The problem of bridge vessel restenosis after coronary artery bypass surgery has always been a prominent problem for clinicians and patients. Due to bridge vessel restenosis, many patients soon develop angina pectoris again within a short period of time, and even serious events of myocardial infarction occur. Many studies have shown that arterial graft materials, such as internal mammary artery and flexural artery, have good long-term patency rates, exceeding 90% 10 years after surgery. In contrast, the most commonly used and most used saphenous vein has a 10-year patency rate of less than 50%. Therefore, we strongly recommend the use of more arterial grafts, especially the use of the flexural artery as a routine. There are many causes of saphenous vein stenosis, and thrombosis is the main cause of stenosis within the early postoperative period (1 month). Early stenosis can be caused by damage to the vessel due to improper extraction, poor quality of the vessel itself, mismatch with the caliber of the coronary artery, or reduced intravascular blood flow due to narrowing of the anastomosis. The saphenous vein begins to show intimal hyperplasia and fibrosis 1 month after surgery, with a 30% reduction in caliber within 1 year. 1 year later the saphenous vein shows signs of atherosclerosis. As a result of stenosis of the saphenous vein bridge, what the clinician needs to do is to slow down the development of stenosis as much as possible, first of all, to operate carefully and gently to avoid damaging the graft, to select the right target vessel and anastomosis location, to make sure that the anastomosis is as open as possible. Avoid twisting, too long or too short bridge vessels. Secondly, use anticoagulants as early as possible, start using aspirin when it can be taken orally after surgery, some units routinely use heparin anticoagulation after surgery, if not much drainage can be used. Third, strict control of blood pressure, blood sugar and lipids. Many studies have shown that high blood lipids are the main risk factor for the occurrence of in stenosis in graft vessels. The higher the cholesterol level, the greater the chance of re-bypass. Hypertension, hyperglycemia, and smoking are all risk factors for atherosclerosis, but there is no clear evidence that restenosis of the bridge vessel is directly related to these conditions. However, in view of the pathological changes of the saphenous vein in the late stage of bypass, it is recommended that hypertension and hyperglycemia should also be given high priority. In addition obese patients need to lose weight and exercise. It is also important to keep a happy mood. When do I need to visit the hospital after bypass surgery? Patients using lipid-lowering drugs and glucose-lowering drugs need to monitor their liver and kidney functions and blood sugar levels. Patients using lipid-lowering drugs and glucose-lowering drugs should have their liver and kidney function and blood sugar levels monitored. If there is no special cardiac condition, patients can come to the hospital for follow-up ultrasound, electrocardiogram, chest X-ray and other routine items three months after discharge. If chest tightness, breath-holding, arrhythmia, or angina attack occurs during discharge, it needs to be taken seriously and timely consultation.