The Nitinol Circular Blade (NCB) is indicated for use in patients with symptomatic aortic stenosis requiring aortic valve replacement, who are going to be operated by conventional sternotomy with native valve resection and replacement by a prosthetic aortic valve. The resection of the diseased leaflets will be performed by the NCB rather than conventional surgical blade.

The patient will be under general anesthesia. The sternum will be opened fully or partially. The patient will be prepared for cardiopulmonary bypass. A transversal aortotomy will be performed as usual. The aortic valve will be exposed for the resection. The NCB will be inserted under visual control from the aorta to the left ventricle. The collection chamber will be closed and the circular blade can be advanced forward to resect the diseased native aortic valve. Once the resection is completed the device will be retrieved carefully. Complementary fine cleaning of the aortic annulus can be done by the surgeon in order to prepare the annulus to receive the prosthetic valve. After implantation of the new valve classically the aortotomy will be closed. Standard weaning of cardiopulmonary bypass will be done and the operation will be safely completed. The aim of this blade is to evaluate the resection time, test the efficiency of a circular Nitinol blade during resection of the calcified native aortic leaflets. A careful examination of the resection edges, aortic annulus, mitral valve and all surrounding tissues will be done in order to validate the efficacy of this Nitinol Circular Blade.

Inclusion Criteria:

• Severe aortic stenosis defined as one or more of the following by Doppler echocardiography: mean gradient >40 mmHg; max velocity >4 m/sec; aortic valve area <=0.8 cm2.
• Symptoms related to aortic valve disease, and NYHA Functional Class II or greater
• Subject is indicated for aortic valve implantation with a biological prosthesis (tissue valve)
• Age >= 65 years
• Echocardiographically determined aortic annulus diameter >=24 mm and <=30 mm in a long-axis view
• Subject understands the implications of participating in the study and provides informed consent

Exclusion Criteria:

• Congenital unicuspid aortic valve
• Severe eccentricity of calcification, defined as calcium deposits larger than 6 mm in diameter
• Echocardiographic evidence of intracardiac mass, thrombus or vegetation
• Left ventricular ejection fraction <25% as determined by contrast ventriculography, or echocardiography or radionuclide angiography if contrast ventriculography not available
• Hypertrophic obstructive cardiomyopathy
• Subjects with life expectancy less than 12 months due to an underlying non-cardiac co-morbid disease
• Known hypersensitivity or contraindication that cannot be adequately controlled with pre-medication to any study medication or material, such as contrast medium or Nitinol
• Blood dyscrasia such as acute anemia, leucopenia, or thrombocytopenia; bleeding diathesis, or coagulopathy
• Renal insufficiency assessed by creatinine >2.5 mg/dl and/or end stage renal disease requiring chronic dialysis
• Poor lung function that in the investigator's opinion is prohibitive for thoracotomy
• Active peptic ulcer or GI bleeding within 3 months from the planned index procedure
• Cardiogenic shock, suspected cardiogenic shock, or hemodynamic instability requiring inotropic support or mechanical heart assistance
• Peripheral vascular disease, including abdominal and thoracic aortic disease, that could pose a problem for eventual transarterial mechanical support (e.g. intraaortic balloon pump)
• History of myocardial infarction in the last 6 weeks
• History of TIA or CVA in the last 6 months
• Subject refuses to have a blood transfusion
• Subject is currently enrolled in another investigational device or drug trial that may influence the outcome of this trial