Objective To summarize the technique and clinical experience of hybrid procedure under cardiopulmonary bypass (CPB) in children with muscular ventricular septal defect (mVSD). Methods From January 2006 to June 2010, 45 cases of mVSD underwent hybrid procedure with CPB. mVSDs were closed with devices under direct vision in 45 cases. Of them, there were 20 males and 25 females. They ranged from 52 days to 12 years [mean (2.05 ±2.48) year] in age and from 3 to 30 kg [(11.93 ±7.70)kg] in body weight. Preoperatively, most of children were highly susceptible to respiratory tract infections. The hybrid approach was used in all patients with CPB under the guidance of transesophageal echocardiography (TEE). The diameter of mVSDs ranged from 2 to 7 mm under TEE. Of 45 cases, 40 patients had increased rates of pulmonary blood flow. 29 patients had left axis deviation and 12 cases had sinus arrhythmia on electrocardiography (ECG). 19 had other congenital heart lesions, including transposition of great arteries in 1 case, tetralogy of Fallot in 2, pulmonary artery stenosis in 3, patent ductus arteriosus in 6, atrial septal defects in 6) and aorta coactation in 1. The quantity of VSDs were from 1 to 7 (single, in 7; two, in 24 case; three, in 8 case; four, in 5 case and seven, in lease. 37 patients were combined with pulmonary hypertension in our cohort. 38 patients with another large VSD and 19 with other congenital heart lesions were required surgical repair at sometime. Results The hybrid procedures were undertaken in all 45 cases of this cohort. All cases were successful and no deaths occurred during operation. A total of 48 devices were implanted in 45 patients, including single devices in 42 cases (device size ranged from 4 to 10 mm) and two devices in 3 cases (device size ranged from 4 -7 mm). The average time on CPB was (58.28 ±20.70) min , while aortic crossclamp time was(34. 94 ± 14.75) min. In addition, the time on mechanical ventilation postoperatively ranged from 2 hours to 6 days. Compared to the older children, 20 infante aged less than 8 monhad a significant difference in cardiac function in the early postoperative period. One infant was given up treatment because of serious infection. Anather cases recovered with the use of supportive treatment, such as using vasoactive agents, digoxin, inhaling nitric oxide, diuresis, and so on. The enteric-coated aspirin was given at dose of 5 mg ? kg -1. day -1 for a period of 3 to 6 months as usual postoperatively. All patients attended follow-up at 1 week, 1 month, 3 months, 6 months, 1 year and 2 years post-procedure. No major complications were encountered during this period. All cases were no instance of migration of any of the devices, residual shunt, aortic regurgitation, atrioventricular valve dysfunction, Ⅲo atrial-ventricular conduction block, new arrhythmia, and so on. There are no death in long-term follow-up. Conclusion Hybrid procedure is safe and effective for the closure of congenital heart defects in children.