The surgical anatomy of ventricular septal defects associated with overriding valvar orifices

This is the second review in a three-part series concerned with the description and categorization of ventricular septal defects. By viewing the defects from the right ventricular aspect, they can be placed into one of three classes: perimembranous, muscular, or doubly committed and juxta-arterial. According to the posteroinferior margin of the third group, these could extend to become perimembranous or muscular. In this review, the complications produced by malalignment of the septal structures associated with overriding of an arterial or atrioventricular valve are described in detail. It shows that although there are problems in defining the extent of any interventricular communication, these ventricular septal defects can be classified with the same categorization as developed for those not associated with overriding. The nosology developed is able to serve as a guide to the surgeon to the site of the specialized axis for atrioventricular conduction.