Elasticity of human aortic valve cusps

Abstract

The elasticity of human aortic valve cusps has been measured by allowing a disc of cusp tissue to bulge under pressure. The resulting pressure/volume curve gives a profile of the overall elasticity and of the change of elasticity over a range of pressures. Two phases are found in all instances. Over a pressure change of 1 to 12·5 mm Hg the cusp behaves in an elastic manner, stretching up to 10% of its original length. After this the cusp becomes relatively inelastic. The implications of this non-Hookean response with respect to valve function are discussed. The elasticity of similar cusps from different hearts, and all three cusps from the same heart are compared. There is no significant difference in the former at the 95% level of confidence. Changes due to age are noted.