Surgical anatomy of the infundibular septum in transposition of the great arteries with ventricular septal defect.

Anatomic variation of the infundibular septum was studied in transposition of the great arteries with ventricular septal defect in 23 hearts and double-outlet right ventricle with anterior position of the aorta in two hearts. Anterior displacement of the infundibular septum (i.e., "false" Taussig-Bing heart) was associated with coarctation or interruption of the aortic arch in 88% of the cases, whereas posterior displacement resulted in subpulmonary narrowing in 100% of the cases. Anterior displacement makes intraventricular rerouting from the left ventricle to the aorta difficult because of a long oblique route. In addition, the right ventricular cavity becomes smaller after closure of the ventricular septal defect. Therefore, arterial switch accompanied with transatrial or transpulmonary closure of the defect without ventriculotomy is recommended. In hearts with posterior displacement of the infundibular septum, the anterosuperior rim of the defect is difficult to approach through the tricuspid valve, and the route from the left ventricle to the aorta is rather straight. Hence, the Rastelli procedure is preferable. In hearts without displacement of the infundibular septum, either arterial or atrial switch with transatrial closure of the ventricular septal defect is applicable.