A 6-MONTH-OLD BOY presented with a history of raspy breathing that disappeared when held upright. He had no feeding problems. On physical examination, a mild expiratory wheeze and a grade 3 ⁄4 systolic heart murmur were heard at his back. A chest radiograph was obtained (Figure 1) . The infant was born at 31 weeks' gestational age weighing 1213 g. He required a short course of respiratory assistance, and an umbilical artery catheter was used for the first 5 days. The hospital course was complicated on day 5 From the