1.Epidemiology of aortic stenosis and its hazards With the increase of human life expectancy and the increase of elderly population, the incidence of aortic stenosis (AS) is increasing.AS has become an important disease affecting human life expectancy and social health. On the one hand, the prevalence of AS is high. According to statistics, in Western populations, the prevalence of AS reaches 2.5% in people >75 years of age and up to 8% in people >85 years of age, and AS is the third most common cardiovascular disease after hypertension and coronary heart disease. On the other hand, AS is a progressive disease with a poor prognosis. For example, AS patients with symptoms without timely intervention have an intermediate survival of only 2-3 years. 2. Advantages and disadvantages of traditional surgical open-heart aortic valve replacement surgery Traditional surgical open-heart aortic valve replacement (SAVR) has been the standard treatment for symptomatic AS because of its ability to significantly improve symptoms, enhance quality of life and prolong survival, but patients are discouraged because of the huge trauma and risks associated with SAVR such as general anesthesia, chest opening, open heart, extracorporeal circulation and blood transfusion; and Therefore, it is urgent to find a less invasive and low-risk treatment method especially for elderly aortic valve lesions. The first human percutaneous aortic valve replacement was reported by Cribier et al. in December 2002, and this new percutaneous treatment technique was rapidly promoted. To date, more than 90,000 TAVIs have been performed worldwide, and large registry studies have demonstrated success rates (defined as normal valve function and patient survival after placement) of more than 95%, with a 30-day survival rate of >90% in high-risk patients. The milestone randomized study PARTNER was able to provide more rigorous clinical results. The randomized controlled trial, PARTNER IA, demonstrated that TAVI is no less effective than SAVR and is an effective alternative to SAVR; the randomized controlled trial, PARTNER IB, demonstrated that TAVI is significantly better than conservative medical treatment for patients with severe AS who are unable to undergo surgery. A total of 170,000 TAVI cases have been performed worldwide. The first transcatheter aortic valve implantation was successfully performed with the CoreValve self-expanding valve stent in China on October 3, 2010. Hundreds of TAVI procedures have been performed in several hospitals with satisfactory initial results.