Tetralogy of Fallot with obstruction of the ventricular septal defect: spectrum of echocardiographic findings.

Tetralogy of Fallot with a restrictive ventricular septal defect and suprasystemic right ventricular pressure is an uncommon anomaly with a high mortality rate. In previous studies, the identity of the tissue obstructing the ventricular septal defect has usually not been determined preoperatively. This report describes the echocardiographic and anatomic features in 4 patients with a restrictive ventricular septal defect among 269 patients with tetralogy of Fallot undergoing surgical repair. Echocardiography determined the presence and identity of the obstructing tissue in all four patients. In one patient, the defect was small in association with marked septal hypertrophy. In three patients, accessory or excessive tricuspid valve tissue obstructed the defect in a manner similar to spontaneous closure of isolated membranous ventricular septal defects. Autopsy and catheterization findings are also presented of an additional case with a unique mechanism of obstruction by a tricuspid valve with Ebstein's anomaly. In patients with tetralogy of Fallot, recognition of an obstructed ventricular septal defect is important because it appears to have a poor prognosis.