[show abstract][hide abstract] ABSTRACT: Using an Amplatzer membranous eccentric occluder, 186 patients with an average weight of 43.5 kg (range 12.5-77) underwent attempted catheter closure of a perimembranous venricular septal defect (PMVSD). Their age ranged from 3 to 51 years, with the an average age being 15.9 years. The patients were divided into three groups according to morphology of PMVSD: 106 patients with single PMVSD, 63 patients with single PMVSD with aneurysmatic formation, and 17 patients with multiple VSD with aneurysmatic formation. Using angiography, PMVSDs were measured to be between 2.5 and 12 mm, with an average of 5.1 mm. In the third group of patients, we did not measure the size of PMVSD and a device was selected according to the size of entry to the aneurysm. The device was successfully implanted in all patients. The immediate closure rate was 90% in the first group, increasing to 100% at 1 month and remained at that level during follow-up. The immediate closure rate in the second group was 98% and remained the same during follow-up. The immediate closure rate in the third group was 89% and during 1 year of follow-up remained the same. There was no clinical evidence of hemolysis and no incidence of device embolization or bacterial endocarditis after implantation. Before the procedure, all patients showed normal electrocardiogram (ECG) or left ventricle enlargement. After the procedure (at least 3 months later) ECG showed left anterior hemiblock (LAH) in nine patients, complete right bundle branch block in eight patients, and incomplete right bundle branch block in seven patients. A complete heart block (CHB) developed in 2 patients after the procedure (1.07%). The first patient developed LAH immediately after closure and CHB within 24 hours, The heart rate was 28 beats per minute. After treatment with steroids and atropine, CHB changed to sinus rhythm with LAH within 2 months. One year later, the ECG revealed the same findings. The second patient developed CHB immediately after the procedure and was on temporary pacing for 1 week. After 1 month, the patient recovered to sinus rhythm and ECG showed LAH.