The Gerbode Defect: The Significance of a Left Ventricular to Right Atrial Shunt

Background: The so-called Gerbode ventriculo-atrial defect is a rare defect that permits shunting from the left ventricle to the right atrium. It takes 2 forms, either a deficiency of the atrioventricular membranous septum, or shunting initially through a ventricular septal defect, with atrial shunting occurring through a deficiency in the septal leaflet of the tricuspid valve. In this review, we describe the natural history and outcomes of surgical repair for the variant with shunting through a deficiency at the site of the atrioventricular membranous septum. Methods: From 1990 to 2008, we identified 6 patients from our departmental database who had undergone surgical closure of a congenital defect of the atrioventricular component of the membranous septum. Median age at repair was 1.6 years, with a range, from 0.4 to 19 years. All patients were symptomatic, with 3 having congestive cardiac failure, 2 failing to thrive, and 2 having intolerance to exercise. All had a dilated right atrium demonstrated by echocardiogram, with a mean preoperative gradient measured by echocardiogram to be 109 millimetres of mercury, with a range from 65 to 150 millimetres of mercury. Results: There was no operative or late mortality. The mean size of the defect was 6.2 +/- 2.0 millimetres, with a range from 4 to 8 millimetres. All were closed by insertion of a patch. The mean period of cardiopulmonary bypass was 90.5 +/- 11.3 minutes, the mean time of aortic cross-clamping 54.8 +/- 6.9 minutes, and the mean length of stay in hospital 4.3 +/- 1.0 days. No patient had a residual defect, and only trivial regurgitation of the tricuspid valve was evident by postoperative echocardiography. There were no complications or reoperations. Conclusion: The membranous ventriculo-atrial defect can be recognized echocardiographically on the basis of dilation of the right atrium in the setting of an unusually high Doppler echocardiogram gradient compared to the ventricular septal defect with shunting only at ventricular level. Since all patients in our series were symptomatic, we recommend surgical closure of all these defects.