Many patients are faced with the problem of choosing the right prosthetic heart valve for them when performing heart valve replacement, and I would like to give some of my experience here in the hope that it will be helpful to patients who need valve replacement. First, what is a bioprosthetic valve? What is a mechanical valve? A biologic valve is an artificial heart valve made by applying material from the body of another animal and processing it. The two most commonly used biomaterials are bovine pericardial valves and porcine aortic valves, both of which have basically no difference in service life; there is also an equine pericardial valve, which is not described here because it is rarely used. Biologic valves can be structurally divided into two types: stented and unstented biologic valves. The stented bioprosthetic valve is a porcine aortic valve or a bovine pericardial piece sewn and fixed on an artificial stent to maintain the shape of the heart valve; the stentless bioprosthetic valve is a porcine aortic valve and the ascending aorta connected to the branch taken off together and treated, thus forming a valve with a segment of the ductal structure. The stented bioprosthetic valve is currently the most clinically used because of its ease of implantation and stable performance. Mechanical valves are prosthetic valves made of non-metallic and metallic materials and resemble the familiar “door”, but with a circular frame and one or two “doors” inside. A single flap is installed for one door, and a double flap for two doors. Most mechanical flaps are made of pyrolytic carbon material, which is as strong and wear resistant as diamond, making them very strong and durable. What are the characteristics of a biopetal flap? Both stented and unstented bioprosthetic valves are structurally similar to the human aortic and pulmonary valve structures and have similar hemodynamics to the human valve after implantation. About 3-6 months after implantation, the leaflet surface will be covered with deposited fibrin and endothelial tissue, and the leaflet material will no longer be in contact with the patient’s blood, avoiding the need for anticoagulation therapy as the blood clotting reaction is activated, which is the greatest advantage of the biologic valve. However, because biomaterials have their own lifespan, it is generally believed that 7-10 years after surgery, the bioprosthetic flap begins to deteriorate to a certain extent, although function can be maintained; 15-20 years after surgery, the flap will need to be replaced again, which is the greatest shortcoming of bioprosthetic flaps. What are the factors that influence the rate of failure of a bioprosthetic valve? The first is the implantation site. Because the pressure on the mitral valve (systolic pressure, commonly known as high pressure) is significantly higher than that on the aortic valve (diastolic pressure, commonly known as low pressure), the life expectancy of a bioprosthetic valve is slightly longer in the aortic than in the mitral valve. The second is age. Because children are in a phase of skeletal growth and development with active blood calcium metabolism, bioprosthetic valves are prone to earlier calcification and damage after implantation. Chronic renal insufficiency can also affect blood calcium metabolism and can occur as described above, although the process is relatively much slower. There is also a rapid heart rate that can accelerate valve breakdown. Preferably, the quality of the biomaterial also has a major impact on the service life, although this factor is not well controlled by the physician or the patient. What is the best stented or unstented bioprosthetic valve? In terms of service life alone, there is essentially no difference between the two types of valves, but theoretically the stentless biologic valve has a slightly larger opening area than the same type of stented biologic valve, especially in the smaller valves. In terms of application sites, stented bioprosthetic valves can be used in all lesions of the heart, including the aortic, mitral, tricuspid, and pulmonary valves, whereas stentless bioprosthetic valves can only be used in the aortic and pulmonary valves. Surgically, the implantation techniques for the two types of valves differ greatly, with stentless bioprosthetic valves being much more complex and poor implantation techniques significantly affecting the function of the valve after implantation. Therefore, stentless bioprosthetic valves are generally not recommended for patients without special needs. However, a stentless bioprosthetic valve may be an option for patients who require concurrent management of aortic root lesions in addition to aortic valve lesions; and for patients who have a relatively small aortic annulus but require or desire implantation of a bioprosthetic valve. What are the characteristics of mechanical valves? The greatest advantage of mechanical valves is their durability. Based on experimental data alone, all modern mechanical valves have a theoretical service life of 50 years or more, so the service life can accommodate patients of all ages. In addition, smaller mechanical valves (e.g., 19 or 21) have a significantly larger opening area than stented bioprosthetic valves of the same type, making them ideal for patients with smaller aortic annuli; mechanical valves also have a significantly lower frame structure than bioprosthetic valves, which are two additional advantages of mechanical valves. The biggest disadvantage of mechanical valves is the need for lifelong anticoagulation, which means that a daily dose of warfarin is required and the dose is adjusted according to the anticoagulation test results (INR). Daily anticoagulation is on the one hand cumbersome, and on the other hand, inadequate adjustment of the medication can easily lead to bleeding (over-anticoagulation) or thrombosis (under-anticoagulation). It is also more problematic to manage when patients on anticoagulation have internal bleeding (cerebral hemorrhage) or need surgical treatment. Since warfarin can cause fetal malformations through the placenta, this is also a serious concern. Which is better, a unilobular or bilobular valve? In patients with larger annuli (especially aortic annuli), there is no significant difference between unilobular and bilobular valves, and there are isolated reports in the literature that unilobular valve hemodynamics appear to be more physiologically correct. However, in patients with smaller annuli, the bilobed valve has a larger opening area and better hemodynamics. In terms of anticoagulation therapy, the incidence of thrombosis and the consequences of thrombosis in mechanical valves are better with bilobed valves than with unilobed valves. Therefore, the clinical use of bileaflet valves is significantly higher than that of unileaflet valves, especially in the tricuspid position, where bileaflet valves are recommended. How do patients choose the right prosthetic valve for them? Once we know the respective characteristics of mechanical and bioprosthetic valves, we can choose them in relation to our own situation. Biologic valves are recommended for patients older than 65 years of age, with a flush heart rate and no atrial fibrillation, especially for patients older than 70 years of age. The bioprosthetic valve is also recommended for patients younger than 65 years of age with a life expectancy of 15-20 years or less. 2. Patients of childbearing age who wish to have children after surgery. Although it is still possible to attempt to apply heparin instead of warfarin for pregnancy after replacement of the mechanical flap, there is still a risk of malformation and bleeding and embolism, though. Therefore, it is strongly recommended that women who are planning to become pregnant opt for a biologic flap. 3. Biologic flaps are recommended for patients with bleeding tendencies. This includes patients with bleeding qualities, bleeding disorders, and other reasons for not receiving long-term anticoagulation therapy. 4. The bioprosthetic valve is recommended for patients who are unable to undergo anticoagulation due to geographic or medical restrictions. 5. Biologic valves are also recommended for patients with tricuspid valve replacement. 6. For patients in whom all conditions are suitable or require replacement of the bioprosthetic valve, but who have a small aortic annulus and aortic development, the application of a stentless valve for aortic root replacement may be considered. Mechanical valves are recommended in patients younger than 65 years of age with no contraindications to anticoagulation, particularly in patients with preoperative persistent atrial fibrillation and multivalvular lesions. 2. Patients who are not suitable for implantation of a bioprosthetic valve. Patients with a small aortic root, for example, or with a small left ventricle and a poorly defined left ventricular outflow tract, in which case implantation of a bioprosthetic valve in the mitral position can often lead to secondary stenosis of the left ventricular outflow tract and support the use of a mechanical valve. 3. If the patient requires tricuspid valve replacement with a mechanical valve, it is recommended to choose a bileaflet valve and avoid the use of a unileaflet valve. Conclusion: The application of biological and mechanical valves is not absolute and can be determined by in-depth communication with the physician based on their own situation. In foreign countries, 80% of flap replacement patients choose biologic flaps, mainly because of the higher quality of life, relatively few postoperative complications, and no economic burden for reoperation. In China, on the contrary, 80% of patients choose mechanical flaps, mainly because of economic problems, and also because of the fear of secondary surgery. However, with the gradual development of biologic flap technology, the service life of biologic flaps will be gradually extended, and the economic and conceptual changes of people will also gradually increase the use of biologic flaps.