Warfarin (Warfarin) is a very important drug that is often used after heart surgery valve surgery. Warfarin is a derivative of coumarin that competes with vitamin K and interferes with the latter’s anticoagulant effect in the synthesis of coagulation factors in the liver. After heart valve surgery, the foreign prosthetic valve comes into direct contact with the blood, is traumatized, and loses endothelial cell-covered tissue exposed in the vascular lumen or in the heart chambers, all of which can lead to thrombus formation in the heart and on the prosthetic valve. Therefore, all valves require some intensity of anticoagulation therapy after valve surgery. However, anticoagulation therapy with warfarin is a double-edged sword; when used well, it can effectively prevent thrombus formation; when used poorly, for example, in insufficient doses, thrombus remains formed; when overdosed, it can trigger fatal bleeding. Therefore it has a very narrow therapeutic window and requires close monitoring of the anticoagulation strength of warfarin, an indicator known as Prothrombin Time (PT). There are 3 ways to report PT in the laboratory: Prothrombin Time in seconds; Prothrombin Time Activity Percentage (PTA) in percent; and International Normalized Ratio (INR). The INR is now referred to in anticoagulation therapy for the prevention of thrombosis after cardiac surgery, and it eliminates the variation in the activity of different batches of test reagents. This test is not complicated and is one of the basic clinical tests performed in hospitals. In addition, this test does not require fasting before the blood is drawn, and eating has no effect on the test results. What should be the appropriate anticoagulation level for the national population? There is only one standard for anticoagulation therapy, which is to minimize the risk of bleeding while ensuring that no thrombosis occurs. The likelihood of thrombosis varies from patient to patient. Patients with mechanical prosthetic heart valves are more likely to thrombose than patients with pure atrial fibrillation without valve disease; the incidence of thrombosis is higher in the mitral valve position than in the aortic valve position. The degree of anticoagulation in the event of thrombosis and bleeding may also be different in different patients. Asian populations are less likely to have thrombosis at lower levels of anticoagulation and more likely to have bleeding at higher levels of anticoagulation than whites and blacks. Therefore, compared with foreign guidelines, the anticoagulation target value for national population should be adjusted appropriately. 1.If it is after simple aortic valve replacement, INR should be kept at 1.5-2.3; 2.If it is simple mitral valve or aortic valve plus mitral valve, INR should be kept at 1.8-2.5; 3.If there is tricuspid prosthetic mechanical valve, INR should be kept at 2.0-2.5; 4.Use of biological valve, or implantation of valvuloplasty ring in mitral or tricuspid valve position, 3 months after surgery Warfarin anticoagulation must be administered within 3 months after surgery, and the INR should be maintained at 1.5-2.0. Of course, if the patient’s INR is within the target window and bleeding from the conjunctiva, gums, etc., or excessive menstrual flow still occurs, it can be appropriately adjusted downward, and if an embolic event or a history of previous embolism occurs within the target window, it can be appropriately adjusted upward. Consultation with the surgeon or an experienced clinical pharmacist is recommended for specific situations. How should patients administer their own anticoagulation therapy? Patients who require warfarin anticoagulation should start taking oral warfarin as soon as the tracheal tube is removed and the patient is able to drink after surgery. The doctor should adjust the warfarin dosage according to the daily examination results in order to achieve the desired anticoagulation intensity as soon as possible and to achieve a relatively stable warfarin dose before the patient is discharged. Dosing schedule: Patients are advised to take their medication at night on a daily basis. This has two advantages. One is to go to the hospital to check the INR are in the morning, get the results may be noon, there may be questions to consult with the doctor, it is possible that the final decision to take the dose of medication has been to the afternoon. If you take the medication in the morning or morning, the dose is not appropriate, but already taken, can only be adjusted the next day, inconvenient. The second is to take the medication at a fixed time, in the long run, to develop a habit, will not miss the dose. In general, the increase or decrease of warfarin in 1/4 tablet, the need to increase or decrease half a tablet or one tablet per day is rare. If warfarin fluctuations are not too great, our experience tends to be that 3 days is used as a cycle to adjust the warfarin dose. In the initial phase of discharge, labs are usually needed once every 3 days to 1 week, and if the INR is stable after a month, labs can be done every 2 weeks. If the INR and warfarin dose remain stable after an extended interval of testing, then monthly testing can be performed. We strongly recommend that patients have monthly tests thereafter, and are highly critical of those who have tests only once every six months or even once a year. It is irresponsible to do that for one’s own life. At present, there are two main types of commercial warfarin available on the domestic market. The most widely used is the domestic warfarin, white sugar-coated tablets, each tablet 2.5 mg. its advantage is the source of stable, inexpensive, the disadvantage is the accurate division of the difficulties, the drug is once a little worse. The second is the imported Warfarin manufactured by Orion of Finland. This brand has a variety of doses of tablets, the Chinese market is currently selling the blue 3mg tablets. The advantages of this drug are that it is easy to be divided accurately and the homogeneity of the drug is good. The disadvantages are that the source is unstable, it is not available in many cities in China, and the price is slightly higher. If a patient is taking a particular type of warfarin, it is best not to change it easily. Drug changes may result in large changes in anticoagulation strength, and clinical complications of anticoagulation due to drug changes are not uncommon. If a change is necessary, the INR should be tested daily for one to two weeks after the change until the value reaches the therapeutic range. What if I miss a dose of warfarin? It does not matter. Simply continue the regular dose of the same day the next day and no additional dose is needed. What should I do if I overdose on warfarin? Symptoms of warfarin overdose are a variety of bleeding manifestations. Symptoms of bleeding, such as continuous wound bleeding, vomiting blood, tarry stools, muscle hematomas, bruising under the skin, hemiplegia or coma, should be seen immediately regardless of the INR value. What factors can alter the anticoagulant effect of warfarin? Some foods can have an effect on the effect of warfarin anticoagulation therapy. However, we recommend not to pay attention to this aspect as long as you keep the type of food constant and eat normally. Some proprietary Chinese medicines and so-called herbal supplements also tend to have a greater effect on warfarin, and there is no evidence-based medical proof of the efficacy of these drugs, so they are not recommended. There are a number of drugs that affect the anticoagulant effect of warfarin, and their mechanisms are complex. For the sake of simplicity, we have divided these drugs into two categories. One category is the drugs that can enhance the anticoagulant effect of warfarin, the most common of which is acetaminophen, including Benadryl and Tylenol, which are commonly used to reduce the symptoms of colds, and many cold medicines contain such ingredients. Therefore, patients taking warfarin should use these drugs or compounded preparations containing such ingredients with caution when they have a cold. Aspirin is a drug commonly used by heart patients, which can enhance the anticoagulant effect of warfarin (first, its anti-platelet aggregation effect is superimposed on the anticoagulant effect of warfarin, and second, it competes with warfarin for plasma protein binding in the blood, which increases the free degree of warfarin and indirectly increases the dose of warfarin). If aspirin is taken concurrently with warfarin, patients are advised to keep the dose of aspirin constant and to monitor the INR at the beginning of the coadministration until it stabilizes. Broad-spectrum antibiotics can enhance the anticoagulant effect of warfarin. In addition to factors such as affecting the metabolism of warfarin, antibiotics can inhibit intestinal flora, reducing the production of vitamin K by intestinal bacteria and reducing the source of vitamin K in the body. Among the commonly used cardiovascular drugs, diltiazem (Hersinol), etanercept (Kotarolone) and statin lipid-lowering drugs increase the anticoagulant effect of warfarin. The antimycotic drug fluconazole (Daifukang) can also enhance the anticoagulant effect of warfarin. The second group of drugs that can diminish the anticoagulant effect of warfarin are relatively few, except for preparations containing vitamin K. Commonly used are ribavirin, rifampin, abciximide, carbamazepine, barbiturates, and mesalazine. In conclusion, the instructions of other drugs should be read carefully before taking them and, if needed, the frequency of INR testing should be increased during the course of administration. What happens when surgery is required elsewhere in the body during warfarin anticoagulation therapy? For some minor outpatient procedures, non-invasive examinations (e.g. general gastroscopy, colonoscopy, no biopsy), warfarin can be stopped without. For some minor surgeries with high chance of bleeding, such as tooth extraction, skin and finger minor surgeries, gastroscopy and colonoscopy containing biopsy or treatment, warfarin can be stopped for 3-4 days without heparin replacement therapy. For some major procedures, warfarin needs to be discontinued 3-4 days before the procedure. 5,000 units of low molecular heparin are administered subcutaneously over 12 hours during this time, and heparin is discontinued 24 hours before the procedure. On the second day after surgery, if there is little drainage, start low molecular heparin immediately at the same dose and in the same way as before, and start warfarin at the same time until the INR reaches the prescribed anticoagulation strength and then stop heparin. In case of emergency surgery, vitamin K1 can be administered intravenously before surgery or fresh frozen plasma can be transfused.