Block 13: Cardiology Board Review: q & A

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Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease, with an incidence of approximately 0.2 in 1,000 live births and accounting for 9% of all congenital heart disease. The four components of TOF are right ventricular outflow/pulmonary stenosis, ventricular septal defect (VSD), overriding aorta, and right ventricular hypertrophy.
The primary lesion is underdevelopment of the pulmonary infundibulum, which has led some to refer to this disease as "monology of Fallot" because all aspects of the tetrad result from this lesion. The result of underdevelopment of the pulmonary infundibulum is deviation of the infundibular septum anteriorly and superiorly, bringing it into the right ventricular outflow tract. This leads to obstructed right ventricular outflow and the commonly seen underdevelopment of the pulmonary valve and pulmonary arteries caused by diminished blood flow through these structures. The underdeveloped pulmonary infundibulum also creates a VSD, which is almost universally large and of the malalignment type. The defect resulting from anterior malalignment of the infundibulum allows the aorta to "override" the ventricular septum. Finally, right ventricular hypertrophy results from exposure to systemic pressures (large VSD and pulmonary stenosis).
Most patients who have TOF do not present with cyanosis in the newborn period, but rather come to medical attention because of a harsh systolic murmur. The murmur results from infundibular stenosis and pulmonary stenosis, not from the VSD. The second heart sound is single.
Because the degree of pulmonary blood flow obstruction can vary among patients, the degree of systemic oxygen desaturation ranges from mild to severe. Children who have mild obstruction may appear "pink," and those who have severe pulmonary stenosis have significantly reduced pulmonary blood flow and an increase in right-to-left shunting across the VSD into the aorta, leading to more pronounced cyanosis. Furthermore, as pulmonary blood flow decreases with tight pulmonary stenosis, pulmonary venous return to the left atrium decreases, resulting in less highly saturated blood leaving the left ventricle and entering the aorta. Conversely, mild pulmonary stenosis is associated with more pulmonary blood flow, less right-to-left intracardiac shunting, and less systemic desaturation. In the mildest cases, there is left-to-right shunting across the VSD and near-normal or normal systemic saturation.
A decreased or absent murmur signifies diminished pulmonary blood flow, as occurs in the cyanotic spell or tetralogy spell. Such spells are marked by distress, crying, inconsolability, hyperpnea, and increasing cyanosis, as described for the infant in the vignette. They frequently occur in the morning or at times of dehydration (eg, fever, gastroenteritis). If not treated quickly, cyanotic spells can lead to serious morbidity and even death.
Treatment of cyanotic spells centers on increasing pulmonary blood flow, which is accomplished by several means. The first step is to alter the ratio of relative resistance of pulmonary and systemic beds. Increasing the systemic vascular resistance relative to the pulmonary vascular resistance decreases the right-to-left shunt at the VSD and can be accomplished by placing the patient in a knee-to-chest position or by squatting in older children. Pharmacologic augmentation of the systemic vascular resistance can be achieved with intravenous phenylephrine. Therapy also includes the use of sedation with morphine, which suppresses the sensation of suffocation and can relieve the patient’s fear. The use of high-flow oxygen, which dilates pulmonary vasculature, constricts systemic vasculature and increases Po2 of pulmonary venous return, and generous intravascular fluid administration to increase preload are important therapies for the patient experiencing a tetralogy spell.
Clubbing of the digits can be seen in cyanotic heart disease as well as a variety of other entities, but it is not typical in patients younger than 1 year of age and its presence is not associated with a tetralogy spell. Hepatomegaly is uncommon in the infant who has TOF; its presence suggests right heart failure. Diminished oxygen saturation is a component of a tetralogy spell, although the physical findings and condition of the patient, not the oxygen saturation, define the spell. Finally, an S3 gallop rhythm can be heard in the patient who has myocardial failure but is not expected in a patient who has TOF, particularly with the pronounced tachycardia described for the patient in the vignette.

9. You are evaluating a 12-year-old girl as part of a sports screening program at the local school. She tells you that she has trouble keeping up with her friends during gym class and on the soccer field. On physical examination, she appears well and is in no distress. Her precordial examination demonstrates a mild lift. The first heart sound is normal, and the second heart sound is prominently split. There is a 3/6 systolic ejection murmur at the upper left sternal border. Diastole is clear, and her pulses are normal in all extremities.

Of the following, the MOST likely cause of this patient’s signs and symptoms is

A. aortic stenosis

B. atrial septal defect

C. patent ductus arteriosus

D. pulmonary stenosis

E. ventricular septal defect

Preferred Response: B
Recognition of cardiac anomalies in pediatric patients requires a complete history and physical examination. The timing and severity of the presentation often depends on the severity of the underlying condition, such as the size of a ventricular septal defect, the degree of semilunar valve stenosis, or the extent of obstruction to pulmonary blood flow. Many of the congenital cardiac anomalies lead to turbulent blood flow within the heart or great vessels, which produces a murmur. The loudness, timing, location, radiation, and pitch of the murmur can suggest the cause of the anomaly.
The girl described in the vignette has the typical findings of an atrial septal defect. When the left-to-right shunt at the atrial level is significant, the patient may report a history of decreased exercise tolerance when compared with peers. Such decreased tolerance likely is the result of the dilated right ventricle, which receives the normal blood flow returning to the right atrium from the systemic veins as well as the abnormal blood flow that results from the left-to-right shunt of the atrial septal defect.
The murmur in patients who have atrial septal defects is not from the blood flow across the atrial septum because this flow usually is not turbulent and at low pressure. Rather, the systolic murmur results from a relative pulmonary stenosis because the left-to-right atrial shunt and the subsequent increased right ventricular volume are required to cross the pulmonary valve. The valve annulus does not dilate and, therefore, the amount of blood (stroke volume) crossing the valve is increased. The increased flow across the valve per heart beat necessitates an increase in the velocity of that blood flow, resulting in turbulence. It is this turbulence that creates the murmur that is heard best at the upper left sternal border. Because there is no structural abnormality of the pulmonary valve, no click is appreciated in patients who have atrial septal defects. In large atrial septal defects, a murmur also may be noted during diastole due to the increased amount of blood that must cross the tricuspid valve during ventricular filling.
Finally, patients who have atrial septal defects often have a fixed and split second heart sound that most likely results from the relative prolonged time required for the dilated ventricle to empty its contents during systole. In contrast, in the healthy heart, the second heart sound splits variably with respiration. The lack of variation of the split most likely is due to the free communication between the two atria, which allows for equalization of the influence of respiration on both the right and left ventricle.
The murmur of pulmonary stenosis often is associated with a systolic click that results from the abnormal structure and function of the pulmonary valve itself. The normal splitting of the second heart sound occurs because the volume of right ventricular blood and its stroke volume generally are normal.
Similarly, aortic stenosis is associated with an ejection click that does not change with position, and the accompanying murmur is heard best at the upper right sternal boarder, with radiation into the neck. Affected patients usually have a normal second heart sound.
The patent ductus arteriosus typically produces a continuous murmur that is characterized as having a "machinery" quality and usually is loudest at the left infraclavicular area. The murmur is continuous because the flow between the systemic and pulmonary circulation is constant due to the higher systemic compared with pulmonary vascular resistance throughout the cardiac cycle and the lack of a valve to separate the two in the structure of the ductus.
The murmur of a ventricular septal defect typically is holosystolic because the left-to-right shunt at the ventricular level begins with the onset of systole, even before the aortic and pulmonary valves open. When the ventricular septal defect is small, it produces a high-pitched murmur, heard along the sternal border, and the second heart sound is normal, with no change in its normal physiologic splitting.
10. You are conducting a preparticipation evaluation of a 14-year-old girl who is trying out for her school volleyball program. She is athletic and has never had any health problems. On physical examination, her height is at the 90th percentile and weight is at the 50th percentile for her age. Her lungs are clear, and cardiac examination reveals a systolic click and an apical systolic murmur that is late systolic and graded at 2/6 with radiation to the left axilla.
Of the following, the MOST likely diagnosis is

A. anemia with high-output state

B. aortic valve stenosis

C. atrial septal defect

D. mitral valve prolapse

E. small midmuscular ventricular septal defect

Preferred Response: D
Normally, the mitral valve closes very early in systole as pressure in the ventricle increases with the onset of contraction. The anterior and posterior leaflet of the valve come together to provide complete and straight apposition, thereby protecting the left atrium from the pressure and content of the left ventricle. In mitral valve prolapse (MVP), the mitral valve moves backwards (prolapses) into the left atrium during systole. The anterior or posterior leaflet does not achieve straight apposition; rather, one or both of the leaflets billows into the space of the left atrium as pressure in the left ventricle increases. If there is retrograde leakage of left ventricular blood into the left atrium, the MVP is associated with mitral regurgitation.
The prolapse may result from either abnormality of one or both of the mitral valve leaflets (eg, redundancy, “floppy”, myxomatous) or of the supporting apparatus (chordae tendineae, papillary muscles). MVP may occur primarily as an intrinsic abnormality of the mitral valve or its apparatus or it can occur secondarily from acquired disease such as rheumatic heart disease, myocarditis, or cardiomyopathy. Primary MVP is more common in females than males (2:1), and the disorder may be diagnosed in any age group.

The diagnosis of MVP is based on physical findings; patients can present with auscultatory findings that include a mid-systolic click that is believed to occur from the snapping of the mitral valve in the closed position during ventricular systole similarly to a sail catching wind. This timing of the click during systole may change, depending on patient position and the relative volume of the left ventricle during the examination. Squatting fills the left ventricle and may make the click occur later; standing reduces the left ventricular volume and may move the click to an earlier portion of systole. If there is regurgitation across the mitral valve, a late systolic murmur may be audible at the cardiac apex, with radiation to the left axilla.

The patient described in the vignette has physical findings indicative of MVP. The murmur associated with anemia typically is ejection, located along the left sternal boarder with radiation to the base, and not associated with a click. Aortic stenosis is associated with an ejection click that does not change with position, and the accompanying murmur is best heard at the upper right sternal boarder with radiation into the neck. An atrial septal defect typically creates a murmur of relative pulmonary stenosis as the left-to-right atrial shunt leads to increased right ventricular volume that subsequently must cross the pulmonary valve. The murmur is heard best at the upper left sternal border. Because there is no structural abnormality of the valve, no click is appreciated in patients who have atrial septal defects. The murmur of a small muscular ventricular septal defect is high-pitched, heard along the sternal border, and not associated with a systolic click.
11. You are evaluating a 14-year-old girl in the clinic. She has had a fever for nearly 2 weeks, which she has attributed to a "cold," although she has not had cough or upper respiratory tract symptoms. She is concerned about some "spots" that she has noticed on her palms and soles. On physical examination, you note splenomegaly and erythematous, nontender macules on her fingers, palms, and soles of her feet. Additionally, she has lost 8 lb since her visit 6 months ago.
Of the following, the MOST appropriate next study for evaluation of this patient is

A. antinuclear antibody

B. echocardiography

C. Lyme titers

D. ophthalmologic examination

E. tuberculin skin test

Preferred Response: B
The fever, Janeway lesions (erythematous, nontender macular lesions on the fingers and soles), splenomegaly, and weight loss reported for the girl in the vignette strongly suggest infective endocarditis. Infective endocarditis describes an infection involving the endocardial surface of the heart that can occur in individuals who have structurally normal hearts, although it is more common in children who have congenital heart disease. The most common sites are the cardiac valves, but infection also may occur on the margins of a ventricular septal defect, along the chordae supporting the atrioventricular valves, or along vascular grafts or foreign material such as a prosthetic valve. Although a relatively rare occurrence in the pediatric population, infective endocarditis continues to be a major source of morbidity and even mortality. Viridans streptococci (eg, S mitis, S bovis) as well as Staphylococcus aureus are the most common bacterial pathogens causing endocarditis in children.
The clinical manifestations of infective endocarditis are many and can present variably in affected individuals. The most common is fever, which may be associated with shaking chills. Constitutional nonspecific manifestations include anorexia, weight loss, malaise, night sweats, arthralgias, myalgias, and splenomegaly. In addition, a number of extracardiac manifestations are associated with infective endocarditis, including petechiae and splinter hemorrhages seen under the nails, hematuria, and glomerulonephritis. Roth spots are retinal hemorrhages that have a clear center and can be seen on ophthalmologic examination. Janeway lesions may be evident on the fingers, palms, or soles. Osler nodes are small, raised erythematous or purple nodules on the pads of the digits that typically are very painful.
Among the cardiac manifestations of infective endocarditis is a murmur, which is heard in nearly 50% of affected patients. Such murmurs typically result from valvular insufficiency, and the left heart valves are affected far more commonly than the right heart valves. Regurgitation of the mitral valve produces a holosystolic murmur typically heard best at the cardiac apex, with radiation to the left axilla. Regurgitation of the aortic valve produces a diastolic murmur that generally is heard best at the mid-left or right sternal border with the patient in the sitting position, leaning forward. If the regurgitation is severe, congestive heart failure also can be present.
The causative pathogen of infective endocarditis can be identified with blood cultures. Imaging of cardiac valves and evaluation of myocardial function by echocardiography are important parts of an assessment that can help guide management of valvular regurgitation and congestive heart failure, if present. An ophthalmologic examination is an important component of the evaluation, but it is not diagnostic and will not affect treatment. With a presentation such as that of the girl described in the vignette, it is important to rule out other possible causes of systemic disease such as lupus erythematosus, Lyme disease, and tuberculosis, but such diagnostic tests do not have the same urgency or impact on management as echocardiography in a patient who clearly has infective endocarditis.
12. You are evaluating a 15-year-old boy in the emergency department who presents with fever, chills, malaise, and blood in his urine. On physical examination, he appears comfortable and alert and has a temperature of 102.7°F (39.3°C), a blood pressure of 110/40 mm Hg, no rashes, and clear breath sounds. He has a diastolic murmur heard best in the sitting position. You elicit no abdominal or flank tenderness.
Of the following, the BEST next step in the management of this patient is

A. administration of broad-spectrum antibiotics

B. blood cultures

C. renal ultrasonography

D. transesophageal echocardiography

E. urine culture

Preferred Response: B
The patient described in the vignette has history and physical examination findings that are highly suggestive of infective endocarditis. These include symptoms of chills and malaise; a history of fever; and the findings of hematuria, a new murmur, and fever.
Typically, the diagnosis is confirmed by isolation of the offending organism from blood cultures. Blood cultures from three to five sites should be obtained prior to initiation of antibiotic therapy. Because the bacterial shedding is constant, the practitioner should not wait until the patient is febrile to obtain blood cultures. Viridans streptococci (eg, S bovis, S mitis) as well as Staphylococcus aureus are the most common bacterial pathogens causing endocarditis in children. However, clinicians must be concerned about organisms such as Enterococcus, coagulase-negative Staphylococcus, fungi, and a group of bacteria referred to as the HACEK organisms (Haemophilus sp, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae). The HACEK organisms are gram-negative oral and pharyngeal flora that are fastidious and slow-growing, often requiring growth factors and carbon dioxide to be isolated in cultures.
Treatment of endocarditis depends on the isolated organism. In general, long-term antibiotic treatment (4 to 6 weeks) is undertaken in an effort to eradicate completely the bacteria that have been sequestered in a nonvascular vegetation. Surgery is reserved for patients who develop severe congestive heart failure from severe valve regurgitation or deterioration.
The boy in the vignette requires intravenous antibiotic treatment, but blood cultures should be obtained before therapy is begun. He also should undergo echocardiography, which may be performed from the transesophageal approach to improve the sensitivity, but similar to renal ultrasonography, such a study is performed after blood cultures have been obtained. The absence of vegetation at the time of echocardiography does not rule out a diagnosis of infective endocarditis. Patients who have infective endocarditis may exhibit hematuria from the deposition of immune complexes resulting in glomerulonephritis. Although fever and hematuria may be associated with urinary tract infection, the presence of a diastolic murmur and absence of urinary symptoms make such a diagnosis unlikely.
13. A 3-day-old infant who was born at 29 weeks’ gestation and weighed 1,200 g has experienced respiratory distress syndrome and is receiving assisted ventilation. This morning, you note a grade III/VI holosystolic murmur, hyperdynamic precordium, and widened pulse pressures.
Of the following, the MOST appropriate next step is to

A. administer ibuprofen treatment

B. administer indomethacin prophylaxis

C. increase maintenance fluids

D. obtain echocardiography

E. reduce the ventilator settings

Preferred Response: D
The 29-weeks’ gestation very low-birthweight infant described in the vignette, who has respiratory distress syndrome, is at risk for a persistent patent ductus arteriosus (PDA). Closure of the ductus arteriosus often is delayed in such infants, but its patency may be of variable hemodynamic or clinical significance. Symptoms or signs resulting from a PDA typically appear between the third and seventh postnatal day, although they can appear later.
The significance of the PDA for the infant in the vignette is suggested by the presence of the murmur, a widened pulse pressure, and a hyperdynamic precordium. Such findings are indicative of a left-to-right shunt of blood from the descending aorta through the PDA into the pulmonary circulation. This condition may volume overload the right heart, contributing to the hyperdynamic precordium. As the shunt continues, pulse pressures widen and the overall adequacy of cardiac output to distal circulatory beds may be jeopardized, resulting in systemic hypotension, metabolic acidemia, oliguria, and potential gastrointestinal compromise. Untreated, the condition may result in pulmonary congestion with reduced pulmonary compliance, congestive heart failure, and hepatomegaly.
Diagnosis of a PDA is made both clinically and echocardiographically. The hemodynamic significance of a PDA is determined echocardiographically by assessing the size of the left atrium, the aortic outlet, the PDA, and the right ventricle as well as the presence of reversed enddiastolic blood flow in the proximal aortic arch.
Judicious fluid management (<150 mL/kg per day) in the first week after birth may reduce the likelihood of clinically significant PDA. However, once the PDA is diagnosed, fluid restriction is a mainstay of treatment. The use of positive end-expiratory pressure (PEEP) also may help reduce pulmonary overcirculation in the ventilated patient. Pharmacologic management consists of intravenous indomethacin or ibuprofen-lysine, usually administered in three successive doses. If the PDA fails to close with these pharmacologic measures, surgical ligation may be warranted.
Treatment with ibuprofen may follow confirmation of the PDA but should not be initiated presumptively due to potential complications and adverse effects. A single dose of intravenous indomethacin may be administered prophylactically in the first 12 to 24 hours after birth, but the window for prophylaxis has passed for the infant in the vignette. Increasing fluids might worsen cardiopulmonary congestion in the setting of a PDA. Reducing ventilator settings (PEEP, inspiratory time, or pressure) can result in a reduction in mean airway pressure, which allows for an increase in left-to-right shunting.
14. You are evaluating a 2-year-old girl for fever and fatigue. Her parents report that she has had a fever for 3 days, a progressive degree of fatigue, loss of appetite, and irritability. On examination, she has a temperature of 102.3°F (39.1°C), a heart rate of 160 beats/min, a respiratory rate of 40 breaths/min, and a blood pressure of 90/60 mm Hg. She has dry mucous membranes, mild intercostal retractions, and a 3/6 holosystolic murmur at the cardiac apex. Her liver is palpable 3 cm below the costal margin. Her pulses are weak but palpable in all extremities.
Of the following, the MOST likely cause of this patient’s clinical presentation is

A. dehydration from viral illness

B. Kawasaki disease

C. meningitis

D. myocarditis

E. rheumatic fever

Preferred Response: D

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