This retrospective, descriptive, non-randomized study utilized data from January 2011–December 2015 from a single medical center (The Second Affiliated Hospital and Yuying Children’s Hospital, Institute of Cardiovascular Development and Translational Medicine, Wenzhou Medical University, Wenzhou, Zhejiang). Two hundred fifty-three patients (126 males, 127 females) were included (Table 1, Additional file 2: Table S2). Informed consent was obtained from all patients or their parents. All patients had clinical and echocardiographic evidence of ventricular septal defect (VSD). The position and distance between each valve and the defect should be carefully assessed preoperatively using echocardiography.

According to the guidelines for interventional therapy via catheter for congenital heart disease, all patients underwent combined intravenous anesthesia and were monitored via electrocardiogram and blood pressure and oxygen saturation measurement. The peritoneal inguinal puncture site was anesthetized locally with 2% lidocaine, and the femoral vein and femoral artery were punctured. Left and right cardiac catheterization and left ventricular and ascending aortic angiography were performed to determine the size, location, shape, and distance from the aortic valve of the defect. The femoral artery, aorta, left ventricle, VSD, right ventricle, and femoral vein were identified. A long sheath was inserted into the left ventricle along the track from the side of the femoral vein, and then fed into the appropriate sealing device in an attempt to plug the defect. Generally, the sealing device must be 1–2 mm larger than the diameter of the defect. Following closure, the patient must be monitored closely for heart murmur via auscultation, left ventricular angiography should be repeated after 15 min to check for residual shunt, and root imaging should be used to assess the presence of aortic valve regurgitation and prolapse. Following successful closure, thoracic echocardiography (TTE) should be used to monitor the occluder location and sharp, and check for residual shunt and tricuspid valve, and to assess the movement of the aortic valve.

The following occluder devices were used (Tables 2, 3, 4 and 5): the Amplatzer Membranous VSD Occluder (AGA Medical Corporation) and Amplatzer-like occluders including Membranous Symmetric VSD Occluder (SHSMA Medical Corporation, China) and Cera™ Membranous VSD (Symmetric) Occluder (ShenZhen Lifetech Scientific Inc., China).

Immediately following the procedure, and in months 1, 3, and 6 and years 1, 2, 3, 4, and 5 of follow-up, the shape and orientation of the device and residual shunt were reevaluated through transthoracic echocardiography, electrocardiogram, and thoracic radiography.

Continuous data were expressed as means ± standard deviations with ranges and were compared using analysis of variance (ANOVA) and the student’s t-test, while categorical data are expressed as number and percentage, and were compared using the X²-test or Fisher method. All statistical analyses were performed using commercially available software (SPSS version 11.0 for Windows; SPSS Inc., Chicago, IL, USA). P values < 0.05 were considered to be significant.

The median age at implantation was 42 months (range 27–216 months) and the median weight was 14.75 kg (range 9.5–86 kg). All patients had continuous systolic murmurs and left-to-right shunts with enlarged left ventricular diastolic dimensions. No patient received diuretics or angiotensin-converting enzyme inhibitors before the procedure for there was not any grade II or higher cardiac dysfunction after preoperative evaluation. Transcatheter femoral venous and arterial approaches were used in all patients. The mean VSD size, measured echocardiographically, was 3.5 ± 1.4 mm. Pulmonary-to-systemic flow ratio (Qp/Qs) was 2.3 ± 0.4 (range 1.5–3.0). One patient with Down syndrome underwent transcatheter closure, and a residual shunt, hemolysis, and arrhythmia was found 24 h postoperative. A surgical operation was subsequently performed. (Tables 1 and 6, Additional file 3: Table S3).

In 252 of 253 (99.6%) procedures, defect closure was successful (Fig. 1). Stable device positioning was demonstrated by angiography and transthoracic echocardiography. Significant shunt reduction was detected in all 252 patients after successful VSD closure, and only minor residual shunts were documented. Procedural data are provided in Table 6. No increase in aortic or tricuspid valve regurgitation was observed postoperatively in any patient.

Pre-operatively, four patients had moderate tricuspid valve regurgitation and nine had mild aortic valve regurgitation. No significant increase or new regurgitation of the aortic or tricuspid valve occurred during or after the procedure. All cases of valve regurgitation had resolved without treatment at the 2-year follow-up evaluation (Fig. 2).

Closure was achieved with the device in all but one patient. In this case, echocardiography revealed a significant shunt at the center and edge of the occluder, and thoracic surgery was performed. Immediate complete occlusion, determine by angiography, was achieved in 38.6% of patients. Echocardiography performed 24 h postoperatively documented an occlusion rate of 86.6% (219 patients). Echocardiography confirmed the achievement of complete closure in the remaining patients, excluding the patient with a significant shunt described above, at 1 month (n = 11), 3 months (n = 3), 6 months (n = 7), 1 year (n = 1), and 2 years (n = 1) postoperatively. The occlusion rate at 2 years postoperatively was 96% (Fig. 3).

The cardiothoracic ratio decreased gradually from 1 to 24 months postoperatively, and had become stable by the 36-month follow-up evaluation (Fig. 4; Table 7). TTE was used to measure the tricuspid valve regurgitation pressure gradient (TR-PG) for the estimation of pulmonary artery pressure. A significant decrease was detected during follow-up (Table 7).

No death occurred. Arrhythmia was detected in 37 patients, hemolysis in 4, moderate tricuspid valve regurgitation in 4, and mild aortic valve regurgitation in 9 patients directly after implantation or during follow-up. No significant complication, such as procedure-related obstruction, cardiac tamponade, thrombosis or air embolism, aortic rupture, or increased valve failure, was observed. One significant complication occurred in a 3-year-old boy, who developed hematuria; significant shunt reduction and complete right bundle branch block were detected.

No significant hemolysis necessitating device retrieval occurred. Although four (1.6%) patients showed erythrocyte positivity (+++) on routine urine tests during the first 24 h postoperatively, the hemolysis was not sufficiently severe in any case to warrant retrieval of the device. Blood analysis showed high values for hemolysis parameters with no relevant decrease in the hemoglobin concentration. Hemolysis regressed by 5 days postoperatively with hydration and urine alkalization. Blood transfusion was not required in any case.

Minor arrhythmic complications occurred in 37 (17.4%) patients: 14 patients had incomplete right bundle branch block and were treated with a conventional dose of methylprednisolone (20–30 ml/kg/d), which was gradually tapered. 8 had complete right bundle branch block, 3 had left bundle branch block, and 12 had left anterior fascicular block. All patients had recovered, as demonstrated by ECG, at the 24-month follow-up evaluation.

Patients with right bundle branch blocks were treated with a conventional dose of methylprednisolone (1–2 mg/kg, q8h), which was gradually tapered. As left bundle and left anterior branch blocks have been reported to lead to death due to heart failure in China, the methylprednisolone dose can be increased to 20–30 mg/kg/d to relieve ventricular septal edema.

VSD closure with an occluder was performed successfully in 252 patient. The patients were followed for a median follow-up period of 36 months (range 6–60 months). And the 6 months of follow-up with clinical examination, chest radiography, TTE and ECG was completed in 250 patients (250/253), 1 year in 236 (236/243), 2 years in 190 (190/208), 3 years in 151 (151/169), 4 years in 101 (101/116), 5 years in 32 (32/45) (Table 8). There were 23 patients had lost at follow-up for the following reasons: surgical follow-up for operation, patients from migrant workers’ families going back to their household registration, contact information been replaced. In addition to 9 patients who changed contact information, none of the rest of the patients lost had significant complications such as death or syncope, and they had so far insisted on regular annual follow-up at local children’s heart centers or comprehensive large hospitals. Pre- and postoperatively, TTE was used to detect the tricuspid valve pressure gradient for the estimation of pulmonary artery pressure. TTE showed that the left atrium was reduced compared with preoperative, and gradually increased during follow-up. The TR-PG decreased significantly during the postoperative follow-up period. TTE showed that the LVEDd, RV, and LA had decreased at 3 days postoperatively, decreased further at 1–6 months postoperatively, and had regressed at the 12-month follow-up examination (Table 9).

Holter 24-h monitoring for patients with postoperative arrhythmias is superior to ECG follow-up. Very few patients lost follow-up. Lack of normal echocardiography control.