Spontaneous Closure of Physiologically Advantageous Ventricular Septal Defects

The clinical and pathological features of two cases in which physiologically advantageous ventricular septal defects closed spontaneously are presented. The first patient, with tricuspid atresia, Type I(c), developed symptoms and signs of increasing systemic hypoxemia, decreasing pulmonary blood flow, and a systolic murmur of decreasing intensity. His ventricular septal defect, previously demon-strated angiocardiographically, could not be found at autopsy; it is presumed to have closed by fusion of its muscular rims with subsequent covering by endocardial proliferation. The second patient, with a double-outlet right ventricle, demonstrated progressive left ventricular enlargement and congestive failure despite increasing pulmonary vascular resistance. Postmortem examination showed that this defect was sealed by adherence of the septal leaflet of the tricuspid valve to the edges of the defect. Appreciation of the true nature of the changing anatomical situation would have resulted in more rational effective therapeutic approaches. The cases presented and review of pertinent literature contribute to more com-plete understanding of circumstances surrounding the spontaneous closure of ven-tricular septal defects. Additional Indexing Words: Tricuspid atresia Double-outlet right Ventricular septal defect, spontaneous closu S PONTANEOUS closure of isolated ven-tricular septal defects is well document-ed.1-3 Even defects of this type large enough to require banding of the pulmonary artery in infancy have been reported to close natural-ly.4-6 Such occurrences are clinically desirable. Spontaneous closure of ventricular septal defects, which if open would be physiological-ly advantageous components of multiple defect complexes, is more rare; there are only a few reports of such anatomic events in cases of tricuspid atresia7, 8 and double-outlet righ