Organ System Pathology USMLE Step 1 Practice Question
A 7-month-old infant presents with episodes of cyanosis worsening during feeding and crying. Parents note the infant instinctively assumes a squatting position during play. Vital signs show HR 145 bpm, RR 32, SpO2 78% on room air, and BP 85/52. Physical examination reveals a harsh systolic ejection murmur at the left upper sternal border. Chest X-ray demonstrates a "boot-shaped" heart. No hepatomegaly is noted. Which cardiac abnormality is most likely present?
Answer choices
- ATransposed great vessels, PDA, and coarctation
- BVentricular septal defect, overriding aorta, right ventricular outflow obstruction, and right ventricular hypertrophyCorrect answer
- CEndocardial cushion defect with mitral atresia
- DAortic stenosis, atrial septal defect, left ventricular hypertrophy, and PDA
- EAtrial septal defect, tricuspid stenosis, pulmonary edema, and left ventricular hypertrophy
- FMitral valve prolapse, ventricular septal defect, left atrial enlargement, and pulmonary stenosis
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.