MECHANICAL ANALYSIS OF HETEROGENEOUS, ATHEROSCLEROTIC HUMAN AORTA

An experimental technique was developed to determine the finite strain field in heterogeneous, diseased human aortic cross sections at physi ologic pressures in vitro. Also, the distributions within the cross se ctions of four histologic features (disease-free zones, lipid accumula tions, fibrous intimal tissue, and regions of calcification) were quan tified using light microscopic morphometry. A model incorporating hete rogeneous, plane stress finite elements coupled the experimental and h istologic data. Tissue constituent mechanical properties were determin ed through an optimization strategy, and the distributions of stress a nd strain energy in the diseased vascular wall were calculated. Result s show that the constituents of atherosclerotic lesions exhibit large differences in their bilinear mechanical properties. The distributions of stress and strain energy in the diseased vascular wall are strongl y influenced by both lesion structure and composition. These results s uggest that accounting for heterogeneities in the mechanical analysis of atherosclerotic arterial tissue is critical to establishing links b etween lesion morphology and the susceptibility of plaque to mechanica l disruption in vivo.