Third-degree conduction block is a complication of congenital heart disease treatment. Although the incidence is low, the consequences are extremely serious and these patients often require permanent pacemakers, which can cause major inconvenience later in life. Third-degree conduction block is caused by surgical procedures and medical and surgical interventions that damage the conduction bundle, respectively. Here I will talk about this aspect based on many years of work experience, so that patients can have an understanding of the treatment of precordial disease. The incidence of third-degree conduction block due to surgical procedures Cardiac surgery has a great relationship with the operator’s surgical experience, a more specialized precardiac surgeon and a higher level of hospital, the incidence of this complication will be lower. In earlier years, the incidence of third-degree conduction block was higher due to the lack of experience and knowledge in the treatment of precordial disease and the fact that the instruments and sutures used in surgery were not as fine as they are now and the surgery was more traumatic, but today, the incidence of this surgical complication is extremely low for an experienced precordial surgeon. For temporary injury, such as myocardial edema and myocardial strain during surgery, normal sinus rhythm will generally be restored within 2 weeks, and if normal sinus rhythm cannot be restored after 2 weeks, the injury is generally permanent and a permanent pacemaker is required. Second, the third degree conduction block caused by minimally invasive surgical and medical interventions Internal blocking treatment of many kinds of precordial disease, its advantage is no surgical incision, no surgical scar, but its disadvantage is the treatment under X-ray, the patient will be damaged by radiation; In addition, due to the difficulty of internal blocking operation, in order to prevent the blocker from falling off, the blocker selected is larger, especially in blocking treatment of precordial ventricular septal defect, the occurrence of The incidence of third-degree conduction block is higher. In recent years, in order to avoid third-degree conduction block, the surgeons of precordial disease have researched and developed the method of surgical minimally invasive blocking for the treatment of precordial disease, which is performed under the guidance of esophageal ultrasound, avoiding radiation damage. In addition, if the block is found to be inappropriate after blocking, the treatment can be changed to surgical repair in time. Third, the prevention of blocking interventions caused by third degree conduction block methods and treatment Minimally invasive treatment of precardiac disease is the development direction of the treatment of precardiac disease, and the complications of third degree conduction block is a problem that we must pay attention to, one is that we must strictly grasp the indications when choosing blocking treatment methods for precardiac disease, and at the same time try to choose minimally invasive treatment methods with fewer complications. In recent years, I have surgically removed the blocker for a number of patients with third-degree conduction block in ventricular septal defect treated by internal blocking, and fortunately these patients eventually recovered normal sinus rhythm, which also shows that for third-degree conduction block caused by interventional treatment, timely surgical removal of blocker is effective and should be actively carried out without hesitation, and also shows that blocking treatment for precordial disease, especially ventricular septal defect, is more effective than other treatments. It also shows that blocking has a good prospect for the treatment of precordial disease, especially ventricular septal defect. In conclusion, it is difficult to completely avoid the occurrence of serious complications of third-degree conduction block in the treatment of precordial disease for many reasons, but understanding the causes and avoiding them can reduce the risk of occurrence.