An unusual form of the transposition complex. Uncorrected levo-transposition with horizontal ventricular septum: Report of two cases.

A distinctive angiographic appearance is described in two patients who had uncorrected levo-transposition of the great vessels. Although levo-transposition with inversion of the ventricles usually results in physiologically corrected transposition, in these patients the anatomy was arranged in such a way as to result in an uncorrected transposition. The following elements were responsible for this physiological condition: normal atrial situs, inverted ventricles with "criss-cross" atrioventricular flow, levo-transposed great arteries. In addition, the morphological right ventricle was hypoplastic, left sided and superior to the left ventricle and the ventricular septum was horizontal in position. The two ventricles were connected via a large ventricular septal defect. The importance of accurate, detailed, preoperative angiographic demonstration of the anatomic situation is stressed.