Safety and Efficacy of TaurusOne® Transcatheter Aortic Valve System in Patients With Severe Calcific Aortic Stenosis

Inclusion Criteria: * Patients who voluntarily participate and sign the informed consent and are able to comply with the entire trial process; * Age ≥ 70 years; * Patients with severe calcific aortic stenosis confirmed by echocardiography (Transaortic flow velocity ≥ 4.0 m/s, or aortic-valve gradient ≥ 40 mmHg (1 mmHg = 0.133 kPa), or aortic valve area \< 0.8 cm2, or effective orifice area \< 0.5 cm2/m2); * Patients who have symptoms obviously caused by aortic stenosis, NYHA Class II or worse; * Patients who are unsuitable for conventional surgery evaluated by the cardiac team (including at least two cardiovascular surgeons) \[13\] \*; * Life expectancy after implantation of prosthetic valve is more than one year evaluated by the cardiac team (including at least two cardiac surgeons); * Aortic annulus diameter ≥ 18 mm and ≤ 29 mm (measured by cardiac CT); * Ascending aorta diameter \< 50 mm \*: If the patient meets any of the following criteria judged by a multidisciplinary cardiac team composed of cardiologists and cardiovascular surgeons, radiologists, anesthesiologists, etc. (at least two cardiovascular surgeons), the patient will be identified as unsuitable for conventional surgery (at least STS ≥ 8 points): * Estimated risk of surgery-related death or disability \> 50% within 1 year; * ≥3 major organ damage that could not be improved by surgery; * Obstacles related to surgical procedures judged as serious Exclusion Criteria: * Patients with bacteremia or toxemia; * Previous endocarditis or active endocarditis; * Acute myocardial infarction (Q-wave MI, or non-Q-wave MI with elevated creatine kinase isoenzyme and troponin T) within 30 days; * Any intracardiac mass, left ventricular or atrial thrombus, vegetation on echocardiography; * Symptomatic atrial fibrillation that cannot be improved by drug therapy; * Familial hypertrophic cardiomyopathy; * Mitral or tricuspid valve insufficiency (grade II regurgitation or higher); * Previous aortic valve graft (mechanical or bioprosthetic valve); * Known allergies to contrast agents, aspirin, heparin, ticlopidine drugs, nitinol shape memory alloy, or bovine products; * Known contraindications or allergies to anticoagulant regimens, or inability to use anticoagulants throughout the trial; * Other serious diseases that may reduce life expectancy to less than 12 months (such as clinically recurrent or metastatic cancer, congestive heart failure, etc.); * Current substance abuse problems (e.g., alcohol, cocaine, heroin, etc.); * Scheduled to undergo surgery that may result in protocol noncompliance or confounding in data interpretation. * Cerebrovascular accident (CVA) in the past 6 months; * Patients with common carotid artery or internal carotid artery or vertebral artery stenosis (\>70%); * White blood cell count \<3×109/L, platelet count \<50×109/L; * Hemoglobin \< 90 g/L; * Patients with severe coagulopathy; * Severe left ventricular dysfunction, left ventricular ejection fraction \< 20%; * Abdominal or thoracic aortic aneurysm; * Hepatic encephalopathy or acute active hepatitis; * On dialysis or baseline creatinine level \> 2.5 mg/dL (221 μ mol/L); * Bleeding tendency or history of coagulation disease or refusal of blood transfusion; * Patients with active peptic ulcer or active gastrointestinal (GI) bleeding; * Patients with neurological diseases that seriously affect mobility and activities of daily living; * Patients with mental illness or psychological disorders who are unable to communicate effectively; * Patients who need emergency surgery for any reason; * Patients who have participated in other drug or medical device clinical trials within 3 months prior to screening; * Other conditions that make the patient ineligible to participate in this clinical trial in judgement of investigators