A
Congenital Defects
Anastasios C. Polimenakos, M.D., F.A.C.S., F.A.C.C., Eric J. Okum, M.D., R. Anthony Perez-Tamayo, M.D., Ph.D., Robert S.D. Higgins, M.D., M.S.H.A.
1 Which of the following statements is true regarding the fetal circulation?
A Blood flows through the ductus arteriosus from the pulmonary artery to the aorta.
B Less than 25% of cardiac output flows through the lungs.
C The blood in the ductus venosus is unoxygenated.
D The atrial septum is intact.
E The right side of the heart pumps against lower resistance than the left side.
Ref.: 1-3
Comments
The circulation in utero differs markedly from postnatal circulation. Gas exchange occurs in the placenta, which receives blood from the umbilical arteries. Oxygenated blood then returns through the ductus venosus, which joins the inferior vena cava at the level of the hepatic veins. This blood is mixed with the venous return from the superior vena cava in the right atrium. Blood in the right atrium may be shunted across the foramen ovale to the left atrium, where it goes to the left ventricle and is pumped into the circulation. Blood in the right atrium may also go to the right ventricle and be pumped into the pulmonary artery. Pulmonary vascular resistance is very high in utero, and much of the blood pumped into the pulmonary artery goes through the ductus arteriosus and into the descending aorta. Because the ductus arteriosus is large and communicates with the aorta, pressure in the pulmonary artery is the same as that in the aorta (systemic). After birth the umbilical cord is ligated, thereby decreasing ductus venosus return to zero and causing the ductus venosus to constrict and obliterate. Pulmonary vascular resistance drops with expansion of the lungs, which causes pulmonary blood flow to increase. Because return to the left atrium is increased, left atrial pressure causes the foramen ovale to close. Increased oxygen tension causes the ductus arteriosus to constrict and close. The pulmonary and systemic circulations at this point become separate.
Answer
A
2 Which of the following choices best characterizes right-to-left shunts?
A Obstructive lesions
B Decreased pulmonary blood flow
C Increased pulmonary blood flow
D Increased ventricular work
E No change in pulmonary blood flow
Ref.: 1-3
Comments
Congenital heart defects can be divided into four categories, each associated with distinct physiologic abnormalities. Obstructive lesions (e.g., aortic stenosis, coarctation of the aorta) restrict the flow of blood and increase the workload of the obstructed ventricle. Without an associated lesion, there is no shunting or mixing of blood between the pulmonary and systemic circulations. Left-to-right shunts occur in the setting of a communication between the pulmonary and systemic circulations at the levels of the atria (e.g., atrial septal defect [ASD]), ventricles (e.g., ventricular septal defect [VSD]), or great vessels (e.g., patent ductus arteriosus [PDA]). When there is no obstruction to pulmonary blood flow, these communications usually result in flow of blood across the defect from the systemic to the pulmonary circuit. The amount of pulmonary blood flow per minute may be as much as four or five times as great as the amount that flows in the systemic circulation. Clinically significant shunts occur when pulmonary blood flow is greater than 1.5 to 2 times systemic flow. Right-to-left shunts occur in the setting of a similar communication but when there is obstruction to pulmonary blood flow (e.g., tetralogy of Fallot, subaortic or doubly committed double-outlet right ventricle). Obstruction of pulmonary blood flow causes blood to flow from the right to left side without having passed through the lungs. If a sufficient amount of desaturated blood enters the systemic circuit without passing through the lungs, the patient becomes cyanotic. Complex lesions include defects such as transposition of the great arteries and hypoplastic left heart syndrome, in which the pathophysiologic features cannot be so easily described. A child with a complex lesion may suffer from cyanosis, pulmonary overcirculation, and obstructive lesions simultaneously.
Answer
B
3 With regard to increased pulmonary blood flow (left-to-right shunts), which of the following statements is true?
A A shunt becomes physiologically important when pulmonary blood flow is five times as great as systemic flow.
B High pulmonary artery pressures preclude surgical correction of the defect.
C Delivery of 100% oxygen to the patient during transesophageal echocardiography may provide crucial information for determining whether the patient is an operative candidate.
D The rapidity with which pulmonary vascular disease develops depends on the magnitude of the shunt regardless of the anatomic location of the defect.
E Increased fixed pulmonary vascular resistance precludes surgical correction of the defect.
Ref.: 1-3
Comments
Large left-to-right shunts have, by definition, an increased amount of pulmonary blood flow. Frequently, pulmonary artery pressure and left atrial pressure are elevated. The combination of these factors causes increased extravascular fluid in the pulmonary parenchyma and thus congestive heart failure. A shunt in which pulmonary blood flow is less than 1.5 times systemic flow is unlikely to produce symptoms and does not usually represent an indication for surgical repair. If a patient has a large communication at the level of the ventricles or the great vessels, pulmonary artery pressure is equal to systemic pressure because there is free communication between systemic pressure and the pulmonary artery. This does not necessarily imply that the patient has pulmonary vascular disease. High pulmonary artery pressure with a large pulmonary flow (Qp)–to–systemic flow (Qs) ratio (e.g., Qp/Qs = 3) implies low pulmonary vascular resistance, thus making the child an appropriate candidate for repair. If a child has high pulmonary artery pressure at cardiac catheterization and relatively low pulmonary blood flow (Qp/Qs < 2), pulmonary vascular resistance is high and the child may not tolerate surgical correction. One hundred percent oxygen is a potent pulmonary vasodilator. If during cardiac catheterization the shunt significantly increases with the administration of 100% oxygen or iNOS, it implies that the pulmonary vascular disease is reversible and the child may yet be a candidate for surgical correction. Because the development of pulmonary vascular disease depends on pressure, as well as flow, severe pulmonary vascular obstructive disease uncommonly develops in patients with large atrial-level shunts, whereas it usually does in patients with large ventricular- or arterial-level shunts.
Answer
E
4 Resolution of congestive heart failure without surgical correction in a patient who has had a large left-to-right shunt:
A Indicates increased pulmonary vascular resistance
B Is a sign of increased left-to-right shunting
C Is a sign of unchanged left-to-right shunting
D Indicates reversible pulmonary vascular resistance
E Is a harbinger for early death in the fourth decade of life
Ref.: 1-3
Comments
The natural history of a large left-to-right shunt (especially at the ventricular or atrial level) is progressive pulmonary vascular obstructive disease. There are considerable variations in the progression of pulmonary vascular disease. In a child with a large ventricular septal defect, pulmonary vascular disease usually develops at 2 to 4 years of age. A child with a large left-to-right shunt may have considerable congestive heart failure during the first year of life. However, as the pulmonary vascular obstructive disease progresses, the left-to-right shunt decreases as pulmonary vascular resistance approaches systemic vascular resistance. During this period, the child’s symptoms may improve, and chest radiographic findings of cardiomegaly and pulmonary plethora may also improve. However, this finding is grave because the pulmonary vascular disease is usually progressive at this point despite surgical correction or any other currently available therapies. Pulmonary vascular disease progresses until pulmonary vascular resistance exceeds systemic vascular resistance. Shunting ceases to be left to right and becomes right to left, thereby resulting in the patient becoming cyanotic. This condition is referred to as Eisenmenger syndrome. This process usually continues until it results in the patient’s death. Most patients who succumb from Eisenmenger syndrome die during their teens or twenties.
Answer
A
5 With regard to left obstructive congenital heart lesions, which of the following statements is true?
A The most common obstructive lesions are pulmonary valve stenosis, aortic valve stenosis, and coarctation of the aorta.
B Obstructive congenital heart lesions produce systolic pressure overloading and concentric hypertrophy.
C Concentric hypertrophy produces marked cardiac enlargement, which can be detected by physical examination and routine chest radiography.
D Myocardial oxygen demand will be unchanged if cardiac catheterization demonstrates normal-appearing coronary arteries (“clean coronaries”).
E A and B
Ref.: 1-3
Comments
The concentric hypertrophy of obstructive congenital heart lesions is not easily detected by chest radiography. Auscultation may give some indication of the severity of aortic or pulmonary stenosis. Coarctation of the aorta may be indicated by differences in the pulses and blood pressure between the arms and legs. The electrocardiogram (ECG) and echocardiogram with Doppler examination are additional noninvasive modalities useful for assessing chamber size, degree of obstruction, and function. Although often not necessary, cardiac catheterization is the definitive modality for assessing the gradient across obstructive lesions. Aortic stenosis causes increased myocardial oxygen demand while reducing supply, especially to the subendocardium. This may lead to myocardial ischemia with all its sequelae, including angina pectoris, arrhythmia, a predisposition to sudden death, and end-stage cardiac failure.
Answer
E
6 Lesions that produce large left-to-right shunts during the newborn period are:
A Multiple muscular VSDs: “Swiss cheese”
B Primum ASD
C Dextro-transposition of the great arteries
D Secundum ASD
E Tetralogy of Fallot
Ref.: 1-3
Comments
Large left-to-right shunting occurs because of a communication between the pulmonary and systemic circuits, combined with lower resistance in the pulmonary circuit. Blood is directed toward the lower resistance. The pulmonary vascular resistance of newborns is at systemic levels and then falls during the first few weeks of life. As pulmonary vascular resistance falls, the shunt becomes greater in magnitude, and signs and symptoms of left-to-right shunting appear.
Answer
A
7 With regard to right-to-left shunts, which of the following statements is true?
A Polycythemia may lead to venous thrombosis and, in patients with a long-standing right-to-left shunt, to systemic emboli.
B The degree of cyanosis depends on both oxygen saturation and hemoglobin concentration.
C Cardiac catheterization is mandatory to determine the degree of pulmonary stenosis and the suitability of the patient for surgery.
D A PO2 of 45 mm Hg is life-threatening and requires immediate surgical treatment if it cannot be increased.
E An oxygen saturation of 75% is life-threatening and requires immediate surgical treatment if it cannot be increased.
Ref.: 1-3
Comments
Cyanosis is present when the amount of desaturated hemoglobin present in the systemic circulation exceeds 5 g/dL. Thus, cyanosis is dependent on both oxygen saturation and hemoglobin level. A patient with severe hypoxia who also has a relatively low hemoglobin concentration may be minimally cyanotic. Conversely, patients with a similar oxygen saturation may appear profoundly cyanotic if they are polycythemic. Polycythemia is a physiologic response to cyanosis that can lead to a hematocrit of greater than 60%. A high hematocrit increases blood viscosity and predisposes individuals to venous thrombosis. Systemic emboli, particularly cerebral emboli, may be life-threatening. In particular, children with long-standing right-to-left shunts are at risk for cerebral abscesses. Most children who have right-to-left shunts can be well evaluated with echocardiography alone. Cardiac catheterization is reserved for those who require better delineation of small branch pulmonary arteries. Children tolerate saturations down to around 75%, which corresponds to a PO2 of 40 mm Hg. A child who chronically has a PO2 of around 45 mm Hg usually does well while waiting for an elective operation.
Answer
E
8 Which of the following best characterizes the tetralogy of Fallot?
A Egg-shaped heart
B Left atrial and ventricular enlargement
C Figure-of-eight abnormality of the pulmonary venous (“snowman”) drainage
D Boot-shaped heart (coeur en sabot)
E Right atrial and ventricular enlargement
Ref.: 1-3
Comments
The chest radiograph plays an important role in the evaluation of congenital heart disease. The right ventricular hypertrophy characteristic of the tetralogy of Fallot tends to produce a boot-shaped heart with an upturned apex. With transposition of the great arteries, the great arteries usually overlie each other, with a resultant narrow mediastinum. The heart looks like an egg on a string. Supracardiac total anomalous pulmonary venous return (TAPVR) has a large vertical vein and a large innominate vein, which results in a wide mediastinum and a figure-of-eight contour, or a “snowman.” ASDs cause right-sided enlargement because of the atrial-level shunt. VSDs cause left-sided heart enlargement (blood goes through the VSD to the pulmonary artery, left atrium, left ventricle, and then back through the VSD; hence, the left atrial and ventricular enlargement). Atrioventricular (AV) valve regurgitation also causes enlargement on its respective side (Ebstein anomaly of the tricuspid valve on the right and the mitral valve on the left) secondary to the volume overload.
Answer
D
9 With regard to the tetralogy of Fallot, which of the following statements is true?
A Cyanosis occurs because of the septal defect associated with the right ventricular hypertrophy.
B A right-to-left shunt occurs because of the septal defect associated with obstruction of the right ventricular outflow tract.
C Patients often become anemic.
D Patients learn to squat because it lowers their pulmonary artery pressure.
E The aorta is overriding, which exacerbates the right-to-left shunt.
Ref.: 1-3
Comments
The classic congenital abnormality producing a right-to-left shunt is the tetralogy of Fallot, a combination of a VSD, pulmonary stenosis, overriding of the aorta, and right ventricular hypertrophy. The amount of shunting across the VSD is related to the amount of pulmonary stenosis. In patients with little pulmonary stenosis, the shunting may be left to right, as with an uncomplicated VSD. Most patients with the tetralogy of Fallot have enough pulmonary stenosis that some of the desaturated blood in the right ventricle goes through the VSD to the systemic circulation. Because of the chronic cyanosis, polycythemia with hemoglobin values exceeding 20 mg/dL may develop. Patients will learn to squat if the problem remains uncorrected past a few years of age. Squatting increases systemic vascular resistance, thereby forcing more blood to go to the lungs. Squatting does nothing directly to the pulmonary vasculature.
Answer
B
10 Treatment strategies for repair of the tetralogy of Fallot during infancy are:
A Always a complete repair
B Staged approach with palliative surgery first followed by complete repair
C Selective use of palliative surgery in early cyanosis and when small pulmonary arteries are present
D Staged approach with balloon valvuloplasty first followed by complete repair
E All of the above
Ref.: 1-3
Comments
Repair of the tetralogy of Fallot involves closure of the VSD and relief of the right ventricular outflow tract obstruction. About 15 to 20 years ago, most patients with the tetralogy of Fallot underwent palliation with a Blalock-Taussig shunt followed by complete repair at 3 to 6 years of age. At that time, complete repair during infancy carried significant morbidity and mortality. Since then, improvements in surgical, anesthetic, and perfusion techniques have allowed single-stage correction during infancy for most patients with the tetralogy of Fallot. Elective repair is usually performed at approximately 6 months of age. Earlier repair may be done if a child is too cyanotic to wait until 6 months. A staged approach may still be performed. One such circumstance involves patients with very small pulmonary arteries. VSD closure may cause right ventricular pressure to become suprasystemic in an attempt to pump blood through the small pulmonary arteries. A staged approach may allow time for growth of the pulmonary artery and definitive repair at a later date.
Answer
C
11 Which of the following statements is true regarding systemic-to-pulmonary artery shunts?
A They join one of the great vessels with the pulmonary vein, either directly or by means of a prosthetic graft.
B They are used to decrease pulmonary blood flow in patients with the tetralogy of Fallot.
C Based on shunt size, a systemic-to-pulmonary shunt may widen the pulse pressure (after shunt construction), and an increase in diastolic runoff will promote coronary flow insufficiency.
D A successful shunt may make definitive surgery unnecessary.
E A shunt is commonly used in a cyanotic infant to delay definitive surgery until the patient is older.
Ref.: 1-3
Comments
Blalock-Taussig shunts are part of the broader classification of systemic-pulmonary artery shunts. Although other kinds of shunt connections were made in the past, most shunts today consist of Gore-Tex grafts between the aorta or one of the great vessels (e.g., innominate artery) and the pulmonary artery. Pulmonary blood flow may be increased to relieve severe hypoxia. A shunt may delay the need for definitive surgery in young patients with complex heart disease. Shunt physiology is inherently inefficient, because the blood going through the lungs via the shunt is already partly oxygenated. Thus, a shunt is never considered the final repair, except in complex cases in which definitive repair is not possible. Because there is runoff through the shunt into the low-resistance pulmonary circuit during diastole, systemic diastolic pressure tends to be low, thus making pulse pressures wide.
Answer
C
12 Which of the following auscultatory findings is associated with an ASD.
A “Innocent” systolic murmur
B A significantly increased second heart sound (S2)
C Diastolic murmurs
D Widely split and “fixed” S2
E Continuous murmur
Ref.: 1-3
Comments
Proper auscultation of the heart often leads to the correct diagnosis of a congenital cardiac abnormality. S2 is heard best at the left upper sternal border and should be evaluated in terms of its degree of splitting and relative intensity. The degree of splitting of S2 normally varies with respirations (increases with inspiration and decreases or becomes single with expiration). An abnormal S2 may be in the form of (1) wide splitting, (2) narrow splitting, (3) single S2, (4) abnormal increase or decrease in the pulmonary component of the second sound (P2), or (5) paradoxical splitting of S2. Systolic murmurs occur between S1 and S2 and may be (1) ejection (through stenotic semilunar valves or secondary to increased flow through normal semilunar valves) or (2) regurgitant (pansystolic or holosystolic). The latter are associated with a VSD, mitral regurgitation, or tricuspid regurgitation. Diastolic murmurs may occur because of an incompetent semilunar valve or increased flow through an AV valve. Diastolic murmurs are virtually always pathologic. Continuous murmurs begin during systole and continue through S2 into all or part of diastole. They are caused by an aortopulmonary or arteriovenous connection (e.g., PDA, arteriovenous fistula, or after a systemic-pulmonary shunt) or a flow disturbance in veins (e.g., venous hum) or arteries (e.g., coarctation or peripheral pulmonary artery stenosis).
Answer
D
13 With regard to echocardiography for the evaluation of congenital heart disease, which of the following statements is true?
A It is the most accurate method by which to delineate intracardiac anatomy.
B It may indicate the gradient across a valve.
C It may indicate whether right ventricular pressure is at or well below systemic pressure.
D It may precisely define pulmonary artery anatomy.
E A, B, and C
Ref.: 1-3
Comments
Echocardiography has become the dominant imaging modality for congenital heart disease. It is the most accurate method by which to delineate intracardiac anatomy, and nearly all diagnoses are determined by echocardiography. Doppler echocardiography measures velocities across valves and outflow tracts, and these velocities may be translated into gradients with the formula ΔP = 4V2 (V is velocity). The velocity of a small amount of tricuspid regurgitation may be translated into the right ventricular–right atrial (RV/RA) gradient and be a good estimate of right ventricular pressure. Pulmonary artery distortion may be difficult to assess by echocardiography, and better delineation is often needed by cardiac catheterization. Coronary arteries may be assessed with a good deal of accuracy, although the images obtained do not always yield definitive information.
Answer
E
14 With regard to pulmonic stenosis, which of the following statements is true?
A The most common morphologic feature is hypoplasia of the pulmonic valve annulus.
B The physiologic abnormality is obstruction of flow from the right ventricle with hypoplasia.
C The intervention of choice is surgical commissurotomy.
D The most common symptom is dyspnea at rest.
E Echocardiography best delineates the anatomy and severity of obstruction.
Ref.: 1-3
Comments
Pulmonic stenosis accounts for 10% of congenital abnormalities. It most commonly involves fusion of the cusps of the pulmonary valve, post-stenotic dilation of the main pulmonary artery, and concentric hypertrophy of the right ventricle. Less common morphologic conditions include hypoplasia of the pulmonary valve annulus, supravalvar stenosis, and subvalvular obstruction from hypertrophied muscle (infundibular stenosis). The condition is usually asymptomatic, but when symptoms are present, the most common is dyspnea on exertion. Echocardiography accurately delineates the nature and severity of the obstruction by visualizing the anatomy and measuring the velocity of the jet across the obstruction. The current treatment of choice is balloon valvotomy, which works in most patients who do not have hypoplasia of the valve annulus. Surgical therapy is reserved for patients with annular hypoplasia, infundibular obstruction, or failed balloon valvuloplasty.
Answer
E
15 With regard to coarctation of the aorta, which of the following statements is correct?
A The lesion involves narrowing of the descending aorta just distal to the left subclavian artery and is surgically correctable.
B Early left ventricular failure requiring surgical correction is common when coarctation is present in a neonate.
C Late recurrence of the coarctation does not occur provided that the appropriate repair technique is used.
D Arm hypertension, decreased or absent leg pulses, and a systolic murmur over the left hemithorax are the typical physical findings early in infancy.
E A and B
Ref.: 1-3
Comments
Coarctation of the aorta accounts for 10% to 15% of congenital heart defects and occurs twice as frequently in males. Associated anomalies include a bicuspid aortic valve, VSD, PDA, and mitral valve disorders. Coarctation of the aorta usually occurs distal to the left subclavian artery in association with the ligamentum arteriosum. When severe, coarctation is manifested in neonates as severe left ventricular failure, which requires immediate surgical correction. Patients who are initially seen later in childhood often do not have symptoms but exhibit severe arm hypertension. The presence of differential pulses or blood pressure between the arms and legs strongly suggests the diagnosis. Because collateral flow via the intercostal arteries is sufficient, ischemic symptoms in the lower part of the body are uncommon when the patient is initially seen after the neonatal period. Findings on physical examination and an ECG showing left ventricular hypertrophy establish the diagnosis. Echocardiography is the diagnostic method of choice. Coarctation is one of the classic causes of surgically correctable hypertension (others include pheochromocytoma, aldosterone-secreting tumor, and renal artery stenosis). Postoperative hypertension may continue to exist even after adequate surgical repair. Repair may be accomplished by several means, including predominantly resection with extended end-to-end anastomosis or, alternatively, a left subclavian flap. Both are associated with a small but definite percentage of late recoarctation. Patch aortoplasty is now seldom used because of a high rate of late pseudoaneurysm formation.
Answer
C
16 With regard to valvular aortic stenosis, which of the following statements is true?
A Aortic stenosis predisposes to sudden death only in children.
B Valve replacement is the treatment of choice.
C A gradient alone is not an indication for intervention, even without symptoms.
D Surgical or balloon valvotomy for aortic stenosis has a high likelihood of causing aortic regurgitation.
E A bicuspid aortic valve is virtually always stenotic.
Ref.: 1-3
Comments
Valvular aortic stenosis may develop from a bicuspid or tricuspid aortic valve. Newborns may be affected with critical aortic stenosis, or the stenosis may progress with time and be manifested at any time in the patient’s life. Newborns with critical aortic stenosis have severe cardiomegaly and heart failure. The symptoms and indications for surgery in older children are similar to those in adults. Symptoms of congestive heart failure, angina, and syncope may develop. A gradient of greater than 50 mm Hg on exertion or greater than 30 mm Hg at rest is thought to be a risk factor for sudden death. The presence of symptoms or an asymptomatic gradient higher than 50 mm Hg is thought to be an indication for intervention. Unlike the situation in adults, aortic stenosis in children does not usually involve calcified leaflets. Therefore, valvuloplasty (surgical or balloon) is an option. Valvuloplasty has produced good results in terms of relieving stenosis as long as the annulus is adequate, but a high rate of postvalvuloplasty aortic regurgitation (20%) is encountered, which often results in valve replacement at a future date. Both balloon valvuloplasty and surgical valvuloplasty are associated with a 50% reintervention rate at 5 years. An increasingly common valve replacement option is a pulmonary autograft (Ross procedure). In addition to not requiring anticoagulation, a pulmonary autograft has growth potential. A bicuspid valve constitutes a common underlying morphologic condition for aortic valve stenosis. However, most people who have a bicuspid aortic valve do not suffer from clinically significant aortic stenosis.
Answer
D
17 Which of the following statements is true regarding subaortic stenosis?
A It is usually caused by diffuse narrowing of the subaortic area.
B A turbulent bloodstream may hit the aortic valve and cause inflammation and valvar aortic stenosis.
C The indications for surgery are the same as those for valvular aortic stenosis.
D Subvalvular aortic stenosis is amenable to balloon valvuloplasty.
E The area of resection of subaortic stenosis is adjacent to the conduction tissue.
Ref.: 1-3
Comments
Subaortic stenosis can occur as a discrete membrane or as a diffuse tunnel-like narrowing, but it is more commonly discrete. Surgery involves removal of the membrane with or without septal myotomy to further widen the outflow tract. Because valve replacement is rarely necessary and the jet from the subaortic stenosis may precipitate aortic regurgitation, the threshold for surgical treatment of subaortic stenosis is far less than for valvar aortic stenosis. Because the membrane requires resection in patients with subaortic stenosis, transcatheter interventions have little role. Despite the fact that the membrane directly overlies the conduction tissue, careful resection of a subaortic membrane rarely leads to heart block.
Answer
D
18 Which of the following statements is not true regarding aortic regurgitation?
A Discrete subaortic stenosis or VSD may be responsible for producing aortic regurgitation.
B The symptoms are those of congestive heart failure.
C Echocardiography accurately estimates the degree of regurgitation and chamber size.
D Because effective cardiac output is reduced, the pulses are weak and the pulse pressure is narrowed.
E Surgery is indicated when symptoms develop.
Ref.: 1-3
Comments
Aortic regurgitation causes volume overload on the left ventricle, which eventually results in left ventricular dilation and failure. Stroke volume is increased because of the regurgitant fraction, and bounding pulses and wide pulse pressure result. The symptoms are those of congestive heart failure. Angina may occur as a late finding. Syncope is not generally associated with aortic regurgitation, as it is with aortic stenosis. Echocardiography facilitates accurate diagnosis of aortic regurgitation and monitoring of the patient’s condition. Indications for surgery include an onset of symptoms or increased left ventricular dimensions even before symptoms occur. Aortic regurgitation may occur as the primary valve pathology, be secondary to valvuloplasty for aortic stenosis, or develop after damage to a normal aortic valve caused by discrete subaortic stenosis or a VSD. The possibility of creating aortic insufficiency is one of the indications for repair of subaortic stenosis and VSDs.
Answer
D
19 With regard to ASDs, which of the following statements is true?
A The magnitude of the shunt is determined by the difference in compliance between the ventricles.
B The left ventricle frequently becomes pressure-overloaded.
C Increased pulmonary vascular resistance may develop in approximately 40% of patients.
D An ASD should be surgically corrected before the patient is 1 year of age to avoid pulmonary hypertension.
E Surgical closure with cardiopulmonary bypass (CPB) is the only option for closure.
Ref.: 1-3
Comments
Atrial septal defects may produce large left-to-right shunts without high pulmonary artery pressure. The magnitude of the shunt is determined by the difference in compliance between the two ventricles. The shunt occurs during diastole, when blood goes from the atria to the ventricles. Because of the defect, the atria have equal pressure, so the filling pressure for the two ventricles is similar. The amount of blood that goes to each side depends on the amount that each ventricle distends given that filling pressure. Because the right ventricle is more compliant, blood from the left atrium has a tendency to cross the defect and enter the right ventricle, thereby creating the left-to-right shunt. Pulmonary artery pressure may be normal or nearly normal because there is no communication between the two sides during systole. Congestive heart failure eventually develops in about 25% of individuals with ASDs, usually during the third to fourth decade of life if the ASD is left untreated. Pulmonary vascular obstructive disease occurs in about 10% if the ASD is left untreated. Because symptoms rarely occur during the first decade of life, repair is entirely elective. Repair is usually done when the child is at a preschool age (3 to 4 years), a time when the child is large enough for easy closure but has few psychological effects from undergoing the surgery. During the current era, many defects are now closed with transcatheter devices by interventional cardiologists. The majority of atrial septal defects are now closed percutaneously. The published literature shows a success rate of 90% to 95% for percutaneous closure and greater than 98% for surgical closure.
Answer
A
20 Which of the following statements is true regarding TAPVR?
A TAPVR is categorized as supracardiac, cardiac, infracardiac, or mixed.
B The pathologic condition occurs when the pulmonary veins fail to empty into the right atrium and, instead, connect directly to the left atrium.
C The connection between the pulmonary veins and the systemic veins may be obstructed with equal frequency, regardless of whether the connection is supracardiac, cardiac, or infracardiac.
D When a patient has obstructed TAPVR, there is reduced pulmonary blood flow, which leaves the lungs relatively dark on a chest radiograph.
E A VSD must be present for survival.
Ref.: 1-3
Comments
During embryologic development, the four pulmonary veins form a confluence that merges with the back of the left atrium. Total anomalous pulmonary venous return is an anomaly in which this connection fails to occur. The pulmonary venous flow then goes through an anomalous vessel that most commonly connects to the innominate vein (supracardiac), the coronary sinus (cardiac), or the portal vein (infracardiac). Supracardiac TAPVR occurs in approximately 50% of cases, cardiac TAPVR in 25%, and infracardiac TAPVR in 20%, with 5% of cases being mixed. Because both systemic and pulmonary venous return goes to the right side of the heart, an ASD must be present to allow blood to go into the left side of the heart and the systemic circulation. The blood returning to the atrium distributes itself between the right and left ventricles according to their relative compliance, as with any large ASD. Because the right ventricle has greater compliance than the left ventricle, there is more pulmonary flow than systemic flow. This is equivalent to a large left-to-right shunt. A serious complication of TAPVR occurs when the connection between the pulmonary venous confluence and the systemic veins is obstructed. With infracardiac TAPVR, obstruction is the rule because pulmonary venous return must go through the hepatic capillary bed. With supracardiac TAPVR, obstruction occurs in only a few patients, and with cardiac TAPVR, obstruction is rare. When obstruction occurs, pulmonary venous pressure is high, which causes severe pulmonary edema.
Answer
A
21 Which of the following statements is true for ASDs?
A Secundum ASDs rarely cause symptoms during infancy.
B Secundum ASDs rarely cause residual problems after closure.
C Secundum ASDs are part of the spectrum of AV canal defects.
D Left ventricular outflow tract obstruction typically develops with secundum ASDs.
E Secundum ASDs are typically associated with left axis deviation.
Ref.: 1-3
Comments
Secundum ASDs and primum atrial septal defects have in common left-to-right shunting at the atrial level but are different malformations. Because of their similar atrial-level shunting, they rarely cause symptoms during infancy and generally require elective repair at 1 to 4 years of age. Secundum ASDs seldom cause any residual problems after closure. However, primum ASDs are truly part of the spectrum of AV canal defects (endocardial cushion defects). Therefore, the AV valves are abnormal, and frequently the left AV valve (mitral valve) becomes insufficient with time. Long-term insufficiency requiring valve repair or replacement is a well-known complication. Left ventricular outflow tract obstruction may also develop in patients with primum ASDs. Patients with primum ASDs have left axis deviation on their ECGs, which also distinguishes them from secundum ASDs. Children with Down syndrome have a high incidence of endocardial cushion defects, although secundum ASDs and typical VSDs may be found as well.
Answer
B
22 With regard to VSDs, which of the following statements is true?
A Multiple muscular VSDs (“Swiss cheese”) with a large left-to-right shunt may become symptomatic within 1 year of age.
B Defects less than 2 cm in diameter are generally well tolerated.
C Irreversible pulmonary vascular obstructive disease is relatively common before 1 year of age.
D Banding of the pulmonary artery is the operation of choice in infants younger than 2 years.
E Subaortic VSDs will close spontaneously.
Ref.: 1-3
Comments
Ventricular septal defects account for 20% to 30% of congenital heart defects. Associated anomalies are common (e.g., PDA, coarctation, ASD, aortic insufficiency). Defects smaller than 4 to 5 mm in diameter are associated with pulmonary blood flow less than two times systemic flow, with few adverse physiologic consequences. Larger defects can produce cardiac failure, pulmonary hypertension, and death. VSDs are usually asymptomatic during the newborn period. Pulmonary vascular resistance is high, which keeps the left-to-right shunting and pulmonary overcirculation minimized. At 1 to 2 months of age, pulmonary vascular resistance decreases and allows a large left-to-right shunt, which produces symptoms of congestive heart failure. In symptomatic infants with large lesions, surgical correction is indicated. If such infants are left untreated, the increased pulmonary vascular resistance may become irreversible by the age of 2 years. It is rare for irreversible pulmonary vascular resistance to occur before 1 year of age. Up to 40% of VSDs close spontaneously by 2 years of age. Pulmonary artery banding, once widely used in infants with significant VSDs, is now rarely used with the increasing success of definitive closure in younger patients. It may be reserved for patients with multiple muscular VSDs (“Swiss cheese”), a large left-to-right shunt, and early symptomatology within 1 year of age. Repair of a VSD was traditionally performed via ventriculotomy. Advances in operative technique now allow most defects to be closed through the right atrium, with retraction of the tricuspid valve. This procedure avoids disruption of the ventricular wall and potential coronary artery damage. Some defects, particularly muscular defects, may still require ventriculotomy.
Answer
A
23 Eisenmenger syndrome represents:
A A classic conduction defect resulting from inappropriate repair of a VSD
B A condition that can occur with VSD, PDA, AV canal defects, transposition of the great arteries, and truncus arteriosus and rarely in association with a large ASD
C A condition in which the increased pulmonary vascular resistance from the left-to-right shunt eventually exceeds systemic vascular resistance and causes reversal to a right-to-left shunt and cyanosis
D B and C
E A and B
Ref.: 1-3
Comments
Eisenmenger syndrome is the end stage that results from a large left-to-right shunt with fixed pulmonary hypertension secondary to irreversible pulmonary vascular resistance. It can occur with VSD, PDA, AV canal defects, transposition of the great arteries, and truncus arteriosus and rarely in association with a large ASD. The increased pulmonary vascular resistance from the left-to-right shunt eventually exceeds systemic vascular resistance and causes reversal to a right-to-left shunt and cyanosis.
Answer
D
24 With regard to PDA, which of the following statements is true?
A It produces a right-to-left shunt at the level of the great arteries.
B Irreversible, increased pulmonary vascular disease generally occurs only in association with another defect.
C Because of low cardiac output, children with PDA tend to have narrow pulse pressure.
D Indomethacin can be used to close PDAs in term infants but not in premature babies.
E The presence of cyanosis is a contraindication to closure.
Ref.: 1-3
Comments
Patent ductus arteriosus is an abnormal communication between the descending aorta and the pulmonary artery. The ductus arteriosus ordinarily closes after birth in response to rising oxygen tension and numerous other hormonal factors. PDA in premature babies usually involves a structurally normal ductus that fails to close because of the low oxygen tension and surrounding mediators (e.g., increased prostaglandins) that maintain patency of the ductus. By changing the hormonal environment with indomethacin (which blocks prostaglandin production), a PDA in a premature infant may be closed. In a term baby, a PDA is caused by a structurally abnormal ductal wall. Indomethacin therefore has little effect on term infants. If a PDA is large, there is a large left-to-right shunt, with the pulmonary artery being exposed to systemic pressure. These children experience the same course of congestive heart failure followed by increased pulmonary vascular resistance as do children with a large VSD. Like children with a large VSD, Eisenmenger syndrome may develop in children with a large PDA. Cyanosis from Eisenmenger syndrome is a contraindication to closure of a PDA. Because of runoff from the aorta into the low-resistance pulmonary artery during diastole, diastolic pressure in children with a PDA tends to be low, with large pulse pressure.
Answer
E
25 Prostaglandins may be indicated to maintain ductal patency in which of the following lesions?
A Pulmonary atresia with an intact ventricular septum
B VSD
C Interrupted aortic arch
D A and C
E All of the above
Ref.: 1-3
Comments
Prostaglandins (prostacyclin [PGE1]) are useful for maintaining ductal patency in newborns. The indications may be for either right- or left-sided obstructive lesions. If a patient has a right-sided obstructive lesion (e.g., pulmonary atresia), pulmonary blood flow may be duct dependent. Prostaglandins may be used to keep the ductus patent until a surgically created systemic-pulmonary artery shunt or definitive repair can be accomplished. With left-sided lesions, such as an interrupted aortic arch, blood flow to parts of the systemic circulation may be duct dependent; that is, before repair can be undertaken, the ductus is the only means by which part of the systemic circulation can receive blood flow. Closure of the ductus is lethal in the setting of a severe left-sided obstruction, such as an interrupted aortic arch. In this situation, blood through the ductus flows from the pulmonary artery to the aorta.
Answer
D
26 Which of the following statements is true regarding complete AV canal defects?
A They are associated with cystic fibrosis.
B There is one AV orifice with clearly defined mitral and tricuspid valves.
C Because most of the shunting occurs at the ventricular level, the natural history of the disease is similar to that of a VSD.
D The decompression through the atrial part of the defect protects against pulmonary vascular disease.
E Recurrent ventricular-level shunting is the most common long-term complication of repair.
Ref.: 1-3
Comments
Common atrioventricular canal defects involve abnormal development of the endocardial cushion. The atrial septum, ventricular septum, and AV valves should join at a central point but fail to do so. The patient is usually left with a large defect in the inferior atrial septum and inlet ventricular septum. Instead of the usual mitral and tricuspid valves, there is one large AV valve that separates both atria from both ventricles. Most patients with complete AV canal defects also have Down syndrome. The pathophysiology is that of a large left-to-right shunt, as with a VSD. Pulmonary vascular disease develops somewhat faster with an AV canal than with a VSD, partly because the shunt is both atrial and ventricular and partly because children with Down syndrome have a tendency for the development of early vascular disease. Significant postoperative AV valve regurgitation, usually of the left-sided AV (mitral) valve, may develop. The incidence of reoperation for left-sided AV valve regurgitation is approximately 10% to 15% at 10 years.
Answer
C
27 Which of the following statements regarding extracorporeal membrane oxygenation (ECMO) is true?
A The survival rate is less than 50% when used for neonatal respiratory support.
B Survival is equal in adults and children.
C Survival with cardiac ECMO is greater than that with respiratory ECMO.
D The overall survival rate is 40%.
E The lowest survival rate occurs in neonates with meconium aspiration syndrome.
Ref.: 1-3
Comments
Extracorporeal membrane oxygenation can be used in infants, children, or adults for acute cardiac or respiratory support. Common indications in the pediatric population include meconium aspiration, congenital diaphragmatic hernia, sepsis, and primary pulmonary hypertension, as well as after repair of intracardiac defects. The survival rate in neonates is higher with respiratory than with cardiac causes (77% versus 38%). Adults have much lower survival rates than children. Overall, the survival rate when extracorporeal life support is used is approximately 40%. The highest survival rate is for meconium aspiration syndrome (94%).
Answer
D
28 With regard to transposition of the great vessels, which of the following statements is not true?
A The aorta arises from the right ventricle and carries unoxygenated blood to the body.
B The pulmonary artery arises from the left ventricle and carries unoxygenated blood to the lungs.
C PDA, VSD, or ASD is necessary for survival (before definitive correction).
D Pulmonary stenosis occurs in approximately 10% of patients.
E VSD occurs in approximately 25% of patients.
Ref.: 1-3
Comments
Transposition of the great arteries is a common form of complex cyanotic heart disease. The aorta arises from the right ventricle and carries unoxygenated blood to the body. The pulmonary artery arises from the left ventricle and carries oxygenated blood to the lungs. For any oxygen to be delivered to the body, there must be mixing between the systemic and pulmonary circuits. This mixing is necessary for survival. The common points of mixing are an ASD, a VSD, and a PDA. If the patient has an intact ventricular septum and a small ASD, it may be necessary to use a large balloon-tipped catheter to enlarge the atrial septum to stabilize the child preoperatively. Transposition of the great arteries has many associated defects, the most common being VSDs and pulmonary stenosis (i.e., left ventricular outflow tract obstruction). Other associations include interrupted aortic arches, coarctation of the aorta, and hypoplastic ventricles. The associated lesions may greatly affect prognosis and treatment. The usual surgical treatment of transposition of the great arteries is the arterial switch operation. This operation involves transecting the great vessels just above the semilunar valves and “switching” their positions such that the aorta would come off the left ventricle and the pulmonary artery off the right ventricle. The difficulty of the arterial switch operation involves switching the coronary arteries.
Answer
B
29 Which of the following statements is true of vascular rings?
A They may cause decreased perfusion to the lower extremities.
B The most common associated anomaly is a Kommerell diverticulum.
C A vascular ring may be manifested as recurrent respiratory infections.
D Repair of a vascular ring requires a bypass graft.
E Dysphagia is the most common sign of a vascular ring.
Ref.: 1-3
Comments
A vascular ring is an encirclement of the trachea and esophagus by an abnormal formation of the arch and great vessels. The most common form is a double aortic arch. During early development all fetuses have two aortic arches: a right (posterior) arch and a left (anterior) arch. These arches encircle the forming trachea and esophagus. Ordinarily, the right arch regresses. If both arches persist, the trachea and esophagus become encircled. A double aortic arch may be asymptomatic, but it often causes symptoms related to compression. The trachea is more often affected, and there may be recurrent respiratory infections. Esophageal compression may be present with or without tracheal symptoms. Although they may occur at any age, symptoms usually develop during infancy or early childhood. Repair consists of dividing the smaller of the two arches, as determined by ultrasound imaging, by magnetic resonance imaging, or at the time of surgery. Repair is generally performed through a left thoracotomy and does not involve CPB. A bypass graft is not necessary for repair. There are other vascular rings in addition to the double aortic arch, and their clinical manifestations, natural history, and principles of repair are similar. A pulmonary artery sling is a vascular congenital anomaly in which the left pulmonary artery originates from the right pulmonary artery and courses posterior to the trachea. Patients are seen in infancy with stridor or recurrent pulmonary infections. One third to one half of patients have associated tracheal stenosis or complete rings, thus giving rise to the term ring-sling complex.
Answer
B, C
30 Which of the following statements regarding pulmonary artery banding is definitely not true?
A May result in pulmonary artery distortion
B May result in pulmonary valve damage
C May result in the development of outflow tract narrowing by muscle band hypertrophy
D Results in volume loading of the ventricle
E May not result in adequate protection of the pulmonary vascular bed
Ref.: 1-3
Comments
Pulmonary artery banding remains a useful palliative maneuver in selected patients with increased pulmonary blood flow. It may result in pulmonary artery distortion, pulmonary damage, or outflow tract narrowing via muscle band hypertrophy. It always results in pressure loading of the ventricle. A loose pulmonary artery band may not adequately protect the pulmonary vascular bed. However, some patients may “grow into” a loose pulmonary artery band.
Answer
D
References
1 Baue AE, Geha AS, Hammond GL, et al, editors. Glenn’s thoracic and cardiovascular surgery. Stamford, Conn.: Appleton & Lange, 1996.
2 Kirklin JW, Barratt-Boyes BG, editors. Cardiac surgery. New York: Churchill Livingstone, 1993.
3 Sellke FW, del Nido PJ, Swanson SJ, editors. Sabiston and Spencer: surgery of the chest, ed 8, Philadelphia: WB Saunders, 2010.
B Acquired Diseases
R. Anthony Perez-Tamayo, M.D., Ph.D., Edward B. Savage, M.D., Eric J. Okum, M.D., Robert S.D. Higgins, M.D., M.S.H.A.
1 A 60-year-old man is successfully resuscitated after an episode of sudden cardiac death. Appropriate evaluation and treatment may include all of the following except:
A Cardiac catheterization and coronary angiography
B If significant coronary stenosis or a left ventricular aneurysm is identified, surgical intervention directed at these targets to achieve satisfactory control of the arrhythmia
C Automatic implantable cardioverter-defibrillator (AICD) in patients whose ventricular tachycardia cannot be mapped or medically/surgically controlled
D Electrophysiologic studies (EPSs) to determine the mechanism, origin, inducibility, and suppressibility of the arrhythmia
E EPS-directed resection
Ref.: 1-3
Comments
Sudden cardiac death is a major cause of morbidity and mortality in the United States. Most cases are thought to be of arrhythmogenic origin. The number of survivors is increasing as a result of the rising number of laypeople trained in cardiopulmonary resuscitation, as well as improved prehospital and emergency medical care. Survivors, however, have a 60% chance of recurrence resulting in sudden death during the first 2 years after hospitalization. When evaluating these patients, one must include the following: EPSs to determine the mechanism of the arrhythmia (automatic versus reentrant), to identify the origin of the arrhythmia, and to identify the inducibility and assess the suppressibility of induced arrhythmias by various pharmacologic agents. Cardiac catheterization and coronary angiography should be performed to identify significant coronary stenosis and the presence of a ventricular aneurysm, which may be the arrhythmogenic focus. However, coronary revascularization alone fails to control the arrhythmia, and blind aneurysmectomy (non–EPS directed) often fails because the endocardial origin of the arrhythmia may be distant from the border of the aneurysm. EPS-directed endocardial resection plus encircling endocardial ventriculotomy with or without adjunctive cryoablation has success rates in the range of 90%.
For inpatients whose arrhythmia cannot be mapped or controlled medically and surgically, an AICD is a last alternative. An AICD is a device that senses ventricular tachycardia/fibrillation through an epicardial or endocardial lead and delivers a defibrillating pulse, originally between two epicardial patches. Currently, the most common form delivers the pulse through a transvenous coil in the right ventricle. An AICD terminates more than 98% of episodes of ventricular fibrillation or ventricular tachycardia and provides the greatest benefit for patients with reduced left ventricular systolic function. A coronary arteriogram should precede the implantation or testing procedure, which has a mortality rate of about 0.5%.
Answer
B
2 Which of the following is the maximum amount of time that extracorporeal circulation can be tolerated before significant risk for physiologic injury and metabolic defects occurs?
A 2 to 4 hours
B 6 to 8 hours
C 10 to 12 hours
D 14 to 16 hours
E 18 to 20 hours
Ref.: 1, 2
Comments
Tolerance of extracorporeal circulation (CPB) is variable. Six to 8 hours is an acceptable range, although physiologic injury may occur earlier. Occasionally, patients undergo longer perfusion with relatively few consequences. With proper myocardial preservation, the heart can be arrested safely for up to 4 hours. Physiologic defects observed with extracorporeal circulation include progressive sludging of blood elements in the capillary microcirculation, red blood cell hemolysis, coagulation defects, denaturation of plasma proteins, fibrinolysis, and activation of inflammatory cascades. The primary culprit within the CPB circuit for these derangements is the oxygenator and its vast surface area for blood–foreign body exposure. Extracorporeal membrane oxygenation circuits are increasingly being used in adult patients for circulatory and respiratory support and can be used for weeks at a time. There are several distinctions between CPB and ECMO. Blood–foreign body exposure is limited by shortening the length of the circuit tubing and minimizing priming volume in ECMO. ECMO is used for partial support, and therefore some measure of the circulating volume remains in the patient’s native cardiopulmonary system. Advances in technology have produced hollow-fiber oxygenators with a tight and very biocompatible gas-blood interface. This tight interface prevents leakage of plasma, thereby extending the durability of the oxygenator, and keeps the formation of gaseous microbubbles in blood to a minimum, thereby preventing hemolysis and organ damage from gaseous emboli.
Answer
B
3 All of the following are complications of prolonged extracorporeal circulation except:
A Postoperative bleeding
B Pancreatitis
C Hypertension
D Psychosis
E Hepatic insufficiency
Ref.: 1, 2
Comments
The physiologic and metabolic injuries resulting from prolonged extracorporeal circulation are exhibited in several ways. Postoperative bleeding may occur as a result of dilution of clotting factors, destruction of platelets, impairment of platelet function, and improper titration of protamine to reverse systemic heparinization. The coagulation defect may be transient and usually resolves within the first 12 hours following perfusion. The importance of meticulous surgical hemostasis is apparent. Renal and respiratory insufficiency is usually transient and often requires only supportive treatment. Hepatic injury can occur with prolonged support, partly from low cardiac output but potentially from derangements in splanchnic and portal flow. A variety of central nervous system changes may occur. These changes have both metabolic and organic causes and may be manifested as localized or generalized deficits of variable severity and duration. With prolonged nonpulsatile CPB and hypothermia, some patients have elevated serum amylase levels, which fortunately is less frequently associated with the signs and symptoms of pancreatitis.
Answer
C
4 After aortic valve replacement for calcific aortic stenosis, a patient experiences seizures. All of the following are the most likely causes except:
A Air embolism
B Calcium emboli
C Emboli from a left atrial thrombus
D Emboli from aortic atherosclerosis
E Extracorporeal circulation
Ref.: 1, 2
Comments
Seizures may occur as a manifestation of focal injury to the central nervous system. Air embolism is a result of incomplete evacuation of air from the cardiac chambers following open heart surgery. Evacuation may be facilitated by the use of a left ventricle vent, an aortic vent, or both. The vents are left in place until after the heart is beating. During this time, CPB is gradually reduced, the patient is rotated, and the heart is manipulated to assist in removing air from within the cardiac chambers. Calcium fragments may embolize after the removal of calcific debris from a diseased aortic valve. Cannulation or clamping of a diseased aorta may result in dislodgement of arteriosclerotic debris. Left atrial thrombi are another potential source of cerebral emboli, although these usually occur in patients with mitral stenosis. The usual neurologic deficit observed following prolonged extracorporeal circulation is a transient generalized depression of cerebral function related to sludging of blood elements in the cerebral capillaries, which results in focal areas of stasis and hypoperfusion of the microcirculation.
Answer
E
5 Indications for coronary artery bypass graft (CABG) surgery include all of the following except:
A Severe triple-vessel occlusive disease
B Stenosis of the left main coronary artery
C Persistent angina and changes on the ECG following percutaneous coronary stenting
D Acute myocardial infarction
E Development of complications during percutaneous transluminal coronary angioplasty (PTCA)
Ref.: 1, 4
Comments
Surgical revascularization provides relief of angina in more than 90% of patients and improves survival in select groups. Patients are referred to as having single-, double-, or triple-vessel disease if significant stenoses are present in one, two, or all three of the major coronary arteries. Numerous studies have concluded that patients with significant triple-vessel disease, especially impaired left ventricular function, are best treated with surgery. Left main artery disease is also a well-accepted indication. Most surgeons and cardiologists agree that double-vessel disease is not always an indication for surgery unless the left anterior descending artery has a severe (>50%) proximal stenosis. Acute myocardial infarction is not an unequivocal indication for surgery. In less than 1% of patients undergoing PTCA do complications requiring surgery develop. Most authorities consider congestive heart failure with pulmonary hypertension (in the absence of mechanical defects such as left ventricular aneurysm, mitral regurgitation, or VSD) the only cardiac contraindication to bypass grafting. Improvements in anesthetic and surgical techniques and methods of myocardial protection have reduced the mortality rate associated with elective coronary artery bypass to approximately 2%. The risk is somewhat higher in certain groups of patients, but even in higher-risk categories, in situations of emergency coronary artery bypass surgery or during revision of failed surgery, the risk rarely exceeds 3% to 5%.
Answer
D
6 With regard to the surgical treatment of atrial fibrillation with the maze procedure, which of the following is true?
A More than 90% of cases of paroxysmal atrial fibrillation arise from an ectopic focus in the sinoatrial node.
B The need for mitral valve repair represents a contraindication.
C The maze procedure results in a greater than 90% long-term cure rate of atrial fibrillation without antiarrhythmic medications.
D The majority of patients will require permanent pacemaker implantation within 1 year of the procedure.
E Pulmonary artery ablation alone will reduce the incidence of atrial fibrillation by 50%.
Ref.: 2
Comments
The Cox maze procedure is designed to cure atrial fibrillation by creating a series of lesions in the left and right atria that insulate against conduction and propagation of fibrillatory impulses. The lesions, created in the earliest forms of the procedure by incision and anastomosis and currently using different forms of ablative energy, subdivide the atria into a maze of channels, with no channel large enough to allow the formation of macro-reentrant loops. The set of lesions isolating the pulmonary veins is especially important in patients with paroxysmal atrial fibrillation, which originates from ectopic foci in these structures in 95% of cases. The maze procedure can be performed alone or in combination with various other cardiac surgery procedures and is ideally applied in patients with pathologic conditions of the mitral valve, because these disease states are often complicated by atrial fibrillation and exposure of the left atrium is already necessary. The greater than 90% long-term cure rate for atrial fibrillation without antiarrhythmic medication resulting from the maze procedure will often unmask a dysfunctional AV node that requires permanent pacemaker implantation in 20% of patients.
Answer
C
7 After a documented acute myocardial infarction, surgery is indicated in all but which of the following situations?
A Postinfarction angina with anatomic lesions not amenable to PTCA
B VSDs
C Acute mitral regurgitation
D Free wall rupture
E Atrial tachyarrhythmia
Ref.: 2, 4
Comments
Postinfarction angina occurs in 10% to 15% of patients, with the incidence increasing to 30% if a thrombolytic agent was used. It generally indicates residual myocardial tissue at risk for subsequent cell death and extension of the infarct. In this setting, cardiac angiography is indicated, with PTCA or surgery performed, depending on the anatomy. Ventricular septal defects occur in about 2% of patients following myocardial infarction, generally 3 to 5 days later. Advocates of delayed repair point to better intraoperative demarcation of necrotic and living tissue and a lower incidence of recurrent VSD because of suture line dehiscence. Nevertheless, early surgical intervention is indicated because natural history studies indicate a 25% mortality rate in the untreated at 24 hours and 80% at 4 weeks, respectively. Acute mitral regurgitation resulting from papillary muscle infarction and rupture occurs in less than 2% of patients. Surgery results in a better survival rate than does medical therapy. Ventricular free wall ruptureoccurs 3 to 6 days following transmural myocardial infarction. Although the incidence is not precisely known, medical therapy almost certainly leads to death, thus leaving surgical repair as the only therapeutic option. Postinfarct ventricular tachyarrhythmias can drive a decision for early revascularization, following the dictum that the best antiarrhythmic is oxygenated blood.
Answer
E
8 Refractory angina develops in a 70-year-old woman in the coronary care unit 2 days after being hospitalized for acute myocardial infarction. With regard to coronary artery bypass in this situation, which of the following statements is true?
A It should be performed only if left main coronary disease is present.
B Operative mortality and long-term survival rates are poor in comparison with those in patients who have unstable angina not precipitated by myocardial infarction.
C It should be preceded by thrombolytic therapy if multivessel disease is also present.
D The operative mortality rate is less than 5%.
E The preoperative work-up should include dobutamine stress echocardiography to assess viability.
Ref.: 1, 2, 4
Comments
Unstable angina is preceded by myocardial infarction in approximately 50% of patients. The initial treatment of patients with unstable angina involves intensive medical therapy with β-blockers, nitrates, and calcium channel blockers. Patients with refractory angina should undergo emergency PTCA with stenting or CABG surgery. PTCA with stenting may be tried for one- and two-vessel disease, but significant left main artery disease should be approached surgically. Most trials have demonstrated reduced in-hospital and 1-year mortality rates when thrombolytic therapy has been effective in reestablishing flow to ischemic tissue within 4 hours. PTCA with stenting has been used alone and in conjunction with thrombolytic therapy and is associated with a 90% successful reperfusion rate, 10% in-house mortality rate, and 10% to 30% reocclusion rate within 6 months. These modalities have been less effective for multivessel disease and in older patients, those in cardiogenic shock, women, and those with poor left ventricular function. CABG surgery is associated with a 4% mortality rate in patients with unstable angina, with approximately 80% of patients surviving 10 years and 80% experiencing long-term relief of angina. The observation of angina during a hospitalization has no bearing on the benefits of the use of CPB during myocardial revascularization. Persistence of the angina is a strong enough suggestion that viable tissue is at risk and the stress of dobutamine echocardiography would not be justified.
Answer
D
9 Angina develops in a patient 5 years after CABG surgery. Angiography most likely reveals which of the following?
A Vein graft thrombosis
B Progressive atherosclerosis in the vein graft
C Progressive atherosclerosis in the coronary arteries
D A dominant right coronary system
E Occlusion of the left internal mammary arterial graft
Ref.: 1, 2, 4
Comments
The rate of recurrence of angina following CABG surgery is approximately 5% to 7% per year. Surgery, unfortunately, does not slow the progression of atherosclerosis, which is the primary cause of recurrent symptoms. Graft occlusion may also occur as a result of thrombosis, intimal fibrosis, or fibrous endarteritis. Vein grafts may also be involved with atherosclerosis, which usually occurs later during the postoperative course. Overall, the rate of vein graft patency is approximately 70% to 80% after 5 years. Internal mammary artery grafts have significantly higher long-term patency and improved event-free survival rates in comparison with vein grafts.
Answer
C
10 Indications for surgical resection of a left ventricular aneurysm include all of the following except:
A Angina
B Congestive heart failure
C Systemic arterial emboli
D Presence of paradoxical motion with systole
E Ventricular tachyarrhythmias refractory to drug therapy
Ref.: 2, 4
Comments
See Question 11.
Answer
D
11 With regard to surgical treatment of ventricular aneurysm, which of the following statements is true?
A Preservation of the left anterior descending artery is mandatory.
B All aneurysms should be excised because of the progressive nature of this lesion and the poor prognosis if it is untreated.
C Complete aneurysmectomy is preferred.
D Concomitant coronary bypass is generally performed.
E Repair must be undertaken before a probable rupture.
Ref.: 1, 2, 5
Comments
Most ventricular aneurysms result from transmural infarction. They frequently involve the anterior left ventricle in the distribution of the left anterior descending artery. The most common complication is congestive heart failure, followed by arrhythmias and angina. Peripheral emboli may occur but are infrequent. Death from rupture of a ventricular aneurysm is an unusual event. Ventricular aneurysms may also be totally asymptomatic, in which case observation rather than resection is usually indicated. Preservation of the left anterior descending artery is preferred, if possible, to provide blood flow to the septum, but preservation is not mandatory. Small aneurysms are generally asymptomatic and can be observed. During surgical resection, total scar removal is not generally performed, but rather, a rim of scar tissue is left by the surgeon to facilitate closure of the defect. Because of the high incidence of concomitant multivessel coronary occlusive disease, approximately 75% of patients considered for aneurysm resection also undergo coronary bypass. The indications for surgical ventricular restoration (SVR) in patients with coronary artery disease and left ventricular aneurysms are a subject of controversy as a result of the Surgical Treatments for Ischemic Heart Failure (STICH) trial, reported in 2009. This prospective randomized controlled trial did not demonstrate any difference in mortality or re-admission for heart failure in patients who underwent bypass grafting and SVR versus bypass grafting alone a median of 48 months after surgery. Critics of this trial believe that determination of aneurysm size and left ventricular volume did not identify patients most likely to benefit from SVR and that the 19% reduction in end-systolic volume index reported for patients in the SVR plus CABG group falls short of the 30% reduction that they believe is necessary for clinical improvement after this type of surgery. Subgroup analysis and comparison of medical and surgical therapies are still pending from this trial. Actual rupture of a true ventricular aneurysm is rare.
Answer
D
12 Treatment of acute pyogenic pericarditis may require which of the following?
A Parenteral antibiotics active against Streptococcus and Mycobacterium
B Initial pericardial aspiration followed by pericardial stripping if there is a recurrence
C Subxiphoid pericardiotomy
D Radical pericardiectomy
E Anterior (phrenic-to-phrenic) pericardiectomy
Ref.: 1, 5
Comments
Pyogenic pericarditis is rare. Today, it is usually seen in infants or young children, in whom it is associated with a high mortality rate. Staphylococcus and gram-negative species are the most common organisms in adults, whereas Staphylococcus and Haemophilus influenzae predominate in infants and children. Parenteral administration of antibiotics combined with serial pericardial aspiration and occasional intrapericardial instillation of antibiotics is usually adequate treatment. Surgical drainage may be necessary, but radical pericardiectomy is not indicated.
Answer
C
13 With regard to chronic constrictive pericarditis, which of the following statements is true?
A It is usually caused by a previous streptococcal infection.
B It is characterized by equalization of right- and left-sided pressure.
C It is best treated with a combination of diuretics and β-blocking agents.
D Pericardiectomy is successful in 50% of patients.
E The “RSR sign” on pulmonary artery catheterization during systole is pathognomonic.
Ref.: 1, 2, 5
Comments
Chronic constrictive pericarditis often occurs secondary to a viral infection, although in most cases the true cause is unknown. Tuberculosis was once thought to be the most frequent cause. The disease is marked by progressive edema, ascites, hepatic enlargement, and dyspnea on exertion. Hemodynamic findings include elevation of right ventricular end-diastolic, right atrial, and central venous pressure to levels equal to those of pulmonary artery wedge and left ventricular end-diastolic pressure. Pericardiectomy is the treatment of choice and is successful in 90% of cases if adequate resection is performed. The “square root sign” is the appearance of the right ventricular waveform during cardiac catheterization in the presence of constrictive pericarditis. It is attributed to rapid filling of the ventricle in early diastole. Initially, filling pressure is normal but becomes substantially increased because of the constrictive pathophysiology. The relatively sudden rise in filling pressure appears as a dip and plateau, or the “square root sign,” on the ventricular pressure tracing.
Answer
B
14 Following open heart surgery, a patient experiences chest pain, fever, tachycardia, and a pericardial friction rub. Which of the following statements is true?
A The most likely diagnosis is postoperative mediastinitis.
B Primary treatment should include surgical exploration.
C The patient most likely responds well to antibiotics.
D There is usually an associated leukocytosis or lymphocytosis.
E This syndrome is generally accompanied by pleural effusion and shortness of breath.
Ref.: 1, 5
Comments
Following procedures in which the pericardium is entered, transient pericardial inflammation, known as the postpericardiotomy syndrome or Dressler syndrome, may occur. Clinical manifestations include fever, pericarditis, pleuritis, and sometimes a pericardial friction rub. The syndrome usually appears 2 to 4 weeks postoperatively, and the erythrocyte sedimentation rate is elevated. There is also leukocytosis with an increase in lymphocytic cells. Patients generally respond well to a short course of an anti-inflammatory agent, although sometimes a corticosteroid is required.
Answer
D
15 Three hours after aortic valve replacement, a patient suddenly becomes hypotensive. The cardiac index has decreased from 2.5 to 1.6 L/min. Central venous pressure is 19 mm Hg with a pulmonary artery wedge pressure of 20 mm Hg. Mediastinal drainage over the last hour has been minimal. Immediate treatment should include which of the following?
A Echocardiogram to assess prosthetic valve function
B Volume resuscitation to increase cardiac output
C Afterload reduction with nitroprusside
D Preload reduction with nitroglycerin
E Mediastinal exploration
Ref.: 1, 2, 4
Comments
Hypotension and low cardiac output following open heart surgery necessitate prompt, careful evaluation. Specific causes include inadequate blood volume, occult bleeding, cardiac tamponade, arrhythmias, myocardial insufficiency, and acidosis. The finding of elevated filling pressure with equalization of right- and left-sided pressures suggests the diagnosis of cardiac tamponade, in which case immediate reoperation is mandatory. Substantial elevation of filling pressure in association with low cardiac output may also be indicative of cardiac failure, which may be treated with inotropic agents, digitalis, and intra-aortic balloon counterpulsation. Chest radiography is of variable diagnostic value but occasionally allows detection of occult accumulation of blood in a pleural space.
Answer
E
16 Aortic stenosis in an adult may result from all of the following except:
A Ehlers-Danlos syndrome
B Marfan syndrome
C Rheumatic fever
D Syphilis
E Bacterial endocarditis
Ref.: 1, 5
Comments
Aortic stenosis in an adult may result from rheumatic fever or from a congenital valve deformity. A congenital bicuspid valve may remain asymptomatic for many years, but the deformed valve is susceptible to endocarditis, and calcification and symptomatic stenosis eventually develop. Aortic insufficiency commonly follows bacterial endocarditis. Aortic insufficiency may also result from dilation of the aortic annulus because of an ascending aortic aneurysm, as seen with Marfan syndrome, Ehlers-Danlos syndrome, or more rarely, syphilis.
Answer
C
17 Clinical manifestations of severe aortic valve stenosis include all of the following except:
A Syncope
B Holosystolic murmur
C Angina pectoris
D Dyspnea on exertion
E Atrial fibrillation
Ref.: 1, 5
Comments
Characteristically, patients with aortic stenosis remain asymptomatic for many years but deteriorate rapidly once symptoms begin. Angina pectoris develops in about two thirds of patients. Left ventricular hypertrophy, increased left ventricular diastolic volume, and prolongation of the isometric contraction phase and systolic ejection time are compensatory mechanisms to allow a longer period of ventricular emptying. However, the duration of diastolic coronary perfusion to the hypertrophied ventricle is decreased, which gives rise to angina pectoris, even in the absence of primary coronary artery disease. Syncope, present in one third of patients, also reflects impaired cardiac output. Signs of left ventricular failure and atrial fibrillation resulting in elevated left atrial pressure are evidence of more advanced disease. A crescendo-decrescendo murmur that radiates to the neck and is accompanied by a thrill is typical of severe aortic stenosis.
Answer
B
18 Indications for surgery in patients with aortic stenosis include all of the following except:
A All symptomatic patients
B Systolic pressure gradient greater than 50 mm Hg in asymptomatic patients
C Associated pericardial effusion
D Valvular cross-sectional area smaller than 1 cm2
E Serial radiographic evidence of rapid cardiac enlargement
Ref.: 1, 5
Comments
Once symptoms develop in patients with aortic stenosis, the prognosis is poor. With angina or syncope, the average life expectancy of untreated patients is 2 to 3 years. Death occurs 1 to 2 years after left ventricular failure. Sudden death occurs more frequently with aortic stenosis than with any other valvular lesion. It accounts for approximately 20% of deaths from aortic stenosis and is always a risk, but it occurs more frequently in symptomatic patients. The loudness of the classic systolic diamond-shaped ejection murmur heard over the aortic area and the apex does not have prognostic significance. All symptomatic patients require prompt valve replacement because of the high risk for sudden death and deterioration. Peak systolic gradients across the valve of greater than 50 mm Hg and cross-sectional areas of 0.8 to 1.0 cm2 are generally found with moderate to severe aortic stenosis and are indications for valve replacement, even if symptoms are absent. Serial radiographic evidence of rapid cardiac enlargement is an ominous sign in patients with aortic stenosis and is an urgent indication for surgery. Severe stenosis (based on the cross-sectional area) but a low transvalvular gradient may result from compromised ventricular function, which increases the risk associated with valve replacement. The 5-year survival rate following aortic valve replacement is approximately 80%.
Answer
C
19 With regard to the selection of prosthetic heart valves, all of the following statements are true except:
A Free aortic homograft valves have a lower incidence of infective endocarditis than do porcine valves.
B Bioprosthetic valves should be avoided in patients with chronic renal failure.
C Mechanical valves should be avoided in children.
D Current bioprosthetic valves now have durability equivalent to that of mechanical valves.
E Reconstructed mitral valves have limited durability and offer no advantage over valve replacement.
Ref.: 1, 2, 4, 5
Comments
The ideal prosthetic heart valve has yet to be developed. Selection is based on the patient’s characteristics, the operative findings, and the surgeon’s preference. Bioprosthetic valves (glutaraldehyde-fixed porcine heterografts or bovine pericardium) have a low rate of associated thromboembolism, and therefore these patients do not require long-term anticoagulation. The problem with bioprosthetic valves, however, is long-term durability. Although the latest-generation valves are more durable, the reoperation rate at 10 years is less than 5% in patients older than 65. These valves are contraindicated in children and in patients younger than 20 to 30 years because structural deterioration begins to develop at 8 to 10 years. In the past, they were not recommended for renal failure patients because of calcification, but recent series show no survival advantage over mechanical valves in this population.
Mechanical heart valves are more durable, but their usefulness is limited by the need for permanent anticoagulation, which is contraindicated in certain clinical states (e.g., pregnancy, coagulopathy, ulcer disease). Thromboembolic complications occur at an annual rate of 1% to 2%, even in patients with adequate anticoagulation. Patients with mechanical valves require permanent anticoagulation therapy, which carries a risk for major hemorrhage of approximately 1% per year. The risk for prosthetic valve endocarditis is about 1% to 2% per year for both bioprosthetic and mechanical valves. Because of the low recurrence rate of endocarditis, free aortic homograft valves are advantageous in the setting of active endocarditis. Even with small valves, there is virtually no gradient across the homograft valve and a markedly decreased incidence of valve cusp calcification in young patients.
Mitral valve reconstruction is preferable to replacement whenever possible because of the freedom from prosthetic valve complications. Chronic anticoagulant therapy is not needed, and endocarditis is rare. Durability has been satisfactory, with approximately 90% of patients remaining free of the need for late valve replacement at 5 years after surgery.
Answer
D
20 Cardiac catheterization of a 50-year-old man with a recent history of dyspnea on exertion, hemoptysis, and paroxysmal nocturnal dyspnea demonstrates a left atrial pressure of 28 mm Hg. One of the primary determinants of this pressure includes which of the following?
A Pulmonary artery pressure
B Cross-sectional area of the mitral opening
C Temperature of the blood
D Plasma viscosity
E Mean systemic arterial pressure
Ref.: 1, 2
Comments
The primary physiologic consequences of mitral stenosis are increased left atrial pressure, decreased cardiac output, and increased pulmonary vascular resistance. The clinical manifestations of these changes include the typical symptoms of congestive heart failure, pulmonary edema, and right-sided heart failure, as well as atrial fibrillation and arterial embolism. Left atrial pressure is determined by the size of the mitral orifice, cardiac output, and heart rate. The severity of disease is best classified by calculating the cross-sectional area of the valve, which takes into consideration both the pressure gradient and cardiac output. A mitral valve area of approximately 1 cm2 or less is indicative of significant stenosis, although low flow rates and the presence of mitral regurgitation may influence calculations. When left atrial pressure exceeds plasma oncotic pressure (24 to 30 mm Hg), pulmonary edema develops.
Answer
B
21 Indications for valve replacement in patients with significant mitral stenosis include all of the following except:
A Congestive heart failure
B Pulmonary hypertension
C Atrial fibrillation
D Asymptomatic status
E Systemic embolization
Ref.: 1
Comments
See Question 22.
Answer
D
22 With regard to the results of surgical treatment of symptomatic mitral stenosis, which of the following statements is false?
A The survival rate is higher than that after medical therapy.
B Commissurotomy decreases the risk for systemic embolization and endocarditis.
C Pulmonary vascular resistance usually diminishes following valve replacement or commissurotomy.
D The 10-year survival rate exceeds 90%.
E Recurrent valvular dysfunction is best treated by mitral valve repair.
Ref.: 1
Comments
The natural history of mitral stenosis is one of progressive manifestation of symptoms. Treatment of mitral stenosis is a judicious combination of medical and surgical therapies. Most asymptomatic patients are treated medically and observed. Symptomatic patients who receive only medical treatment eventually die of their cardiac disease. Indications for operative intervention include congestive heart failure (with New York Heart Association class III or IV symptoms), onset of atrial fibrillation with significant mitral stenosis, pulmonary hypertension, systemic embolization, and infective endocarditis. Surgical therapy is also recommended for patients who have mild symptoms and a severe reduction in valvular area. In this situation, mitral commissurotomy can be performed if leaflet flexibility and the subvalvular apparatus are preserved. This operation produces physiologic and clinical improvements, but these benefits tend to deteriorate. Recurrent valvular dysfunction that necessitates treatment is almost always best treated by valve replacement.
Answer
E
23 Which of the following is the most common cause of mitral insufficiency in Western countries?
A Bacterial endocarditis
B Degenerative mitral valve disease
C Marfan syndrome
D Silent myocardial infarction
E Rupture of the chordae tendineae
Ref.: 1, 2, 5
Comments
See Question 24.
Answer
B
24 With regard to patients with mitral regurgitation versus those with mitral stenosis, which of the following statements is true?
A Left ventricular failure is more common.
B Atrial fibrillation rarely develops.
C Systemic emboli are frequent.
D The postoperative prognosis is better with replacement than with repair.
E Pulmonary hypertension usually fails to resolve following valve replacement.
Ref.: 1, 4
Comments
Degenerative mitral valve disease (e.g., Barlow disease) is the most common cause of mitral regurgitation. Worldwide, rheumatic heart disease is a major cause, and it produces both stenosis and regurgitation. Although mitral stenosis almost exclusively results from rheumatic fever, mitral regurgitation may have other causes, including mitral valve prolapse, idiopathic calcification, bacterial endocarditis, chordae rupture, and ischemic heart disease. A cause other than rheumatic fever is often suspected on the basis of the history and clinical findings. The physical signs of pulmonary hypertension and right heart failure produced by mitral regurgitation are similar to those seen with mitral stenosis. Unlike patients with mitral stenosis, however, moderate to severe mitral regurgitation can be tolerated for many years with minor symptoms until left ventricular failure ultimately develops as a result of chronic overload. Atrial fibrillation is a common manifestation of mitral regurgitation. Embolization does occur, but it is less common than with mitral stenosis. The natural history of mitral regurgitation and the results of operative correction are somewhat more variable than those of mitral stenosis because of the different etiologic factors that may produce mitral incompetence. Clinical severity depends on the degree of regurgitation, the status of left ventricular function, and the course of valve disease.
In patients with infective endocarditis, trauma, or chordae rupture, emergency surgery is required and can be lifesaving. The long-term prognosis with surgery is poor in patients with ischemic mitral regurgitation and poor ventricular function and in elderly patients with severe associated conditions. Pulmonary hypertension usually resolves after successful valve repair or replacement. Repair is associated with better survival rates than replacement. Some measure of this advantage may be attributed to preservation of the subvalvular apparatus and its relationship to the ventricular walls.
Answer
A
25 A 75-year-old man with a history of dyspnea on exertion, palpitations, and episodes of severe diaphoresis has a high-pitched diastolic murmur along the left sternal border and a blood pressure of 140/60 mm Hg. Expected findings include which of the following?
A Systolic ejection murmur
B Enlargement of the left ventricle on chest radiographs
C Atrial fibrillation
D History of syphilis
E Weak peripheral pulses
Ref.: 1
Comments
Common symptoms of aortic insufficiency include angina, progressive dyspnea, palpitations, and peripheral vasomotor changes. Signs of pulmonary congestion occur later as left ventricular failure develops. Findings on physical examination include a normal cardiac rhythm and bounding peripheral pulses because of the widened pulse pressure. The classic diastolic murmur is present and is accentuated when the patient leans forward. A systolic ejection murmur may also be heard but usually represents aortic stenosis. Enlargement of the left ventricle is seen on chest radiographs or echocardiography and represents the ventricular response to the mixed pressure and volume overload of aortic insufficiency.
Answer
B
26 Indications for operative intervention to correct aortic insufficiency include which of the following?
A The finding of aortic insufficiency alone, which warrants correction even in asymptomatic patients
B Loudness and length of the diastolic murmur
C Left ventricular end-diastolic volume of 40 mL/m2
D Magnitude of the regurgitation
E Age of the patient
Ref.: 1, 4
Comments
Patients with aortic insufficiency generally remain asymptomatic for many years, although there is substantial variability. Progressive symptoms of heart failure or ischemia and increasing left ventricular size on chest radiography or echocardiography are considered indications for surgery. The loudness of the diastolic murmur is not correlated with the severity of the disease. The length of the murmur to some extent reflects the patient’s physiologic status in that a longer murmur indicates a greater degree of regurgitation. Short murmurs may be heard, however, in patients with early disease and minimal regurgitation and in those with end-stage disease and elevated left ventricular end-diastolic pressure. A left ventricular end-diastolic volume of 55 mL/m2 is generally accepted as an indication for aortic valve surgery. Severe (“wide-open”) aortic insufficiency is poorly tolerated and indicates the need for replacement.
Answer
D
27 All of the following statements commonly apply to tricuspid valvular disease except:
A Replacement carries a significant risk for heart block.
B Intravenous drug abuse is a common cause of tricuspid valvular endocarditis.
C Total valve excision is well tolerated because of the passive nature of the right atrium.
D Permanent epicardial pacing leads may be necessary with mechanical valves.
E The lower-pressure right-sided valve lends itself well to repair.
Ref.: 1, 5
Comments
The location of the AV node along the base of the septal leaflet (triangle of Koch) exposes this structure to injury. Because transvenous pacing leads are not practical with a mechanical valve replacement, epicardial leads are often left in place in anticipation of treatment of complete heart block. Isolated organic disease of the tricuspid valve is most commonly seen as a result of endocarditis secondary to intravenous drug abuse. Total valve excision without replacement has occasionally been an alternative in this difficult situation but is not well tolerated long term. The lower pressures of the right ventricle and right atrium and the size of the tricuspid annulus allow the opportunity for a variety of repair techniques, including bicuspidization, wherein one third of the circumference of the valve can be sewn shut.
Answer
C
28 A 30-year-old man arrives at the emergency department following a high-impact automobile accident. The initial chest radiograph demonstrates a widened mediastinum. Which of the following statements is true?
A Despite normal blood pressure, the patient should be explored to drain the hemopericardium before impending tamponade occurs.
B The finding of normally palpable femoral pulses makes aortic rupture unlikely, and the patient should be managed medically with β-blocking agents.
C Aortography is the “gold standard” diagnostic evaluation.
D The most common site of aortic disruption is the proximal arch, which should be approached through a left thoracotomy.
E Surgical repair of traumatic aortic rupture carries a 15% to 20% incidence of paraplegia, but it is the only effective therapy.
Ref.: 1, 4
Comments
Traumatic rupture of the aorta requires urgent diagnosis and therapy. Most patients with this lesion do not reach the hospital alive. The history of a sudden deceleration injury along with chest radiographic findings of a widened mediastinum and loss of the aortic knob contour is strongly suggestive of the diagnosis. Aortography demonstrates the site of injury. Ninety-five percent of traumatic disruptions occur in the proximal descending aorta, just distal to the left subclavian artery, and are best approached through a left thoracotomy. Open surgical repair is the traditional treatment option and is associated with paraplegia in approximately 5% of patients. In the past, simple cross-clamping during repair was often used, but techniques that provide distal perfusion during clamping, such as left atriofemoral bypass, femorofemoral partial bypass, and the Gott shunt, have become the standards of care. Endovascular approaches using stent grafts to exclude the transection are being used with increasing frequency, particularly in patients with complex multisystem trauma, who might not tolerate the anticoagulation necessary during CPB. These grafts can be deployed with or without exclusion of the left subclavian artery as required by the pathology, with subsequent bypass of this vessel performed if needed. Although stent grafts appear to be safe and effective for this application, the long-term results are still being studied.
Answer
C
29 Which cardiac chamber is most frequently injured by penetrating trauma?
A Left ventricle
B Right ventricle
C Left atrium
D Right atrium
E Equivalent incidence in all four chambers
Ref.: 1, 2
Comments
The right ventricle is the most anterior chamber of the heart and consequently is the area most susceptible to penetrating injury. Cardiac injury may produce exsanguination, cardiac tamponade, and rarely, cardiac failure secondary to damage to a major coronary artery, a valve, or the conduction system. The key to saving patients who arrive at the emergency department with cardiac injury is prompt recognition and treatment of tamponade while other resuscitative measures are instituted. Pericardiocentesis can be lifesaving as well as diagnostic while the operating room is being made ready. Most penetrating injuries can be treated without the need to resort to pump support. Nonpenetrating cardiac trauma usually produces diffuse contusion, which warrants cardiac monitoring.
Answer
B
30 Which of the following is the most common primary cardiac neoplasm?
A Myxoma
B Rhabdomyoma
C Sarcoma
D Lymphoma
E Metastatic sarcoma
Ref.: 1, 2
Comments
The most common cardiac neoplasms are metastatic. Primary cardiac tumors are rare, with an incidence of 0.33% noted on postmortem studies. Most primary cardiac neoplasms are benign, and of them, myxoma is the most common, followed by rhabdomyoma. Approximately 20% of primary tumors are malignant. They are almost always rhabdomyosarcomas and angiosarcomas, and they generally have systemic metastases at the time of diagnosis. The clinical manifestations of cardiac tumors are the result of local invasion, mass effect, embolization, or systemic constitutional signs such as fever, malaise, weight loss, and autoimmune phenomena, particularly associated with atrial myxomas. Echocardiography is the initial diagnostic technique of choice, followed by computed tomography, magnetic resonance imaging, and transesophageal echocardiography. Myxomas constitute 50% of benign primary cardiac tumors. They are most frequently found in women and are usually located in the left atrium.
Answer
A
31 The physiologic effects of the intra-aortic balloon pump (IABP) include which of the following?
A Decreased cardiac afterload
B Decreased coronary blood flow
C Increased left ventricular end-diastolic pressure
D Decreased cerebral perfusion
E Increased left ventricular preload
Ref.: 1, 2
Comments
An electronically synchronized intra-aortic balloon pump that inflates during diastole and deflates at the onset of systole has physiologic effects that both decrease myocardial oxygen consumption and increase coronary blood flow. The IABP decreases systolic blood pressure, decreases time during systole, and improves emptying of the heart (decreased radius). Deflation of the IABP reduces impedance to aortic flow, thereby reducing afterload and improving cardiac output. Left ventricular end-diastolic volume and pressure are reduced, and diastolic coronary blood flow is enhanced, particularly in failing hearts. Pulmonary artery diastolic pressure is decreased, thereby reducing left ventricular preload.
Answer
A
32 Which of the following statements describes the clinical effects of the IABP?
A Use of an IABP in patients with myocardial infarction and cardiogenic shock decreases infarct size.
B Most patients using an IABP for cardiogenic shock after myocardial infarction can be weaned from this device.
C An IABP effectively relieves pain in patients with unstable angina.
D An IABP is not indicated for support of cardiac failure following CBP because of the availability of ventricular assist devices.
E An IABP is indicated in patients with severe aortic insufficiency to decrease peripheral resistance.
Ref.: 1
Comments
Indications for use of the intra-aortic balloon pump include the following: cardiac failure after CPB, refractory unstable angina, preoperative treatment of septal defects, mitral regurgitation, arrhythmias, ventricular aneurysms, and occasionally, cardiogenic shock. The IABP is used to treat cardiogenic shock associated with myocardial infarction, but only 15% to 20% of patients can be weaned successfully from this device, and there is no conclusive evidence that an IABP decreases infarct size. The IABP is particularly effective in controlling pain in patients with angina refractory to pharmacologic manipulation. The device has also been successful in the support of patients with cardiac failure following CPB. Most such patients can be weaned successfully, with excellent long-term survival. Severe aortic insufficiency is a contraindication to use of the IABP because regurgitation and cardiac failure are exacerbated with its use.
Answer
C
33 Which of the following is not an indication for placement of a permanent cardiac pacemaker?
A Sick sinus syndrome
B Complete AV block
C Mobitz type I AV block
D Mobitz type II AV block
E Stokes-Adams attacks
Ref.: 1, 3
Comments
There is some disagreement regarding the indications for temporary or permanent cardiac pacing. Most agree that the indications for permanent pacing include the following: severe or symptomatic sick sinus syndrome, Mobitz type II AV block (because it frequently leads to complete AV block), complete AV block, symptomatic bilateral bundle branch block, and bifascicular or incomplete trifascicular block with an intermittent complete AV block following myocardial infarction. Stokes-Adams attacks, which consist of intermittent syncopal episodes and sometimes convulsions, are manifestations of complete heart block. Mobitz type I AV block (Wenckebach block) rarely necessitates pacing.
Answer
C
34 Open cardiac massage may be indicated in patients with which of the following?
A Blunt thoracic trauma
B Penetrating thoracic trauma
C Barrel chest
D Spinal deformities
E Postoperative CABG patient with cardiac arrest
Ref.: 1
Comments
External cardiac massage transmits pressure and flow energy to the cardiovascular system by direct cardiac compression. The stroke work is generated through forceful displacement of the chest wall, which compresses the ventricles, closes the mitral valve, opens the aortic valve, and produces unidirectional pressure and flow. Intrathoracic pressure, once considered a more plausible explanation for the beneficial effect of closed cardiac massage, accounts for less than 25% of cavitary cardiac pressure. Stroke volume is optimized by compressions of high velocity, moderate force, and brief duration. Coronary artery flow occurs during diastole and is optimized at a compression rate of 100 to 120/min. Open methods are used when arrest occurs after cardiac surgery and in cases of thoracic injury when cardiac tamponade, massive intrathoracic hemorrhage, penetrating cardiac injury, or an open pericardium is suspected. It may be necessary in patients with a barrel chest, emphysema, or spinal deformities because closed chest resuscitation is sometimes unsuccessful in such settings. Most patients with cardiac arrest in the field following blunt thoracic trauma cannot be successfully resuscitated even by open cardiac massage. Those who survive the initial episode may have a dismal outcome.
Answer
A
35 With regard to blood conservation during cardiac surgery, which of the following statements is true?
A Transfusion of blood components during or after cardiac surgery is largely unavoidable.
B The risks associated with transfusions are primarily related to red blood cells, not plasma.
C Cardiotomy suction can reclaim blood while not increasing the incidence of microembolization.
D Antifibrinolytics, such as ε-aminocaproic acid, can reduce bleeding.
E Aprotinin has both antifibrinolytic and renal-protective effects.
Ref.: 5
Comments
Strict blood conservation should be practiced by meticulous hemostasis during surgery and the use of blood reclamation systems such as the Cell Saver suction. During routine procedures, transfusions can usually be avoided. The risks associated with the transfusion of blood components such as platelets and plasma are similar to those associated with the transfusion of red blood cells. Cardiotomy suction returns blood shed from the mediastinum to the CPB circuit but in so doing draws up lipid globules and pericardial debris that can escape the filters. ε-Aminocaproic acid (Amicar) and tranexamic acid (Cyklokapron) are antifibrinolytic agents that have been shown to reduce postoperative blood loss. Aprotinin (Trasylol) is also an effective antifibrinolytic, but large retrospective series suggested an increased incidence of renal dysfunction and mortality, and the drug was withdrawn from use in 2008.
Answer
D
36 Which of the following statements regarding adult cardiac transplantation is true?
A Despite improved immunosuppression, the 5-year survival rate following cardiac transplantation is approximately 50%.
B The number of cardiac transplants performed annually in the United States is limited by the number of donors rather than by the number of suitable recipients.
C Patients with ventricular assist devices who survive to transplantation have significantly greater 1-year mortality rates than do those who receive transplants primarily.
D Coronary occlusive disease, otherwise known as “graft vasculopathy,” is relatively rare and has the same pathophysiology and morphology as atherosclerosis.
E With improved medical therapy available, the number of patients awaiting a heart transplant has remained relatively constant.
Ref.: 1, 2, 4
Comments
Results following cardiac transplantation have continued to improve, largely because of improved immunosuppression. Currently, the 1-year survival rate is approximately 80%, and the 5-year survival rate is 65% to 70%. The number of transplants performed annually is limited almost solely by the number of available donors. The development of coronary occlusive disease in the transplanted heart, or “graft vasculopathy,” remains a major determinant of long-term survival. Many researchers believe that it is a manifestation of a low-intensity, chronic form of rejection. The number of cardiac transplants performed annually has remained relatively constant, whereas the number of patients waiting continues to increase. Although patients requiring ventricular assist devices as a bridge to transplantation are clearly sicker, those who survive to transplantation have comparable post-transplant survival rates at 1 year.
Answer
B
References
1 Sellke FW, del Nido PJ, Swanson SJ, editors. Sabiston and Spencer: surgery of the chest, ed 8, Philadelphia: WB Saunders, 2010.
2 Cohn LH, Edmunds LH, editors. Cardiac surgery in the adult, ed 3, New York: McGraw-Hill, 2009.
3 American Heart Association, American College of Cardiology, North American Society of Pacing and Electrophysiology. 2002 Guidelines. J Am Coll Cardiol. 2008;51:1-62.
4 Yang SC, Cameron DE, editors. Current therapy in thoracic and cardiovascular surgery. Philadelphia: CV Mosby, 2004.
5 Kaiser LF, Kron IL, Spray TL, editors. Mastery of cardiothoracic surgery, ed 2, Philadelphia: Lippincott-Raven, 2007.