August 18th, 2020
10 hours after delivery, a newborn develops cyanosis and respiratory distress. He was delivered at term after an uncomplicated pregnancy. His birth weight was 3000 g (6 lb 10 oz), and Apgar scores were 8 and 9 at 1 and 5 minutes, respectively. On examination, his temperature is 37 degrees ˚C (98.6 ˚F), pulse is 160/min and respirations are 70/min. His blood pressure is 90/50 mm Hg in the right arm. Examination shows moderate subcostal retractions and nasal flaring. Cardiac examination shows a single loud S2 with no murmur. Electrocardiogram (ECG) is within normal limits. Chest x-ray shows mediastinal narrowing with an egg-shaped heart; lung fields are clear. Which of the following is the most likely cause of these findings?