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Myocardial dysfunction is unlikely. It can be acquired by injury to the myocardium from severe intrapartum hypoxemia. Onset of symptoms at age two weeks rules this out. Severe viral myocarditis, perhaps acquired in utero, remains a possibility. Prolonged reentrant supraventricular tachycardia can result in myocardial failure. In a newborn, reentrant SVT usually produces a heart rate of at least 280 bpm. This patient's heart rate is lower. Other rare congenital conditions, such as Pompe's disease, a glycogen storage disease and anomalous origin of the left coronary artery from the pulmonary artery, rarely manifest heart failure as early as age two weeks.