The conduction system in corrected transposition with situs inversus.

The location and course of the conduction system were investigated by serial section in two hearts with corrected transposition of the great arteries in situs inversus. In the first case, characterized by dextrocardia, the interventricular septum was intact, while in the second case with levocardia, a high ventricular septal defect was associated with pulmonary atresia. In both hearts, a regular posterior connecting AV node was present, left-sided in one case and right-sided in the other. The bundle branches were distributed in the morphologically appropriate ventricles. Extensive hemorrhage and coagulation necrosis of the common bundle and bundle branches were observed in the first case, being consequent upon surgical replacement of the right-sided tricuspid valve. The common bundle ran below the membranous septum in this case. In the heart with ventricular septal defect it was related to the postero-inferior rim of the defect. In both cases, an accessory AV node was located anteriorly in the interatrial septum but did not connect with the ventricular musculature. The different position of the atrioventricular conducting tissue in corrected transposition, between cases in situs solitus and situs inversus, is emphasized.