Native aortic valve leaflets contain a network of strong collagen fibers within a matrix of relatively distensible tissue. This composite structure leads to anisotropic mechanical properties and is believed to play an important role in the ability of the structure to withstand the stresses of cyclic loading over billions of heart beats. Replacement valves that consist of animal tissues also contain such fibers, but all designs in clinical use are chemically cross-linked, which increases the in-plane stiffness of the tissue and decreases anisotropy. Tissue replacement valves suffer from poor durability due to calcification and tissue degeneration in regions of high stress, including at the base of the coaptation region and at the leaflet commissures [1]. A better understanding of leaflet stresses in these regions and how to mitigate them is important in order to improve the design of replacement heart valves to improve durability.
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