Congenital Heart Disease USMLE Step 1 Practice Question
A 3-week-old male born at term presents to the emergency department with cyanosis. The mother reports poor feeding and rapid breathing since day of life 2. Vital signs show SpO2 58% on room air, heart rate 148/min, respiratory rate 46/min, and blood pressure 64/40 mmHg. On examination, the infant is alert but cyanotic with a single loud S2 and no murmur. A hyperoxia test (FiO2 1.0) shows minimal improvement in SpO2 to 61%. Chest X-ray demonstrates a right aortic arch with a narrow mediastinum and "egg-on-string" appearance. Echocardiography shows all four pulmonary veins draining to a confluence posterior to the left atrium with no connection to the left atrium. The patient receives prostaglandin E1 and undergoes balloon atrial septostomy with minimal improvement in oxygenation. Which of the following is the most likely diagnosis?
Answer choices
- ATotal anomalous pulmonary venous return (supracardiac type)Correct answer
- BTransposition of the great arteries with intact ventricular septum
- CTricuspid atresia with severe restrictive atrial septum
- DPulmonary atresia with intact ventricular septum
- ECritical tetralogy of Fallot
- FTruncus arteriosus with severe pulmonary stenosis
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