A ventricular septal defect is, almost always, an integral part of double outlet right ventricle and has been classified into the subaortic, subpulmonary, doubly committed and non-committed varieties. This study was performed to correlate the cross-sectional imaging characteristics of such ventricular septal defect in double outlet right ventricles using pathological specimens. The extent and the orientation of the outlet septum were the most important in the differentiation of the four varieties of ventricular septal defect. In the subaortic variety, the outlet septum fused with the left anterior margin of the defect, this being marked by the anterior limb of the septomarginal trabeculation. In the subpulmonary variety, the outlet septum fused with the right posterior margin of the defect, this being the posterior limb of the septomarginal trabeculation. The outlet septum was vestigial in case with doubly committed defects. In those with non-committed defects, the defect was not shown in those images or sections which demonstrated the outlet septum.
