Novel Methodology for Characterizing Regional Variations in the Material Properties of Murine Aortas

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Bersi, Matthew R. | Bellini, Chiara | Di Achille, Paolo | Humphrey, Jay D. | Genovese, Katia | Avril, Stéphane

Edité par CCSD ; American Society of Mechanical Engineers -

International audience. Many vascular disorders, including aortic aneurysmsand dissections, are characterized by localized changes in wall composition and structure. Notwithstanding the importance of histopathologic changes that occur at the microstructural level, macroscopic manifestations ultimately dictate the mechanical functionality and structural integrity of the aortic wall. Understanding structure–function relationships locally is thus critical for gaining increased insight into conditions that render a vessel susceptible to disease or failure.Given the scarcity of human data, mouse models are increasingly useful in this regard. In this paper, we present a novel inverse characterization of regional, nonlinear, anisotropic properties of the murine aorta. Full-field biaxial data are collected using a panoramic-digital image correlation system. An inverse method, based on the principle of virtual power, is used to estimate values of material parameters regionallyfora microstructurally motivated constitutive relation. We validate our experimental-computational approach by comparing results to those from standard biaxial testing. Results for the non-diseased suprarenal abdominal aorta from apolipoprotein-E null mice reveal material heterogeneities, withsignificant differences between dorsal and ventral as well as between proximal and distal locations, which may arise in part due to differential perivascular support and localized branches.Overall results were validated for both a membrane and a thick-wall model that delineated medial and adventitial properties. Whereas full-field characterization can be useful in the study of normal arteries, we submit that it will be particularly useful for studying complex lesions such as aneurysms, which can now be pursued with confidence given the present validation.

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