To Evaluate the Safety and Effectiveness of Transcatheter Aortic Valve System ( Chengdu Silara Medtech Inc. ,Chengdu, China)in Patients with Severe Aortic Stenosis with or without Moderate or Lower Degree Regurgitation

Transcatheter Aortic Valve System (Chengdu Silara Medtech Inc. ,Chengdu, China) will be used for this study.

Inclusion Criteria:

1. Age ≥70 years old;
2. Symptomatic severe aortic stenosis determined by echocardiogram, defined as: mean gradient ≥40 mmHg or peak jet velocity ≥4.0 m/s, or an aortic valve area <0.8 cm2 or aortic valve area index <0.5 cm2/m2.
3. NYHA Functional Class ≥II;
4. Life expectancy after aortic valve implantation thought to be >1 year;
5. Native valvular or peripheral vascular anatomy is appropriate for TAVR;
6. Patient is assessed by at least two cardiothoracic surgeons and recorded as not suitable for surgery;
7. Patient can understand the purpose of the study, voluntarily participates and signs the informed consent form and is willing to accept the relevant examination and clinical follow-up visits.

Exclusion Criteria:

1. Anatomy is not appropriate for percutaneous valve implantation. Native valve annulus diameter is not in the scope of application(native TAV diameter ≤21mm, or ≥30mm);
2. Evidence of an acute myocardial infarction within 30 days prior to the study procedure, defined as: Q-wave myocardial infarction, or non-Q-wave myocardial infarction, with CK-MB≥2 ULN/or elevated TN (WHO definition);
3. Any treatment for traumatic cardiac surgery within 30 day prior to the study procedure(except coronary revascularization);
4. Pre-existing prosthetic valve in any position(except severely dysfunctional aortic bioprosthesis), or severe (>3+) mitral insufficiency, or Gorlin syndrome;
5. Hematological abnormality, defined as: Leukopenia (WBC <3x10^9/L), acute anemia (Hb <90g/L), or thrombocytopenia (platelet count<50×109/L),history of bleeding diathesis or coagulopathy;
6. Hemodynamic unstable requiring myocardial contractile support or mechanical cardiac assistance;
7. Severe ventricular insufficiency. Left ventricular ejection fraction (LVEF) <20%;
8. Echocardiographic evidence of intra-cardiac thrombus or vegetation etc.;
9. Active pepticulcer or upper GI bleeding within 3 months prior to the study procedure;
10. Cerebral Vascular Accident (CVA) within 3 months prior to the study procedure, including TIA;
11. A known hypersensitivity or contraindication to aspirin, heparin, ticlopidine or clopidogrel, or sensitivity to contrast media, which cannot be adequately pre-medicated;
12. Patients with infective endocarditis or other active stage of infection;
13. Currently participating in an investigational drug or another device trial.