re t e s i u

Clearly, multi-protocol biaxial mechanical data are necessary ventricle. This seemingly simple function belies the structural complexity and the elegant solid–fluid mechanical interaction necessary for normal AV function. The AV is capable of with-standing 30–40 million cycles per year, resulting in a total of;3 billion cycles in single lifetime @1#. This staggering level of per-formance can be cut short by aortic valve disease, the most com-mon being stenosis resulting from calcification. Currently, the treatment of such diseases is complete valve replacement using either a mechanical or bioprosthetic heart valve. Porcine biopros-thetic heart valves ~PBHV! have excellent hemodynamics and generally do not require the anti-coagulation therapy necessary for mechanical prostheses. Despite their excellent short-term perfor-mance, PBHV continue to suffer from poor long-term durability due to calcification and mechanical damage. A rigorous study of the mechanics of the natural and biopros-thetic aortic valve could aid in understanding how the natural AV functions, as well as provide insight into the degradative process of the PBHV. Most previous work on the mechanical properties of the natural and chemically treated AV has relied on uniaxial me-chanical testing @2–4#. While yielding important qualitative infor-mation, uniaxial loading is nonphysiologic and the fiber kinemat-ics are not preserved. Mayne et al. @5 # and Christie and Barratt-Boye