Congenital Heart Disease USMLE Step 1 Practice Question
A 3-day-old female infant born at term presents for evaluation of a cardiac murmur detected on routine newborn screening. Her mother has a history of Turner syndrome. On examination, the infant is afebrile with BP 68/42 mmHg, HR 152 bpm, RR 41/min, and SpO2 99% on room air. A systolic ejection murmur is heard best at the right upper sternal border. Echocardiography reveals a bicuspid aortic valve with a peak instantaneous gradient of 32 mmHg across the valve. Left ventricular wall thickness and cavity dimensions are currently normal. The aortic valve shows no regurgitation. The cardiologist counsels the family regarding the natural history of progressive aortic stenosis. Which of the following pathophysiologic changes occurs earliest in the progression of hemodynamically significant aortic stenosis?
Answer choices
- AEccentric left ventricular hypertrophy with chamber dilation
- BConcentric left ventricular hypertrophy due to increased afterloadCorrect answer
- CSecondary aortic regurgitation from leaflet prolapse
- DPulmonary edema from elevated left atrial filling pressures
- EAortic root dilatation from chronic turbulent flow
- FMitral regurgitation from left ventricular dysfunction
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