Prevalence, relation to spontaneous closure, and association of muscular ventricular septal defects with other cardiac defects.

Previous studies on muscular ventricular septal defect (VSD) have not taken into account the specific defect location in the septum. We retrospectively reviewed all patients with a muscular VSD, with and without associated malformations, diagnosed over 32 months to determine the prevalence and rate of spontaneous closure of single defects in relation to location in the muscular septum. Defects were classified into 4 groups: midmuscular, apical, anterior, and posterior. Two hundred seven patients were identified, of whom 125 had a single defect. The relative prevalence of single muscular VSD was: midmuscular 55 (44%), apical 31 (25%), anterior 33 (26%), and posterior 6 (5%). Thirty patients had signs of spontaneous closure and only 1 underwent surgery. There was no difference in rate of closure with respect to anatomic locations. Patients with multiple muscular VSD were either referred for surgery in the first year of life or had a course similar to patients with a single VSD. Muscular VSD associated with other cardiac malformations was more often encountered in patients with conoventricular VSD and coarctation of the aorta. The distribution of anatomic groups of muscular VSD in association with malformations was similar to the single VSD.