At present, existing studies have summarized the minimally invasive closure of transthoracic ventricular septal defect. Xu and colleagues  have reported a series of 235 cases of minimally invasive closure of transthoracic ventricular septal defect of children with a success rate of 94.9%, Chen and colleagues reported 1090 cases of minimally invasive closure of transthoracic ventricular septal defect with a success rate of 94.8%. They all concluded that the method is safe and reliable. Our research further confirmed their conclusions. However, there is no research to thoroughly explore the postoperative complications of this operation and the corresponding risk factors. This study further summarizes and analyzes the postoperative complications of patients with minimally invasive closure of transthoracic ventricular septal defect. Postoperative complications include long-term hospitalization after operation, residual shunt and serious adverse events, the corresponding risk factors were analyzed.
cAVB is one of the serious complications. There are early literature reports that the incidence of this complication accounts for 1–5% of patients undergoing interventional closure of ventricular septal defect [7–9]. Chen's study shows the incidence of this complication accounts for 1.6% of patients undergoing minimally invasive closure of transthoracic ventricular septal defect , our research shows it is 0.9%. According to the report of Zhou , the possible cause of cAVB is the result of mechanical damage caused by the catheter or the occluder itself. Compared with interventional closure of ventricular septal defect, minimally invasive closure of transthoracic ventricular septal defect has a shorter transmission path, which affects the conduction system. The potential risk of mechanical damage to the conduction system is smaller, so the incidence of cAVB will be lower. Aortic regurgitation is another serious complication. Fang reported that no moderate to severe aortic regurgitation was found after traditional surgical repair. Our study showed that 2 patients had moderate to severe aortic regurgitation during the postoperative and follow-up period and were treated again by surgery. Considering that the lower edge of the aorta of VSD is short and the distance between the occluder and the aortic valve is close, the eccentric surface of the occluder is adjusted to the apex during the operation to avoid the occurrence of aortic regurgitation in the VSD near the aortic valve.
As one of the important indicators to evaluate the effect of surgical treatment of ventricular septal defect, residual shunt has received extensive clinical attention. In this study, 15.8% of patients were found to have residual shunts after surgery. All patients were followed up for 1 year. Except for 4 patients who were lost to follow-up, 2 patients had residual shunts, and the remaining shunts were closed spontaneously. Deng  reported that the incidence of residual shunt after repair of ventricular septal defect under cardiopulmonary bypass was 31.2%, Dodge-khatami  reported 35%; Mahimarangaiah reported the incidence of residual shunt after interventional closure of ventricular septal defect by percutaneous puncture was 29.4%, and Bai  reported that it was 6.8%. Our results are similar to previous studies, and all the residual shunts found are low-to-moderate, and there is no need for additional surgical intervention after surgery and follow-up.
Long-term hospitalization, residual shunt, and serious adverse events are considered to be important indicators of postoperative complications . For these indicators, we analyzed their corresponding risk factors. In our study, serious adverse events occurred in 3.3% of patients, including 1 patient who had mechanical hemolysis after surgery and 2 patients who underwent surgery for moderate to severe aortic regurgitation. 2 patients who had cAVB after operation, 3 patients who underwent pericardiocentesis due to moderate to severe pericardial effusion after operation. Because of the rarity of serious adverse events in our study, we only performed a univariate logistics regression. Previous studies believed that low body weight was a risk factor of serious adverse events and prolonged hospital stay after traditional surgical repair  .However, our results showed that no risk factors related to transthoracic closure were found, so we believe that for transthoracic closure, patients with low body weight are not at greater risk of serious adverse events after surgery. This study shows that the risk factors of early residual shunt after minimally invasive closure of transthoracic ventricular septal defect are related to the size of the occluder. The specific reason is not clear and needs to be further studied in the future. Long postoperative hospitalization is related to the size of the VSD defect. The main reason for the prolonged postoperative hospital stay is respiratory tract infection. We believe that the larger the VSD defect, the greater the left to right shunt flow in children and the worse the cardiopulmonary function, the greater the difference in hemodynamics after the operation, the immune function of the body will be further reduced, and the postoperative hospital stay will be further prolonged.
At present, for minimally invasive closure of transthoracic ventricular septal defect, the largest report we have known is Chen's analysis of the efficacy of 1090 patients, but there is no research specifically to discuss and summarize the postoperative complications and risk factors of this operation. We evaluated the complications of the operation based on the three indicators of postoperative hospital stay, residual shunt and serious adverse events and analyzed their risk factors separately. However, due to the rarity of serious adverse events, we only performed a univariate logistics regression on them. In future research In order to truly determine its risk factors, a multicenter and larger sample size study should be conducted.