Adult Congenital Heart Disease
The number of patients with congenital cardiac disease reaching adulthood is increasing steadily. Many adults with such disease face both medical and surgical difficulties. Most clinicians know very little about basic cardiac defects, their natural history, complications after surgery, and adequate management of these patients.
Over the past 20 to 30 years, major advances have been made in the diagnosis and treatment of congenital heart disease in children. As a result, many children with such disease now survive to adulthood. In the United States alone, the population of adults with congenital heart disease, either surgically corrected or uncorrected, is estimated to be increasing at a rate of about 5 percent per year; this year there will be almost 1 million such patients. Here we are focusing on the more common acyanotic and cyanotic congenital heart conditions that physicians who care for adults are likely to encounter.
Acyanotic Conditions
Atrial Septal Defect
Atrial septal defect accounts for about one third of the cases of congenital heart disease detected in adults. It occurs in women two to three times as often as in men. Anatomically, it may take the form of ostium secundum, in the region of the fossa ovalis; ostium primum, in the lower part of the atrial septum; or sinus venosus, in the upper atrial septum. Ostium secundum defects make up 75 percent of all atrial septal defects, ostium primum defects make up 15 percent, and sinus venosus defects make up 10 percent. Additional cardiac abnormalities may occur with each type of defect; these include mitral-valve prolapse (with ostium secundum defects), mitral regurgitation (due to a cleft in the anterior mitral-valve leaflet, which occurs with ostium primum defects), and partial anomalous drainage of the pulmonary veins into the right atrium or venae cavae (with sinus venosus defects). Although most atrial septal defects result from spontaneous genetic mutations, some are inherited.
Regardless of anatomical location, the physiologic consequences of atrial septal defects are the result of the shunting of blood from one atrium to the other; the direction and magnitude of shunting are determined by the size of the defect and the relative compliance of the ventricles. A small defect (less than
Figure 1. Atrial Septal Defect with Resultant Left-to-Right Shunting.
Blood from the pulmonary veins enters the left atrium, after which some of it crosses the atrial septal defect into the right atrium and ventricle (longer arrow).
In a patient with a large atrial septal defect, a right ventricular or pulmonary arterial impulse may be palpable. The first heart sound is normal, and there is wide and fixed splitting of the second heart sound. The splitting of the second heart sound is fixed because phasic changes in systemic venous return to the right atrium during respiration are accompanied by reciprocal changes in the volume of shunted blood from the left atrium to the right atrium, thereby minimizing the respiratory changes in right and left ventricular stroke volumes that are normally responsible for physiologic splitting. A systolic ejection murmur, audible in the second left intercostal space, peaks in mid-systole, ends before the second heart sound, and is usually so soft that it is mistaken for an “innocent” flow murmur. Flow across the atrial septal defect itself does not produce a murmur.
Electrocardiographically, a patient with atrial septal defect often has right-axis deviation and incomplete right bundle-branch block. Left-axis deviation occurs with ostium primum defects. A junctional or low atrial rhythm (inverted P waves in the inferior leads) occurs with sinus venosus defects. A patient with an atrial septal defect usually has normal sinus rhythm for the first three decades of life, after which atrial arrhythmias, including atrial fibrillation and supraventricular tachycardia, may appear. On chest radiography, the patient has prominent pulmonary arteries and a peripheral pulmonary vascular pattern of “shunt vascularity” (in which the small pulmonary arteries are especially well visualized in the periphery of both lungs).
Transthoracic echocardiography may reveal dilatation of the atria and right ventricle. Ostium primum or ostium secundum defects are often visualized directly, but transthoracic echocardiography usually does not identify sinus venosus defects. The sensitivity of echocardiography may be enhanced by injecting microbubbles of air in solution into a peripheral vein, after which the movement of some of the bubbles across the defect into the left atrium can be visualized. Transesophageal and Doppler color-flow echocardiography are particularly useful in detecting and determining the location of atrial septal defects and in identifying sinus venosus defects and anomalous pulmonary venous drainage. Although echocardiography may provide enough information to guide the management of an atrial septal defect, catheterization may be required to determine the magnitude and direction of shunting, as well as whether pulmonary hypertension is present and, if so, its severity.
Since atrial septal defects initially produce no symptoms and are not accompanied by striking abnormalities on physical examination, they often remain undetected for years. A small defect with minimal left-to-right shunting (characterized by a ratio of pulmonary to systemic flow of less than 1.5) usually causes no symptoms or hemodynamic abnormalities and therefore does not require closure. Patients with moderate or large atrial septal defects often have no symptoms until the third or fourth decades of life despite substantial left-to-right shunting (characterized by a ratio of pulmonary to systemic flow of 1.5 or more). Over the years, the increased volume of blood flowing through the chambers of the right side of the heart usually causes right ventricular dilatation and failure. Obstructive pulmonary vascular disease (Eisenmenger’s syndrome) occurs rarely in adults with atrial septal defect.
A symptomatic patient with an atrial septal defect typically reports fatigue or dyspnea on exertion. Alternatively, the development of such sequelae as supraventricular arrhythmias, right heart failure, paradoxical embolism, or recurrent pulmonary infections may prompt the patient to seek medical attention. Although a few patients with an unrepaired atrial septal defect have survived into the eighth or ninth decade of life, those with sizable shunts often die of right ventricular failure or arrhythmia in their 30s or 40s.
An atrial septal defect with a ratio of pulmonary to systemic flow of 1.5 or more should be closed surgically to prevent right ventricular dysfunction. Surgical closure is not recommended for patients with irreversible pulmonary vascular disease and pulmonary hypertension. Although devices for percutaneous atrial septal closure are under investigation, their safety and efficacy are unknown. Prophylaxis against infective endocarditis is not recommended for patients with atrial septal defects (repaired or unrepaired) unless a concomitant valvular abnormality (e.g., mitral-valve cleft or prolapse) is present.
Ventricular Septal Defect
Ventricular septal defect is the most common congenital cardiac abnormality in infants and children. It occurs with similar frequency in boys and girls. Twenty-five to 40 percent of such defects close spontaneously by the time the child is 2 years old; 90 percent of those that eventually close do so by the time the child is 10. Anatomically, 70 percent are located in the membranous portion of the interventricular septum, 20 percent in the muscular portion of the septum, 5 percent just below the aortic valve (thereby undermining the valve annulus and causing regurgitation), and 5 percent near the junction of the mitral and tricuspid valves (so-called atrioventricular canal defects).
The physiologic consequences of a ventricular septal defect are determined by the size of the defect and the relative resistance in the systemic and pulmonary vascular beds. If the defect is small, there is little or no functional disturbance, since pulmonary blood flow is increased only minimally. In contrast, if the defect is large, the ventricular systolic pressures are equal and the magnitude of flow to the pulmonary and systemic circulations is determined by the resistances in the two beds. Initially, systemic vascular resistance exceeds pulmonary vascular resistance, so that left-to-right shunting predominates (Figure 2). Over time, the pulmonary vascular resistance usually increases, and the magnitude of left-to-right shunting declines. Eventually, the pulmonary vascular resistance equals or exceeds the systemic resistance; the shunting of blood from left to right then ceases, and right-to-left shunting begins.
Figure 2. Ventricular Septal Defect with Resultant Left-to-Right Shunting.
When the left ventricle contracts, it ejects some blood into the aorta and some across the ventricular septal defect into the right ventricle and pulmonary artery (arrow).
With substantial left-to-right shunting and little or no pulmonary hypertension, the left ventricular impulse is dynamic and laterally displaced, and the right ventricular impulse is weak. The murmur of a moderate or large defect is holosystolic, loudest at the lower left sternal border, and usually accompanied by a palpable thrill. A short mid-diastolic apical rumble (caused by increased flow through the mitral valve) may be heard, and a decrescendo diastolic murmur of aortic regurgitation may be present if the ventricular septal defect undermines the valve annulus. Small, muscular ventricular septal defects may produce high-frequency systolic ejection murmurs that terminate before the end of systole (when the defect is occluded by contracting heart muscle). If pulmonary hypertension develops, a right ventricular heave and a pulsation over the pulmonary trunk may be palpated. The holosystolic murmur and thrill diminish and eventually disappear as flow through the defect decreases, and a murmur of pulmonary regurgitation (Graham Steell’s murmur) may appear. Finally, cyanosis and clubbing are present.
Electrocardiography and chest radiography provide insight into the magnitude of the hemodynamic impairment. With a small ventricular septal defect, both are normal. With a large defect, there is electrocardiographic evidence of left atrial and ventricular enlargement, and left ventricular enlargement and “shunt vascularity” are evident on the radiograph. If pulmonary hypertension occurs, the QRS axis shifts to the right, and right atrial and ventricular enlargement are noted on the electrocardiogram. The chest film of a patient with pulmonary hypertension shows marked enlargement of the proximal pulmonary arteries, rapid tapering of the peripheral pulmonary arteries, and oligemic lung fields. Two-dimensional echocardiography with Doppler flow can confirm the presence and location of the ventricular septal defect, and color-flow mapping provides information about the magnitude and direction of shunting. With catheterization and angiography, one can confirm the presence and location of the defect, as well as determine the magnitude of shunting and the pulmonary vascular resistance.
The natural history of ventricular septal defect depends on the size of the defect and the pulmonary vascular resistance. Adults with small defects and normal pulmonary arterial pressure are generally asymptomatic, and pulmonary vascular disease is unlikely to develop. Such patients do not require surgical closure, but they are at risk for infective endocarditisand should therefore receive antibiotic prophylaxis. In contrast, patients with large defects who survive to adulthood usually have left ventricular failure or pulmonary hypertension with associated right ventricular failure. Surgical closure of the defect is recommended, if the magnitude of pulmonary vascular obstructive disease is not prohibitive. Once the ratio of pulmonary to systemic vascular resistance exceeds 0.7, the risk associated with surgery is prohibitive.
Patent Ductus Arteriosus
The ductus arteriosus connects the descending aorta (just distal to the left subclavian artery) to the left pulmonary artery. In the fetus, it permits pulmonary arterial blood to bypass the unexpanded lungs and enter the descending aorta for oxygenation in the placenta. It normally closes soon after birth, but in some infants it does not close spontaneously, and there is continuous flow from the aorta to the pulmonary artery (i.e., left-to-right shunting) (Figure 3). Patent ductus arteriosus accounts for about 10 percent of cases of congenital heart disease. Its incidence is higher than average in pregnancies complicated by persistent perinatal hypoxemia or maternal rubella infection and among infants born at high altitude or prematurely.
Figure 3. Patent Ductus Arteriosus with Resultant Left-to-Right Shunting.
Some of the blood from the aorta crosses the ductus arteriosus and flows into the pulmonary artery (arrows).
A patient with patent ductus arteriosus and a moderate or large shunt has bounding peripheral arterial pulses, a widened pulse pressure, and a hyperdynamic left ventricular impulse. The first heart sound is normal. A continuous “machinery” murmur, audible in the second left anterior intercostal space, begins shortly after the first heart sound, peaks in intensity at or immediately after the second heart sound (thereby obscuring it), and declines in intensity during diastole. With a large shunt, mid-diastolic and systolic murmurs (from increased flow through the mitral and aortic valves, respectively) may be noted. If pulmonary vascular obstruction and hypertension develop, the continuous murmur decreases in duration and intensity and eventually disappears and a pulmonary ejection click and a diastolic decrescendo murmur of pulmonary regurgitation may appear.
With a small patent ductus arteriosus, the electrocardiogram and chest x-ray film are normal. With a large patent ductus arteriosus and substantial left-to-right shunting, left atrial and ventricular hypertrophy are evident, and the chest film shows pulmonary plethora, proximal pulmonary arterial dilatation, and a prominent ascending aorta. The ductus arteriosus may be visualized as an opacity at the confluence of the descending aorta and the aortic knob. If pulmonary hypertension develops, right ventricular hypertrophy is noted. With two-dimensional echocardiography, the ductus arteriosus can usually be visualized, and Doppler studies demonstrate continuous flow in the pulmonary trunk. Catheterization and angiography make it possible to quantify the magnitude of shunting and the pulmonary vascular resistance as well as visualize the ductus arteriosus.
A patent ductus arteriosus rarely closes spontaneously after infancy. A small patent ductus arteriosus causes no symptoms, and a person with a defect of this size can have a normal life expectancy. However, the presence of a small patent ductus arteriosus entails an elevated risk of infective endocarditis, which involves the pulmonary side of the ductus arteriosus or the pulmonary artery opposite the duct orifice, from which septic pulmonary emboli may arise. A patent ductus arteriosus of moderate size may cause no symptoms during infancy; during childhood or adulthood, fatigue, dyspnea, or palpitations may appear. In addition, the ductus arteriosus may become aneurysmal and calcified, which may lead to its rupture. With larger shunts, flow is markedly increased, which may precipitate left ventricular failure. Eventually, pulmonary vascular obstruction may develop; when the pulmonary vascular resistance equals or exceeds the systemic vascular resistance, the direction of shunting reverses. One third of patients with a patent ductus arteriosus that is not surgically repaired die of heart failure, pulmonary hypertension, or endarteritis by the age of 40 years, and two thirds die by the age of 60 years.
Surgical ligation of patent ductus arteriosus, generally accomplished without cardiopulmonary bypass, has an associated mortality of less than 0.5 percent. However, in patients with ductal aneurysmal dilatation or calcification, resection with cardiopulmonary bypass may be required. Because of the risk of endarteritis associated with unrepaired patent ductus arteriosus (estimated at 0.45 percent annually after the second decade of life) and the low risk associated with ligation, we recommend that even a small patent ductus arteriosus be ligated surgically or occluded with a percutaneously placed closure device. Once severe pulmonary vascular obstructive disease develops, surgical ligation or percutaneous closure is contraindicated.
Aortic Stenosis
The most common pathological finding in patients with symptomatic aortic stenosis who are younger than 65 years of age is a bicuspid aortic valve, which is found in 2 to 3 percent of the population. It is four times as common in men and boys as in women and girls. Twenty percent of patients with bicuspid aortic valve have an associated cardiovascular abnormality, such as patent ductus arteriosus or aortic coarctation. In patients with bicuspid aortic valve, the bicuspid valve has a single fused commissure and an eccentrically oriented orifice. Although the deformed valve is not stenotic at birth, it is subjected to abnormal hemodynamic stress, which may lead to thickening and calcification of the leaflets, with resultant immobility. In many patients, there is a coexisting abnormality of the medial layer of the aorta above the valve, which predisposes patients to have dilatation of the aortic root. The area of the aortic orifice in a normal adult is 3.0 to 4.0 cm2. Aortic stenosis does not become hemodynamically important unless the valve area is reduced to approximately 1.0 cm2.
In patients with severe aortic stenosis, the carotid upstroke is usually delayed and diminished, but it may be normal in elderly patients with noncompliant carotid arteries. The aortic component of the second heart sound is diminished or inaudible, and a fourth heart sound is present. A harsh systolic crescendo–decrescendo murmur is audible over the aortic area and often radiates to the neck. As the aortic steno-sis worsens, the murmur peaks progressively later in systole.
Left ventricular hypertrophy results from gradually worsening aortic stenosis and is usually evident on electrocardiography. Unless the left ventricle dilates, the chest x-ray film demonstrates a normal cardiothoracic silhouette. In most patients, transthoracic echocardiography with Doppler flow permits an accurate assessment of the severity of the stenosis and of left ventricular systolic function. Cardiac catheterization is performed to determine the severity of aortic stenosis in cases in which it cannot be assessed noninvasively and to determine whether concomitant coronary artery disease is present.
The classic symptoms of aortic stenosis are angina pectoris, syncope or near-syncope, and heart failure. Adults with aortic stenosis who are asymptomatic have a normal life expectancy; they should receive antibiotic prophylaxis against infective endocarditis. Once symptoms appear, survival is limited: the median survival is only five years after angina develops, three years after syncope occurs, and two years after symptoms of heart failure appear. Therefore, patients with symptomatic aortic stenosis should undergo valve replacement.
Pulmonary Stenosis
Pulmonary stenosis constitutes 10 to 12 percent of the cases of congenital heart disease in adults. Obstruction of right ventricular outflow is valvular in 90 percent of patients, and in the remainder it is supravalvular or subvalvular. Supravalvular pulmonary stenosis results from the narrowing of the pulmonary trunk, its bifurcation, or its peripheral branches; it often coexists with other congenital cardiac abnormalities (valvular pulmonary stenosis, atrial septal defect, ventricular septal defect, patent ductus arteriosus, or tetralogy of Fallot). It is a common feature of Williams syndrome, which is characterized by infantile hypercalcemia, elfin facies, and mental retardation, in addition to supravalvular pulmonary stenosis. Subvalvular pulmonary stenosis, which is caused by the narrowing of the right ventricular infundibulum or subinfundibulum, usually occurs in association with a ventricular septal defect.
Valvular pulmonary stenosis typically is an isolated abnormality, but it may occur in association with ventricular septal defect or lead to secondary hypertrophic subpulmonary stenosis. The valve leaflets usually are thin and pliant; all three valve cusps are present; and the commissures are fused, so that during ventricular systole the valve is dome-shaped with a small central orifice. Among patients with valvular stenosis, 10 to 15 percent have dysplastic leaflets, which are thickened, immobile, and composed of myxomatous tissue. About two thirds of patients with Noonan’s syndrome have pulmonary stenosis due to valve dysplasia.
The area of the pulmonary-valve orifice in a normal adult is about 2.0 cm2 per square meter of body-surface area, and there is no systolic pressure gradient across the valve. When the valve becomes stenotic, the right ventricular systolic pressure increases and a systolic pressure gradient is observed between the right ventricle and pulmonary artery. Pulmonary stenosis is considered mild if the valve area is larger than 1.0 cm2 per square meter, the transvalvular gradient is less than
In patients with moderate or severe pulmonary stenosis, a right ventricular impulse may be palpated at the left sternal border, and there may be a thrill at the second left intercostal space. The first heart sound is normal, and the second heart sound is widely split but moves normally with respiration; its pulmonary component is soft and delayed. A harsh crescendo–decrescendo systolic murmur that increases in intensity with inspiration is audible along the left sternal border. If the valve is pliable, an ejection click often precedes the murmur; typically, the click softens or disappears with inspiration. As the stenosis becomes more severe, the systolic murmur peaks later in systole and the ejection click moves closer to the first heart sound, eventually becoming virtually superimposed on it.
In cases of moderate or severe pulmonary stenosis, the electrocardiogram shows right-axis deviation and right ventricular hypertrophy. Post-stenotic dilatation of the main pulmonary artery and diminished pulmonary vascular markings are evident on radiography. The cardiac silhouette is usually normal in size. An enlarged cardiac silhouette may be seen if the patient has right ventricular failure or tricuspid regurgitation. On echocardiography, right ventricular hypertrophy and paradoxical septal motion during systole are evident. The site of obstruction can be visualized in most patients. With the use of Doppler flow studies, the severity of stenosis can usually be assessed, so that catheterization and angiography are unnecessary.
The presence or absence of symptoms, their severity, and the prognosis are influenced by the severity of stenosis, the right ventricular systolic function, and the competence of the tricuspid valve. Adults with valvular pulmonary stenosis are often asymptomatic; in such patients the condition is identified by auscultation of a loud systolic murmur. When the stenosis is severe, dyspnea on exertion or fatigability may occur; less often, patients may have retrosternal chest pain or syncope with exertion. Eventually, right ventricular failure may develop, with resultant peripheral edema and abdominal swelling. Finally, if the foramen ovale is patent, shunting of blood from the right to the left atrium may occur, causing cyanosis and clubbing.
Adults with mild valvular pulmonary stenosis are usually asymptomatic; in such patients the condition does not require correction. Survival among such patients is excellent, with 94 percent still alive 20 years after diagnosis. Patients with mild valvular stenosis who are undergoing elective dental or surgical procedures should receive antibiotic prophylaxis against infective endocarditis. In contrast, patients with severe stenosis should have the stenosis relieved, since only 40 percent of such patients do not require any intervention by 10 years after diagnosis. Patients with moderate pulmonary stenosis have an excellent prognosis with either medical or interventional therapy. Interventional therapy is usually recommended, since most patients with moderate pulmonary stenosis eventually have symptoms requiring such therapy. Relief of valvular stenosis can be accomplished easily and safely with percutaneous balloon valvuloplasty, and a delay in intervention offers no advantage. Balloon valvuloplasty, the procedure of choice, is usually successful, provided the valve is mobile and pliant; its long-term results are excellent. The secondary hypertrophic subpulmonary stenosis that may occur with valvular stenosis usually regresses after successful intervention. Valve replacement is required if the leaflets are dysplastic or calcified or if marked regurgitation is present.
Aortic Coarctation
Coarctation of the aorta typically consists of a discrete, diaphragm-like ridge extending into the aortic lumen just distal to the left subclavian artery at the site of the aortic ductal attachment (the ligamentum arteriosum) (Figure 4). This condition results in hypertension in the arms. Less commonly, the coarctation is immediately proximal to the left subclavian artery, in which case a difference in arterial pressure is noted between the arms. Extensive collateral arterial circulation to the distal body through the internal thoracic, intercostal, subclavian, and scapular arteries frequently develops in patients with aortic coarctation. The condition, which is two to five times as frequent in men and boys as in women and girls, may occur in conjunction with gonadal dysgenesis (e.g., Turner’s syndrome), bicuspid aortic valve, ventricular septal defect, patent ductus arteriosus, mitral stenosis or regurgitation, or aneurysms of the circle of Willis.
Figure 4. Coarctation of the Aorta.
Coarctation causes severe obstruction of blood flow in the descending thoracic aorta. The descending aorta and its branches are perfused by collateral channels from the axillary and internal thoracic arteries through the intercostal arteries (arrows).
On physical examination, the systolic arterial pressure is higher in the arms than in the legs, but the diastolic pressures are similar; therefore, a widened pulse pressure is present in the arms. The femoral arterial pulses are weak and delayed. A systolic thrill may be palpable in the suprasternal notch, and left ventricular enlargement may be noted. A systolic ejection click (due to a bicuspid aortic valve) is frequently present, and the second heart sound is accentuated. A harsh systolic ejection murmur may be identified along the left sternal border and in the back, particularly over the coarctation. A systolic murmur, caused by flow through collateral vessels, may be heard in the back. In about 30 percent of patients with aortic coarctation, a systolic murmur indicating an associated bicuspid aortic valve is audible at the base.
The electrocardiogram usually shows left ventricular hypertrophy. On the chest radiograph, increased collateral flow through the intercostal arteries causes notching of the posterior third of the third through eighth ribs; such notching is usually symmetric. Notching is not seen in the anterior ribs, since the anterior intercostal arteries are not located in costal grooves. The coarctation may be visible as an indentation of the aorta, and one may see prestenotic and poststenotic dilatation of the aorta, producing the “reversed E” or “3” sign. The coarctation may be visualized echocardiographically, and Doppler examination makes possible an estimate of the transcoarctation pressure gradient. Computed tomography, magnetic resonance imaging, and contrast aortography provide precise anatomical information regarding the location and length of the coarctation; in addition, aortography permits the visualization of the collateral circulation.
Most adults with aortic coarctation are asymptomatic. The diagnosis is made during routine physical examination, when systemic arterial hypertension is observed in the arms, with diminished or absent femoral arterial pulses. When symptoms are present, they are usually those of hypertension: headache, epistaxis, dizziness, and palpitations. Occasionally, diminished blood flow to the legs causes claudication. Patients sometimes seek medical attention because they have symptoms of heart failure or aortic dissection. Women with coarctation are at particularly high risk for aortic dissection during pregnancy.
Complications of aortic coarctation include hypertension, left ventricular failure, aortic dissection, premature coronary artery disease, infective endocarditis, and cerebrovascular accidents (due to the rupture of an intracerebral aneurysm). Two thirds of patients over the age of 40 years who have uncorrected aortic coarctation have symptoms of heart failure. Three fourths die by the age of 50, and 90 percent by the age of 60.
Surgical repair should be considered for patients with a transcoarctation pressure gradient of more than
Similarly, survival after repair of aortic coarctation is also influenced by the age of the patient at the time of surgery. After surgical repair during childhood, 89 percent of patients are alive 15 years later and 83 percent are alive 25 years later. When repair of coarctation is performed when the patient is between the ages of 20 and 40 years, the 25-year survival is 75 percent. When repair is performed in patients more than 40 years old, the 15-year survival is only 50 percent.
Cyanotic Conditions
Patients with cyanotic congenital heart disease have arterial oxygen desaturation resulting from the shunting of systemic venous blood to the arterial circulation. The magnitude of shunting determines the severity of desaturation. Most children with cyanotic heart disease do not survive to adulthood without surgical intervention. In adults, the most common causes of cyanotic congenital heart disease are tetralogy of Fallot and Eisenmenger’s syndrome.
Tetralogy of Fallot
Tetralogy of Fallot, the most common cyanotic congenital heart defect after infancy, is characterized by a large ventricular septal defect, an aorta that overrides the left and right ventricles, obstruction of the right ventricular outflow tract (obstruction may be subvalvular, valvular, supravalvular, or in the pulmonary arterial branches), and right ventricular hypertrophy (Figure 5). Several abnormalities may occur in association with tetralogy of Fallot, including right aortic arch in 25 percent of patients, atrial septal defect in 10 percent (so-called pentalogy of Fallot), and coronary arterial anomalies in 10 percent.
Figure 5. Tetralogy of Fallot.
Tetralogy of Fallot is characterized by a large ventricular septal defect, an aorta that overrides the left and right ventricles, obstruction of the right ventricular outflow tract, and right ventricular hypertrophy. With substantial obstruction of the right ventricular outflow tract, blood is shunted through the ventricular septal defect from right to left (arrow).
Most patients with tetralogy of Fallot have substantial right-to-left shunting and therefore have cyanosis. Because of the large ventricular septal defect, the right and left ventricular pressures are equal. Right-to-left shunting of venous blood occurs because of increased resistance to flow in the right ventricular outflow tract, the severity of which determines the magnitude of shunting. Since the resistance to flow across the right ventricular outflow tract is relatively fixed, changes in systemic vascular resistance affect the magnitude of right-to-left shunting. A decrease in systemic vascular resistance increases right-to-left shunting, whereas an increase in systemic resistance decreases right-to-left shunting.
Most patients with tetralogy of Fallot have cyanosis from birth or beginning in the first year of life. In childhood, such patients may have sudden hypoxic “spells,” characterized by tachypnea and hyperpnea, followed by worsening cyanosis and, in some cases, loss of consciousness, seizures, cerebrovascular accidents, and even death. Such spells do not occur in adolescents or adults. Adults with tetralogy of Fallot have dyspnea and limited tolerance of exercise. They may have complications of chronic cyanosis, including erythrocytosis, hyperviscosity, abnormalities of hemostasis, cerebral abscesses or stroke, and endocarditis. Without surgical intervention, most patients die in childhood: the rate of survival is 66 percent at 1 year of age, 40 percent at 3 years, 11 percent at 20 years, 6 percent at 30 years, and 3 percent at 40 years.
Patients with tetralogy of Fallot have cyanosis and digital clubbing, the severity of which is determined by the degree of obstruction of the right ventricular outflow tract. The peripheral pulses are normal. A right ventricular lift or tap is palpable. In some patients, a systolic thrill (caused by turbulent flow across the right ventricular outflow tract) is palpable. The first heart sound is normal, but the second heart sound is single, since its pulmonary component is inaudible. An aortic ejection click (due to a dilated, overriding aorta) may be heard. A systolic ejection murmur, audible along the left sternal border, is caused by the obstruction of right ventricular outflow. The intensity and duration of the murmur are inversely related to the severity of the obstruction of right ventricular outflow; a soft, short murmur suggests that severe obstruction is present.
The electrocardiogram shows right-axis deviation and right ventricular hypertrophy. On radiography, the size of the heart is normal or small, and lung markings are diminished. The heart is classically “boot-shaped,” with an upturned right ventricular apex and a concave main pulmonary arterial segment. A right-sided aortic arch may be present. Arterial oxygen desaturation is evident, as is compensatory erythrocytosis, the magnitude of which is proportional to the severity of the desaturation.
Echocardiography can be used to establish the diagnosis, as well as to assess the presence of associated abnormalities, the level and severity of the obstruction of the right ventricular outflow tract, the size of the main pulmonary artery and its branches, and the number and location of ventricular septal defects. Right-to-left shunting through the ventricular septal defect can be visualized by color Doppler imaging, and the severity of right ventricular outflow tract obstruction can be determined by spectral Doppler measurement. With catheterization, it is possible to confirm the diagnosis and obtain additional anatomical and hemodynamic data, including the location and magnitude of right-to-left shunting, the level and severity of right ventricular outflow obstruction, the anatomical features of the right ventricular outflow tract and the main pulmonary artery and its branches, and the origin and course of the coronary arteries. Magnetic resonance imaging can also provide much of this information.
Surgical repair is recommended to relieve symptoms and to improve survival. Previously, infants underwent one of three palliative procedures to increase pulmonary blood flow (all three involve anastomosis of a systemic artery to a pulmonary artery), thereby reducing the severity of cyanosis and improving exercise tolerance. These procedures are the Waterston operation (a side-to-side anastomosis of the ascending aorta and the right pulmonary artery), the Potts operation (a side-to-side anastomosis of the descending aorta to the left pulmonary artery), and the Blalock–Taussig operation (end-to-side anastomosis of the subclavian artery to the pulmonary artery). Often, however, these procedures were associated with long-term complications, such as pulmonary hypertension, left ventricular volume overload, and distortion of the pulmonary arterial branches.
Currently, complete surgical correction (closure of the ventricular septal defect and relief of right ventricular outflow obstruction) is performed when patients are very young. The mortality associated with surgery is less than 3.0 percent in children and 2.5 to 8.5 percent in adults. At present, palliative shunting or balloon pulmonary valvuloplasty is performed only in severely ill infants for whom complete repair is unsuitable (e.g., those with underdeveloped pulmonary arteries). These procedures increase pulmonary blood flow and allow the pulmonary arteries to enlarge so that corrective surgery may be undertaken at a later time. Patients with tetralogy of Fallot (either repaired or unrepaired) are at risk for endocarditis and should therefore receive prophylaxis with antibiotics before dental or elective surgical procedures.
Although patients with repaired tetralogy of Fallot are usually asymptomatic, their survival is somewhat poorer than that of an age-matched control population, because of an increased risk of sudden death (presumably from cardiac causes). In one series, the rate of survival 32 years after surgery was 86 percent among patients with repaired tetralogy and 96 percent in an age-matched control population. Ventricular arrhythmias can be detected with Holter monitoring in 40 to 50 percent of patients with repaired tetralogy of Fallot and are most likely to occur in patients who are older at the time of surgical repair and those with moderate or severe pulmonary regurgitation, systolic and diastolic ventricular dysfunction, prolonged cardiopulmonary bypass, or prolongation of the QRS interval (to >180 msec). Patients with repaired tetralogy of Fallot often have atrial fibrillation or flutter, which may cause considerable morbidity.
Patients with repaired tetralogy of Fallot are at risk for other chronic complications. Pulmonary regurgitation may develop as a consequence of surgical repair of the right ventricular outflow tract. Although even substantial regurgitation can be tolerated for long periods, enlargement of the right ventricle eventually occurs, with resultant right ventricular dysfunction, and repair or replacement of the pulmonary valve may be required. An aneurysm may form at the site where the right ventricular outflow tract was repaired. Although such aneurysms are usually identified incidentally, rupture has been reported in rare cases.
Alternatively, patients may have residual or recurrent obstruction of the right ventricular outflow tract, requiring repeated surgery. Approximately 10 to 20 percent of patients with repaired tetralogy of Fallot have residual ventricular septal defects, and such patients may require repeated surgery if the defects are of sufficient size. Right bundle-branch block is common after repair of tetralogy of Fallot, but complete heart block is rare. Finally, aortic regurgitation may occur but is usually mild.
Ebstein’s Anomaly
Ebstein’s anomaly is an abnormality of the tricuspid valve in which the septal leaflets and often the posterior leaflets are displaced into the right ventricle and the anterior leaflet is usually malformed, excessively large, and abnormally attached or adherent to the right ventricular free wall. Thus, a portion of the right ventricle is “atrialized” in that it is located on the atrial side of the tricuspid valve, and the remaining functional right ventricle is small (Figure 6). The tricuspid valve is usually regurgitant but may be stenotic. Eighty percent of patients with Ebstein’s anomaly have an interatrial communication (atrial septal defect or patent foramen ovale) through which right-to-left shunting of blood may occur.
Figure 6. Ebstein’s Anomaly.
In patients with Ebstein’s anomaly, a portion of the right ventricle is atrialized (i.e., located on the atrial side of the tricuspid valve), and as a result, the functional right ventricle is small. In addition, most patients have an interatrial communication (atrial septal defect or patent foramen ovale), through which right-to-left shunting may occur.
The severity of the hemodynamic derangements in patients with Ebstein’s anomaly depends on the degree of displacement and the functional status of the tricuspid-valve leaflets. Patients with mild apical displacement of the tricuspid leaflets have normal valvular function, whereas those with severe tricuspid-leaflet displacement or abnormal anterior leaflet attachment, with valvular dysfunction, have elevated right atrial pressure and right-to-left interatrial shunting. Similarly, the clinical presentation of Ebstein’s anomaly varies from severe heart failure in a fetus or neonate to the absence of symptoms in an adult in whom it is discovered incidentally.
When Ebstein’s anomaly is discovered during fetal life, the rate of intrauterine mortality is high. Neonates with severe disease have cyanosis, with heart failure and a murmur noted in the first days of life. Transient improvement may occur as pulmonary vascular resistance falls, but the condition worsens after the ductus arteriosus closes, thereby decreasing pulmonary blood flow. Older children with Ebstein’s anomaly often come to medical attention because of an incidental murmur, whereas adolescents and adults present with a supraventricular arrhythmia. In adults with Ebstein’s anomaly, the most important predictors of outcome are the New York Heart Association (NYHA) functional class, the heart size, the presence or absence of cyanosis, and the presence or absence of paroxysmal atrial tachycardias. Such tachycardias may lead to cardiac failure, worsening cyanosis, and even syncope. Patients with Ebstein’s anomaly and an interatrial communication are at risk for paradoxical embolization, brain abscess, and sudden death.
On physical examination, the severity of cyanosis depends on the magnitude of right-to-left shunting. The first and second heart sounds are widely split, and a third or fourth heart sound is often present, resulting in a “triple” or “quadruple” rhythm. A systolic murmur caused by tricuspid regurgitation is usually present at the left lower sternal border. Hepatomegaly (resulting from passive hepatic congestion due to elevated right atrial pressure) may be present.
Tall and broad P waves are common on the electrocardiogram, as is right bundle-branch block. First-degree atrioventricular block occurs frequently. Since about 20 percent of patients with Ebstein’s anomaly have ventricular preexcitation by way of an accessory electrical pathway between the atrium and ventricle (Wolff–Parkinson–White syndrome), a delta wave may be present. The radiographic findings depend on the severity of the anatomical abnormality. In mild cases, the heart size and pulmonary vasculature are normal. In more severe cases, marked cardiomegaly, which is largely due to right atrial enlargement, is present. In severe cases (with little functional right ventricle and marked right-to-left shunting), pulmonary vascular markings are decreased. Echocardiography is used to assess right atrial dilatation, anatomical displacement and distortion of the tricuspid-valve leaflets, and the severity of tricuspid regurgitation or stenosis; in addition, the presence and magnitude of interatrial shunting can be determined (by color Doppler imaging or bubble study), as can the presence of associated cardiac abnormalities. Electrophysiologic evaluation is warranted in patients with atrial tachyarrhythmias.
The management of Ebstein’s anomaly centers on the prevention and treatment of complications. Prophylaxis against infective endocarditis is recommended. Patients with symptomatic heart failure are given diuretic agents and digoxin. Those with atrial arrhythmias may be treated pharmacologically or with catheter ablation (if an accessory pathway is present). Ablation of accessory pathways has a lower rate of success in patients with Ebstein’s anomaly than in those with structurally normal hearts, and the risk of recurrence of arrhythmia is higher. In severely ill infants with Ebstein’s anomaly, an arterial shunt from the systemic circulation to the pulmonary circulation is created to increase pulmonary blood flow, thereby decreasing cyanosis. Further surgery to create a univentricular heart (i.e., by the Fontan procedure) may also be considered in neonates.
Repair or replacement of the tricuspid valve in conjunction with closure of the interatrial communication is recommended for older patients who have severe symptoms despite medical therapy. In addition, repair or replacement should be considered for patients with less severe symptoms who have cardiac enlargement, since this condition has a poor prognosis. When possible, valve repair is preferable to valve replacement, because it is associated with lower mortality and has fewer long-term complications. However, when valve replacement is required, a bioprosthesis is preferable to a mechanical prosthesis. The complications of surgery to correct Ebstein’s anomaly include complete heart block, persistence of supraventricular arrhythmias, residual tricuspid regurgitation after valve repair, and prosthetic-valve dysfunction.
Transposition of the Great Arteries
With d-transposition of the great arteries (also known as complete transposition), the aorta arises in an anterior position from the right ventricle and the pulmonary artery arises from the left ventricle (Figure 7A). Therefore, there is complete separation of the pulmonary and systemic circulations: systemic venous blood traverses the right atrium, right ventricle, aorta, and systemic circulation, whereas pulmonary venous blood traverses the left atrium, left ventricle, pulmonary artery, and pulmonary circulation. In order for an infant with this condition to survive, there must be a communication between the two circuits. In about two thirds of patients, no other associated cardiac defect is present, so that the ductus arteriosus and foramen ovale allow communication between the two circuits. Infants with this condition have severe cyanosis. The one third of patients with other associated defects that permit intracardiac mixing (e.g., atrial septal defect, ventricular septal defect, or patent ductus arteriosus) are less critically ill, since they have less severe cyanosis. However, they are at risk for left ventricular failure due to volume overload caused by left-to-right shunting.
Figure 7. Transposition and Switching of the Great Arteries.
In d-transposition of the great arteries (complete transposition) (Panel A), systemic venous blood returns to the right atrium, from which it goes to the right ventricle and then to the aorta. Pulmonary venous blood returns to the left atrium, from which it goes to the left ventricle and then to the pulmonary artery. Survival is possible only if there is a communication between the two circuits, such as a patent ductus arteriosus. With the “atrial switch” operation (Panel B), a pericardial baffle is created in the atria, so that blood returning from the systemic venous circulation is directed into the left ventricle and then the pulmonary artery (blue arrows), whereas blood returning from the pulmonary venous circulation is directed into the right ventricle and then the aorta (red arrow). With the “arterial switch” operation (Panel C), the pulmonary artery and ascending aorta are transected above the semilunar valves and coronary arteries, then switched (neoaortic and neopulmonary valves).
Patients with complete transposition have cyanosis from birth and often have heart failure in the newborn period. The findings on physical examination are nonspecific. Infants have cyanosis and tachypnea. The second heart sound is single and loud (due to the anterior position of the aorta). In patients with mild cyanosis, a holosystolic murmur caused by a ventricular septal defect may be heard. Likewise, a soft systolic ejection murmur (due to pulmonary stenosis, ejection into the anteriorly located aorta, or both) may be audible. The electrocardiogram shows right-axis deviation and right ventricular hypertrophy (since the right ventricle is the systemic ventricle). Patients with a large ventricular septal defect or patent ductus arteriosus, as well as those with pulmonary stenosis, have left ventricular hypertrophy. The chest radiograph shows cardiomegaly with increased pulmonary vascularity. Classically, the cardiac silhouette is described as being egg-shaped, with a narrow “stalk.”
Without intervention, patients with complete transposition have a poor prognosis. Unless intracardiac mixing is improved, progressive hypoxemia and acidosis develop; the mortality rate is 90 percent by six months of age. Infants who have less severe cyanosis (because of a sizable ventricular septal defect or patent ductus arteriosus) fare better in the neonatal period, but pulmonary vascular obstructive disease (due to increased pulmonary blood flow) is more likely to develop than in infants with more severe cyanosis; infants with less severe cyanosis are also more likely to have higher operative mortality and are less likely to have complete repair of their defect.
The immediate management of complete transposition involves creating intracardiac mixing or increasing its extent. This can be accomplished with an infusion of prostaglandin E (to maintain or restore patency of the ductus arteriosus), the creation of an atrial septal defect by means of balloon atrial septostomy (the Rashkind procedure), or both. In addition, oxygen is given to most patients (to decrease pulmonary vascular resistance and to increase pulmonary blood flow), as are digoxin and diuretic drugs (to treat heart failure).
Two surgical procedures have been used in patients with complete transposition of the great arteries. With the initial approach, known as the “atrial switch” operation (the Mustard or Senning operation), the atrial septum was excised, then a “baffle” within the atria was constructed to direct systemic venous blood across the mitral valve into the left ventricle and pulmonary venous blood across the tricuspid valve into the right ventricle (Figure 7B). Thus, physiologic circulation was restored; however, after this procedure was performed, the right ventricle continued to function as the “systemic ventricle.” This operation corrected cyanosis and improved survival. The complications associated with it were leakage of the atrial baffle (often clinically inconsequential); obstruction of the baffle (often insidious and frequently asymptomatic); sinus-node dysfunction and atrial arrhythmias, particularly atrial flutter; right (systemic) ventricular dysfunction; and an increased risk of sudden death.
The atrial-switch operation has been replaced by the arterial-switch operation, in which the pulmonary artery and ascending aorta are transected above the semilunar valves and coronary arteries and then switched, so that the aorta is connected to the neoaortic valve (formerly the pulmonary valve) arising from the left ventricle, and the pulmonary artery is connected to the neopulmonary valve (formerly the aortic valve) arising from the right ventricle (Figure
Eisenmenger’s Syndrome
A patient with Eisenmenger’s syndrome has a large left-to-right shunt that causes severe pulmonary vascular disease and pulmonary hypertension, with resultant reversal of the direction of shunting (Figure 8). With substantial left-to-right shunting, the exposure of the pulmonary vasculature to increased blood flow as well as increased pressure often results in pulmonary vascular obstructive disease. The initial morphologic alterations (medial hypertrophy of the pulmonary arterioles, intimal proliferation and fibrosis, and occlusion of capillaries and small arterioles) are potentially reversible. However, as the disease progresses, the more advanced morphologic changes (plexiform lesions and necrotizing arteritis) are irreversible. The result is obliteration of much of the pulmonary vascular bed, leading to increased pulmonary vascular resistance. As the pulmonary vascular resistance approaches or exceeds systemic resistance, the shunt is reversed.
Figure 8. Eisenmenger’s Syndrome.
In patients with Eisenmenger’s syndrome, in response to substantial left-to-right shunting, morphologic alterations occur in the small pulmonary arteries and arterioles (inset), leading to pulmonary hypertension and the resultant reversal of the intracardiac shunt (arrow). In the small pulmonary arteries and arterioles, medial hypertrophy, intimal cellular proliferation, and fibrosis lead to narrowing or closure of the vessel lumen. With sustained pulmonary hypertension, extensive atherosclerosis and calcification often develop in the large pulmonary arteries. Eisenmenger’s syndrome may occur in association with a ventricular septal defect (as shown), but it also may occur in association with an atrial septal defect or patent ductus arteriosus.
The morphologic changes in the pulmonary vasculature that occur with Eisenmenger’s syndrome usually begin in childhood, but symptoms may not appear until late childhood or early adulthood. In many patients, pulmonary congestion in early infancy (a result of the large left-to-right shunt) resolves in later infancy or early childhood as pulmonary vascular resistance increases and the magnitude of shunting decreases. Likewise, the patient may have a murmur in early childhood that disappears (as the pulmonary disease progresses and the magnitude of shunting decreases), leading to the mistaken assumption that the intracardiac communication has closed. Occasionally, patients have no history of pulmonary congestion or a murmur in childhood.
As right-to-left shunting develops, cyanosis appears. Most patients will have impaired exercise tolerance and exertional dyspnea, but these symptoms may be well compensated for years. Palpitations are common and are most often due to atrial fibrillation or flutter. As erythrocytosis due to arterial desaturation develops in patients with Eisenmenger’s syndrome, symptoms of hyperviscosity (visual disturbances, fatigue, headache, dizziness, and paresthesias) may appear. Hemoptysis may occur, as a result of pulmonary infarction or rupture of dilated pulmonary arteries, arterioles, or aorticopulmonary collateral vessels. Since patients with arterial desaturation have abnormal hemostasis, they are at risk for both bleeding and thrombosis. Cerebrovascular accidents may occur as a result of paradoxical embolization, venous thrombosis of cerebral vessels, or intracranial hemorrhage. In addition, patients with this condition are at risk for brain abscess. Patients with Eisenmenger’s syndrome may have syncope owing to inadequate cardiac output or, less commonly, an arrhythmia. Symptoms of heart failure, which are uncommon until the disease is far advanced, portend a poor prognosis. Finally, these patients are at risk for sudden death.
On physical examination, patients have digital clubbing and cyanosis, the severity of which depends on the magnitude of right-to-left shunting. The jugular venous pressure may be normal or elevated, and prominent V waves are seen if tricuspid regurgitation is present. Arterial pulses are small in volume. A right parasternal heave (due to right ventricular hypertrophy) is present, and the pulmonary component of the second heart sound is loud (and often palpable). The murmur caused by a ventricular septal defect, patent ductus arteriosus, or atrial septal defect disappears when Eisenmenger’s syndrome develops. Many patients have a decrescendo diastolic murmur caused by pulmonary regurgitation or a holosystolic murmur caused by tricuspid regurgitation. A right-sided fourth heart sound is usually present. The lungs are clear. Peripheral edema and hepatic congestion are absent unless there is substantial right ventricular dysfunction.
The electrocardiogram shows right ventricular hypertrophy. Atrial arrhythmias may be present, particularly in patients with atrial septal defect. The chest film reveals prominent central pulmonary arteries and decreased vascular markings (“pruning”) of the peripheral vessels. The size of the heart is normal in patients with a ventricular septal defect or patent ductus arteriosus, but cardiomegaly (due to right ventricular enlargement) is usually seen in those with atrial septal defect. On transthoracic echocardiography, there is evidence of right ventricular pressure overload and pulmonary hypertension. The underlying cardiac defect can usually be visualized, although shunting across the defect may be difficult to demonstrate by color Doppler imaging because of the low velocity of the jet. Contrast echocardiography permits the location of the shunt to be determined. Catheterization should be performed in any patient with suspected Eisenmenger’s syndrome in order to assess the severity of pulmonary vascular disease and to quantify the magnitude of intracardiac shunting. Pulmonary vasodilators — such as oxygen, inhaled nitrous oxide, or intravenous adenosine or epoprostenol — should be administered to permit assessment of the reversibility of pulmonary hypertension.
The rate of survival among patients with Eisenmenger’s syndrome is 80 percent 10 years after diagnosis, 77 percent at 15 years, and 42 percent at 25 years. Death is usually sudden, presumably caused by arrhythmias, but some patients die of heart failure, hemoptysis, brain abscess, or stroke. A history of syncope, clinically evident right ventricular systolic dysfunction, low cardiac output, and severe hypoxemia portend a poor outcome.
Patients with Eisenmenger’s syndrome should avoid intravascular volume depletion, heavy exertion, high altitude, and the use of vasodilators. Because of high maternal and fetal morbidity and mortality, pregnancy should be avoided. Although no therapy has been proved to reduce pulmonary vascular resistance, intravenous epoprostenol may be beneficial. Phlebotomy with isovolumic replacement should be performed in patients with moderate or severe symptoms of hyperviscosity; it should not be performed in asymptomatic or mildly symptomatic patients (regardless of the hematocrit). Repeated phlebotomy may result in iron deficiency, which may worsen symptoms of hyperviscosity, since iron-deficient erythrocytes are less deformable than iron-replete erythrocytes.
Patients with Eisenmenger’s syndrome who are undergoing noncardiac surgery require meticulous management of anesthesia, with attention to the maintenance of systemic vascular resistance, the minimization of blood loss and intravascular volume depletion, and the prevention of iatrogenic paradoxical embolization. In preparation for noncardiac surgery, prophylactic phlebotomy (usually of 1 to 2 units of blood, with isovolumic replacement) is recommended for patients with a hematocrit above 65 percent in order to reduce the likelihood of perioperative hemorrhagic and thrombotic complications. In general, anticoagulants and antiplatelet agents should be avoided, since they exacerbate the hemorrhagic diathesis.
Lung transplantation with repair of the cardiac defect or combined heart–lung transplantation is an option for patients with Eisenmenger’s syndrome who have markers of a poor prognosis (syncope, refractory right-sided heart failure, a high NYHA functional class, or severe hypoxemia). Because of the somewhat limited success of transplantation and the reasonably good survival among patients treated medically, careful selection of patients for transplantation is imperative.
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Atrial septal defect: case 1
A 43-year-old businessman presents to the accident and emergency department having had palpitations for 12 h. He admits to having increasing shortness of breath over the past two years, and having to rest after climbing three flights of stairs. On examination, his pulse was irregular at a rate of 110 beats per minute, and his jugular venous pulsation (JVP)
Atrial septal defects are some of the most common congenital cardiac malformations in adults, representing up to 40% of acyanotic shunt lesions in patients older than 40 years. They arise from either excessive resorption of the septum primum or from deficient growth of the septum secundum, and are occasionally associated with anomalous pulmonary venous connection (about 10%). The degree of left-to-right atrial shunting depends on the size of the defect and the diastolic filling properties of the two ventricles. A substantial shunt (Qp/Qs >1·5/1·0) will probably cause symptoms over time, and the movement of such patients will become progressively more restricted with age. Effort dyspnoea is seen in about 30% of patients by their third decade whereas supraventricular arrhythmias (atrial fibrillation or flutter) and right heart failure develop in about 10% of patients by age 40 years.
Treatment
Haemodynamically unimportant atrial septal defects (Qp/Qs <1·5) do not need closure, except for the prevention of paradoxical emboli in patients who have had cryptogenic stroke. In the absence of clinically significant pulmonary hypertension, closure is recommended for severe defects (Qp/Qs >1·5, or those associated with right ventricular volume overload). In patients without symptoms, indications for closure are somewhat controversial. In those younger than 40 years, severe defects should probably be closed. The appropriate treatment for patients who are older than 40 years is in some dispute, although results of one randomised clinical trial which showed an overall survival benefit among surgical patients would suggest that closure is advisable.
Surgical closure of these defects can be done by primary suture closure or by an autologous pericardial or synthetic patch. Surgical mortality in adults with no pulmonary hypertension should be less than 1%, with a low morbidity related mainly to the development of perioperative arrhythmias (atrial flutter or fibrillation, or junctional rhythm). The use of devices to close defects percutaneously under fluoroscopy and transoesophageal echocardiographic guidance is gaining popularity.
Transoesophageal echocardiographical image of a secundum atrial septal defect after closure with Amplatzer device
LA=left atrium. RA=right atrium. Arrows point at both sides of the Amplatzer device after insertion.
Indications for closure by devices are the same as for surgical closure but selection criteria are stricter than for surgery. Devices are available only for patients with one secundum atrial septal defect and with an adequate septal margin for proper device support. Anomalous pulmonary venous connection precludes the use of this technique. This procedure is safe and effective when done by a skilled cardiologist, and major complications (eg, device embolisation, atrial perforation) arise in less than 1% of patients. Complete closure is achieved in 80% or more of patients. Long-term follow-up data, however, are not available. Notwithstanding, closure by device can be appealing to a patient wishing to avoid the consequences of surgery (general anaesthesia, cardiopulmonary bypass, pain, scar, and time for convalescence), or to a patient believed to be at high surgical risk.
Patent ductus arteriosus: case 2
A 72-year-old woman is referred by her family doctor for atypical chest pain. Risk factors for coronary artery disease are few. Physical examination revealed a grade 1/6 continuous murmur in the left subclavian area. Transthoracic echo confirmed a small colour flow jet area seen between the aorta and the pulmonary artery in the suprastemal view, suggestive of a small patent ductus arteriosus. Left-heart chambers are of normal size and function.
The incidence of isolated persistent patency of the ductus arteriosus is estimated at one in 2000 to one in 5000 births. The ductus arteriosus derives from the left sixth primitive aortic arch and connects the proximal left pulmonary artery to the descending aorta, distal to the left subclavian artery. Occasionally, the ductus fails to close at birth and presents as a potential clinical problem.
Physiological consequences of a patent ductus arteriosus depend on the degree of left-to-right shunting, which is determined by both the size of the duct and the difference between systemic and pulmonary vascular resistances. A small ductus accompanied by a small shunt does not cause significant haemodynamic disruption but might predispose to endarteritis, especially if accompanied by an audible murmur. A moderate sized duct and shunt put a volume load on the left atrium and ventricle that results in dilation and often dysfunction of the left ventricle, and development of a trial fibrillation, or both. A large duct results initially in left-ventricular volume overload (which disappears after pulmonary hypertension develops), with a progressive rise in pulmonary artery pressure. This rise in pressure leads to high pulmonary vascular resistance and eventually, irreversible pulmonary vascular changes and systemic pulmonary pressures.
Treatment
Closure of a clinically detectable patent ductus arteriosus, in the absence of irreversible pulmonary hypertension, is usually recommended, although controversial, to avoid infective endarteritis. The risk of endarteritis in a patient with a small silent patent ductus arteriosus is regarded as negligible, and closure of such small ducts is therefore not recommended. Over the past 20 years, the effectiveness and safety of transcatheter device closure for ducts smaller than
Surgical closure, by ductal ligation or division, or both, has been done for over 50 years with a slightly better closure rate, but greater morbidity and mortality, than that for closure with device. Surgical closure of a duct should be reserved for patients with ducts larger than
Bicuspid aortic valve: case 3
A 25-year-old woman (Gravida one, pregnancy none, abortioone) is referred at 18 weeks’ pregnancy for a heart murmur. The patient is asymptomatic. Her blood pressure is 90/60 mm Hg. On examination she had an ejection click best heard at the apex, a grade 3/6 systolic ejection murmur best heard at the second right intercostal space, with radiation to the carotids with a soft diastolic murmur grade 2/6 heard clearest along the left sternal border. A transthoracic echocardiogram confirmed the presence of a bicuspid aortic valve with moderate aortic stenosis (aortic valve area 1·0 cm2), and mild-to-moderate aortic regurgitation. Cardiac MRI showed a dilated ascending aorta measuring
MRI of a dilated ascending aorta in a patient with a bicuspid aortic valve
Arrows indicate the sides of the dilated ascending aorta.
Bicuspid aortic valve has a male preponderance of 4 to 1. This lesion accounts for about half the cases of surgically important isolated aortic stenosis in adults. A bicuspid aortic valve consists of two cusps, often of unequal size, the larger usually containing a false raphe. This lesion generally arises in isolation but is associated with other abnormalities in 20% of patients, the most common of which is coarctation of the aorta and patent ductus arteriosus.
At least half the patients with a bicuspid aortic valve have no complications, although there is always the risk of endocarditis. Mild aortic stenosis or regurgitation from bicuspid aortic valve generally progresses as the patient ages, but the rate is variable. Enlargement of the aortic root resulting from cystic medial changes in patients with bicuspid aortic valve has a high prevalence, and occurs irrespective of altered haemodynamics or age. Aortic dissection is rare.
Treatment
Bicuspid aortic valves need intervention for stenosis when symptoms (exertional dyspnoea, angina, pre-syncope, or syncope) are present and should be considered before pregnancy when the stenosis is severe. Intervention for asymptomatic severe aortic stenosis to allow safe pregnancy is controversial, but severe aortic stenosis has proved to be a risk factor for cardiac decompensation during pregnancy.30 Bicuspid aortic stenosis can be treated with balloon valvuloplasty if the patient is younger than 30 years and if the valve is not calcified. Other treatment options include open aortic valvotomy, or valve replacement with a mechanical valve, a biological valve, or a pulmonary autograft (Ross procedure).
Prophylactic surgery for proximal aortic dilation (>
This patient would be best treated with close medical follow-up and echocardiography every 3 months or so, to look for signs of progressive aortic root dilation. Treatment with β blockers (if blood pressure is normal) and bedrest, with or without early delivery, should be considered when rapid progression of the ascending aortopathy is seen or the ascending aorta reaches more than
Coarctation of aorta: case 4
A 44-year-old man with a history of coarctation repair in his childhood is referred for persistent mild systolic hypertension. The patient is otherwise asymptomatic. The blood pressure is 145/80 mm Hg on the right arm, 120/80 mm Hg on the left arm, 120/80 mm Hg on the right leg with a mild radiofemoral delay. MRI confirms the presence of a mild discrete narrowing at the site of previous coarctation repair and cardiac catheter shows a withdrawal gradient of 20 mm Hg between the proximal and distal descending aorta.
Coarctation of the aorta is seen most frequently in men with a ratio of almost 3 to 1. It usually resides in the region of the ligamentum arteriosum. It might be discrete or associated with hypoplasia of the aortic arch and isthmus. Related abnormalities include bicuspid aortic valve in 50-85% of cases. Despite initial successful correction of coarctation, the risk of late systemic hypertension (due to residual or recurrent coarctation, or merely to abnormal aortic wall compliance) in these patients is fairly high. If inadequately controlled, hypertension leads to an increased risk of premature death from late heart failure. Other causes of premature death might be coronary artery disease with or without aortic rupture or dissection. Careful long-term follow-up and aggressive management of patients with hypertension is therefore recommended. Local complications such as re-coarctation and aneurysm formation at the site of previous transcatheter or surgical correction should be identified through periodic chest radiography, echocardiogram, MRI, or spiral CT examinations.
Treatment
All patients with serious coarctation or recoarctation having proximal hypertension, a withdrawal gradient greater than 20 mm Hg at angiography or an echo peak gradient of more than 20 mm Hg in the absence of extensive collaterals or less than 20 mm Hg in their presence, warrant treatment to eliminate the gradient and reduce the risk of long-term complications. Balloon dilatation with stent insertion in patients with native coarctation and recoarctation can be done with good immediate and medium-term results in adolescents and adults and should probably be the procedure of choice when the anatomy is suitable and expert skills are available. If the anatomy is not suitable (ie, long tunnel-like stenosis) surgery might be needed. After surgical repair of isolated aortic coarctation, the obstruction is usually relieved with minimum mortality (<2%). However, mortality is increased for reoperation (5-15%).
Angiograms of mild re-coarctation of the aorta (A); balloon dilatation and stenting of the re-coarctation segment of the descending aorta (B); and stented descending aorta (C)
Arrow in (A) indicates re-coarctation segment.
This patient has mild re-coarctation of the aorta (peak gradient >20 mm Hg) at the site of previous surgical repair with superimposed mild systolic hypertension. Balloon dilatation and stenting of the re-coarctation segment (if the anatomy is suitable) should be done to reduce proximal systolic blood pressure. The procedure should only be done, however, by experienced cardiologists. Surgical revision or antihypertensive medication, or both, might also be appropriate.
Tetralogy of Fallot: case 5
A 46-year-old woman is brought to the emergency room by ambulance after a witnessed collapse. Sustained ventricular tachycardia was ended and the patient successfully revived.
Electrocardiogram showing ventricular tachycardia in a patient after repair of tetralogy of Fallot
The patient has a history of repaired tetralogy of Fallot in childhood. She was lost to follow-up. Physical examination showed a right ventricular impulse and a low-pitched diastolic murmur grade 3/6 best heard along the left sternal border. Transthoracic echo showed a dilated right ventricle and severe pulmonary regurgitation. Cardiac MRI confirmed a severely dilated right ventricle (right ventricular end-diastolic volume 350 mL—normal range up to 108 mL/m2), severe pulmonary regurgitation, and fairly normal right ventricular systolic function.
MRI showing right right ventricular dilation in a patient after repair of tetralogy of Fallot
LA=left atrium.
Electrophysiological studies confirmed the presence of easily inducible ventricular tachycardia from the right ventricular outflow tract, and angiography shows normal pulmonary and coronary arteries.
Tetralogy of Fallot is the most common form of cyanotic congenital heart disease after 1 year of age, with a frequency of almost 10% of all congenital heart disease. The defect is caused by anterocephalad deviation of the outlet septum resulting in four features: (1) a non-restrictive ventricular septal defect; (2) an overriding aorta (<50% override); (3) obstruction of the right ventricular outflow tract which may be infundibular, valvar, or (usually) both, with or without supravalvar or branch pulmonary artery stenosis; and (4) consequent right ventricular hypertrophy.
Reparative surgery is usually done early in infancy, by closure of the ventricular septal defect with a Dacron patch and relief of the right ventricular outflow tract obstruction. Obstruction relief might include resection of infundibular muscle and insertion of a right ventricular outflow tract or transannular patch—a patch across the pulmonary valve annulus that disrupts the integrity of the pulmonary valve and causes important pulmonary regurgitation. Significant pulmonary regurgitation is almost always encountered when the transannular patch repair technique is used. Pulmonary regurgitation is usually well-tolerated indefinitely, if mild to moderate. Severe chronic pulmonary regurgitation might be well tolerated for 20 years or more, but could then lead to symptomatic right ventricular dysfunction, and increase the susceptibility to ventricular tachycardia and sudden cardiac death.
Residual obstruction of the right ventricular outflow tract can arise in the infundibulum, the pulmonary valve, and the main pulmonary trunk or branches of the left and right pulmonary arteries, or both branches. Right ventricular dilation in this setting is usually due to longstanding free pulmonary regurgitation, but might result from operative injury. Substantial tricuspid regurgitation might occur because of right ventricular dilation, which then leads to further dilation of the right ventricle.
Atrial tachyarrhythmia arises in about a third of adults and contributes to late morbidity and even mortality. It usually takes the form of atrial flutter or intra-atrial re-entrant tachycardia. Often indicative of haemodynamic trouble (significant right ventricular dilation and dysfunction, increased tricuspid regurgitation), the substrate is most likely a surgical scar in the atria and the trigger, atrial dilation.
Sustained monomorphic ventricular tachycardia is rare, compared with other types, and is highly associated with pronounced right ventricular dilation. The QRS duration from the standard surface ECG has been shown to correlate well with right ventricle size in these patients. A maximum QRS duration of 180 ms or more is a highly sensitive marker for sustained ventricular tachycardia and sudden cardiac death in adults with previous tetralogy repair, although its positive predictive value is low. Dilation of the right ventricle is thought to trigger ventricular tachycardia, whereas surgical scars (near the right ventricular outflow tract or ventricular septal defect patch) form the arrhythmia substrate. The reported frequency of sudden death, presumably due to arrhythmia, in late follow-up series is 0·5—6% over 30 years, accounting for about a third to a half of late deaths. Older age at repair, severe left ventricular dysfunction, postoperative right ventricular hypertension, transannular patching (causing free pulmonary regurgitation), and an accelerated rate of QRS prolongation are all predictors of sudden death in these patients.
Treatment of complications
Replacement of the pulmonary valve (with either a homograft or porcine bioprosthesis) might be necessary for severe pulmonary regurgitation leading to right ventricular dilation, sustained arrhythmias or symptoms, or both. Such replacement might also be needed for a grossly calcified pulmonary valve. It has a low operative risk and leads to symptomatic improvement. Timely pulmonary valve replacement, before irreversible severe right ventricular dilation and systolic right ventricular dysfunction begins, is a major clinical goal. Concomitant tricuspid valve annuloplasty might also be necessary when at least moderate tricuspid regurgitation is present.
Patients presenting with sustained atrial flutter, atrial fibrillation, or ventricular tachycardia, should undergo a thorough assessment of their haemodynamics and should have residual haemodynamic lesions repaired—eg, significant right ventricular dilation from pulmonary regurgitation with resulting tricuspid regurgitation that needs pulmonary valve replacement and tricuspid valve annuloplasty50, 51. Radiofrequency ablation, after mapping for atrial re-entry tachycardia, now yields better results than before for classic atrial flutter or incisional atrial reentrant tachycardia, or both, and should be done either percutaneously (if there is no need for concomitant surgery) or intraoperatively at the time of surgical repair of underlying haemodynamic lesions. For atrial fibrillation, a biatrial maze procedure should also be considered, and ideally done at reoperation. Likewise, transcatheter (when surgery is unnecessary) or concomitant intraoperative ablative procedures of the ventricular tachycardial pathway should be done when appropriate. Antiarrhythmic medications and the new generation of atrial antitachycardia pacemakers (for supraventricular tachycardia) can be used as adjunct treatments. Patients who were resuscitated after sudden cardiac death and are ieed of surgery without a haemodynamic substrate should probably receive an automated implantable cardioverter defibrillator (AICD).
This patient should probably have pulmonary valve replacement since the right ventricle is severely dilated, with repair of the ventricular septal defect patch as well as cryoablation of the ventricular tachycardia focus at the time of surgery. Pulmonary valve replacement will lead to a smaller right ventricle and cryoablation of the ventricular tachycardia focus would eliminate the arrhythmia substrate and probably prevent a further episode of sudden cardiac death.
Transposition of the great arteries: case 6
A 32-year-old man who had the Mustard procedure for D-transposition of the great arteries presents with increasing exertional dyspnoea and fatigue. Cardiac examination revealed a right ventricular impulse, a loud single S2 (second heart sound) and a holosystolic murmur best heard at the left sternal border. Transthoracic echo confirmed the presence of severe systemic tricuspid regurgitation and severe systemic right ventricular systolic dysfunction (ejection fraction 15%).
In patients with complete transposition of the great arteries, the connections between the atria and ventricles are concordant (normal), and the connections between ventricles and great arteries are discordant. Thus, the pulmonary and systemic circulations are connected in parallel rather than the normal in-series connection. In one circuit, systemic venous blood passes to the right atrium, the right ventricle, and then to the aorta. In the other, pulmonary venous blood passes through the left atrium and ventricle to the pulmonary artery. This situation is fatal unless the two circuits mix. About half of patients with transposition of the great arteries have additional abnormalities, most often a ventricular septal defect.
The most common previously done surgical procedure seen in adults is the atrial switch operation. Patients will have had either a Mustard or a Senning procedure. Blood is redirected at atrial level with a baffle made of Dacron or pericardium (Mustard operation) or with atrial flaps (Senning operation), to achieve physiological correction. Systemic venous return is diverted through the mitral valve into the subpulmonary morphological left ventricle and the pulmonary venous return is rerouted via the tricuspid valve into the subaortic morphological right ventricle. This repair, however, leaves the morphological right ventricle to support the systemic circulation.
Diagram showing atrial baffle in a patient with D-transposition of the great arteries
RA=right atrium. RV=right ventricle. LA=left atrium.
After atrial baffle surgery, most patients reaching adulthood will be in New York Heart Association class I—II. During 25 years of follow-up, about half these patients will have moderate systemic dysfunction of the right ventricle with only a few presenting with symptoms of congestive heart failure. Severe systemic tricuspid regurgitation is present in about a third, which exacerbates right ventricular dysfunction. Atrial flutter arises in 20% of patients by age 20 and progressive sinus node dysfunction is seen in half the patients by that time. These rhythm disturbances are thought to be a result of atrial and sinus node damage at the time of atrial baffle surgery. Baffle leak or obstruction can also occur.
The atrial switch operation was gradually replaced by the arterial switch operation (Jatene) in the 1980s, but few of these patients have yet become adults. Blood is redirected at the great artery level by switching the aorta and pulmonary arteries such that the morphological left ventricle becomes the subaortic ventricle and the morphological right ventricle becomes the subpulmonary ventricle. Reliable data for the clinical outcome in adults after the arterial switch procedure should be available over the next decade. Clinical arrhythmia promises to be less of a problem in this group of patients, but concerns about the development of supra neopulmonary artery stenosis, ostial coronary artery disease, and progressive neoaortic valve regurgitation warrant serial follow-up
Treatment
The benefits of angiotensin-converting enzyme inhibitors in patients with systemic right ventricular dysfunction after an atrial switch have not been established, and are being investigated in a double-blind multicentre randomised trial of ramipril. Occasionally, patients with a failed Mustard or Senning operation might need heart transplantation. Alternatively, a conversion procedure to an arterial switch, after re-training of the left ventricle with a pulmonary artery band, could be considered, but few data for the outcome of such a procedure are available in adults.
The degree of right ventricular dilation and systolic dysfunction should be confirmed by MRI or multiple gated acquisition examinations. An angiotensin-converting enzyme inhibitor with or without other heart failure therapies could be tried in this patient. If no clinical improvement is noted, however, a switch conversion procedure (pulmonary artery banding with left ventricular training followed by pulmonary artery debanding, and arterial switch with take down of the atrial baffle) should be used. Tricuspid valve replacement in this patient would probably lead to worsening of right ventricular function and is not recommended. Cardiac transplantation could also be considered at an appropriate time.
Fontan procedure: case 7
A 26-year-old college student with a diagnosis of tricuspid atresia palliated by the Fontan procedure goes to her local emergency room because of 6 h of continuous rapid palpitations. The patient is haemodynamically stable, and a cardiac monitor reveals atrial fibrillation with a ventricular response of ten beats per minute.
The Fontan procedure is the palliative, non-curative, surgical treatment for patients with univentricular hearts. The principle is diversion of the systemic venous return directly to the pulmonary arteries without the need for a subpulmonary ventricle. Many modifications of this procedure have been described, eg—direct atrio-pulmonary connection, total cavopulmonary connection, and extracardiac conduit. Progressive deterioration of functional status with time is the rule, with survival at 10 years after the procedure reported to be 60—71%. The most common complications after a Fontan procedure include atrial flutter or fibrillation, right atrial thrombus formation, obstruction of the Fontan circuit, and ventricular dysfunction.
Atrial flutter or fibrillation are common (15—20% at 5-year follow-up), and increases with duration of follow-up. They are associated with serious morbidity (especially the development of atrial thrombi within hours), and can lead to profound haemodynamic deterioration. Such patients need prompt and expert medical attention. The combination of atrial incisions and multiple suture lines at the time of Fontan surgery with increased right atrial pressure and size probably accounts for the high frequency of atrial arrhythmias in these patients. Obstruction of the Fontan connection should be ruled out in all patients presenting with new onset atrial arrhythmias.
The reported frequency of thromboembolic complications in the Fontan circuit varies from 6% to 33%, dependent on the diagnostic method used and the length of follow-up. Right atrial thrombus formation relates to the presence of atrial flutter or fibrillation, right atrial dilation, right atrial smoke (spontaneous echo contrast), and the presence of artificial material used to construct the Fontan circuit.
Part obstruction of the Fontan connection leads to exercise intolerance, atrial tachyarrhythmias, and right-sided heart failure. Sudden total obstruction presents as sudden death. Protein-losing enteropathy is seen in about 2—3% of patients after the Fontan procedure. Patients present with generalised oedema, ascites, pleural effusion, or chronic diarrhoea. The diagnosis is confirmed by low serum albumin and protein and high α1-antitrypsin stool clearance. The prognosis is poor, with a 5-year survival of 46—59%.
Treatment of complications
In patients with atrial fibrillation or flutter, prompt anticoagulation and transoesophageal echo assessment to rule out atrial thrombi before cardioversion is recommended. Long-term management with antiarrhythmic therapy is successful in less than 50%. Transcatheter atrial ablation can be done in specialised centres, with a 50% success rate. For recalcitrant cases, surgical revision with antiarrhythmic surgery is recommended.
Transoesophageal echocardiogram showing a right atrial clot
LA=left atrium. RA=right atrium. Arrow indicates right atrial clot.
For established thrombus, thrombolytic therapy or surgical removal of the clot and conversion of the Fontan circuit have been described. Long-term anticoagulation is recommended for patients with known thrombi. Some centres anticoagulate all Fontan circuits for the rest of the patient’s life. For patients with Fontan obstruction, surgical revision of the Fontan connection is usually needed. Alternatively, balloon angioplasty with or without stenting can be used when appropriate. Patients with protein-losing enteropathy might be candidates for creation of a fenestration in the atrial septum or revision of the Fontan. Alternatively, subcutaneous heparin, octreotide treatment, and prednisone treatment have also been tried with variable success, No particular treatment seems more successful than any other.
In this patient, who is haemodynamically stable, ventricular rate should be controlled with digoxin or other agents, and prompt anticoagulation with heparin should be started. The patient should be transferred to a highly specialised hospital for transoesophageal echo to rule out right atrial clot before cardioversion. Fontan obstruction as the cause of atrial fibrillation (conduit obstruction with secondary right atrial stretch) should be ruled out either at the time of transoesophageal echo or by cardiac catheterisation. Long-term coumadin is recommended for all patients with Fontan obstruction who have a history of atrial fibrillation. Maintenance of sinus rhythm after cardioversion is probably best achieved with amiodarone, although the success rate is low at 50%. Antitachycardia pacing, catheter ablation or surgical revision, or both, with concomitant biatrial maze procedure are used as second-line treatment in patients with Fontan obstruction and chronic or paroxysmal atrial fibrillation that is unresponsive to medical management. Other causes of atrial fibrillation such as ethanol binge or hyperthyroidism should also be ruled out.
Overview of keypoints
Congenital abnormalities of the heart and cardiovascular system are reported in almost 1% of live births (see Figure 1) and about half of these childreeed medical or surgical help during infancy. In the first decade, a further 25% require surgery to maintain or improve their life. Only 10% survive to adolescence without surgery. Of these 10%, however, many live a normal life for years before their abnormality is discovered.
Recognizing adult congenital heart disease
There are a few signs that should alert generalists to the possibility of congenital heart disease:
· murmurs, especially continuous – there are few degenerative diseases that produce continuous murmurs
· cyanosis, clubbing – unless there is coexistent lung disease, a patient with a murmur and cyanosis should be referred for echocardiography
· right bundle branch block (RBBB) – this occurs in 1% of the middle-aged population without disease. When combined with a murmur, the patient should be referred for echocardiography
In most cases, suspicion of congenital heart disease leads to a cardiology referral. However, an awareness of the possible diagnoses will help your referral.
Ventricular septal defect
Ventricular septal defect (VSD) (see Figures 2 and 3) is the most common congenital heart defect. Symptoms depend on the size of the defect and the age of the patient. Small VSDs are usually asymptomatic and compatible with a normal life (in fact, about 40% close spontaneously in early childhood). Large VSDs cause cardiac failure in the second or third month after birth. If a large shunt does not produce symptoms during infancy, there is usually little disturbance until late adolescence or early adult life when the patient develops high pulmonary vascular resistance, breathlessness, fatigue, and cyanosis. There is progression to effort syncope, recurrent hemoptysis, and heart failure.
Recognizing VSD
In VSD patients, the apex beat may be hyperdynamic and there could be a systolic thrill. The classic sign is a loud pansystolic murmur, often accompanied by a mid diastolic murmur at the apex (due to high flow through the mitral valve) (see Table 1). In patients with raised pulmonary vascular resistance, right ventricular hypertrophy (RVH) is evident and the pulmonary second sound might be accentuated, followed by the early diastolic murmur of pulmonary regurgitation.
With small VSDs, the electrocardiogram (ECG) is normal. With larger ones, there is evidence of biventricular enlargement (tall R waves and deep S waves in leads V1–V6), especially when pulmonary vascular resistance is high. Similarly, with a small defect the chest x-ray (CXR) is normal, but with a large shunt there is cardiomegaly and prominence of the pulmonary vessels.
Large shunts should be closed surgically. However, if pulmonary hypertension has developed, surgery is usually contraindicated as closing it may worsen the pulmonary hypertension.
The main complication of VSD is infective endocarditis. Vegetations may appear at the tricuspid valve, opposite or around the defect, or on the aortic valve. In certain lesions, aortic incompetence may develop due to loss of support of the valve.
The prognosis for adults with uncomplicated VSD is good. Few patients have defects large enough to cause serious hemodynamic problems, but all are exposed to the risk of infective endocarditis.
Atrial septal defect
Three types of atrial septal defect (ASD) can occur:
· ostium secundum is the most common type (70%). It can be large, but usually does not affect the atrioventricular valves (see Figures 3 and 4)
· ostium primum – the hole is situated close to the atrioventricular valves and can be associated with an atrioventricular septal defect
· sinus venosus is a defect situated near the entrance of the superior vena cava (SVC) or inferior vena cava to the right atrium. It is unusual and is often associated with partial anomalous pulmonary venous drainage (usually drainage of the right upper lobe into the SVC)
Pathophysiology
The shunt of blood from the left atrium to the right atrium results in:
· increased volume load and dilatation of the right atrium and right ventricle (RV)
· increased pulmonary blood flow and enlargement of the pulmonary arteries
· increase in size of the pulmonary veins
· reduced filling of the left ventricle (
Over time, the aorta and
Recognizing ASD
Most patients with secundum ASD remain asymptomatic throughout their thirties, but visit their doctor in middle-age with the onset of breathlessness and fatigue (note the nonspecific signs). Symptoms are usually progressive and worsened by the development of atrial arrhythmias. Patients with primum ASD tend to present earlier and with more severe symptoms.
The classic sign of ASD is wide, fixed splitting of the second heart sound, together with a systolic murmur due to high flow across the pulmonary valve (see Table 1). Primum ASD may be accompanied by mitral regurgitation.
ECG might indicate RBBB and either RVH and right axis deviation (secundum) or left axis deviation (primum) (see Table 1). CXR may show cardiomegaly with a prominent pulmonary trunk.
Management
ASDs that are large enough to give clear physical signs should be closed. Closure of an ostium secundum defect is relatively easy and carries a low mortality rate. Correction of an ostium primum defect, with its associated anomalies, is more difficult and carries a higher mortality rate. More recently, percutaneous device closure of small and moderate size ASDs has been possible. In this procedure, a “butterfly” device (eg, the Clamshell occluder, the Starflex occluder, or the Amplatzer occluder) is manipulated noninvasively into the heart and “opened”, whereupon it grasps the defect on either side and closes it (see Figures 5 and 6).
Primum ASD requires prophylaxis for infective endocarditis, while secundum ASD does not.
Eisenmenger syndrome
This is the name given to reversal in the direction of a cardiac shunt caused by the development of pulmonary hypertension. It applies regardless of whether the shunt is atrial or ventricular. Initial flow is always from high pressure (left) to low pressure (right), but pulmonary pressure can rise above systemic pressure and cause a reversal of flow.
Signs of pulmonary hypertension are RVH, pulmonary systolic click, and loud pulmonary valve closure. CXR shows large main pulmonary arteries and branches with peripheral pruning. After the development of Eisenmenger physiology, only heart–lung transplantation is of value in management.
Bicuspid aortic valve
Bicuspid aortic valves often functioormally throughout most of a patient’s life. However, fibrosis and calcification ultimately lead to aortic stenosis (see Chapter 9, Valve disease) and an eventual requirement for surgical correction.
Coarctation of the aorta
Coarctation of the aorta is a narrowing of the lumen, usually just distal to the origin of the left subclavian artery (see Figure 7). Most commonly, the patient presents in their twenties or thirties, usually with hypertension. Without surgery, 50% die before the age of 30 years. Potential treatments include resection of the narrowed segment with end-to-end anastomosis, repair involving the subclavian artery, and balloon angioplasty – the role of which remains controversial. Hypertension, which is often the presenting feature, must be aggressively treated both before and after surgery (it commonly persists).
Pulmonary valve stenosis
Patients with mild to moderate pulmonary stenosis usually remain asymptomatic until the onset of atrial flutter/fibrillation or right heart failure, which lead to breathlessness, ascites, peripheral edema, and a visit to the doctor. Fatigue, slight dyspnea, and effort syncope occur with severe narrowing. The physical signs depend on the severity of the obstruction and secondary effects on RV function. In severe stenosis, the arterial pulse is small and the jugular venous pulse exhibits a large “a” wave. On palpation, there is nearly always a systolic thrill in the second left intercostal space and there is a left parasternal heave. An early systolic “ejection” click and a loud ejection murmur are best heard in the second intercostal space. The second sound is normal in mild cases, but in more severe cases it is widely split and the second (pulmonary) element is soft. ECG shows RVH in severe stenosis, while CXR shows a dilated pulmonary trunk with oligemic lung fields. Balloon valvotomy is indicated in severe pulmonary stenosis. Surgical valvotomy is an alternative.
Patent ductus arteriosus
Patent ductus arteriosus (PDA) describes a preservation of the connection between the pulmonary artery and the aorta that exists in the fetus (see Figure 8). Since aortic diastolic pressure is higher than pulmonary artery systolic pressure, there is continuous flow into the pulmonary circulation, creating the characteristic continuous (“machinery”) murmur, heard best just below the left clavicle. In hemodynamically insignificant lesions (>50% of cases), patients are asymptomatic. Patients with bigger shunts develop cardiac failure at an age that depends on the severity of the lesion. Eisenmenger syndrome can occur with PDA. Treatment is surgical closure of the duct; this can be carried out percutaneously.
Fallot’s tetralogy
Fallot’s tetralogy is one of the causes of cyanotic congenital heart disease. The features derive from an abnormally positioned aorta that “over-rides” the interventricular septum (see Figure 9). This causes:
· perimembranous VSD
· RV outflow obstruction (pulmonary stenosis)
· RVH
The chief symptom is cyanosis on exercise. Children typically “squat” for relief of dyspnea after exercise (almost pathognomonic). Chest pain, arrhythmia, and congestive heart failure are more common in adults than in children. Clubbing is common. Surgical correction usually involves resection of the hypertrophied RV infundibulum and VSD closure with incorporation of the aorta into the RV. Adult Fallot’s patients often suffer impaired exercise capacity due to poor RV function.
Transposition of the great arteries
In transposition of the great arteries (TGA), the RV connects to the aorta and the
Ebstein’s anomaly
Ebstein’s anomaly is the downward displacement of a portion of the tricuspid valve with atrialization of a large part of the RV (see Figure 12). There is often an associated ostium secundum ASD. The atrialized portion of the ventricle hinders rather than helps the forward flow of blood and there is tricuspid regurgitation. Occasionally Ebstein’s anomaly is asymptomatic, but it generally presents in childhood or early adulthood with dyspnea, fatigue, signs of tricuspid regurgitation, and right-sided cardiac failure. Patients with Ebstein’s anomaly require prophylaxis for endocarditis.
Figures
Figure 1
The relative incidence of common congenital heart defects. ASD: atrial septal defect; PDA: patent ductus arteriosus; TGA: transposition of the great arteries; VSD: ventricular septal defect.
Figure 2
Ventricular septal defect.
Figure 3
Atrial septal defect.
Figure 4
Atrial septal defect (ASD) shown by (a) transesophageal echocardiography, and (b) transesophageal Doppler.
Figure 5
The Clamshell occluder for closure of an atrial septal defect. IVC: inferior vena cava; LA: left atrium; RA: right atrium.
Figure 6
The Amplatzer occluder (a) before and (b) after deployment.
Figure 7
Coarctation of the aorta.
Figure 8
Patent ductus arteriosus (PDA).
Figure 9
Fallot’s tetralogy with an “over-riding aorta”.
Figure 10
Transposition of the great arteries (right-hand image).
Figure 11
Balloon atrial septostomy – Rashkind’s procedure. ASD: atrial septal defect.
Figure 12
Ebstein’s anomaly.
Tables
Table 1Characteristics of atrial septal defect and ventricular septal defect. Note the wide, fixed splitting of the second heart sound in atrial septal defect
|
Ventricular septal defect |
Atrial septal defect |
|
Biventricular hypertrophy |
LAD, RBBB (primum) |
|
RVH |
RVH, RAD, RBBB (secundum) |
|
|
|
LAD: left axis deviation; MDM: mid diastolic murmur; MSM: mid systolic murmur; PSM: pansystolic accentuation of murmur; RAD: right axis deviation; RBBB: right bundle branch block; RVH: right ventricular hypertrophy.
References.
A – Basic:
1. Davidson’s Principles and Practice of Medicine (1st Edition) / Edited by N. R. Colledge, B. R. Walker, S. H. Ralston. – Philadelphia
2. Harrison’s Principles of Internal Medicine /Dan L. LongoA. S. FauciD. L. Kasper. –
3. Kumar and Clark’s Clinical Medicine (8th Revised ed.) (With STUDENTCONSULT Online Access) / P. KumarM. L. Clark. –
4. Web -sites:
a) http://emedicine.medscape.com/cardiology
b) http://meded.ucsd.edu/clinicalmed/introduction.htm
B – Additional:
1. Braunwald’s Heart Disease Review and Assessment / L. S. Lilly. – Philadelphia
2.
3. Oxford Handbook of Cardiology2nd Revised edition) / P. RamrakhaJ. Hill. –
2. Mayo Clinic Cardiology: Concise Textbook (4rd ed.) / by Murphy J.G., Lloyd M.A., eds. – New York
3. ESC Guidelines for the management of grown-up congenital heart disease (2010) // European Heart Journal. – 2010. – №31. – 2915–2957 p.
4. Warnes et al. ACC/AHA 2008 Guidelines for the Management of Adults With Congenital Heart Disease: Executive Summary J Am Coll Cardiol 2008:52:e143-e263.
