Atypical Fallot's tetralogy with doubly committed subarterial ventricular septal defect. Diagnostic value of 2-Dimensional echocardiography.

Five patients with clinical features of tetralogy of Fallot had subarterial doubly committed ventricular septal defect (VSD) with absence or deficiency of the infundibular septum. Two-dimensional (2-D) echocardiography differentiated this special group from those with the usual Fallot's anatomy. In addition to the long-axis view of the left ventricle which showed the subaortic VSD and the aortic and mitral fibrous continuity, the short-axis view at the cardiac base clearly demonstrated the subpulmonary extension of the VSD in the atypical group. Two-dimensional echocardiography was found superior to biplane angiography, which in 3 patients suggested the erroneous diagnosis of double-outlet right ventricle with pulmonic valve stenosis. This variant form of Fallot's tetralogy poses special surgical problems.