Fluid Structure Interactions in Ascending Thoracic Aortic Aneurysms

The fluid mechanics community has been interested for many years in hemodynamics. More recently, significant endeavours of the solid mechanics community have permitted to establish constitutive equations and to achieve stress analyses in arterial lesions (atheromatous plaque in coronary or carotid arteries, aneurysms of the aorta). The mechanical properties of blood vessels have often been characterized ex vivo, but medical imaging, including MRI, now allows non-intrusive identifications in vivo. The spatial heterogeneity of these mechanical properties, even at the macroscopic scale, remains poorly explored despite its undeniable interest in understanding the mechanisms of remodeling and degeneration of the tissue. We are interested in the problem of identifying the fields of mechanical properties of aneurysms of the aorta. Scientific barriers are related to the complex geometry, the nonlinear and anisotropic behavior of tissues, the multiaxial loading conditions, and to the measurement of a local response in these tissues. Our identification approaches, based on digital image correlation field measurements and inverse methods, have demonstrated the link between the heterogeneity of mechanical properties and the existence of localized failure modes. A micromechanical approach has also made it possible to develop a mechanobiological model to reproduce the behavior of the aorta in surgical situations and a simulation software is being developed for assistance to personalized surgery in the cardiovascular field.