Multiple Muscular Ventricular Septal Defects.

APPROXIMATELY 10 per cent of interventricular communications occur in the muscular portion of the ventricular septum.1-3 Of 259 cases of isolated ventricular septa] defects,2' 4-9 4.0 per cent had multiple muscular defects. Scant mention of these multiple defects as a distinct entity can be found in the recent literature, although the incidence is significant. We have observed characteristic findings in seven patients with multiple muscular ventricular septal defects. The purpose of this report is to describe the clinical picture, demonstrate the serious nature of this malformation, and emphasize the need for more thorough preoperative evaluation as well as careful inspection at the time of surgery. In addition, we wish to contrast this entity with the isolated muscular septal defect. A number of authors have commented that the latter anomaly has little functional significance.2, 4, 10-12