ADVANCE Direct Aortic Study

Inclusion Criteria: 1. Severe symptomatic aortic valve stenosis requiring treatment 2. Acceptable candidate for elective treatment with the Medtronic CoreValve® System according to the most recent version of the Medtronic CoreValve® Instructions For Use 3. 21 years of age or older 4. Patient is willing and able to comply with all protocol-specified follow-up evaluations 5. The patient or legal representative has been informed of the nature of the study and has consented to participate, and has authorized the collection and release of his/her medical information by signing a consent form ("Patient Informed Consent Form") 6. Patient will receive the CoreValve® device via direct aortic approach TAVI - Exclusion Criteria: 1. Known hypersensitivity or contraindication to aspirin, heparin, ticlopidine, clopidogrel, nitinol, or sensitivity to contrast media which cannot be adequately pre-medicated 2. Sepsis, including active endocarditis 3. Recent myocardial infarction (\<30 days) 4. Left ventricular or atrial thrombus by echocardiography 5. Uncontrolled atrial fibrillation 6. Mitral or tricuspid valvular insufficiency (\>grade II) 7. Previous aortic valve replacement (mechanical valve or stented bioprosthetic valve) 8. Evolutive or recent (within 6 months of implant procedure) cerebrovascular accident (CVA) or transient ischemic attack (TIA) 9. Patients with: 1. Vascular conditions that make insertion and endovascular access to the aortic valve impossible, or 2. Symptomatic carotid or vertebral arterial narrowing (\>70%) disease, or 3. Thoracic aortic aneurysm in the path of delivery system 10. Bleeding diathesis or coagulopathy 11. Patient refuses blood transfusion 12. Estimated life expectancy of less than 12 months unless TAVI is performed 13. Creatine clearance \<20 mL/min 14. Active gastritis or peptic ulcer disease 15. Pregnancy or intent to become pregnant during study follow up 16. Patient is participating in another trial that may influence the results of this study \-