VitaFlow™ II Transcatheter Aortic Valve System Pre-market Trial

Inclusion Criteria: 1. Age≥70 years; 2. Symptomatic , severe, aortic valve stenosis : peak velocity ≥4.0m/s, or mean transvalvular gradient ≥40mmHg(1 mmHg=0.133kPa), or effective orifice area\<0.8cm² (or EOA index\<0.5cm²/m²); 3. NYHA≥II class; 4. Estimated life-expectancy\>12 months after implantation of the prosthetic valve; 5. Anatomically suitable for the transcatheter aortic valve implantation procedure; 6. The patients considered to high-risk or not suitable for surgical aortic valve replacement (SAVR), as assessed by two or above heart surgeons; The patient has been informed of the nature of the study, is willing to enroll in the study by signing a patient informed consent and agreeing to the scheduled follow up requirement. Exclusion Criteria: 1. Acute myocardial infarction (MI) in last 30 days before the treatment; 2. Aortic root anatomy not suitable for the implantation of the transcatheter aortic valve； 3. Complicated lesion of the aortic valve (aortic stenosis with severe regurgitation); moderate-severe mitral valve stenosis; severe mitral valve regurgitation; severe tricuspid valve regurgitation; 4. Previous implantation of heart valve at any position； 5. Hemodynamic instability requiring mechanical hemodynamic support devices; 6. Need for emergency surgery for any reason; 7. Hypertrophic cardiomyopathy with obstruction; 8. Severe left ventricular dysfunction with left ventricular ejection fraction (LVEF) \< 20%;Severe right ventricular dysfunction; 9. Active peptic ulcer or upper gastro-intestinal bleeding within the past 3 months; 10. Known hypersensitivity or contraindication to all anticoagulation/antiplatelet regimens, to nitinol, contrast media or other relevant elements. 11. Congenital aortic valve stenosis or unicuspid aortic valve; 12. Vascular diseases or anatomical condition preventing the device access; 13. Active endocarditis or other active infections at the time of treatment; 14. Participating in another trial and the primary endpoint is not achieved. 15. Inability to comply with the clinical investigation follow-up or other requirements.