Anomalous right coronary artery origin in otherwise unexplained infant death.

Anomalous origin of the right coronary artery from the left sinus of Valsalva has only recently become recognized as a cause of sudden death in neonates, infants, and young children. The mechanism of death in these cases may be decreased myocardial perfusion by the anomalous vessel due to a combination of factors. Tangential takeoff of the vessel with resultant slitlike ostium and its initial investment in the aortic adventitia with diastolic entrapment and compression are both thought to be at play. Since 1983, three infants with this anomaly and associated sudden death have been described. We describe a fourth case and offer an assessment of the overall frequency of this potentially fatal abnormality.