Morphology of ventricular septal defects in complete transposition. Surgical implications

Postmortem examination of 62 hearts with complete transposition (concordant atrioventricular and discordant ventriculoarterial connections) and an accompanying ventricular septal defect was performed to determine the morphologic variability of ventricular septal defects and to explore the surgical implications of these defects. Particular attention was directed toward assessing alignment of the outlet septum relative to the muscular septum. Coronary arterial distributions were also evaluated, but specific patterns of distribution did not correlate with morphology of the defect. Of 49 hearts with a normally aligned outlet septum, there were 24 perimembranous, 21 muscular, and 2 doubly committed and juxtaarterial defects. Two hearts had both perimembranous and muscular defects. Twelve of the 21 muscular defects were "central," being surrounded entirely by muscle and located just below the leaflets of the pulmonary valve, and 9 were located in the inlet or apical trabecular septum. There were 13 hearts with malalignment of the outlet septum, anteriorly in 11 and posteriorly in 2. All with anterior malalignment had a subpulmonary defect that was perimembranous in 7 and muscular in 4. Both defects with posterior malalignment had a subaortic perimembranous defect. Because variations in morphology of a ventricular septal defect have a direct impact on selection of the most suitable surgical repair, specific operative approaches are discussed.