Assessment of the St. Jude Medical PorticoTM Re-sheathable Aortic Valve System - Alternative Access

Inclusion Criteria: * Subject has provided written informed consent. * Subject is 65 years of age or older at the time of index procedure, and/or has comorbidities that, in the opinion of the Principal Investigator or the Subject Selection Committee, preclude surgical valve replacement. * Subject's aortic annulus diameter meets the range indicated in the Instructions for Use as measured by multislice CT conducted within 120 days prior to the index procedure. * Subject has senile degenerative aortic stenosis with echocardiography within 30 days of index procedure as defined by at least 1 of the following: * derived mean gradient greater than 40 mmHg, OR * jet velocity greater than 4.0 m/s, OR * aortic valve area of less than 0.8 cm2, OR * aortic valve area index less than or equal to 0.6 cm2/m2. * Subject has symptomatic aortic stenosis as demonstrated by NYHA Functional Classification of II, III, or IV. * Subject is deemed high operable risk and delivery route is suitable for TAVI per the medical opinion of the Subject Selection Committee. * Subject's predicted operative mortality or serious, irreversible morbidity risk is less than 50% at 30 days post index procedure. Exclusion Criteria: * Subject is unwilling or unable to comply with all study-required follow-up evaluations. * Subject has a documented history of a cerebral vascular accident (CVA) or transient ischemic attack (TIA) within 6 months (less than or equal to 180 days) prior to the index procedure. * Subject has carotid artery disease requiring intervention. * Evidence of an acute myocardial infarction (MI) within 30 days prior to patient providing consent (defined as: ST Segment Elevation as evidenced on 12 Lead ECG). * Subject has a native aortic valve that is congenitally unicuspid, bicuspid, quadricuspid or non-calcified as seen by echocardiography. * Subject has mitral valvular regurgitation greater than grade III. * Subject has moderate or severe mitral stenosis. * Subject has a pre-existing prosthetic cardiac device, valve, or prosthetic ring in any position. * Subject refuses any blood product transfusion. * Subject refuses surgical valve replacement. * Subject has left ventricular ejection fraction (LVEF) less than 20%. * Subject has documented, untreated symptomatic coronary artery disease (CAD) requiring revascularization. * Subject has had a percutaneous interventional or other invasive cardiovascular or peripheral vascular procedure less than or equal to 14 days of index procedure. * Subject has severe basal septal hypertrophy that would interfere with transcatheter aortic valve placement. * Subject has a history of, or is currently diagnosed with endocarditis. * There is imaging evidence of intracardiac mass, thrombus, or vegetation. * Subject is considered hemodynamically unstable (requiring inotropic support or mechanical heart assistance). * Subject is in acute pulmonary edema or requiring intravenous diuretic therapy to stabilize heart failure. * Subject with significant pulmonary disease as determined and documented by the Investigator. * Subject has significant chronic steroid use as determined and documented by the Investigator. * Subject has a documented hypersensitivity or contraindication to anticoagulant or antiplatelet medication. * Subject has renal insufficiency as evidenced by a serum creatinine greater than 3.0 mg/dL (265.5 µmol/L) or end-stage renal disease requiring chronic dialysis. * Subject has morbid obesity defined as a BMI greater than or equal to 40. * Subject has ongoing infection or sepsis. * Subject has blood dyscrasias (eg, leukopenia, acute anemia, thrombocytopenia, history of bleeding diathesis, or coagulopathy). * Subject has a current autoimmune disease that, in the opinion of the Principal Investigator or the Subject Selection Committee, precludes the subject from study participation. * Significant ascending aortic disease documented by diameter greater than 40mm. * Subject has an active peptic ulcer or has had gastrointestinal (GI) bleeding within 90 days prior to the index procedure. * Subject is currently participating in another investigational drug or device study. * Subject requires emergency surgery for any reason. * Subject has a life expectancy less than 12 months. * Subject has other medical, social or psychological conditions that, in the opinion of the Principal Investigator or the Subject Selection Committee, preclude the subject from study participation. * Subject is diagnosed with dementia or admitted to a chronic care facility which would fundamentally complicate rehabilitation from the procedure or compliance with follow-up visits. * Subject is unwilling or unable to comply with all study-required follow-up evaluations. * Subject has a documented history of a cerebral vascular accident (CVA) or transient ischemic attack (TIA) within 6 months (less than or equal to 180 days) prior to the index procedure. * Subject has carotid artery disease requiring intervention. * Evidence of an acute myocardial infarction (MI) within 30 days prior to patient providing consent (defined as: ST Segment Elevation as evidenced on 12 Lead ECG). * Subject has a native aortic valve that is congenitally unicuspid, bicuspid, quadricuspid or non-calcified as seen by echocardiography. * Subject has mitral valvular regurgitation greater than grade III. * Subject has moderate or severe mitral stenosis. * Subject has a pre-existing prosthetic cardiac device, valve, or prosthetic ring in any position. * Subject refuses any blood product transfusion. * Subject refuses surgical valve replacement. * Subject has left ventricular ejection fraction (LVEF) less than 20%. * Subject has documented, untreated symptomatic coronary artery disease (CAD) requiring revascularization. * Cardiovascular or peripheral vascular procedure less than or equal to 14 days of index procedure. * Subject has severe basal septal hypertrophy that would interfere with transcatheter aortic valve placement. * Subject has a history of, or is currently diagnosed with endocarditis. * There is imaging evidence of intracardiac mass, thrombus, or vegetation. * Subject is considered hemodynamically unstable (requiring inotropic support or mechanical heart assistance). * Subject is in acute pulmonary edema or requiring intravenous diuretic therapy to stabilize heart failure. * Subject with significant pulmonary disease as determined and documented by the Investigator. * Subject has significant chronic steroid use as determined and documented by the Investigator. * Subject has a documented hypersensitivity or contraindication to anticoagulant or antiplatelet medication. * Subject has renal insufficiency as evidenced by a serum creatinine greater than 3.0 mg/dL (265.5 µmol/L) or end-stage renal disease requiring chronic dialysis. * Subject has morbid obesity defined as a BMI greater than or equal to 40. * Subject has ongoing infection or sepsis. * Subject has blood dyscrasias (eg, leukopenia, acute anemia, thrombocytopenia, history of bleeding diathesis, or coagulopathy). * Significant ascending aortic disease documented by diameter greater than 40mm. * Subject has an active peptic ulcer or has had gastrointestinal (GI) bleeding within 90 days prior to the index procedure. * Subject is currently participating in another investigational drug or device study. * Subject requires emergency surgery for any reason. * Subject has a life expectancy less than 12 months. * Subject has other medical, social or psychological conditions that, in the opinion of the Principal Investigator or the Subject Selection Committee, preclude the subject from study participation. * Subject is diagnosed with dementia or admitted to a chronic care facility which would fundamentally complicate rehabilitation from the procedure or compliance with follow-up visits. * Subject has a documented allergy to contrast media, nitinol alloys, porcine tissue, or bovine tissue.