... 10 to 15 years but the patient replacing with tissue valve are not require warfarin but they may be danger if they replace before the age of 50. Whereas mechanical valve are made from carbon and they are life long valve and there is no need for resurgery but they need warfarin and they cannot give a birth because giving birth is to dangerous so avoid of marriage. I know this from my dear aunty moirangthem thoibi and iam balchandnandeibam?