Subneoaortic stenosis complicating the arterial switch operation.

We report obstruction of the reconstructed left ventricular outflow tract diagnosed 18 months after an arterial switch operation that included closure of a ventricular septal defect. We speculate that either turbulences created by the patch used to close the ventricular septal defect, or postoperative modifications of ventricular geometry, were responsible for producing this unusual complication.