Interlayer Micromechanics of Semilunar Heart Valve Leaflets

The aortic and pulmonary semilunar heart valve leaflets (AV and PV respectively) are heterogeneous structures comprised of three distinct tissue layers. All three layers contain varying amounts of collagen, elastin and glycosaminoglycans (GAGs). The fibrosa layer is an undulated structure that faces the aorta comprised primarily of Type 1 collagen highly aligned in the circumferential direction. On the opposite face of the valve is the ventricularis layer that is populated with an organized elastin network. The spongiosa layer resides between the fibrosa and ventricularis and is rich in GAGs. All three layers work in unison at the tissue level to produce effective leaflet mechanical behavior. While the mechanical behavior of the fibrosa and ventricularis layers have been well studied [1], little information exists on the effective mechanical behavior of the GAG rich spongiosa layer.