Histological Composition and Mechanical Properties of Cryopreserved Samples of Aortic and Pulmonary Valves
Abstrakt
Human cryopreserved allografts of pulmonary and aortic valves are routinely used as total valve replacement. For successful surgery it is needed to sufficiently preserve biomechanical properties and histological structures of allografts.
However, it is not known how the mechanical properties of these allografts relate to their histological composition. The aim of our study was to compare the histological composition and mechanical properties of the valves.
From allografts we prepared 2 valve cusps and samples of aorta or pulmonary trunk. In a previous study we had measured following parameters: ultimate stress, ultimate strain, Young's moduli of elasticity, intima-media thickness, wall thickness, area fraction of elastin and area fraction of collagen in the whole wall.
We found weak positive correlation between ultimate stress and Young's modulus in small and large deformation with wall thickness in the valve cusps. In the arteries we found positive correlation between Young's modulus in large deformation with intima-media thickness and ultimate strain with intima-media thickness and area fraction of collagen, and negative correlation between ultimate strain with area fraction of elastin.
In our study we quantified also the other components of wall with mechanical significance, such as the fraction of smooth muscle cells and chondroitin sulfate, which belong to glycosaminoglycans. We did not find correlation between these components and mechanical properties of these valves.
Therefore, it is recommended to perform both mechanical and histological analysis to further characterize cryopreserved allografts.