Aneurysm of the membranous septum in adult patients with perimembranous ventricular septal defect.

OBJECTIVE The aneurysm of the membranous septum (AMS) has often been considered as benign in the minds of many previous investigators. We have analyzed the complications with AMS in adult patients. METHODS Fifty-one cases (20%) of AMS in 254 adult patients with perimembranous ventricular septal defect (VSD) are described. The diagnosis of AMS was based on angiographic criteria. Thirty-nine (76.5%) of the 51 patients with AMS were aged between 20 and 29 years. All patients but one with AMS had a pulmonary-to-systemic flow (Qp/Qs) of less than 2.3 (range 1-2.1, mean 1.4). In a patient who had a ruptured aneurysm, the Qp/Qs was 2.7. There were six main complications affected by AMS and/or VSD; aortic valve prolapse in 24 patients (47%), aortic regurgitation in 15 (29.4%), tricuspid insufficiency in nine (17.6%), right ventricular outflow tract obstruction in two (4%), and rupture of the aneurysm in one patient (2%). Seven patients (13.7%) had prior bacterial endocarditis. All patients underwent surgery. Aneurysm and VSD were closed by direct suture in nine and with a patch in 42 patients. Aortic valve repair was performed in 13 patients in whom regurgitation was mild to moderate, and replacement was required in two patients with severe aortic regurgitation. RESULTS There were no early or late deaths. Residual communication and recurrence of the aneurysm was noted three and seven years postoperatively in two patients where VSD had been closed by direct suture. CONCLUSIONS According to present data, aneurysm formation functionally reduces the VSD size, but it has the potential consequence of promoting tricuspid insufficiency, aortic valve prolapse, right ventricular outflow tract obstruction, rupture and bacterial endocarditis. Therefore, we recommend that AMS should be resected completely and the defect produced closed with a patch in order to prevent further enlargement and consequent complications even if there are no cardiac symptoms.