 Prospective, two academic center, non-randomized pilot, acute in-patient study correlating pre-operative imaging studies, intra-operative measurements and intra-operative balloon aortic valvuloplasty BAV in patients with degenerative aortic stenosis undergoing surgical aortic valve replacement SAVR to understand the requirements device size and radial strength of emerging percutaneous heart valve technologies in the treatment of aortic stenosis. 