Biologic valves are biologic valves of homologous (human) or heterologous (porcine or bovine) origin and are indicated for older patients. The advantage of biologic valves is that they require only six months of anticoagulation after surgery and do not require continuous anticoagulation therapy thereafter. A special point to note here is that patients with persistent atrial fibrillation after prosthetic valve implantation must be treated with anticoagulation. The American Heart Association guidelines recommend warfarin anticoagulation for patients with no valve disease and simply persistent atrial fibrillation. This is true for simple atrial fibrillation, not to mention valve replacement. Of course, the obvious disadvantage of a biologic valve is that it is not very durable; the valve generally lasts between 10 and 20 years, beyond which time it may fail and require reoperation for valve replacement. Zhang Hao, Department of Thoracic Surgery, Shanghai Changhai Hospital Mechanical valves are made of carbon, metal, and synthetic fabrics. Advantages: the first is strong, that is, good durability, and will not be damaged by wear and tear. The service life is long; the second is a mechanical valve of small caliber (19 mm and below) with a relatively large geometric orifice area, especially the new generation of mechanical valves in certain patients with small aortic roots. However, mechanical valves require patients to be on lifelong anticoagulation therapy and should not be used in patients with contraindications to anticoagulation therapy. Anticoagulation carries the risk of fatal complications, including bleeding and embolism. In addition, patients with implanted mechanical valves have trouble getting pregnant and undergoing other procedures, and require staged heparin replacement warfarin therapy, which many local hospitals do not currently have experience in treating such conditions. Female patients may also have problems with increased menstruation.