[Tetralogy of Fallot with a restrictive ventricular septal defect caused by a membranous flap]

A 5-year-old boy who had typical tetralogy of Fallot (TOF) with mild cyanosis was referred to us. Preoperative echocardiogram revealed that in addition to the TOF morphology, an abnormal piece of tissue attached to the right side of the ventricular septum was floating and obstructing flow through the ventricular septal defect (VSD) in systole. Preoperative cardiac catheterization showed suprasystemic right ventricular pressure with a gradient of 60 mmHg between the right ventricle and the aorta, and a right ventriculogram demonstrated a narrow radiolucent structure beneath the aortic valve in the right ventricle. During surgery a fibrous membranous tissue, with no relation to the tricuspid valve, was found to extend from the edge of the VSD to the aortic valve and to partially occlude the defect. This tissue was used as a suture anchorage for patch closure of the defect. Preoperative echocardiography is useful to detect such flaps and early surgical correction should be done to prevent right ventricular failure resulting from right ventricular pressure overload.