Congenital Heart Disease USMLE Step 1 Practice Question
A 1-day-old male with cyanosis and severe respiratory distress presents with HR 165, RR 48, BP 58/32, SpO2 68% on room air, and temperature 37.2°C. Physical examination reveals a single loud S2 and minimal murmur. Chest X-ray demonstrates an "egg-on-string" appearance with increased pulmonary vascular markings. Arterial blood gas shows PaO2 of 42 mmHg. The infant has received no prior cardiac medications. Prostaglandin E1 infusion fails to improve oxygenation. Which diagnosis best explains these findings?
Answer choices
- ATetralogy of Fallot
- BPulmonary atresia
- CTotal anomalous pulmonary venous return
- DTricuspid atresia
- ETransposition of the great arteriesCorrect answer
- FTruncus arteriosus
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