Study of Transcatheter Aortic Valve Replacement With A² Flex and Commissural Alignment Technology in Severe Aortic Stenosis

Inclusion Criteria: * Patients who are willing to participate and sign the informed consent and can cooperate with the whole trial process; * Age ≥60 years old; * Patients with severe calcified aortic stenosis confirmed by echocardiography (trans-aortic valve flow velocity ≥ 4.0m /s, or trans-active valvular pressure difference ≥40mmHg (1mmHg=0.133kPa), or aortic valve orientation area \< 0.8cm2, or effective aortic valve orifice the product index is \< 0.5cm2/m2); * The cardiac team (at least two specialists in cardiovascular surgery) assessed the patient as unsuitable for routine surgery ; * The aortic angel ≥60 degree. Exclusion Criteria: * The left and right coronary ostiums originate from the junctional zone or from both coronary ostiums; * previous CABG history; * Coronary ostial lesions（PCI or not）; * Prior aortic valve prosthesis implantation (interventional/surgical, bioprosthetic/mechanical); * Spoor peripheral arterial condition precluded transfemoral TAVR; * Severe coronary stenoses requiring intervention for which concomitant PCI is not possible; * Concomitant diseases requiring cardiac surgery; * Other serious diseases that may reduce life expectancy to less than 12 months (e.g. clinically recurrent or metastatic cancer, congestive heart failure, etc.); * contraindications to conventional cardiac catheterization, such as intracardiac thrombosis, infection, outflow obstruction, hypertrophic cardiomyopathy, etc; * other surgical anatomical contraindications, such as the risk of coronary artery occlusion; * clinically significant active bleeding * platelet count \< 30×10/ L; * participating in other drug or medical device clinical studies that have not yet been completed ; * considered inappropriate by the investigator to participate in the clinical study.