P27. Relation Between Local Collagen Fiber Architecture and Flexural Properties in Glutaraldehyde Treated Bovine Pericardium
OBJECTIVE: Tissue flexure has been observed in bioprosthetic heart valves and is implicated in the failure process as a mechanism to disrupt tissue structural integrity. While collagen structure degradation is not a strict prerequisite for calcification, studies have demonstrated that maintaining tissue structural integrity is a prime factor in inhibiting calcification and extending valve durability. Since collagen fiber architecture is paramount in determining mechanical properties, we explored the relation between it and flexural mechanical properties using glu-taraldehyde treated bovine pericardium (GLBP).
METHODS: Collagen fiber architecture of 10 cm x 50 cm sheets of GLBP was quantified by small angle light scattering (SALS), from which 2 mm x 15 mm strips were cut aligned parallel and perpendicular to the local collagen preferred fiber direction. Strips from each group were subjected to flexural mechanical testing to determine the bending stiffness in the two bending directions: toward the smooth inner visceral or the rough outer parietal sides.
RESULTS: A total of 10 strips were tested in each fiber direction. Results indicated that the GLBP strips exhibited increasing stiffness with increasing flexure. No statistical differences were found between bending directions for either collagen orientation group. Paradoxically, strips having perpendicular aligned collagen fibers had a greater stiffness (2.7 MPa) compared to those with parallel orientation (2.0 MPa) at maximum flexure (p < 0.05).
CONCLUSION: GLBP had a greater stiffness in the cross-fiber direction, suggesting that flexural properties are dominated by chemical cross-linking between collagen fibers as opposed to the stiffness of the collagen fibers themselves.