Patch repair of subsemilunar conal septal defect resulting in severe left ventricular outflow tract obstruction.

A subsemilunar conal septal defect was closed at 8 months of age with a redundant Dacron patch that bowed into the left ventricular outflow tract, resulting in severe subaortic stenosis and massive left ventricular hypertrophy. Mistaken for cardiomyopathy or myocarditis, this rare complication of subsemilunar ventricular septal defect patch closure led to orthotopic cardiac transplantation followed by death.