Morphology of perimembranous ventricular septal defects: implications for transcatheter device closure

Several clinical series have reported successful closure of perimembranous ventricular septal defects using trancatether devices. This review presents the morphological aspects of ventricular septal defects focusing on perimembranous septal defects. By definition, a part of the margin of perimembranous septal defects is the area of fibrous continuity abutting the central fibrous body that bears the atrioventricular conduction bundle. Depending on the excursion of the remaining margin, these defects are in proximity to the aortic, tricuspid, or mitral valves. Defects that extend to be doubly committed and juxtaarterial are roofed by contiguity between pulmonary and aortic valves. Recognition of the proximity or distance of important structures is relevant in considering perimembranous defects for device closure.