Morphologic demonstration of spontaneous and surgical closure of membranous ventricular septal defect

Abstract

This report demonstrates morphologic features of membranous ventricular septal defect that was closed spontaneously in one patient and operatively in the other.

Relatively few reports have illustrated morphologically either spontaneous or surgical closure of membranous ventricular septal defect (VSD) (1–10). Such is the purpose of this report.

DESCRIPTION

Certain findings in each of the two patients are summarized in Table 1. Patient 1 died from multisystem failure, primarily consequences of severe obesity. Necropsy disclosed an isolated membranous VSD that had closed spontaneously by the adhesion of the septal tricuspid valve leaflet to the margins of the defect (Figure 1). A small, thin layer of fibrous tissue presumably produced by the left-to-right shunt jet flow through the VSD was present on the mural endocardium in the right ventricular outflow tract in apposition to the “VSD.”

Table 1.

Certain clinical and necropsy findings in the two white men with a membranous ventricular septal defect that was closed by two different mechanisms

Variables	Patient 1	Patient 2
Type of closure	Spontaneous	Surgical
Age (years) at examination of heart	71	48
Age (years) at surgical closure of VSD	–	5
Body mass index (kg/m2)	44.5	19.8
Precordial murmur	0	+
Heart block	Complete	–
ICD/pacemaker	+	+
Died	+	0 (Transplant)
Heart weight (g)	515	600
Myocardial infarct	0	+*
Heart floated in formaldehyde	+	0

^*Secondary to operative damage of the left circumflex coronary artery at the time of mitral valve replacement for severe mitral regurgitation at age 32.

ICD indicates implantable cardioverter defibrillator; VSD, ventricular septal defect; –, not available.

Figure 1.

Case 1. Photographs of the basal portion of the heart. (a) Membranous ventricular septal defect (VSD) located immediately below the right aortic valve cusp was spontaneously closed by the septal tricuspid valve leaflet. (b) A close-up of spontaneous closure of VSD showing the adherence of the tricuspid valve leaflet (arrow) to the margins of the defect and a dead-end tunnel-like space between the top and bottom portion of the defect. AML indicates anterior mitral leaflet; ATL, anterior tricuspid leaflet; AV, aortic valve; PML, posterior mitral leaflet; RV, right ventricle; STL, septal tricuspid leaflet; VS, ventricular septum.

Patient 2 had an atrioventricular canal defect, which was closed at age 5 years. At age 31 years, he was found to have severe mitral regurgitation and underwent mitral valve replacement with inadvertent left circumflex coronary artery injury, resulting in one-vessel coronary artery bypass grafting. He developed heart failure symptoms at age 47 and underwent heart transplantation a year later. Pathologic examination of the native heart revealed the surgically closed previous membranous VSD (Figure 2).

Figure 2.

Case 2. Photographs of the basal portion of the heart. (a) Membranous ventricular septal defect (VSD) located immediately below the right aortic valve cusp was closed surgically at age 5 years. (b) A close-up of the surgically closed VSD shows a Teflon patch (arrow) located at the junction of the anterior and septal tricuspid leaflet just below the aortic valve. (c) A deeper cut of the surgically closed VSD shows the relation of the “defect” to the aorta and aortic valve. ATL indicates anterior tricuspid leaflet; AV, aortic valve; LV, left ventricle; STL, septal tricuspid leaflet; TV, tricuspid valve; VS, ventricular septum.

DISCUSSION

Both patients presented in this report had VSDs located immediately caudal to the right aortic valve cusp. One closed spontaneously and the other by operative insertion of a patch. Spontaneous closure of VSD appears to be much more common than operative closure. Although this report focuses exclusively on the membranous location of VSD, muscular VSD, although much less common than the membranous variety, probably has a higher rate of spontaneous closure than does the membranous variety. The result of spontaneous closure can easily be missed at necropsy if the entire ventricular septum is not carefully examined.