DORV is a specific malformation representing one of the types of malposition of the great arteries. A ventricular septal defect (VSD), which provides the only outlet for the left ventricle, is located beneath either the pulmonary artery or the aorta or, rarely, remote from both great arteries (Fig. 266.1). Associated subpulmonic stenosis, which restricts pulmonary blood flow, is present in more than 50% of patients with DORV.

The relationship of the VSD to the great arteries and the presence or absence of pulmonic stenosis are the primary determinants of the circulatory physiology in DORV. When the VSD is related closely to the aorta (see Fig. 266.1A), the physiologic features are similar to those of a large VSD with left-to-right shunt and pulmonary hypertension. In this setting, symptoms of congestive heart failure dominate after the anticipated decrease of pulmonary vascular resistance occurs, with little or no cyanosis. Conversely, when the pulmonary artery overrides the VSD, without associated pulmonic stenosis (see Fig. 266.1B), the hemodynamics simulate those of transposition of the great arteries with a large VSD. Frequently called the Taussig-Bing complex, clinical features of this condition include both cyanosis and congestive heart failure. Coarctation of the aorta and variable degrees of hypoplasia of the subaortic outflow tract often occur in this form of DORV. In either of these subsets of DORV, the clinical course is determined by pulmonary vascular resistance and the presence or absence of left heart obstructive lesions. Severe subpulmonic or pulmonary valvar stenosis occurs most frequently when the VSD is subaortic (see Fig. 266.1C). The resultant physiology and clinical manifestations are indistinguishable from tetralogy of Fallot, with cyanosis and pulmonary oligemia.