Safety and Performance of TAVI of Venus MedTech Aortic Valve Prosthesis

Inclusion Criteria: * Senile degenerative aortic valve stenosis with echocardiography derived criteria: mean gradient ≥ 40 mm Hg, or jet velocity ≥ 4.0 m/s, or an aortic valve area (AVA) of \< 0.8 cm2 (or AVA index \< 0.5 cm2/m2) * Symptomatic due to aortic valve stenosis as demonstrated by NYHA Functional Class ≥ II * The subject or the subject's legal representative was informed of the nature of the study, agreed to its provisions and provided written informed consent as approved by the Institutional Review Board of the respective clinical site. * The subject agreed to comply follow-up evaluation * is evaluated by at least one cardiologist and two cardiovascular surgeon, and they agreed that medical factors precluding operation suitable for surgery (the probability of death or serious, irreversible morbidity exceeded 50%) * STS score ≥ 10% Exclusion Criteria: * Patient refuses aortic valve replacement surgery. * Evidence of an acute myocardial infarction ≤ 1 month before the intended treatment \[defined as: Q wave MI, or non-Q wave MI with total CK elevation of CK-MB ≥ twice normal in the presence of MB elevation and/or troponin level elevation (WHO definition)\]. * Aortic valve is a congenital unicuspid or congenital bicuspid valve, or is non-calcified. * Mixed aortic valve disease (aortic stenosis and aortic regurgitation with predominant aortic regurgitation \>3+). * Any therapeutic invasive cardiac procedure resulting in a permanent implant that is performed within 30 days （6 month if DES implant） * Implanted any heart valve prosthesis, prosthetic valve ring, severe mitral valve ring calcification (MAC), severe（\>3＋）mitral valve insufficiency, or Gorelin symptom * Blood dyscrasia such as leukopenia (WBC \< 3×109/L), acute anemia (Hgb \< 90 g/L), thrombocytopenia (PLT \< 50×109/L), bleeding diathesis, or history of coagulopathy. * Untreated clinically significant coronary artery disease requiring revascularization * Hemodynamic instability requiring inotropic therapy or mechanical hemodynamic support devices * Need for emergency surgery for any reason * Hypertrophic cardiomyopathy with or without obstruction (HOCM) * Severe ventricular dysfunction with LVEF \< 20% * Echocardiographic evidence of intracardiac mass, thrombus or vegetation * Active peptic ulcer or upper gastro-intestinal bleeding within the prior 3 months * A known hypersensitivity or contraindication to aspirin, heparin, ticlopidine, clopidogrel, Nitinol, or sensitivity to contrast media which cannot be adequately pre-medicated. * Native aortic annulus size \< 20 mm or\> 29 mm as measured by echocardiogram. * Cerebrovascular Accident (CVA) within 6 months, including TIA. * Renal insufficiency (creatinine \> 3.0 mg/dL) and/or end stage renal disease requiring chronic dialysis. * Life expectancy \< 12 months * Significant abdominal or thoracic aorta disease, including aneurysm (defined as maximal luminal diameter 5cm or greater), marked tortuosity (hyperacute bend), aortic arch atheroma (especially if thick \[\> 5 mm\], protruding or ulcerated), narrowing of the abdominal aorta (especially with calcification and surface irregularities), or severe "unfolding" and tortuosity of the thoracic aorta * Iliofemoral vessel characteristics that would preclude safe placement of 16F or 18F introducer sheath such as severe obstructive calcification, severe tortuosity or vessel size diameter \< 7 mm. * Currently participating in an investigational drug or another device study. * Active bacterial endocarditis or other active infections. * Bulky calcified aortic valve leaflets in close proximity to coronary ostia