Case 353

History An 8-month-old term-born female infant presented to the pediatric emergency department with progressively increasing respiratory distress and episodic hypoxic spells for 2 months. Antenatal and birth histories were uneventful. There was absence of any preceding documented infections. On examination, she was lethargic, afebrile, and had mild tachycardia (heart rate, 157 beats per minute) and hypoxia (oxygen saturation of 83% on room air), with audible grunting, nasal flaring, wheezing, suprasternal retractions, and an audible P2. Echocardiography done elsewhere excluded any intracardiac shunt but revealed pulmonary arterial hypertension with tricuspid regurgitation. Chest radiography (Fig 1) and contrast-enhanced CT of the chest (Figs 2, 3) were performed for the indication. The child had a seizure during the admission, for which MRI of the brain (Fig 4) was also performed.