A 9-year-old girl with Down's syndrome had a one-week history of cough, fever, and dyspnea. Three days prior to hospital admission, she had been started on a regimen of penicillin by her local physician for a presumed pneumonia. However, her respiratory distress increased, and a chest roentgenogram was obtained on admission (Fig 1). Although she had had a known heart murmur since infancy, she had remained asymptomatic until this illness.
On physical examination she was an agitated dyspneic child with the stigmata of Down's syndrome. Her temperature was 38°C; respirations, 30/min; pulse rate, 120 beats per minute; blood pressure, 90/72 mm Hg, with a paradoxical pulse of 20 mm Hg. There were a few bilateral basilar rhonchi. The heart sounds were soft and distant, and the second heart sound was widely split and fixed. There was a grade 2/6 systolic ejection murmur maximal at the high left sternal border. No