete, or near complete, obstruction of the right ventricular outflow tract. (C) Murmur. Auscultation detects a harsh grade 3-5/6 systolic ejection murmur along the left sternal border. The murmur is due to the right ventricular outflow tract obstruction; the ventricular septal defect is usually silent because it is large and has no pressure gradient. (D) Squatting. Children with the TOF soon discover the symptomatic relief obtained by squatting after exercise. Indeed, the trick is probably usually learnt in infancy when they adopt a knee-chest posture. Squatting is associated with external compression of the femoral arteries, a temporary rise in systemic arterial pressure, a temporary rise of the LV pressure above the RV pressure, thereby producing a temporary reversal of the shunt. A temporary left-to-right shunt will increase the amount of blood going to the lungs for oxygenation, which will help relieve dyspnea and counteract a cyanotic spell. (E) Clubbing of the fingers. Certain clinical features classically associated with TOF appear only beyond infancy. Chronic cyanosis is associated with clubbing of the fingers and toes and may also cause delayed physical growth and diminished cognitive function. (F) Chest x-ray. The hallmark of tetralogy of Fallot in infants is the classic 'boot-shaped' heart with upturned cardiac apex due to right ventricular hypertrophy and concave pulmonary segment. Vascularity of the lungs is diminished with diminished prominence of the pulmonary arteries. (G) Cardiac catheterization. The right ventricular systolic pressure is equal to the pressure in the left ventricle and aorta. The pressure in the pulmonary artery is normal or low. Systemic arterial oxygen saturation is reduced because of the right-to-left shunting from the right ventricle to the left one.

How is the heart affected in right ventricular outflow obstruction?

The degree of right ventricular outflow obstruction is quite variable, ranging from very mild in some patients to critically severe in others. The aorta is displaced to the right, overlying the ventricular septal defect rather the left ventricle. This results in blood flow from both ventricles into the aorta. Further, just as the degree of infundibular hypoplasia varies, so does the extent of aortic override. The ventricular septal defect is typically large and subaortic, involving membranous septum. The heart is hypertrophied. Since the ventricular septal defect is large with an area about as great as that of the aortic valve, both ventricles and the aorta have essentially the same systolic pressures. The shunting is right-to-left, i.e., from the right ventricle to the left ventricle because the resistance to the blood flow is higher across the obstructed right ventricular outflow tract than the resistance to flow out of the aorta into the systemic circulation. The volume of the ventricular right-to-left shunting and hence the degree of cyanosis reflects the severity of right ventricular outflow tract obstruction.

What is the pathology/pathogenesis of patients with patent foramen ovale?

The septum primum is located on the left aspect of the definitive atrial septum, whereas septum secundum is on the right aspect. Septum secundum is a thick muscular structure, whereas septum primum is a thin membranous structure. Foramen ovale is located at the area of fossa ovalis, a depression on the right atrial aspect of the definitive atrial septum. This depression corresponds to ostium secundum of the fetal period. This depression is surrounded by a muscular rim. The floor of the fossa ovalis is constituted by septum primum. If both septa are sealed, there is no passage between the right and left atria. If the septa are not sealed, the floor of the fossa ovalis (i.e., septum primum) is like a flap that is large enough to overlap the muscular rim formed by the septum secundum. Since the flap valve is larger than the fossa, the length of the overlap can be considerable, resulting in a tunnel-like PFO. As long as the left atrial pressures are higher than right atrial pressures, the PFO valve is competent and there is no shunt. During Valsalva maneuver in healthy individuals, the right atrial pressure exceeds left atrial pressure. As the limbus is on the right side, when the PFO valve is pushed into the left atrial cavity, a right-to-left shunt develops. Right-to-left shunts also occur in individuals that have right-sided heart failure (due to emphysema and cor pulmonale) and pressure overload of the right ventricle and atrium. The right-to-left shunt in these cases is small (there is no cyanosis) but is able to trigger paradoxical embolism.

What is total anomalous pulmonary venous return?

The total anomalous pulmonary venous return (TAPVR) refers to draining of all four pulmonary veins into the superior vena cava or directly into the right atrium. Systemic and pulmonary venous blood mix in the right atrium. A right-to-left shunting of blood is required for survival and is usually via a large patent foramen ovale. Children with TAPVR present within the first weeks of life with cyanosis, cardiomegaly, and congestive heart failure.

What is transposition of the great arteries?

The transposition of the great arteries (TGA) is a ventriculoarterial discordance, in which the aorta arises from the morphologic right ventricle and the pulmonary artery arises from the morphologic left ventricle. Consequently, the pulmonary and systemic circulations are connected in parallel rather than the normal in-series connection. In one circuit, deoxygenated systemic venous blood passes to the right atrium, to the right ventricle, and then to the aorta. In the other, oxygenated pulmonary venous blood passes through the left atrium and ventricle to the pulmonary artery. This situation is incompatible with life unless mixing of the two circuits occurs. Almost all patients have an atrial septal defect. Most patients with TGA present within the first 30 days of life. The most commonly observed clinical manifestations are cyanosis, congestive heart failure, and failure to thrive. There is a less frequent variant of TGA, called "congenitally corrected TGA". In this variant, the right atrium connects to a ventricle with the internal morphology of a left ventricle (atrioventricular discordance); at the same time, the left atrium connects to a morphologic right ventricle, which empties into the aorta. Congenitally corrected TGA does not present with cyanosis and entirely asymptomatic, being diagnosed in adulthood only during a workup for other cardiac issues.

What is tricuspid atresia?

Tricuspid atresia consists of a complete lack of formation of the tricuspid valve with absence of direct connection between the right atrium and right ventricle. Blood passes from the right atrium through an atrial defect to the left atrium and from there to left ventricle. The right ventricle is hypoplastic and communicates to the dominant left ventricle via a VSD. The entry to the pulmonary circulation occurs through the VSD or PDA. Patients with tricuspid atresia present with cyanosis, congestive heart failure, digital clubbing, and failure to thrive

What is truncus arteriosus?

Truncus arteriosus (TA) is characterized by a single arterial vessel that originates from the heart, overrides the ventricular septum, and supplies the systemic, coronary and pulmonary circulations, all from the proximal ascending vessel. TA results from absent partitioning of the truncus arteriosus. The arterial trunk is positioned above the ventricular septum and receives the output of both ventricles. The presenting symptoms in patients with TA include cyanosis, polycythemia, clubbing of the fingers, congestive heart failure, failure to thrive, recurrent respiratory infections.