Safety and Performance Study of the Optimum Transcatheter Aortic Valve

Inclusion Criteria: 1. Willing and capable to provide informed consent; 2. 70 years of age or older; 3. Echocardiographic or hemodynamic based evidence of calcific (senile) aortic stenosis with one of the following: aortic valve Effective Orifice Area (EAO) ≤ 1.0 cm2 or 0.6 cm2/m2, mean aortic valve gradient ≥35 mmHg or peak aortic valve velocity \> 4 m/sec. 4. Symptomatology due to native aortic stenosis resulting in a New York Heart Association (NYHA) functional classification of II or greater. 5. Aortic valve annular diameter ≥ 21 and ≤ 23mm measured by MSCT (Multi-Slice Computed Tomography). 6. A STS (Society of Thoracic Surgeons) score ≥ 8; or Logistic EuroScore I ≥ 15; or a determination by the local heart team that the co-morbidities not captured by the STS or EuroScore are expected to increase the operative mortality risk to \> 15%. 7. Geographically available and willing to comply with follow up. Exclusion Criteria: 1. Congenital unicuspid or bicuspid aortic valve; 2. Noncalcified aortic valve; 3. Valve eccentricity (calcific or otherwise) that in the opinion of the investigator could compromise procedural success; 4. Severe (Grade 3 to 4) aortic, mitral, or tricuspid valve regurgitation; 5. Moderate to severe mitral stenosis; 6. Myocardial infarction within the past 30 days\* 7. Echocardiographic evidence of intracardiac mass, thrombus or vegetation; 8. LVEF (Left Ventricular Ejection Fraction) \< 30%; 9. Severe pulmonary hypertension with pulmonary systolic pressure greater than two-thirds of systemic pressure; 10. Hemodynamic instability requiring inotropic drug therapy within the past 14 days or mechanical support within the past 6 months; \* 11. Presence of significant aortic disease such as atheroma, thrombus, or aneurysm which, in the opinion of the investigator, precludes safe implant delivery; 12. Blood dyscrasias defined as: acute leukopenia, acute anemia, acute thrombocytopenia, history of bleeding diathesis or coagulopathy; 13. Patient ineligible for or refuses blood transfusions; 14. Unfavorable peripheral vascular anatomy or disease (e.g. severe obstructive calcification, severe tortuosity or small vessels) that would preclude passage of catheters from the femoral arterial access to the aorta as evidenced by peripheral MSCT; 15. Gastrointestinal bleeding within the past 30 days; \* 16. Stroke or transient ischemic attack (TIA) within past 3 months;\* 17. Renal insufficiency as demonstrated by a serum creatinine \> 3.0 mg/dL; 18. End stage renal disease requiring chronic dialysis; 19. Active infection requiring ongoing treatment; 20. Need for emergent surgery or intervention other than the investigational procedure; 21. Hypersensitivity or contraindication to procedural medication(s) and device material(s) (e.g. titanium, nickel, pork) which cannot be adequately pre-medicated; 22. Life expectancy \< 1 year due to non-cardiac co-morbid conditions; 23. Currently participating in any other investigational drug or device study; 24. Patient lacking capacity to provide informed consent (history of any cognitive or mental health status that would interfere with study participation) 25. Subject found to have an International Normalized Ratio (INR) greater than 2.0 right before the procedure. * At the time of procedure, if a subject's medical status has changed since enrollment, the subject shall be re-evaluated for eligibility.