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MD Consult: Books: Goldman: Cecil Medicine: Chapter 68 – CONGENITAL HEART DISEASE IN ADULTS

Goldman: Cecil Medicine, 23rd ed.

Copyright © 2007 Saunders, An Imprint of Elsevier

Chapter 68 – CONGENITAL HEART DISEASE IN ADULTS

Ariane J. Marelli

The convergence of major progress in medicine, pediatrics, and cardiovascular surgery has resulted in the survival to adulthood of an increasingly large number of patients with complex structural heart lesions. Adult physicians are becoming increasingly responsible for these patients, commonly in concert with a cardiologist and a tertiary care facility.

Definitions

Patients can be subdivided into three categories according to the surgical status: not operated on, surgically palliated, or physiologically repaired. Congenital heart lesions can be classified as acyanotic or cyanotic. Cyanosis refers to a blue discoloration of the mucous membranes resulting from an increased amount of reduced hemoglobin. Central cyanosis occurs when the circulation is mixed because of a right-to-left shunt.

A native lesion refers to an anatomic lesion present at birth. Acquired lesions, naturally occurring or as a result of surgery, are superimposed on the native anatomy. Palliative interventions are performed in patients with cyanotic lesions and are defined as operations that serve either to increase or to decrease pulmonary blood flow while allowing a mixed circulation and cyanosis to persist ( Table 68-1 ). Physiologic repair applies to procedures that provide total or nearly total anatomic and physiologic separation of the pulmonary and systemic circulations in complex cyanotic lesions and result in patients who are acyanotic.


TABLE 68-1   — 
PALLIATIVE SURGICAL SHUNTS FOR CONGENITAL HEART LESIONS

Palliative Shunt Anastomosis
SYSTEMIC ARTERIAL TO PULMONARY ARTERY SHUNTS
Classic Blalock-Taussig Subclavian artery to PA
Modified Blalock-Taussig Subclavian artery to PA (prosthetic graft)
Potts anastomosis Descending aorta to left PA
Waterston shunt Ascending aorta to right PA
SYSTEMIC VENOUS TO PULMONARY ARTERY SHUNTS
Classic Glenn SVC to right PA
Bidirectional Glenn SVC to right and left PA
Bilateral Glenn Right and left SVC to right and left PA

From Marelli A, Mullen M: Palliative surgical shunts for congenital heart lesions. Clin Paediatr 1996;4:189.

PA = pulmonary artery; SVC = superior vena cava.

Eisenmenger’s complex refers to flow reversal across a ventricular septal defect (VSD) when pulmonary vascular resistance exceeds systemic levels. Eisenmenger’s physiology designates the physiologic response in a broader category of shunt lesions in which a right-to-left shunt occurs in response to an elevation in pulmonary vascular resistance. Eisenmenger’s syndrome is a term applied to common clinical features shared by patients with Eisenmenger’s physiology.

Each congenital lesion can influence the course of another. For example, the physiologic consequences of a VSD are different if it occurs in isolation or in combination with pulmonary stenosis. A simple lesion is defined as either a shunt lesion or an obstructive lesion of the right or left heart occurring in isolation. A complex lesion is a combination of two or more abnormalities.

Epidemiology

In 90% of patients, congenital heart disease is attributable to multifactorial inheritance; only 5 to 10% of malformations are due to primary genetic factors, either chromosomal or related to a single mutant gene. The most common defect observed in patients with chromosomal aberrations is a VSD, which occurs in 90% of patients with trisomy 13 and trisomy 18. Defects of the endocardial cushions and the ventricular septum are found in 50% of patients with Down syndrome (trisomy 21). The most frequently observed defects in patients with Turner’s syndrome (45,X) are aortic coarctation, aortic stenosis, and atrial septal defect (ASD). About 15% of patients with tetralogy of Fallot have a deletion on chromosome 22q11; prevalence is higher in those with a right aortic arch. Abnormalities involving the chromosomal band 22q11 can also result in a group of syndromes, the most common of which is DiGeorge syndrome. The shared phenotypic features are designated CATCH-22 syndromes, that is, a combination of cardiac defects, abnormal facies, thymic hypoplasia, cleft palate, and hypocalcemia. The recurrence risk for families with a child who carries a congenital cardiac malformation due to a chromosomal anomaly is related to the recurrence risk of the chromosomal anomaly itself.

Typically, single mutant genes are also associated with syndromes of cardiovascular malformations, although not every patient with the syndrome has the characteristic cardiac anomaly. Examples include osteogenesis imperfecta (autosomal recessive), associated with aortic valve disease; Jervell and Lange-Nielsen syndrome (autosomal recessive) and Romano-Ward syndrome (autosomal dominant), associated with a prolonged QT interval and sudden death; and Holt-Oram syndrome (autosomal dominant), in which an ASD occurs with a range of other skeletal anomalies. Osler-Weber-Rendu telangiectasias are associated with pulmonary arteriovenous fistulas. Williams syndrome occurs with supravalvular aortic stenosis in most cases. Noonan’s syndrome is associated with pulmonary stenosis, ASD, and hypertrophic cardiomyopathy. Although autosomal dominant inheritance has been implicated for both, most cases are sporadic. Deletion at chromosome 7q11.23 has been identified in patients with Williams syndrome, and a gene defect has been mapped to 12q22-qter in patients with Noonan’s syndrome.

The risk of recurrence when the mother carries a sporadically occurring congenital lesion varies from 2.5 to 18%, depending on the lesion. Obstructive lesions of the left ventricular outflow tract have the highest recurrence rates in offspring. When the father carries the lesion, 1.5 to 3% of the offspring are affected. When a sibling has a congenital cardiac anomaly, the risk of recurrence in another sibling varies from 1 to 3%.

Incidence and Prevalence

Cardiac malformations occur at a rate of 8 per 1000 live births, or 32,000 infants with new diagnoses yearly in the United States. The prevalence of congenital heart disease has increased in the general population, with the steepest rise observed in adults with severe or complex lesions. An estimated 20% die in the first year of life—a substantial decrease from the late 1960s. An overall prevalence of 4 per 1000 adults has been documented. The median age of patients with severe lesions has increased from childhood to late adolescence. Currently, about 900,000 patients are thought to be alive in the United States with congenital heart disease.

Bicuspid aortic valve occurs in about 2% of the general population, is the most common congenital cardiac anomaly encountered in adult populations, and accounts for up to half of surgical cases of aortic stenosis in adults ( Chapter 75 ). ASDs constitute 30 to 40% of cases of congenital heart disease in adults, with ostium secundum ASD accounting for 7% of all congenital lesions. A solitary VSD accounts for 15 to 20% of all congenital lesions and is the most common congenital cardiac lesion observed in the pediatric population; its high spontaneous closure rates explain the lesser prevalence in adults. Patent ductus arteriosus (PDA) accounts for 5 to 10% of all congenital cardiac lesions in infants with a normal birthweight. Pulmonary stenosis and coarctation of the aorta account for 3 to 10% of all congenital lesions.

Tetralogy of Fallot is the most common cyanotic congenital anomaly observed in adults. Together with complete transposition of the great arteries, these lesions account for 5 to 12% of congenital heart disease in infants. More complex lesions such as tricuspid atresia, univentricular heart, congenitally corrected transposition of the great arteries, Ebstein’s anomaly, and double-outlet right ventricle account for 2.5% or less of all congenital heart disease.

Clinical Manifestations

Congenital heart disease is a lifelong condition during which the patient and the lesion evolve concurrently. A patient may have been monitored for many years because of an erroneous diagnosis made in infancy or childhood when diagnostic techniques were more limited. The differential diagnosis of native and surgical anatomy in the adult with an unknown diagnosis depends on whether the patient is cyanotic or acyanotic. On completion of the evaluation, the following questions should be answered ( Fig. 68-1 ): What is the native anatomy? Has this patient undergone surgery for the condition? What is the physiology? What can and should be done for this patient both medically and surgically, and importantly, who should do it?

FIGURE 68-1  The goals of complete clinical assessment in congenital heart disease are to define the anatomy and physiology to determine appropriate management.

If the patient has not undergone surgery, the question is, Why not? If the patient is palliated, has the degree of cyanosis progressed as evidenced by a drop in systemic saturation or a rise in hemoglobin? If the patient has undergone a physiologic repair, what procedure was performed? Are residual lesions present and have new lesions developed as a consequence of surgery? The patient’s physiology is determined by the presence or absence of cyanosis, pulmonary hypertension, adequate filling of the cardiac chambers, and any resulting medical complications.

A clinical assessment, 12-lead electrocardiogram (ECG), chest radiograph, and baseline oxygen saturation should be part of every initial assessment. Two-dimensional transthoracic echocardiography ( Chapter 53 ) and Doppler and color flow imaging are used to establish the diagnosis and to monitor the evolution of documented hemodynamic complications. Transesophageal echocardiographic examination is particularly useful in adults and is increasingly important during interventional catheter-guided therapy and surgery. Magnetic resonance imaging ( Chapter 55 ) and computed tomography ( Chapter 54 ) are useful adjuncts. Cardiac catheterization for congenital heart disease has shifted from pure diagnosis to include intervention. Coronary arteriography is recommended for adults older than 40 years in whom surgical intervention is contemplated.

Pulmonary Hypertension

Pulmonary hypertension secondary to structural disease of the heart or circulation can occur with or without an increase in pulmonary vascular resistance. Pulmonary vascular obstructive disease occurs when pulmonary vascular resistance rises and becomes fixed and irreversible. In the most common congenital anomalies, pulmonary hypertension is a result of increased pulmonary blood flow because of a native left-to-right shunt. Examples include ASD, a moderately sized VSD, PDA, and a variety of complex lesions. The rate at which pulmonary hypertension progresses to become pulmonary vascular obstructive disease varies from one lesion to another and depends at least in part on the source of pulmonary blood flow. Pulmonary hypertension typically develops in patients with an ASD after the fourth decade; Eisenmenger’s syndrome is a late complication seen in only 5 to 10% of cases. In contrast, in patients with a large VSD or persistent PDA, progressive elevation in pulmonary vascular resistance occurs rapidly because the pulmonary vascular bed is exposed not only to the excess volume of the left-to-right shunt but also to systemic arterial pressures. As a result, Eisenmenger’s complex develops in approximately 10% of patients with a large VSD during the first decade. Surgical pulmonary artery banding is a palliative measure aimed at decreasing pulmonary blood flow and protecting the pulmonary vascular bed against the development of early pulmonary vascular obstructive disease.

If forward flow from the right side of the heart is insufficient, native collaterals or surgical shunts provide an alternative source of pulmonary blood flow (see Table 68-1 ). With large surgical shunts, however, direct exposure of the pulmonary vascular bed to the high pressures of the systemic circulation causes pulmonary vascular obstructive disease. As a result, systemic to pulmonary arterial shunts are currently less favored in neonates and infants, in whom systemic venous to pulmonary arterial shunts are now preferred.

Eisenmenger’s Syndrome

The term Eisenmenger’s syndrome should be reserved for patients in whom pulmonary vascular obstructive disease is present and pulmonary vascular resistance is fixed and irreversible. These findings in combination with the absence of left-to-right shunting render the patient inoperable.

The clinical manifestations of Eisenmenger’s syndrome include dyspnea on exertion, syncope, chest pain, congestive heart failure, and symptoms related to erythrocytosis and hyperviscosity. On physical examination, central cyanosis and digital clubbing are hallmark findings. Systemic oxygen saturations typically vary between 75 and 85%. The pulse pressure narrows as the cardiac output falls. Examination of jugular venous pressure can reveal a dominant a wave reflecting a noncompliant right ventricle until tricuspid insufficiency is severe enough to generate a large v wave. A prominent right ventricular impulse is felt in the left parasternal border in end-expiration or in the subcostal area in end-inspiration. A palpable pulmonary artery is commonly felt. The pulmonary component of the second heart sound is increased and can be felt in most cases. Pulmonary ejection sounds are common when the pulmonary artery is dilated with a structurally normal valve. Right atrial gallop is heard more frequently when the a wave is dominant. A murmur of tricuspid insufficiency is common, but the inspiratory increase in the murmur (Carvallo’s sign) disappears when right ventricular failure occurs. In diastole, a pulmonary insufficiency murmur is often heard. The 12-lead ECG shows evidence of right atrial enlargement, right ventricular hypertrophy, and right axis deviation. Chest radiographic findings include a dilated pulmonary artery segment, cardiac enlargement, and diminished pulmonary vascular markings. Echocardiography confirms the right-sided pressure overload and pulmonary artery enlargement as well as the tricuspid and pulmonary insufficiency. Cardiac catheterization is indicated if doubt exists about the potential reversibility of the elevated pulmonary vascular resistance in a patient who might otherwise benefit from surgery.

Systemic Complications of Cyanosis

Cyanosis occurs when persistent venous to arterial mixing results in hypoxemia. Adaptive mechanisms to increase oxygen delivery include an increase in oxygen content, a rightward shift in the oxyhemoglobin dissociation curve, a higher hematocrit, and an increase in cardiac output. When cyanosis is not relieved, chronic hypoxemia and erythrocytosis result in hematologic, neurologic, renal, and rheumatic complications.

Hematologic complications of chronic hypoxemia include erythrocytosis, iron deficiency, and bleeding diathesis. Hemoglobin and hematocrit levels as well as red blood cell indices should be checked regularly and correlated with systemic oxygen saturation levels. Symptoms of hyperviscosity include headaches, faintness, dizziness, fatigue, altered mentation, visual disturbances, paresthesias, tinnitus, and myalgia. Symptoms are classified as mild to moderate when they interfere with only some activities, or they can be marked to severe and interfere with most or all activities. Patients with compensated erythrocytosis establish an equilibrium hematocrit at higher levels in an iron-replete state with minimal symptoms. Patients with decompensated erythrocytosis manifest unstable, rising hematocrit levels and experience severe hyperviscosity symptoms.

In the iron-replete state, moderate to severe hyperviscosity symptoms typically occur when hematocrit levels exceed 65%. If no evidence of dehydration is present, removal of 500 mL of blood during a 30- to 45-minute period should be followed by quantitative volume replacement with normal saline or dextran ( Fig. 68-2 ). The procedure may be repeated every 24 hours until symptomatic improvement occurs.

FIGURE 68-2  Treatment algorithm for erythrocytosis of cyanotic congenital heart disease.

Hemostatic abnormalities can occur in up to 20% of cyanotic patients with erythrocytosis. Bleeding is usually mild and superficial and leads to easy bruising, skin petechiae, or mucosal bleeding, but epistaxis, hemoptysis, or even life-threatening postoperative bleeding can occur. A variety of clotting factor deficiencies and qualitative and quantitative platelet disorders have been described.

Treatment for spontaneous bleeding is dictated by its severity and the abnormal hemostatic parameters ( Fig. 68-3 ). For severe bleeding, platelet transfusions, fresh-frozen plasma, vitamin K, cryoprecipitate, and desmopressin have been used. Reduction in erythrocyte mass also improves hemostasis, so cyanotic patients undergoing surgery should have prophylactic phlebotomy if the hematocrit is greater than 65%.

FIGURE 68-3  Treatment algorithm for bleeding diathesis of cyanotic congenital heart disease. ASA = acetylsalicylic acid; FFP = fresh-frozen plasma; Hb = hemoglobin; Hct = hematocrit; NSAIDs = nonsteroidal anti-inflammatory drugs; Plts = platelets; PT = prothrombin time; PTT = partial thromboplastin time.

Iron deficiency is common in cyanotic adult patients because of excessive bleeding or phlebotomy. In contrast to normocytic erythrocytosis, which is rarely symptomatic at hematocrit levels less than 65%, iron deficiency may be manifested by hyperviscosity symptoms at hematocrit levels well below 65%. The treatment of choice is not phlebotomy but oral iron repletion until a rise in hematocrit is detected, typically within 1 week.

Neurologic complications, including cerebral hemorrhage, can be caused by hemostatic defects and are most often seen after inappropriate use of anticoagulant therapy. Patients with right-to-left shunts may be at risk for paradoxical cerebral emboli. Focal brain injury may provide a nidus for brain abscess if bacteremia supervenes. Attention should be paid to the use of air filters in peripheral intravenous lines to avoid paradoxical emboli through a right-to-left shunt.

Prophylactic phlebotomy has no place in the prevention of cerebral arterial thrombosis. Indications for phlebotomy are the occurrence of symptomatic hyperviscosity in an iron-repleted patient and prevention of excessive bleeding perioperatively.

Pulmonary complications include massive pulmonary hemorrhage and in situ arterial thrombosis. A rapid clinical deterioration associated with progressive hypoxemia often marks the terminal stage of disease. No clear benefits are observed with the use of anticoagulants (systemic or intrapulmonary) because of the risk of prolonged bleeding due to the underlying coagulopathy. The chronic disease process and high mortality prohibit pulmonary endarterectomy.

Chronic oxygen therapy is unlikely to benefit hypoxemia secondary to right-to-left shunting in the setting of a fixed pulmonary vascular resistance. Chronic oxygen therapy results in mucosal dehydration with an increased incidence of epistaxis and is therefore not recommended.

Renal dysfunction can be manifested as proteinuria, hyperuricemia, or renal failure. Focal interstitial fibrosis, tubular atrophy, and hyalinization of afferent and efferent arterioles can be seen on renal biopsy. Increased blood viscosity and arteriolar vasoconstriction can lead to renal hypoperfusion with progressive glomerulosclerosis. Hyperuricemia is commonly seen in patients with cyanotic congenital heart disease and is thought to be due mainly to the decreased reabsorption of uric acid rather than overproduction from erythrocytosis. Asymptomatic hyperuricemia need not be treated because lowering of uric acid levels has not been shown to prevent renal disease or gout.

Rheumatologic complications include gout and hypertrophic osteoarthropathy, which is thought to be responsible for the arthralgias affecting up to one third of patients with cyanotic congenital heart disease. In patients with right-to-left shunting, megakaryocytes released from the bone marrow bypass the lung and are entrapped in systemic arterioles and capillaries, where they release platelet-derived growth factor, which promotes local cell proliferation. Digital clubbing and new osseous formation with periostitis occur and cause the symptoms of arthralgia. Symptomatic hyperuricemia and gouty arthritis can be treated as necessary with colchicine, probenecid, or allopurinol; nonsteroidal anti-inflammatory drugs are best avoided, given the baseline hemostatic anomalies in these patients.

   Specific Simple Lesions

   Isolated Shunt Lesions

Hemodynamic complications of significant shunts relate to volume overload and chamber dilation of the primary chamber receiving the excess left-to-right shunt and to secondary complications of valvular dysfunction and damage to the pulmonary vascular bed. The size and duration of the shunt determine the clinical course and therefore the indications for closure. The degree of shunting is a function of both the size of the communication and, depending on its location, biventricular compliance or pulmonary and systemic vascular resistance. Clinically apparent hemodynamic sequelae of shunts are typically apparent or can be expected to occur when pulmonary-to-systemic flow ratios exceed 1.5 to 1.

Shunt size can be inferred and measured with cardiac ultrasonography. Secondary enlargement of the cardiac chambers receiving excess shunt flow in diastole occurs as the shunt size becomes hemodynamically significant; in addition, the pulmonary artery becomes enlarged as pulmonary pressure rises. When tricuspid insufficiency occurs primarily from right ventricular dilation or secondary to pulmonary hypertension, the regurgitant jet can be used to estimate the pulmonary pressure as another indicator of shunt significance. When the pulmonary-to-systemic flow (Q.p:Q.s) exceeds 2:1, the volume of blood in both circulations can be estimated by comparing the stroke volume at the pulmonary and aortic valves. Shunt detection and quantification can also be obtained by a first-pass radionuclide study. As a bolus of radioactive substance is injected into the systemic circulation, the rise and fall of radionuclide activity can be measured in the lungs. When a shunt is significant, the rate of persistent activity in the lungs over time can be used to calculate the shunt fraction. For both echocardiographic and radionuclide quantification of shunt size, sources of error are multiple. The most predictable results are obtained only in experienced laboratories. Uncertainty about the physiologic significance of a borderline shunt can be minimized by integrating serial determinations from multiple clinical and relevant diagnostic sources rather than basing management decisions on a single calculated shunt value.

   Atrial Septal Defect

Classification of ASDs is based on anatomic location. Most commonly, an ostium secundum ASD occurs in the central portion of the interatrial septum as a result of an enlarged foramen ovale or excessive resorption of the septum primum. The combination of a secundum ASD and acquired mitral stenosis is known as Lutembacher’s syndrome, the pathophysiology of which is determined by the relative severity of each. Abnormal development of the embryologic endocardial cushions results in a variety of atrioventricular canal defects, the most common of which consists of a defect in the lower part of the atrial septum in the ostium primum location, typically accompanied by a cleft mitral valve and mitral regurgitation. The sinus venosus defect, which accounts for 2 to 3% of all interatrial communications, is located superiorly at the junction of the superior vena cava and right atrium and is generally associated with anomalous drainage of the right-sided pulmonary veins into the superior vena cava or right atrium. Less commonly, interatrial communications can be seen at the site of the coronary sinus, typically associated with an anomalous left superior vena cava.

The pathophysiology is determined by the effects of the shunt on the heart and pulmonary circulation. Right atrial and right ventricular dilation occurs as shunt size increases with pulmonary-to-systemic flow ratios greater than 1.5:1.0. Superimposed systemic hypertension and coronary artery disease modify left ventricular compliance and favor left-to-right shunting. Mitral valve disease can occur in up to 15% of patients older than 50 years. Right-sided heart failure, atrial fibrillation, or atrial flutter can occur as a result of chronic right-sided volume overload and progressive ventricular and atrial dilation. Stroke can result from paradoxical emboli, atrial arrhythmias, or both. A rise in pulmonary pressure occurs because of the increased pulmonary blood flow. Pulmonary hypertension is unusual before 20 years of age but is seen in 50% of patients older than 40 years. The overall incidence of pulmonary vascular obstructive disease is 15 to 20% in patients with ASD. Eisenmenger’s disease with reverse shunting, a late and rare complication of isolated secundum ASD, is reported in 5 to 10% of patients.

Diagnosis

Although most patients are minimally symptomatic in the first three decades, more than 70% become impaired by the fifth decade. Initial symptoms include exercise intolerance, dyspnea on exertion, and fatigue caused most commonly by right-sided heart failure and pulmonary hypertension. Palpitations, syncope, and stroke can occur with the development of atrial arrhythmias.

On physical examination, most adults have a normal general physical appearance. When Holt-Oram syndrome is present, the thumb may have a third phalanx or may be rudimentary or absent. With an uncomplicated nonrestrictive communication between both atria, the a and v waves are equal in amplitude. Precordial palpation typically discloses a normal left ventricular impulse unless mitral valve disease occurs. Characteristically, if the shunt is significant, a right ventricular impulse can be felt in the left parasternal area in end-expiration or in the subxiphoid area in end-inspiration. A dilated pulmonary artery can sometimes be felt in the second left intercostal space. On auscultation, the hallmark of an ASD is the wide and fixed splitting of the second heart sound. Pulmonary valve closure, as reflected by P2, is delayed because of right ventricular overload and the increased capacitance of the pulmonary vascular bed. The A2-P2 interval is fixed because the increase in venous return elevates the right atrial pressure during inspiration, thereby decreasing the degree of left-to-right shunting and offsetting the usual phasic respiratory changes. In addition, compliance of the pulmonary circulation is reduced from the high flow, thus making the vascular compartment less susceptible to any further increase in blood flow. A soft midsystolic murmur generated by the increased flow across the pulmonary valve is usually heard in the second left interspace. In the presence of a high left-to-right shunt volume, increased flow across the tricuspid valve is heard as a mid-diastolic murmur at the lower left sternal border. With advanced right-sided heart failure, evidence of systemic venous congestion is present.

The ECG characteristically shows an incomplete right bundle branch block pattern ( Fig. 68-4 ). Right axis deviation and atrial abnormalities, including a prolonged PR interval, atrial fibrillation, and flutter, are also seen. Typically, the chest radiograph shows pulmonary vascular plethora with increased markings in both lung fields consistent with increased pulmonary blood flow (see Fig. 51-13 ). The main pulmonary artery and both its branches are dilated. Right atrial and right ventricular dilation can be seen. Cardiac ultrasonography is diagnostic and provides important prognostic information ( Fig. 68-5 ). Ostium primum and secundum ASDs are easily identifiable with transthoracic imaging, but a sinus venosus ASD can be missed unless it is specifically sought. For more accurate visualization of the superior interatrial septum and localization of the pulmonary veins, transesophageal echocardiography is useful. With Doppler study, pulmonary artery pressures can be quantified, and the Q.p:Q.s can be measured.

FIGURE 68-4  Electrocardiographic hallmark in atrial septal defect. Right precordial leads V1 and V2 illustrate two variants of an incomplete right bundle branch block pattern, the rSrT pattern (A) and the rsR’ pattern(B).

FIGURE 68-5  Color flow Doppler apical four-chamber view showing blood flow from the left atrium (LA) to the right atrium (RA) through a moderately sized atrial septal defect. LV = left ventricle; RV = right ventricle.  (From Forbes CD, Jackson WF: Color Atlas and Text of Clinical Medicine, 3rd ed. London, Mosby, 2003.)

Treatment

The decision to close an ASD is based on the size of the shunt and the presence or absence of symptoms. In the presence of a significant shunt, closure of an ASD before 25 years of age without evidence of pulmonary hypertension results in a long-term outcome that is similar to that of age- and sex-matched controls. After the age of 40 years, closure is indicated in symptomatic patients with significant shunts because it results in improved survival, prevention of deterioration in functional capacity, and improvement in exercise capacity compared with patients treated medically.[1] Advanced age (60 years) is not a contraindication to ASD closure in the presence of a significant shunt because a significant number of patients will show evidence of symptomatic improvement. Closure is also indicated in patients with systemic embolization in the presence of patent foramen ovale.

Uncomplicated secundum ASDs may be closed surgically in children and adults with minimal operative mortality, in the range of 1 to 3% or less. Preoperative pulmonary artery pressure and the presence or absence of pulmonary vascular disease are important predictors of successful surgical outcome.

Centrally located defects measuring up to 3.5 cm can be occluded by transcatheter techniques in a cardiac catheterization laboratory. Advantages of this approach include the avoidance of sternotomy and cardiopulmonary bypass. Complications, including device fracture with embolization and residual shunts, should decrease as newer devices are used.

   Patent Foramen Ovale

Integrity of the fetal circulation depends on the patency of the foramen ovale. In the majority of cases, the fall in pulmonary vascular resistance at birth induces the foramen to become sealed. Necropsy studies have revealed that the foramen ovale remains patent beyond the first year of life in about 30% of individuals, and clinical studies have demonstrated that the prevalence of patent foramen ovale is three times greater in patients with cryptogenic stroke ( Chapter 431 ), particularly before the age of 55 years, because of right-to-left shunting and paradoxical embolization of material from the venous circulation. Cardiac investigation of the patient with cryptogenic stroke includes transesophageal echocardiography with agitated saline injection to visualize the presence of a right-to-left shunt ( Chapter 53 ). Patent foramen ovale most likely to result in future paradoxical embolization is found in patients younger than 55 years with a prior cryptogenic stroke, in association with a hypermobile septum with aneurysm formation, and when a significant amount of right-to-left shunting is present at rest without provocative maneuvers. Some data suggest that a patent foramen ovale also may be associated with migraine headaches.

Treatment

There are no indications for primary stroke prevention in a patient in whom a patent foramen ovale is fortuitously diagnosed on routine echocardiography. Warfarin to an international normalized ratio of 2.0 to 3.0 is usually preferred to aspirin for secondary stroke prevention in high-risk patients. Primary closure of a patent foramen ovale is indicated when a patient has contraindications to medical therapy, if medical therapy has failed, or in the presence of a hypercoagulable state not treatable by medical therapy. Device closure in experienced centers is usually preferred to surgical closure, although surgical closure is performed if the patient undergoes cardiac surgery for other reasons. Device closure appears to be associated with a low incidence of yearly recurrence rates.

   Ventricular Septal Defect

For anatomic classification of VSDs, the interventricular septum can be divided into four regions. Defects of the membranous septum, or infracristal VSDs, are located in a small translucent area beneath the aortic valve and account for up to 80% of VSDs. These VSDs typically show a variable degree of extension into the inlet or outlet septum, hence their designation as perimembranous. Infundibular defects or supracristal outlet VSDs occur in the conal septum above the crista supraventricularis and below the pulmonary valve. Inlet defects are identified at the crux of the heart between the tricuspid and mitral valves and are usually associated with other anomalies of the atrioventricular canal. Defects of the trabecular or muscular septum can be multiple and occur distal to the septal attachment of the tricuspid valve and toward the apex.

The pathophysiology and clinical course of VSDs depend on the size of the defect, the status of the pulmonary vascular bed, and the effects of shunt size on intracardiac hemodynamics. Unlike ASDs, a VSD may decrease in size with time. Approximately half of all native VSDs are small, and more than half of them close spontaneously; moderate or even large VSDs may also close in 10% or less of cases. The highest closure rates are observed in the first decade of life; spontaneous closure in adult life is unusual.

Patients who have a small defect with trivial or mild shunts are defined as those with a Q.p:Q.s of less than 1.5 and normal pulmonary artery pressure and vascular resistance. Patients with moderate defects have a Q.p:Q.s ratio of greater than 1.2 and elevated pulmonary artery pressure but not elevated pulmonary vascular resistance. Patients with a large and severe defect have an elevated Q.p:Q.s ratio with high pulmonary pressure and elevated pulmonary vascular resistance. Eisenmenger’s complex develops in about 10% of patients with VSDs, usually when there is no resistance to flow at the level of the defect, which can be as large as the aorta. When a systolic pressure gradient is present between the ventricles, the physiologic severity may be trivial or mild but can also be moderate or severe.

Minimal or mild defects usually cause no significant hemodynamic or physiologic abnormality. A moderate or severe defect causes left atrial and ventricular dilation consistent with the degree of left-to-right shunting. Shunting across the ventricular septum occurs predominantly during systole when left ventricular pressure exceeds that on the right; diastolic filling abnormalities occur in the left atrium. With moderate or severe defects, the right side of the heart becomes affected as a function of the rise in pulmonary pressure and pulmonary blood flow.

Diagnosis

An adult with a VSD most commonly has a small restrictive lesion that either was small at birth or has undergone some degree of spontaneous closure. A second group of patients consists of those with large, nonrestrictive VSDs that have not been operated on; these patients have had Eisenmenger’s complex for most of their lives. Patients with a moderately sized defect are typically symptomatic as children and are therefore more likely to have repair at a young age.

Patients with a trivial or mild shunt across a small, restrictive VSD are usually asymptomatic. Physical examination discloses no evidence of systemic or pulmonary venous congestion, and jugular venous pressure is normal. A thrill may be palpable at the left sternal border. Auscultation reveals a normal S1 and S2 without gallops. A grade 4 or louder, widely radiating, high-frequency, pansystolic murmur is heard maximally in the third or fourth intercostal space and reflects the high-pressure gradient between the left and right ventricles throughout systole. The striking contrast between a loud murmur and an otherwise normal cardiac examination is an important diagnostic clue. The ECG and chest radiograph are also normal in patients with small VSDs.

At the other end of the spectrum are patients with Eisenmenger’s complex (see earlier). Between these two extremes are patients with a moderate defect, whose pathology reflects a combination of pulmonary hypertension and left-sided volume overload resulting from a significant left-to-right shunt. In adults, shortness of breath on exertion can be the result of both pulmonary venous congestion and elevated pulmonary pressure. On physical examination, a diffuse palpable left ventricular impulse occurs with a variable degree of right ventricular hypertrophy and an accentuated second heart sound. A systolic murmur persists as long as pulmonary vascular resistance is below systemic resistance. The ECG commonly shows left atrial enlargement and left ventricular hypertrophy. The chest radiograph shows shunt vascularity with an enlarged left atrium and ventricle. The degree of pulmonary hypertension determines the size of the pulmonary artery trunk.

Echocardiography can identify the defect and determine the significance of the shunt by assessing left atrial and ventricular size, pulmonary artery pressure, and the presence or absence of right ventricular hypertrophy. Cardiac catheterization is reserved for those in whom surgery is considered. Adults with a small defect of no physiologic significance need not be studied invasively. Those with Eisenmenger’s complex have severe pulmonary vascular disease and are not surgical candidates. Patients who have a moderately sized shunt that appears hemodynamically significant and in whom pulmonary pressures are elevated are most likely to benefit from direct measurements of pulmonary vascular resistance and reactivity.

Treatment

All patients with a VSD of any size require endocarditis prophylaxis ( Chapter 76 ). Patients with Eisenmenger’s complex have pulmonary vascular resistance that is prohibitive to surgery. For this group of patients, management centers on the medical complications of cyanosis (see earlier). In a few patients with small defects, complications can relate to progressive tricuspid insufficiency caused by septal aneurysm formation or to acquired aortic insufficiency when an aortic cusp becomes engaged in the high-velocity jet flow generated by the defect. The intermediate group of patients with a defect of moderate physiologic significance should have surgical closure unless it is contraindicated by high pulmonary vascular resistance.

Late results after operative closure of isolated VSDs include residual patency in up to 20% of patients, only about 5% of whom need a reoperation. Rhythm disturbances after surgical closure of VSDs include tachyarrhythmias and conduction disturbances. Right bundle branch block occurs in one third to two thirds of patients, whereas first-degree atrioventricular block and complete heart block occur in less than 10%. Sudden cardiac death after surgical repair of VSD occurs in 2% of patients.

   Patent Ductus Arteriosus

The ductus arteriosus connects the descending aorta to the main pulmonary trunk near the origin of the left subclavian artery ( Fig. 68-6 ). Normal postnatal closure results in fibrosis and degenerative changes in the ductal lumen, leaving in its place the residual ligamentum arteriosum, which rarely can become part of an abnormal vascular ring. When the duct persists, significant calcification of the aortic ductal end is observed.

FIGURE 68-6  The anatomy of a patent ductus arteriosus is shown. Note the relation between the position of the ductus, the left subclavian artery, and the pulmonary artery bifurcation. Ao = aorta; BCA = brachiocephalic; CCA = common carotid artery; L = left; PDA = patent ductus arteriosus; PT = pulmonary trunk; RPA = right pulmonary artery; SCA = subclavian artery.  (From Perloff JK [ed]: Clinical Recognition of Congenital Heart Disease, 4th ed. Philadelphia, WB Saunders, 1994, p 510.)

The physiologic consequences of a PDA are determined by its size and length as well as by the ratio of pressure and resistance of the pulmonary and aortic circulations on either end of the duct. If systolic and diastolic pressure in the aorta exceeds that in the pulmonary artery, aortic blood flows continuously down a pressure gradient into the pulmonary artery and then returns to the left atrium. The left atrium and subsequently the left ventricle dilate, whereas the right side of the heart becomes progressively affected as pulmonary hypertension develops.

A small PDA has continuous flow throughout the entire cardiac cycle without left-sided heart dilation, pulmonary hypertension, or symptoms. Patients with a small PDA, although protected from hemodynamic complications of a significant left-to-right shunt, remain at risk for infectious endarteritis, which usually develops on the pulmonary side of the duct and occurs at a rate of about 0.45% per year after the second decade. Because endarteritis accounts for up to one third of the total mortality in patients with PDA, ductal closure should be considered even when the PDA is small.

A PDA is of moderate or large size but still restrictive when a left-to-right shunt occurs throughout systole and diastole is of variable duration. Left atrial or ventricular dilation and pulmonary hypertension will vary with the quantity of left-to-right shunting as well as with the secondary effects on the pulmonary vascular bed. Symptoms generally increase by the second and third decades and include dyspnea, palpitations, and exercise intolerance. As heart failure, pulmonary hypertension, or endarteritis develops, mortality rises to 3 to 4% per year by the fourth decade, and two thirds of patients die by 60 years of age. Eisenmenger’s physiology with systemic or suprasystemic pulmonary pressure and a right-to-left shunt develops in 5% of patients with an isolated PDA.

Diagnosis

In patients with Eisenmenger’s physiology, a right-to-left shunt from the pulmonary artery to the descending aorta results in decreased oxygen saturation in the lower extremities compared with the upper extremities. This difference in cyanosis and clubbing are most prominent in the toes; the left arm is variably affected through the left subclavian artery, and the right arm is typically spared. With a large left-to-right shunt, the pulse pressure widens as diastolic flow into the pulmonary artery lowers systemic diastolic pressure. The arterial pulse becomes bounding as a result of increased stroke volume. Precordial palpation discloses variable left and right ventricular impulses as determined by the relative degree of left-sided volume overload and pulmonary hypertension. In the presence of a continuous aortopulmonary gradient, the classic “machinery” murmur of a PDA can be heard at the first or second left intercostal space below the left clavicle. As the pulmonary pressure rises, the diastolic component of the murmur becomes progressively shorter. With the development of Eisenmenger’s physiology and equalization of aortic and pulmonary pressure, the entire murmur may disappear and the clinical findings are dominated by pulmonary hypertension.

In adult patients with a significant left-to-right shunt, the ECG shows a bifid P wave in at least one limb lead consistent with left atrial enlargement and a variable degree of left ventricular hypertrophy. The PR interval is prolonged in about 20% of patients. In older patients, the chest radiograph shows calcification at the location of the PDA. Characteristically, the ascending aorta and pulmonary artery are dilated, and the left-sided chambers are enlarged. Echocardiography may not directly visualize the PDA but can accurately identify it by a Doppler signal that often parallels the length of the murmur. Left-sided heart dilation and pulmonary hypertension can be quantified and monitored. Cardiac catheterization to assess pulmonary vascular resistance is commonly indicated before closure.

Treatment

After ligation of a PDA in infancy or early childhood, bacterial endocarditis prophylaxis is not required, cardiac function is commonly normal, and no special follow-up is required. In patients with an audible PDA by auscultation but without Eisenmenger’s disease, the combined risk of endarteritis, heart failure, and late mortality provides the rationale for shunt closure. If pulmonary artery pressure and pulmonary vascular resistance are substantially elevated, preoperative evaluation should assess the degree of reversibility. With Eisenmenger’s disease, closure is contraindicated.

The PDA can be closed surgically or by transcatheter methods. Reported operative mortality rates vary from less than 1 to 8%, depending on the presence of calcification and the degree of pulmonary hypertension. Transcatheter or coil occlusion is an accepted procedure in adults. Residual shunt rates vary from 0.5 to 8%, depending on the device used. Small residual defects that are detected by echocardiography but are not associated with an audible murmur or hemodynamic findings do not appear to carry a significant risk for endarteritis.

   Aortopulmonary Window

An aortopulmonary window is typically a large defect across the adjacent segments of both great vessels above their respective valves and below the pulmonary artery bifurcation. The pathophysiology is similar to that of a PDA. The shunt is usually large, so pulmonary vascular resistance rises rapidly and abolishes the aortopulmonary gradient in diastole. The murmur is usually best heard at the third left intercostal space. With a right-to-left shunt, differential cyanosis never occurs because the shunt is proximal to the brachiocephalic vessels. Differentiation of an aortopulmonary window from a PDA can usually be confirmed with echocardiography; the left-to-right shunt is seen in the main pulmonary artery in the aortopulmonary window compared with the left pulmonary artery bifurcation in PDA. Cardiac catheterization confirms the diagnosis and hemodynamics. Surgical repair is necessary unless pulmonary vascular obstructive disease precludes closure.

   Pulmonary Arteriovenous Fistulas

Pulmonary arteriovenous fistulas can occur as isolated congenital disorders or as part of generalized hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome). These fistulas typically occur in the lower lobes or the right middle lobe and can be small or large, single or multiple. The arterial supply usually comes from a dilated, tortuous branch of the pulmonary artery.

The most common finding is that of abnormal opacity on a chest radiograph in a patient with buccal ruby patches or in an otherwise healthy adult who has mild cyanosis. Shunting between deoxygenated pulmonary arterial blood and the oxygenated pulmonary venous blood results in a physiologic right-to-left shunt. The degree of shunting is typically small and not significant enough to result in dilation of the left atrium and ventricle. Heart failure is unusual. Hemoptysis can result if a fistula ruptures into a bronchus. In patients with hereditary hemorrhagic telangiectasia, angiomas occur on the lips and mouth as well as in the gastrointestinal tract and on pleural, liver, and vaginal surfaces. Epistaxis is most common, but cerebrovascular accidents can also occur. Patients with hereditary hemorrhagic telangiectasia can have symptoms that resemble those of a transient ischemic attack even in the absence of right-to-left shunting. On physical examination, cyanosis and clubbing can be notable or barely detectable. Auscultation can disclose soft systolic or continuous noncardiac murmurs on the chest wall adjacent to the fistula. The murmur typically increases with inspiration. The ECG is usually normal. The chest radiograph shows one or more densities, typically in the lower lobes or in the right middle lobe. An echocardiogram can confirm the presence of the fistula by showing early opacification of the left atrium in the absence of any other intracardiac communication when saline is injected into a peripheral vein. The absence of a hemodynamically significant shunt can be confirmed by documenting normal cardiac chamber size.

If the hypoxemia is progressive or if a neurologic complication is documented to have occurred because of paradoxical emboli, fistula closure should be considered. Options include percutaneous catheter techniques if the fistula is small and accessible or a pulmonary wedge resection or lobectomy if the fistula is large. Multiple or recurrent fistulas create a major therapeutic challenge.

   Isolated Obstructive Lesions of the Right and Left Ventricular Outflow Tract

Complications of obstructive lesions of the outflow tract relate to the secondary effects of exposure to pressure overload in the chamber proximal to the obstruction. The inability to increase systemic or pulmonary blood flow in the face of a fixed obstruction can cause exercise intolerance, inadequate myocardial perfusion, ventricular arrhythmias, and sudden death.

   Right Ventricular Outflow Tract Obstruction

Obstruction of the right ventricular outflow tract can occur at the level of the pulmonary valve (see later), above it in the main pulmonary artery or its branches, or below it in the right ventricle itself. Supravalvular and branch pulmonary artery stenoses are important and common complications of patients with the tetralogy of Fallot (see later). Residual supravalvar pulmonary stenosis is sometimes seen after palliative pulmonary artery banding to decrease pulmonary blood flow in patients with large left-to-right shunts. Congenital branch pulmonary artery stenosis can occur in isolation or with valvar pulmonary stenosis, shunt lesions, or a variety of syndromes. Patients with Noonan’s syndrome have a characteristic phenotypic facial appearance, short stature, and webbed neck; cardiac lesions may include a dysplastic pulmonary valve, left ventricular hypertrophic cardiomyopathy, and peripheral pulmonary artery stenosis. Supravalvular pulmonary stenosis can be seen with supravalvular aortic stenosis in Williams (elfin facies) syndrome.

Pulmonary atresia refers to an absent, imperforate, or closed pulmonary valve, which typically occurs in conjunction with other malformations. Pulmonary atresia with a nonrestrictive VSD is a complex cyanotic malformation that is discussed later.

Primary infundibular stenosis with an intact ventricular septum can result from a fibrous band just below the infundibulum. In a double-chambered right ventricle, obstruction is caused by anomalous muscle bundles that divide the right ventricle into a high-pressure chamber below the hypertrophied muscle bundles and a low-pressure chamber above the bundles and below the valve. The clinical features vary according to the presence or absence of other lesions, such as pulmonary valvular stenosis or VSD.

   Valvular Pulmonary Stenosis

Isolated congenital valvular pulmonary stenosis ( Chapter 75 ) is a common lesion due to a bicuspid valve in 20% of cases, a dysplastic valve caused by myxomatous changes and severe thickening in 10% of cases, and an abnormal trileaflet valve in most of the remaining cases. Fusion of the leaflets results in a variable degree of thickening and calcification in older patients.

The 25-year survival of patients with valvular pulmonary stenosis is greater than 95% but is worse in those with severe stenosis and peak systolic gradients greater than 80 mm Hg. For patients with mild (<50 mm Hg gradients) and moderate (50 to 80 mm Hg gradients) pulmonary stenosis, bacterial endocarditis, complex ventricular arrhythmias, and progression of the stenosis are uncommon.

Diagnosis

A patient with moderate or even severe pulmonary stenosis may be asymptomatic. With severe stenosis, exercise intolerance can be associated with presyncope and ventricular arrhythmias. Progressive right-sided heart failure is the most common cause of death. On physical examination of patients with significant pulmonary stenosis, jugular venous pressure has a dominant a wave, reflecting a noncompliant right ventricle. Palpation discloses a sustained parasternal lift of right ventricular hypertrophy. An expiratory systolic ejection click is characteristic if the leaflets are still mobile. In moderate or severe stenosis, a grade 3 or louder systolic murmur can be heard and felt in the second left interspace. The length of the murmur increases as it peaks progressively later in systole with an increasing degree of obstruction. If right-sided heart failure occurs, tricuspid insufficiency and systemic venous congestion develop. The ECG can show right axis deviation and tall, peaked right atrial P waves in lead II. With more than mild stenosis, the R wave exceeds the S wave in lead V1. On chest radiography, the main pulmonary artery can be dilated even if the stenosis is mild. Characteristically, the left pulmonary artery is more dilated than the right because of the leftward direction of the high-velocity jet. A variable degree of right ventricular hypertrophy is manifested as right-sided chamber enlargement. Echocardiography can establish the diagnosis and determine the severity by Doppler ultrasound examination.

Treatment

For patients with valvular pulmonic stenosis and gradients less than 50 mm Hg, conservative management is usually indicated unless symptoms are present. For patients with gradients greater than 80 mm Hg by cardiac catheterization and for symptomatic patients with gradients greater than 50 mm Hg, intervention is recommended. Percutaneous pulmonary angioplasty is the procedure of choice for adults, who achieve persistently good results at 10-year follow-up. For patients with subvalvular stenosis (double-chambered right ventricle), surgical resection of right ventricular muscle bands can be performed.

   Left Ventricular Outflow Tract Obstruction

Stenosis of the left ventricular outflow tract can occur at, below, or above the aortic valve. Discrete subaortic stenosis, most commonly caused by a fibromuscular ring just below the valve, accounts for 15 to 20% of all cases of congenital obstruction of the left ventricular outflow tract. Concomitant aortic insufficiency occurs in 50% of cases. Supravalvular aortic stenosis results from thickened media and intima above the aortic sinuses; early coronary atherosclerosis or even ostial coronary obstruction can occur.

   Congenital Valvular Aortic Stenosis

The normal aortic valve has three cusps and commissures. A unicuspid aortic valve accounts for most cases of severe aortic stenosis in infants ( Chapter 75 ). A bicuspid aortic valve, which is the most common congenital cardiac malformation, functions normally at birth but often becomes gradually obstructed as calcific and fibrous changes occur; prolapse of one or both cusps can cause aortic insufficiency.

The pathophysiology of aortic stenosis depends not only on its severity but also on the age at diagnosis. When a functionally normal bicuspid aortic valve becomes stenotic in adulthood because of degenerative changes, criteria for diagnosis and intervention parallel those for other forms of acquired aortic stenosis ( Chapter 75 ). When the valve is congenitally stenotic, myocardium with a lifelong exposure to pressure overload behaves differently than if the hemodynamic burden occurred later in life.

The estimated overall 25-year survival rate for patients with congenital valvular aortic stenosis diagnosed in childhood is 85%. Children with initial peak cardiac catheterization gradients less than 50 mm Hg have long-term survival rates of higher than 90%, as opposed to survival rates of 80% in those with gradients of 50 mm Hg or greater.

Diagnosis

Symptoms include angina, exertional dyspnea, presyncope, and syncope and may progress to heart failure. The auscultatory hallmark of a bicuspid aortic valve is an audible systolic ejection click that is typically of a higher pitch than the first heart sound and is best heard not at the cardiac base but at the apex. The sound is caused by sudden movement of the stenotic valve as it moves superiorly in systole and is followed by the typical aortic stenosis murmur ( Chapter 75 ). When significant calcification of the valve results in reduced mobility, the ejection sound is no longer heard. The diagnosis is easily confirmed by two-dimensional echocardiography, with which the number and orientation of aortic cusps can readily be identified.

Treatment

Conservative management is generally indicated for mild stenosis with a peak gradient of less than 25 mm Hg, but close supervision is required because 20% of these patients require an intervention during long-term follow-up. Unlimited athletic participation is allowed only for asymptomatic patients with peak gradients of less than 20 to 25 mm Hg, a normal ECG, and a normal exercise test. For children who are symptomatic or have gradients greater than 30 mm Hg but do not have significant aortic insufficiency, transcatheter aortic valvotomy is preferred. Aortic valvuloplasty can be considered in young adults, but calcification limits its success, and valve replacement is usually required ( Chapter 75 ). For adults, treatment decisions are similar to those for aortic stenosis from other causes. For patients with subvalvular aortic stenosis, surgical intervention is indicated in the presence of peak gradients above 50 mm Hg, symptoms, or progressive aortic insufficiency.

   Coarctation of the Aorta

Aortic coarctation typically occurs just distal to the left subclavian artery at the site of the aortic ductal attachment or its residual ligamentum arteriosum. Less commonly, the coarctation ridge lies proximal to the left subclavian. A bicuspid aortic valve is the most common coexisting anomaly, but VSDs and PDAs are also seen. Pseudocoarctation refers to buckling or kinking of the aortic arch without the presence of a significant gradient.

The most common complications of aortic coarctation are systemic hypertension ( Chapter 66 ) and secondary left ventricular hypertrophy with heart failure. Systemic hypertension is caused by decreased vascular compliance in the proximal aorta and activation of the renin-angiotensin system in response to renal artery hypoperfusion below the obstruction. Left ventricular hypertrophy occurs in response to chronic pressure overload. Congestive heart failure occurs most commonly in infants and then after 40 years of age. The high pressure proximal to the obstruction stimulates the growth of collateral vessels from the internal mammary, scapular, and superior intercostal arteries to the intercostals of the descending aorta. Collateral circulation increases with age and contributes to perfusion of the lower extremities and the spinal cord. This mechanism, although adaptive in a patient who has not undergone surgery, accounts for significant morbidity during surgery when the motor impairment results from inadequate protection of spinal perfusion. Aneurysms occur most notably in the ascending aorta and in the circle of Willis. Premature coronary disease is thought to be related to the resulting hypertension. Complications, including bacterial endarteritis at the coarctation site or, more commonly, endocarditis at the site of a bicuspid aortic valve, cerebrovascular complications, myocardial infarction, heart failure, and aortic dissection, occur in 2 to 6% of patients, more frequently in those with advancing age who have not undergone surgery.

Diagnosis

Young adults may be asymptomatic with incidental systemic hypertension and decreased lower extremity pulses. Coarctation should always be considered in adolescents and young adult men with unexplained upper extremity hypertension. The pressure differential can cause epistaxis, headaches, leg fatigue, or claudication. Older patients have angina, symptoms of heart failure, and vascular complications.

On physical examination, the lower half of the body is typically slightly less developed than the upper half. The hips are narrow and the legs are short, in contrast to broad shoulders and long arms. Blood pressure measurements should be obtained in each arm and one leg; an abnormal measurement is an increase of less than 10 mm Hg in popliteal systolic blood pressure compared with arm systolic blood pressure. The diastolic pressure should be the same in the upper and lower extremities. A pressure differential of more than 30 mm Hg between the right and the left arms is consistent with compromised flow in the left subclavian artery. Right brachial palpation characteristically reveals a strong or even bounding pulse compared with a slowly rising or absent femoral, popliteal, or pedal pulse. Examination of the eyegrounds can reveal tortuous or corkscrew retinal arteries. Precordial palpation is consistent with left ventricular pressure overload. On auscultation, a systolic ejection sound reflecting the presence of a bicuspid aortic valve should be sought. The coarctation itself generates a systolic murmur heard posteriorly, in the midthoracic region, the length of which correlates with the severity of the coarctation. Over the anterior of the chest, systolic murmurs reflecting increased collateral flow can be heard in the infraclavicular areas and the sternal edge or in the axillae.

In adult coarctation, the most common finding on the ECG is left ventricular hypertrophy. Chest radiographic findings are diagnostic. Location of the coarctation segment between the dilated left subclavian artery above and the leftward convexity of the descending aorta below results in the “3 sign” ( Fig. 68-7 ). Bilateral rib notching as a result of dilation of the posterior intercostal arteries is seen on the posterior of the third to eighth ribs when the coarctation is below the left subclavian. Unilateral rib notching sparing the left ribs is observed when the coarctation occurs proximal to the left subclavian artery. Transthoracic echocardiography documents the gradient in the descending aorta and determines the presence of left ventricular hypertrophy. Magnetic resonance imaging ( Chapter 55 ) is the best modality for visualizing the anatomy of the descending aorta. Cardiac catheterization should measure pressures and assess collaterals when surgery is contemplated.

FIGURE 68-7  Chest radiograph of a patient with coarctation of the aorta showing the radiographic “3” formed by the dilated subclavian artery above and the dilated aorta below (short arrow). Note the notching best seen at the level of the seventh and eighth ribs (long arrows). The dilated ascending aortic segment can also be seen.

Treatment

Intervention is considered in patients with gradients greater than 30 mm Hg on cardiac catheterization ( Chapter 56 ). Fifty percent of patients repaired when they are older than 40 years have residual hypertension, whereas those who have undergone surgery between the ages of 1 and 5 years have a less than 10% prevalence of hypertension on long-term follow-up. Balloon angioplasty is the treatment of choice for focal recoarctation in patients who have previously been operated on. The incidence of incomplete relief and restenosis is decreased in adults by endovascular stent placement. Focal complications include aortic aneurysms and, rarely, aortic rupture.

   Anomalies of the Sinuses of Valsalva and Coronary Arteries

   Sinus of Valsalva Aneurysms

At the base of the aortic root, the aortic valve cusps are attached to the aortic wall, above which three small pouches, or sinuses, are seated. The right coronary artery originates from one sinus and the left main coronary artery from a second; the third is called the noncoronary sinus. A weakness in the wall of the sinus can result in aneurysm formation with or without rupture. In more than 90% of cases, the aneurysm involves the right or noncoronary cusp. Rupture typically occurs into the right side of the heart at the right atrial or ventricular level with a resulting large left-to-right shunt driven by the high aortic pressure.

A previously asymptomatic young man typically has chest pain and rapidly progressing shortness of breath sometimes after physical strain. The physical examination is consistent with significant heart failure. Even if the communication is between the aorta and the right side of the heart, biventricular failure is not unusual. The classic murmur is loud and continuous, often with a thrill. A murmur of aortic insufficiency secondary to damage to the adjacent aortic valve may be superimposed. The chest radiograph shows volume overload of both ventricles with evidence of shunt vascularity and pulmonary venous congestion. The echocardiogram is diagnostic. Cardiac catheterization can verify the integrity of the coronary artery adjacent to the ruptured aneurysm.

Even though symptoms may abate as the heart dilates, progressive cardiac decompensation typically results in death within 1 year of the rupture. A ruptured sinus of Valsalva aneurysm therefore requires urgent surgical repair.

   Coronary Artery Fistulas

Fistulas arise from the right or left coronary arteries and in 90% of cases drain into the right ventricle, the right atrium, or the pulmonary artery in order of decreasing frequency. Typically, young patients are asymptomatic, but supraventricular arrhythmias are seen with progressive dilation of the intracardiac chambers. Angina can occur as the fistula creates a coronary steal by diverting blood away from the myocardium. Heart failure is seen with large fistulas. A continuous murmur heard in a young, otherwise normal acyanotic, asymptomatic patient should suggest the diagnosis. Most fistulas are associated with a small shunt, and hence the murmur is often less than grade 3 and is heard in the precordial area. Unless the shunt is large, the ECG is normal, as is the chest radiograph. The echocardiogram, especially the transesophageal echocardiogram, is diagnostic. Percutaneous transcatheter closure with coil embolization is preferred, but surgical ligation is also an alternative.

   Anomalous Origin of the Coronary Arteries

The left main coronary artery normally arises from the left sinus of Valsalva and courses leftward, posterior to the right ventricular outflow tract. The right coronary artery arises from the right sinus of Valsalva and courses rightward to the right ventricle. Isolated ectopic or anomalous origins of the coronary arteries (see Fig. 55-4 ) are seen in 0.6 to 1.5% of patients undergoing coronary angiography.

The most common anomaly is ectopic origin of the left circumflex artery from the right sinus of Valsalva, followed by anomalous origin of the right coronary artery from the left sinus and anomalous origin of the left main coronary artery from the right sinus. If the anomalous coronary artery does not course between the pulmonary artery and aorta, the prognosis is favorable. Risks of ischemia, myocardial infarction, and death are greatest when the left main coronary artery courses between both great vessels.

Coronary arteries can also originate from the pulmonary trunk. If both the right and left arteries originate from the pulmonary trunk, death usually occurs in the neonatal period. If only the left anterior descending coronary artery originates from the pulmonary trunk, the rate of survival to adulthood is approximately 10%, depending on the development of collateral retrograde flow to the anomalous artery from a normal coronary artery. This collateral flow may cause a continuous murmur along the left sternal border, congestive heart failure from the large shunt, and a coronary steal syndrome as blood is diverted away from the normal artery.

A single coronary ostium can provide a single coronary artery that branches into right and left coronary arteries, the left then giving rise to the circumflex and the anterior descending arteries. The ostium can originate from the right or left aortic sinus. The coronary circulation is functionally normal unless one of the branches passes between the aorta and the pulmonary artery.

Diagnostic procedures include angiography, magnetic resonance imaging, and transesophageal echocardiography. For an anomalous coronary artery that originates from the pulmonary artery, surgical reimplantation into the aorta is preferred. For an anomalous artery that courses between the pulmonary artery and aorta, a bypass graft to the distal vessel is preferred.

   SPECIFIC COMPLEX LESIONS

   Tetralogy of Fallot

Tetralogy of Fallot, the most common cyanotic malformation, is characterized by superior and anterior displacement of the subpulmonary infundibular septum, which causes the tetrad of pulmonary stenosis, VSD, aortic override, and right ventricular hypertrophy. The VSD is perimembranous in 80% of cases. Additional cardiac anomalies include a right-sided aortic arch in up to 25% of patients. An anomalous left anterior descending artery originating from the right coronary cusp and crossing over the right ventricular outflow tract is seen in 10% of cases. Other associated anomalies include ASD, left superior vena cava, defects of the atrioventricular canal, and aortic insufficiency. With pulmonary atresia, pulmonary blood flow occurs through aortic to pulmonary collaterals. Life expectancy is limited unless staged reconstructive surgery is performed.

The physiology in unrepaired tetralogy of Fallot is determined by the severity and location of the pulmonic outflow obstruction and by the interaction of pulmonary and systemic vascular resistance across a nonrestrictive VSD. Because the pulmonary stenosis results in a relatively fixed pulmonary resistance, a drop in systemic vascular resistance as occurs with exercise is associated with increased right-to-left shunting and increasing cyanosis. A child who squats after running is attempting to reverse the process by increasing systemic vascular resistance by crouching with bent knees. Native pulmonary blood flow is typically insufficient. Unless a PDA has remained open, a cyanotic adult will typically have undergone a palliative procedure to increase pulmonary blood flow.

Examination of unrepaired patients reveals central cyanosis and clubbing. The right ventricular impulse is prominent. The second heart sound is single and represents the aortic closure sound with an absent or inconspicuous P2. Typically, little or no systolic murmur is heard across the pulmonary valve because the more severe the obstruction, the more right-to-left shunting occurs and the less blood flows across a diminutive right ventricular outflow tract. A diastolic murmur of aortic insufficiency is often heard in adults. In the presence of a palliative systemic arterial to pulmonary artery shunt, the high-pressure gradient generates a loud continuous murmur. In a patient who has not undergone surgery, progressive infundibular stenosis and cyanosis occur. Before the advent of palliative surgery, mortality rates were 50% in the first few years of life and survival past the third decade was unusual.

Complete surgical repair consists of patch closure of the VSD and relief of the right ventricular outflow tract obstruction. Adequate pulmonary blood flow is ensured by reconstruction of the distal pulmonary artery bed. Previous palliative shunts are usually taken down. Complete repair in childhood yields a 90 to 95% 10-year survival rate with good functional results, and 30-year survival rates may be as high as 85%. Total correction with low mortality and a favorable long-term follow-up is possible even in adulthood.

After repair, residual pulmonary stenosis, proximal or distal, with a right ventricular pressure greater than 50% of systemic occurs in up to 25% of patients. Some degree of pulmonary insufficiency is common, particularly if a patch has been inserted at the level of the pulmonary valve or if a pulmonary valvotomy has been performed. Residual VSDs can be found in up to 20% of patients. Patients may be asymptomatic or may have symptoms related to long-term complications after surgical repair. Symptoms can reflect residual right ventricular pressure or volume overload or arrhythmias at rest or with exercise. Angina can occur in a young patient if surgical repair has damaged an anomalous left anterior descending artery as it courses across the right ventricular outflow tract. In acyanotic adults, clubbing commonly regresses. A right ventricular impulse is often felt as a result of residual pulmonary insufficiency or stenosis. Typically, no functioning pulmonary valve is present, and hence the second heart sound is still single. A systolic murmur can represent residual pulmonary stenosis, residual VSD, or tricuspid insufficiency. A diastolic murmur can reflect aortic or pulmonary insufficiency. Ventricular arrhythmias are common after repair, with an incidence of sudden death as high as 5%.

The ECG in unrepaired tetralogy of Fallot shows right axis deviation, right atrial enlargement, and dominant right ventricular forces over the precordial leads. The most common finding after repair is complete right bundle branch block, which is seen in 80 to 90% of patients. The chest radiograph typically shows an upturned apex with a concave pulmonary artery segment giving the classic appearance of a boot-shaped heart. Figure 68-8 demonstrates the findings in an adult after repair. The apex is persistently upturned, although the pulmonary artery segment is no longer concave. Echocardiography can confirm the diagnosis and document intracardiac complications in repaired and unrepaired patients. Shunt patency can be determined by Doppler examination. Magnetic resonance imaging can accurately document stenosis in the distal pulmonary artery bed. Cardiac catheterization is reserved for patients in whom operative or reoperative treatment is contemplated or in whom the integrity of the coronary circulation needs to be verified.

FIGURE 68-8  Chest radiograph of an adult after tetralogy of Fallot repair. A right aortic arch with rightward indentation of the trachea (long arrow) can be seen. The right ventricular apex remains upturned (short arrow). Note the sternal wires consistent with intracardiac repair, thus clarifying the fullness of the pulmonary artery segment often seen after extensive enlargement of the right ventricular outflow tract.

Patients with a change in exercise tolerance, angina, or evidence of heart failure as well as those with symptomatic arrhythmias or syncope should be referred for complete evaluation. Surgical reintervention is generally considered when right ventricular pressure is more than two thirds as high as systemic pressure because of residual right ventricular outflow tract obstruction, free pulmonary regurgitation occurs with right ventricular dysfunction or sustained arrhythmias, or a residual VSD causes a significant shunt.

   Complete Transposition of the Great Arteries

Complete transposition of the great arteries is the second most common cyanotic lesion, and surgically corrected adults are increasingly common. In simple transposition of the great arteries, the atria and ventricles are in their normal positions but the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle. When the aorta is anterior and rightward with respect to the pulmonary artery, as is most common, D-transposition is present. The native anatomy has the pulmonary and systemic circulations in parallel, with deoxygenated blood recirculating between the right side of the heart and the systemic circulation, whereas oxygenated blood recirculates from the left side of the heart to the lungs. The condition is incompatible with life unless a VSD, PDA, or ASD is present or an ASD is created; a hemodynamically significant VSD is present in 15% of cases. Subpulmonary obstruction of the left ventricular outflow tract occurs in 10 to 25% of cases.

The Senning or Mustard atrial baffle repairs, which were the first corrective procedures, redirect oxygenated blood from the left atrium to the right ventricle so that it may be ejected into the aorta while deoxygenated blood detours the right atrium and heads for the left ventricle and into the pulmonary artery. Although this operation results in acyanotic physiology, the right ventricle assumes a permanent position under the aorta and pumps against systemic pressures, a lifelong task for which it was not designed. When the subpulmonary obstruction is significant, the Rastelli procedure reroutes blood at the ventricular level by tunneling the left ventricle to the aorta inside the heart through a VSD. A conduit is then inserted outside the heart between the left ventricle and aorta. More recently, the arterial switch operation transects the aorta and pulmonary artery above their respective valves and switches them to become realigned with their physiologic outflow tracts and appropriate ventricles. The proximal coronary arteries are translocated from the sinuses of the native aorta to the neoaorta (native pulmonary artery). In this operation, each ventricle reassumes the role that it was embryologically destined to fulfill.

If an adult patient is cyanotic and has a native intracardiac shunt or a palliative shunt, referral to an appropriate facility should be undertaken to explore the possibility of intracardiac repair. At present, adults with transposition of the great arteries most commonly have undergone an atrial baffle repair, with an expected 15-year survival rate of 75% and a 20-year survival rate of 70%. For patients with an atrial baffle procedure, symptoms include exercise intolerance, palpitations caused by bradyarrhythmias or atrial flutter, and right ventricular failure. The patient is typically acyanotic unless a baffle leak exists. The clinical findings are determined by the presence or absence of systemic right ventricular failure. On auscultation, the second heart sound is classically single. The ECG reveals sinus bradycardia, but nodal rhythms and heart block occur as the patient ages. The chest radiograph shows a variable degree of right ventricular enlargement. Echocardiography can be used to confirm the diagnosis and to explore related abnormalities. Cardiac catheterization is performed when an operation or reoperation is contemplated. Reoperation is performed in approximately 20% of patients for baffle-related complications, progressive left ventricular outflow tract stenosis, or severe tricuspid regurgitation.

   Congenitally Corrected Transposition of the Great Arteries

In congenitally corrected transposition of the great arteries, the great arteries are transposed, the ventricles are inverted, but the atria remain in their normal position. The systemic circulation (left atrium, morphologic right ventricle, and aorta) and pulmonary circulation (right atrium, morphologic left ventricle, and pulmonary artery) are in series. The patient is therefore acyanotic unless an intracardiac shunt is also present. The right ventricle is aligned with the aorta and performs lifelong systemic work, which accounts in part for its eventual failure. Associated lesions include a VSD, pulmonary stenosis, and Ebstein’s malformation of the left-sided tricuspid valve. Complete heart block develops at a rate of 2% per year. Patients with congenitally corrected transposition of the great arteries and no other associated defects can remain free of symptoms until the sixth decade, at which time significant atrioventricular valve regurgitation, failure of the right (systemic) ventricle, supraventricular arrhythmias, and heart block occur.

   Right-Sided Ebstein’s Anomaly

The septal and posterior cusps of the tricuspid valve are largely derived from the right ventricle as it liberates a layer of muscle that skirts away from the cavity to become valve tissue. When this process occurs abnormally, the posterior and septal cusps of the tricuspid valve remain tethered to the muscle and adhere to the right ventricular surface—hence the diagnostic hallmark of Ebstein’s anomaly, apical displacement of the septal tricuspid leaflet.

In right-sided Ebstein’s anomaly of the tricuspid valve, the right side of the heart consists of three anatomic components: the right atrium proper, the true right ventricle, and the atrialized portion of the right ventricle between the two. The displaced septal and posterior tricuspid leaflets lie between the atrialized right ventricle and the true right ventricle. In mild Ebstein’s anomaly, the degree of tricuspid leaflet tethering is only mild, the anterior leaflet retains mobility, and the size of the true right ventricle is only mildly reduced. Severe Ebstein’s anomaly is associated with severe tethering of the tricuspid leaflet tissue and a diminutive, hypocontractile true right ventricle. Functionally, the valve is regurgitant because it is unable to appose its three leaflets during ventricular contraction. Valvular regurgitation and asynchronous, abnormal right ventricular function cause the dilation and right-sided heart failure observed in the more severe forms of the lesion. The wide spectrum of severity of the anomaly is based on the degree of tricuspid leaflet tethering and the relative proportion of atrialized and true right ventricle. The most common associated cardiac defect, a secundum ASD or patent foramen ovale, is reported in more than 50% of patients. On physical examination, a clicking “sail sound” is heard as the second component of S1 when tricuspid valve closure becomes loud and delayed.

The 12-lead ECG typically shows highly peaked P waves with a wide, often bizarre-looking QRS complex. Preexcitation occurs in 20% of patients; supraventricular tachyarrhythmias, atrial fibrillation, and atrial flutter occur in 30 to 40% of patients and constitute the most common findings in adolescents and adults with right-sided Ebstein’s anomaly.

When patients of all ages are taken together, the predicted mortality is approximately 50% by the fourth or fifth decade. Complications include atrial arrhythmias due to severe right atrial enlargement and cyanosis caused by a right-to-left atrial shunt as tricuspid insufficiency increases and the right ventricle fails. Atrial arrhythmias, cyanosis, and the presence of an intra-atrial communication also increase the risk of stroke.

Intervention is considered when functional status or cyanosis worsens, significant atrial arrhythmias are documented, or a cerebrovascular accident occurs. Surgical options include replacement or repair of the tricuspid valve and closure of the ASD. The feasibility of tricuspid valvuloplasty depends on the size and mobility of the anterior tricuspid leaflet, which is used to construct a unicuspid right-sided valve.

   Atrioventricular Canal Defect

Embryologic septation of the atrioventricular canal results in closure of the inferior portion of the interatrial septum and the superior portion of the interventricular septum. Septation is achieved with the growth of endocardial cushions, which also contribute to development of the mitral and tricuspid valves. Hence, the nomenclature atrioventricular canal defect or endocardial cushion defect is used to designate this group of anomalies.

A partial atrioventricular canal defect refers to an ostium primum ASD with a cleft mitral valve. The anomaly is manifested as a hemodynamic combination of an ASD with a variable degree of mitral regurgitation. The 12-lead ECG shows the typical findings of left axis deviation with a Q wave in leads I and aVL and a prolonged PR interval. The echocardiogram shows a defect in the inferior portion of the interatrial septum and a cleft mitral valve.

A complete atrioventricular canal defect is an uncommon defect consisting of a primum ASD, an inlet VSD that usually extends to the membranous interventricular septum, and a common atrioventricular valve. Adults who have not been operated on usually have Eisenmenger’s syndrome unless concomitant pulmonary stenosis has protected the pulmonary vascular bed or the VSD has undergone spontaneous closure, in which case the physiologic consequences are similar to those of a partial atrioventricular canal.

Surgical repair of an atrioventricular defect consists of closing the interatrial or interventricular communication with reconstruction of the common atrioventricular valve or closure of the cleft in the mitral valve. An adult who has undergone repair may have significant residual regurgitation of the mitral or tricuspid valve. Even after surgery, acquired subaortic obstruction can occur in the long left ventricular outflow tract, which has a classic gooseneck deformity on cardiac angiography.

   Univentricular Heart and Tricuspid Atresia

The terms single ventricle, common ventricle, and univentricular heart have been used interchangeably to describe the double-inlet ventricle, in which one ventricular chamber receives flow from both the tricuspid and mitral valves. In 75 to 90% of cases, the single ventricle is a morphologic left ventricle. Obstruction of one of the great arteries is common, and life expectancy is short without an operation. The patients most likely to survive to adulthood palliated or, rarely, without surgery have a single ventricle of the left morphologic type, with pulmonary stenosis protecting the pulmonary vascular bed.

In tricuspid atresia, no orifice is found between the right atrium and right ventricle, and an underdeveloped or hypoplastic right ventricle is present. The morphologic left ventricle is consistently normally developed and therefore becomes the single functional ventricle. Typically, blood flows into the right atrium, then through an obligatory ASD and to the left atrium, where it then proceeds to the left ventricle. Variable features include a VSD, the abnormal position of the great arteries, and the relative degree of pulmonary stenosis, all of which are used to classify tricuspid atresia. Without surgery, 50% of patients die in the first 6 months and 90% in the first decade.

Adult patients rarely have not been operated on. They may be acyanotic after the Fontan operation; if cyanotic and palliated, the patient may benefit from further palliation or may be eligible for the Fontan operation. With the Glenn shunt or the Fontan operation, a direct anastomosis is created between the systemic venous and pulmonary circulations. Venous blood flows passively from the systemic veins to the pulmonary circulation and returns oxygenated to a left-sided atrium and into the single functional ventricle, which then pumps oxygenated blood into the systemic circulation. The Glenn anastomosis diverts part of the systemic venous return to the lungs, whereas the Fontan procedure makes the patient acyanotic by diverting the entire systemic venous circulation to the pulmonary vascular bed. For optimum results, a successful Fontan operation requires low pulmonary vascular resistance, preserved single ventricular function, and unobstructed anastomosis between the systemic veins and the pulmonary arteries. At 5-year follow-up, 80% or more of Fontan survivors are in New York Heart Association functional class I or II, with successful pregnancy reported in a small number of patients. When patients of all ages are considered together, 10-year survival rates vary from 60 to 70%. Late deaths are due to reoperation, arrhythmia, ventricular failure, and protein-losing enteropathy.

   Vascular Malformations

   Aortic Arch Anomalies

Vascular Rings and other Arch Anomalies

One of the most frequent developmental errors of the aortic arch is an aberrant right subclavian artery originating distal to the left subclavian and coursing rightward behind the esophagus at the level of the third thoracic vertebrae. Although the finding is frequent, symptoms are uncommon. When symptoms occur, the term dysphagia lusoria has been used in reference to swallowing difficulties that result from esophageal compression. Abnormal development of the brachial arches and dorsal aorta can result in a variety of anomalies that lead to the formation of vascular rings around the trachea and esophagus. The outcome is often benign, but symptoms of respiratory compromise or dysphagia warrant surgery. When the left pulmonary artery arises from the right and passes leftward between the trachea and esophagus, a pulmonary artery sling occurs. Symptoms of tracheal compression warrant correction.

A right aortic arch occurs when the aortic arch courses toward the right instead of the left. Mirror-image branching is the most common anatomic variant. In most cases, this anomaly coexists with other congenital lesions, notably tetralogy of Fallot.

   Anomalous Venous Connections

Anomalies of Systemic Venous Return

A persistent left superior vena cava can be fortuitously diagnosed on chest radiography or on echocardiography. Its clinical relevance depends on development of the coronary sinus. If the coronary sinus is normally formed, typically the left superior vena cava drains into the right atrium through the coronary sinus. If the coronary sinus is not normally developed, the persistent left superior vena cava drains into the left atrium and cyanosis results from the obligatory right-to-left shunt. The latter commonly occurs with an ASD or a complex cardiac anomaly.

Venous return above the renal veins can be abnormal with inferior vena cava interruption and azygos or hemiazygos continuation. In the former, inferior vena cava flow above the renal veins continues into the azygos vein, which courses normally up the right of the spine to empty into the junction between the superior vena cava and right atrium. In a less common anatomic arrangement, the caval flow empties into a hemiazygos vein, which empties into a persistent left superior vena cava. The finding rarely occurs in isolation but can be seen in patients with associated simple or complex malformations.

Anomalies of Pulmonary Venous Return

In partial anomalous pulmonary venous return, one or more but not all four pulmonary veins are not connected to the left atrium. The most common pattern has the right pulmonary veins connected to the superior vena cava, usually with a sinus venosus ASD. Anomalous connection of the right pulmonary veins to the inferior vena cava results in a chest radiographic shadow that resembles a Turkish sword, hence the designation scimitar syndrome. Associated anomalies include hypoplasia of the right lung, anomalies of the bronchial system, hypoplasia of the right pulmonary artery, and dextroposition of the heart. Partial anomalous pulmonary venous return results in a left-to-right shunt physiology similar to that of an ASD.

In total anomalous pulmonary venous return, all the pulmonary veins connect abnormally to either the right atrium or one of the systemic veins above or below the diaphragm. Concurrent obstruction of the pulmonary veins is present when drainage occurs below the diaphragm and variable when drainage occurs above it. An ASD is essential to sustain life. One third of cases occur with major complex cardiac malformations.

In cor triatriatum, the pulmonary veins drain into an accessory chamber that is usually connected to the left atrium through an opening of variable size. The hemodynamic consequences are determined by the size of this opening and are similar to those of mitral stenosis. If symptoms of pulmonary venous hypertension occur, surgical treatment is indicated.

   Cardiac Malpositions

The normal heart is left sided and hence the designation levocardia. Cardiac malpositions are defined in terms of the intrathoracic position of the heart in relation to the position of the viscera (visceral situs), which are usually concordant with the position of the atria. That is, when the liver is on the right and the stomach is on the left, the atrium receiving systemic venous blood (right atrium) is right sided and the atrium receiving pulmonary venous blood (left atrium) is left sided. Asplenia and polysplenia syndromes are associated with a variety of complex cardiovascular malformations.

Dextrocardia and Mesocardia

In dextrocardia, the heart is on the right side of the thorax with or without situs inversus. When the heart is right sided with inverted atria, a right-sided stomach, and a left-sided liver, the combination is dextrocardia with situs inversus. In this arrangement, also called mirror-image dextrocardia, the ventricles are inverted, but so are the viscera and therefore the atria. The heart usually functions normally, and the diagnosis is often fortuitous. The heart sounds are louder on the right side of the chest and the liver is palpable on the left. The chest radiograph shows a right-sided cardiac apex with a lower left hemidiaphragm and a right-sided stomach bubble. The ECG shows an inverted P and T wave in lead I with a negative QRS deflection and a reverse pattern between aVR and aVL. A mirror-image progression is seen from V1 to a right-sided V6 lead. An echocardiogram should be performed to ensure that intracardiac anatomy is normal.

When dextrocardia with situs solitus occurs, the ventricles are inverted but not the viscera and therefore not the atria. Associated severe cardiac malformations are typical.

In mesocardia, the heart is centrally located in the chest with normal atrial and visceral anatomy. The apex is central or rightward displaced on the chest radiograph. Typically, no associated cardiac malformations are present.

   Specialized Issues

Endocarditis Prophylaxis

Prolonged survival of patients with complex congenital heart disease has resulted in a population at increased risk for infective endocarditis ( Chapter 76 ). Infection most commonly affects sites of turbulent blood flow on the low-pressure side of gradients. Such sites include restrictive VSDs, PDAs, cleft mitral valve, aortic coarctation (most often at the site of an associated bicuspid aortic valve), and prosthetic shunts, valves, and conduits in a postoperative patient. The risk of endocarditis associated with isolated low-pressure lesions in the right side of the heart is low.

Endocarditis should be suspected early and culture specimens obtained before antibiotic therapy is begun. Current recommendations for the prevention of bacterial endocarditis apply to most congenital heart lesions, with the exception of an isolated ASD and surgically repaired ASD, VSD, or PDA without residual shunting beyond 6 months after repair.

Exercise

The goal of exercise evaluation is to assess the functional results of therapeutic interventions and to provide guidelines for exercise prescriptions. Patients with residual hemodynamic lesions or unrepaired congenital cardiac anomalies should be evaluated on an annual basis with a physical examination, an ECG, and a cardiac ultrasonographic examination if indicated. Pertinent additional tests may include Holter monitoring and exercise testing. Attention should be directed to the detection of pulmonary hypertension, arrhythmias, myocardial dysfunction, and symptoms such as exercise-induced dizziness, syncope, dyspnea, or chest pain.

A series of exercise guidelines have been proposed for major groups of congenital heart defects ( Table 68-2 ). Patients beyond 6 months after repair of a single shunt lesion without pulmonary hypertension, arrhythmias, or evidence of myocardial dysfunction can participate in all sports. With residual shunts, if the peak pulmonary artery pressure is less than 40 mm Hg in the absence of ventricular dysfunction or significant arrhythmias, patients can enjoy a free range of activity. Patients with elevated pulmonary vascular resistance are at risk of sudden death during intense exercise; although most self-limit their activity, participation in competitive sports is contraindicated. Patients with aortic and pulmonary stenosis should be counseled as recommended earlier, according to gradient severity. For patients with uncomplicated aortic coarctation, athletic participation is permitted if the arm-leg blood pressure gradient is 20 mm Hg or less at rest and the peak systolic blood pressure during exercise is normal. For patients after tetralogy of Fallot repair, repair of transposition of the great arteries, and the Fontan operation, exercise recommendations vary according to residual ventricular function and the presence or absence of arrhythmias.


TABLE 68-2   — 
EXERCISE RECOMMENDATIONS IN ADULTS WITH CONGENITAL HEART DISEASE

Condition Unrestricted Low-Moderate Intensity[*] Prohibited
ASD[] No PHT; no arrhythmia; normal ventricular function PA pressure >40 mm Hg with normal ETT; no arrhythmia Eisenmenger’s
VSD[] Small; no PHT; no arrhythmia; normal ventricular function Moderate VSD Eisenmenger’s
PDA[] Small; no PHT; no arrhythmia; normal ventricular function PA pressure >40 mm Hg with normal ETT; no arrhythmia Eisenmenger’s
Coarctation[] Gradient ≤20 mm Hg arm to leg; normal BP at rest and exercise Gradient ≥20 mm Hg arm to leg with normal BP and normal ETT Gradient ≥50 mm Hg arm to leg or aortic aneurysm
PS Gradient <50 mm Hg; no arrhythmia; normal ventricular function Gradient ≥50 mm Hg Gradient ≥70 mm Hg or ventricular arrhythmia
AS Gradient ≤20 mm Hg; normal ECG; normal ETT; asymptomatic Gradient >20 mm Hg with normal ECG, normal ETT; asymptomatic Gradient ≥50 mm Hg or ventricular arrhythmia
TOF after repair Normal RV pressure; no shunt; no arrhythmia Increased RV pressure or moderate PR or SVT RV pressure ≥65% systemic or ventricular; arrhythmia on ETT or severe PR
Mustard or Senning   No cardiomegaly, arrhythmia, or syncope; normal ETT Cardiomegaly or arrhythmia at rest or exercise
c-TGA unoperated No cardiomegaly; mild TR; no arrhythmia; normal ETT Moderate RV dysfunction, moderate TR; no arrhythmia Severe TR or uncontrolled arrhythmia
Ebstein’s Mild Ebstein’s; no arrhythmia; operated with mild TR Moderate TR with no arrhythmia Severe Ebstein’s or uncontrolled arrhythmia
Fontan   Normal O2 saturation with near-normal ETT and ventricular function Moderate-severe MR or TR or uncontrolled arrhythmia

Based on guidelines recommended in Graham TP, Bricker TJ, James FW, et al: 26th Bethesda conference: Recommendations for determining eligibility for competition in athletes with cardiovascular abnormalities. Task Force 1: Congenital heart disease. J Am Coll Cardiol 1994;24:867. Reprinted with permission of the American College of Cardiology.

AS = aortic stenosis; ASD = atrial septal defect; BP = blood pressure; c-TGA = corrected transposition of the great arteries; ECG = electrocardiogram; ETT = exercise tolerance test; MR = mitral regurgitation; PA = pulmonary artery; PDA = patent ductus arteriosus; PHT = pulmonary hypertension; PR = pulmonary regurgitation; PS = pulmonary stenosis; RV = right ventricle; SVT = supraventricular tachyarrhythmia; TOF = tetralogy of Fallot; TR = tricuspid regurgitation; VSD = ventricular septal defect.

* Based on peak dynamic and static components of exercise during competition for individual sports (see credit line).
Unoperated or 6 months after surgery.
Unoperated or 1 year after surgery.

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