OBJECTIVEPerimembranous ventricular septal defects (PMVSDs) is the most common type of congenital ventricular septal defects (VSD), which accounts for 70% approximately 80% of VSD. The structure of PMVSDs is very complex, it is close to tricuspid valve, mitral valve and aortic valve. The atrioventricular (AV) node is located in the posterior upper membranous ventricular septum and branches into left and right bundle in the posterior lower margin. This increases the risk of transcatheter closure of PMVSDs. Arrhythmias is the common complication after transcatheter closure of PMVSDs. The present study aimed to identify the risk factors resulting in arrhythmias after transcatheter closure of PMVSDs in patients under 18 years of age to decrease the incidence of arrhythmias after the interventional catheterization.

METHODSA retrospective analysis was performed on the patients treated with transcatheter intervention from June 2002 to June 2004. Transcatheter closure of PMVSDs with Amplatzer membranous septal occluder and a domestic product was performed in 89 cases after obtaining consent themselves and/or their guardian or parents, 47 cases were males and 42 females. The age of the cases ranged from 3 to 18 years (mean 8.2 years) and the body weight ranged from 13 to 55 kg (mean 26.7 kg). They were all diagnosed as having PMVSDs with trans-thoracic echocardiography (TTE) before the interventional catheterization, the electrocardiographic (ECG) and chest X-ray (CXR) findings were recorded. A simultaneous care ECG and TTE were performed during operation in order to identify the effect of the transcatheter closure, the heart structure and functional changes and whether or not arrhythmias occurred, respectively. In 80 cases AGA Amplatzer membranous septal occluder was used and in 9 cases a domestic product was used. Follow-up was performed based on the echocardiography and ECG.

RESULTSThe devices were successfully implanted in 89 cases; 11 cases (12%) developed various block of heart conduction within 5 days, which included first degree AV block in 1 patient, third degree AV block in 1, left anterior bundle branch block in 5, partial right bundle branch block in 4, complete right bundle branch block in 3, and 3 patients had two kinds of heart block. Eight patients were treated with corticosteroids, 6 of them recovered within 14 days, 1 patient within 1 month and in 1 case the problem shifted from first degree block and left anterior bundle branch block to left anterior bundle branch block 5 days later and that persisted for 6 months. It was found that the distance from upper margin of defects to the aortic valve < 3 mm, the diameter of ventricular septal defect > or = 8 mm, the diameter of device > or = 10 mm, blood pH < 7.35 and arteriovenous track building time after the success of the Seldinger technique > or = 60 min were independent predictors of post-closure arrhythmias.

CONCLUSIONArrhythmias remain the severe early complications after interventional catheterization for PMVSDs in patients under 18 years of age. Shortening of operation time, prevention of acidosis and strict selection of indications may be the most effective measures to prevent arrhythmias after transcatheter closure of PMVSDs in patients under 18 years of age.