1. Oral warfarin (3mg per tablet, made in Finland, blue color) for life after surgery for those who have mechanical flaps; oral warfarin for six months after surgery for those who have biological flaps. 2. The maintenance dosage of warfarin is around 3mg in most cases, which is adjusted according to the INR. 3. The international standard ratio (INR) or prothrombin activity is obtained through blood tests, and the oral dose of warfarin is adjusted according to the results of anticoagulation tests. The aim is to keep the INR between 1.8-2.2. When the INR is >2.2, reduce the oral dose of Warfarin. When the INR is 2.5, stop taking Warfarin on the same day, and then go to the hospital the next day for anticoagulation test, and then decide the oral dose of Warfarin according to the result. The amount of each addition or subtraction is usually 0.5-1mg (1/6/1/3 of a tablet). It is better to stay in Hangzhou for a period of time after discharge, and return to the local area after mastering the method of adjusting the oral dose of Warfarin. 4. The timing of laboratory tests; gradually extend the time between tests as follows: check the anticoagulation every other day after discharge, adjust the dosage according to the above method, when the INR stabilizes at 1.8-2.2, you can extend the time between tests to check the anticoagulation twice a week, adjust the dosage according to the above method, and when the INR stabilizes at 1.8-2.2, then extend the time between tests to check the anticoagulation weekly; when the INR stabilizes at 1.8-2.2, check the test every two weeks; more stable; more stable check every two weeks; more stable once a month. Stable is defined as three to four consecutive INR lab results between 1.8-2.2, no need to increase or decrease the oral dose of warfarin 5. Each lab result and oral dose of warfarin should be recorded in the table 6. If there is any bleeding or coagulation complications after discharge from the hospital, go to the local hospital. A complete examination, including echocardiogram, chest X-ray and ECG, should be done at 3 months after discharge.