Board Simulation: Cardiology
Daniel J. Murphy Jr.
QUESTIONS
Case 1
While performing ultrasonography on a 31-week fetus, an obstetrician notes that the heart rate ranges from 62 to 66 beats/minute. The fetal growth appears normal, and no structural cardiac anomalies are identified. On echocardiography, the fetal atria appear to be contracting at 140 beats/minute, with a ventricular rate of 65 beats/minute.
1. Which of the following is the next step in the management of this infant?
a) Administer β-agonist drug therapy to the mother.
b) Assess the cardiac status of the infant following labor and delivery.
c) Counsel the parents that intrauterine fetal death is likely.
d) Perform amniocentesis to confirm lung maturity, and if the lungs are mature, perform an immediate cesarean section.
e) Repeat fetal echocardiography and ultrasonography in 1 week.
View Answer
Answer
The answer is e. This fetus has complete (third-degree) AV block with a slow regular ventricular rate and no relationship between the atrial rate and ventricular rate. Congestive heart failure and intrauterine fetal demise are common when complete AV block accompanies structural heart disease. With normal anatomy, congestive heart failure and hydrops fetalis may develop, and close observation with serial ultrasonographic exami-nations is indicated. If signs of congestive heart failure develop, medical management is unlikely to be beneficial, and delivery is indicated.
Case 2
2. A 1-day-old term infant has dysmorphic features that include a low nasal bridge, flat occiput, clinodactyly of the fifth digits, wide spacing between the first and second toes, and hypotonia. He is cyanotic, and results of the lung and abdominal examinations are normal. No heart murmur is heard, and the pulses are normal. The likelihood that this infant has clinically significant congenital heart disease is closest to:
a) <20%
b) 20%-35%
c) 40%-55%
d) 60%-70%
e) 80%-95%
View Answer
Answer
The answer is c. This infant has features suggestive of trisomy 21 (Down syndrome). The incidence of congenital heart disease in association with Down syndrome is approximately 50%. The presence of cyanosis could be secondary to a cardiac defect or mild persistent pulmonary hypertension. The absence of a heart murmur should not reassure the clinician, and echo cardiography is indicated for any infant with Down syndrome.
Case 3
A 1-year-old child is brought to the emergency department because his parents thought his heart was “pounding” as they were putting him to bed. Electro-cardiography reveals a heart rate of 300 beats/min that spontaneously converts to sinus rhythm at 100 beats/min. The parents estimate that the tachycardia lasted 20 minutes; the child was asymptomatic throughout.
3. Of the following, the most appropriate management of this child is:
a) Administration of a β-blocker
b) Administration of digoxin
c) Administration of procainamide
d) Administration of verapamil
e) Observation without drug therapy
View Answer
Answer
The answer is e. This child likely has reentrant SVT through either the AV node or an accessory bypass tract. An electrocardiogram would be appropriate, and if it showed preexcitation (Wolff-Parkinson-White syndrome), a cardiology consultation would be indicated.
If the child presented in tachycardia, vagal maneuvers or intravenous adenosine could be used to restore sinus rhythm. Long-term drug therapy is generally not indicated for infrequent, brief, unsustained episodes of SVT.
If the child presented in tachycardia, vagal maneuvers or intravenous adenosine could be used to restore sinus rhythm. Long-term drug therapy is generally not indicated for infrequent, brief, unsustained episodes of SVT.
Case 4
A 3-month-old boy has respiratory distress and lethargy. Findings include tachypnea, hepatomegaly, heart rate of 300 beats/min, and a narrow QRS complex consistent with supraventricular tachycardia (SVT).
4. Of the following, the most appropriate treatment for the patient at this time is:
a) Electric cardioversion
b) Intravenous verapamil
c) Oral digoxin
d) Oral verapamil
e) Parenteral digoxin
View Answer
Answer
The answer is a. Of the choices presented, cardioversion is most appropriate. Intravenous verapamil is contraindicated in infants, and a prompt response is not obtained with oral drugs. Vagal maneuvers or the administration of intravenous adenosine would be appropriate options for prompt conversion to sinus rhythm.
Case 5
A 30-year-old woman who has active systemic lupus erythematosus is pregnant.
5. Of the following abnormalities of cardiac conduction, the one that is most likely to occur in her infant is:
a) Atrial flutter
b) First-degree heart block
c) SVT
d) Third-degree heart block
e) Ventricular tachycardia
View Answer
Answer
The answer is d. Infants of mothers who have connective tissue disease with or without clinical symptoms, especially in the presence of anti-Ro (SS-A) or anti-La (SS-B) antibodies, are at significant risk for the development of conduction abnormalities, most commonly third-degree AV block. Close observation with fetal echocardiography is indicated. A neonatal lupus syndrome can develop that is characterized by dermatologic, hematologic, or cardiac abnormalities, or a combination thereof. The skin lesions and cytopenia resolve spontaneously, but the cardiac manifestations are permanent.
Case 6
A 5-year-old girl is very excited following a ride on a Ferris wheel. In the midst of her excitement, she suddenly loses consciousness and falls to the ground. Paramedics on the scene document ventricular tachycardia. The family history reveals a maternal uncle who died suddenly at 16 years of age.
6. Following treatment of the ventricular tachycardia, an electrocardiogram most likely will demonstrate:
a) Corrected QT interval of 0.52 seconds
b) P-wave axis of 30 degrees
c) PR interval of 0.81 seconds
d) QRS axis of — 15 degrees
e) QRS interval of 0.12 seconds
View Answer
Answer
The answer is a. This child most likely represents a case of long QT syndrome. A sudden loss of consciousness during activity without a prodrome is not suggestive of neurocardiogenic syncope (simple faint). Wolff-Parkinson-White syndrome (short PR interval) might cause SVT but would rarely result in a sudden loss of consciousness or ventricular tachycardia. Arrhythmogenic right ventricular dysplasia is a familial disorder that generally presents as ventricular tachycardia, syncope, or sudden death in adolescents or adults. The electrocardiographic findings are usually normal.
7. In addition to a prolonged QT interval, a person with Jervell and Lange-Neilsen syndrome is most likely to have:
a) Alopecia universalis
b) Cranial bruits
c) Hepatosplenomegaly
d) Rotary nystagmus
e) Sensorineural hearing loss
View Answer
Answer
The answer is e. In addition to being associated with sensorineural hearing loss, long QT syndrome can be inherited in an autosomal-recessive or autosomal-dominant pattern with variable penetrance. The mutations cause abnormalities in cellular sodium or potassium channels.
8. The sport you are most likely to suggest that patients with long QT syndrome avoid is:
a) Bicycling
b) Bowling
c) Ice skating
d) Swimming
e) Tennis
View Answer
Answer
The answer is d. In addition to swimming, patients are restricted from vigorous exercise, competitive sports, and high-risk occupations, such as flying. β-Blockade is the mainstay of therapy, along with the avoidance of medications that have the potential to prolong the QT interval further, including tricyclic antidepressants, erythromycin, and QT-prolonging antiarrhythmic drugs.
9. The upper limit of a normal corrected QT interval (QTc) is:
a) 0.40 second in boys
b) 0.40 second in girls
c) 0.46 second in boys
d) 0.46 second in girls
e) 0.46 second in boys and girls
View Answer
Answer
The answer is e. The QTc is calculated according to the formula QTc = QT/(R-R)1/2, with the R-R interval measured in seconds. The upper limit of normal is 0.46 second for boys and girls.
Case 7
A 16-year-old athlete has a syncopal episode immediately following a high school basketball game. The electrocardiogram reveals a QTc of 0.52 second.
10. Which of the following family members would you recommend must have a screening electrocardiogram?
a) All first-degree relatives
b) Brothers and male first cousins
c) Sisters and female cousins
d) Father and both grandfathers
e) Mother and both grandmothers
View Answer
Answer
The answer is a. In most cases, long QT syndrome is inherited as an autosomal-dominant trait. Some mutations may be transmitted in an autosomal-recessive pattern. The condition is not gender specific.
Case 8
A 14-year-old girl falls during a race. She is unconscious and cyanotic and has no pulse, but she revives spontaneously within seconds. Both the patient and family histories are benign. Results of a physical examination, chest roentgenography, echocardiography, electroencephalography, and exercise electrocardiography during a treadmill stress test are normal.
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