Discussion
VSD is one of the most common congenital heart diseases, accounting for up to 40% of all congenital cardiac malformations[5]. Because of fetal heart color Doppler ultrasound screening and heart murmurs after birth, most VSDs are detected at birth and are treated in infancy and early childhood. Only a small percentage of these patients are re-tested in adulthood, either because VSD was not detected at birth as a result of relatively low screening levels for congenital cardiac disease decades ago, or because surgery was delayed for financial reasons. Because of most patients being asymptomatic, these patients were found to have VSDs in the course of college entrance examinations or orientation medical examination in China. With the rapid development of endoscopic technology over the past ten years, increasing numbers of patients begin to choose this minimally invasive technique. In addition, compared with conventional surgery and thoracotomy, total thoracoscopic technology is favored by patients because there is no metal implant and there is not much trouble on physical examinations at the company or security check at airports or railway stations. Results of conventional surgical VSD patch closure are excellent with low operative mortality and morbidity. Patients undergoing VSD repair are younger and relatively healthier than other patients undergoing cardiac surgery, and they are interested in more cosmetically appealing incisions. Nevertheless, they doubt that the less invasive approach provides cosmesis at the expense of the excellent outcomes typical of conventional surgery[6].
The total thoracoscopic technique, with or without robotic surgery, has been widely used for ASD repair, VSD repair, mitral valve repair or replacement, tricuspid valve repair or replacement, ablation of atrial fibrillation, resection of cardiac myxoma, and even coronary bypass grafting[7-12]. However, in China, because robots are expensive, only a handful of hospitals have robots to perform surgery. Chinese surgeons tried to perform total thoracoscopic procedures without the aid of robots. At present, almost all clinical studies have shown that the mortality and complication rates of total thoracoscopic surgery are not inferior to those of median thoracotomy, and the former affords less bleeding, faster recovery and less trauma. Our institution’s comparative outcomes also support the conclusion that total thoracoscopic VSD repair results in similar excellent results as those of mini-sternotomy. Although the mean CPB and ACC time in the total thoracoscope group were significantly longer than those of the mini-sternotomy group, few postoperative complications were suffered in the thoracoscopy group. Although the difference in tracheal intubation time, ICU time, postoperative hospital-stay time and chest drainage did not reach statistical significance, these variables tended to be lower in the thoracoscopy group, which possibly demonstrating the superiority of less bleeding, faster recovery and less trauma.
Our institution believes that the perimembranous, membranous or inlet VSD are more suitable for total thoracoscopic surgery. If pouch formation of the septal leaflet of the tricuspid valve or multiple chordae tendineae cross over the defect, the detachment of septal leaflet of tricuspid valve is performed to expose these VSDs. Perhaps traditionalists remain concerned that detachment may increase the incidence of iatrogenic complications such as atrioventricular conduction block and tricuspid valve insufficiency. However, tricuspid valve detachment has been previously shown excellent outcomes[13-16]. Our results also suggest the detachment was a safe and effective technique. Twenty-four patients underwent tricuspid valve detachment in our study and none showed atrioventricular conduction block or tricuspid regurgitation. By contrast, outlet ventricular septal defects are difficult to expose in the visual field of the thoracoscopic approach, and the surgical instruments are usually not long enough because of the depth of the thorax in adults. Muscular VSDs are usually situated near the apex and often have many outlets on the right ventricular side. As a result, if thoracoscopy is used, residual shunt is more likely to occur, so muscular ventricular septal defects are more suitable interventions[17, 18].
Total thoracoscopic surgery is not available for all patients. If patients have concomitant thoracic deformities, pleural adhesions, femoral artery or aortic malformations, severe aortic atherosclerosis, or other cardiac malformations (patent ductus arteriosus, persistent left superior vena cava), total thoracoscopic surgery is not appropriate. At our institution, if thoracoscopic surgery is required, thoracic CT and total aortic CT should be performed before surgery to exclude these concomitant diseases, so as to avoid intraoperative transition to surgery due to severe pleural adhesions, or failure to perform peripheral femoral arteriovenous cannulation due to femoral artery malformation, or aortic dissection due to severe aortic atherosclerosis.
Of course, total thoracoscopic surgery is not without its disadvantages and limitations. Although total thoracoscopy reduces the incision and trauma in the chest, it increases use of neck and groin vessels, thereby increasing the risk of peripheral nerve or vessel injuries such as femoral arteriovenous stenosis, femoral arteriovenous fistula, femoral nerve injury, and jugular arteriovenous fistula. Attention should be paid to vascular dissociation and vascular puncture and intubation operation to avoid injury. The intubation operation should be soft, and if the operation run into resistance, forced insertion should not be carried out to avoid vascular injury or even femoral artery dissection. There was one case of retrograde aortic dissection caused by femoral artery cannulation in our center in the early stages of total thoracoscopic surgery. In addition, due to the need for double lumen endotracheal tube intubation with a transient single lung ventilation strategy in total thoracoscopic surgery, postoperative atelectasis or pneumothorax often occurs.