Generally, patients with valve replacement take between half a tablet and one and a half tablets of Warfarin, but individual differences are significant, so it is important to regularly review pt+a, monitor and adjust Warfarin dosage. It is recommended that patients with valve replacement have their pt+a reviewed every other day, and that Warfarin dosage be adjusted according to the inr and pt values, generally by no more than one-third of a tablet (i.e., 1 mg) each time. When the pt value and Inr results are stable, the interval should be changed to three or four days. After that, the interval was gradually extended to 7 days, 10 days, 14 days, three weeks, one month, six weeks and two months. It is appropriate to review each interval change twice. The longest interval for Pt review is recommended not to exceed three months.