Contribution à l’évaluation hémodynamique et biomécanique des anévrysmes de l’aorte thoracique ascendante

Aneurysmal disease of the ascending thoracic aorta is rare but can be complicated by dissection or rupture with resultant high mortality. There is substantial inter-individual variation in aneurysms growth. Although there is an increased lifetime risk when the aortic diameter exceeds 55 mm, predicting aneurysms progression is nearly impossible and dissections also occur at smaller diameters. Hemodynamics and biomechanics can influence the aortic wall behavior over time and aneurysm geometry and aortic valve phenotype affect the flow patterns in ascending aorta. Coupling 4D MRI and CFD allows to assess the specific-patient flow conditions and altered aortic hemodynamics and biomechanics. We applied the approach combining CFD and 4D MRI to study the relative contribution of aneurysm geometry and aortic valve phenotype in deranging ascending aorta flow patterns in subsets of non-surgical patients. Further, we studied variations in distributions of wall shear stress and other related metrics in a limited number of surgical patients harboring different patterns of ascending aorta dilatation and valve phenotype. We found that restoring the regular geometry of ascending aorta allow better flow conditions and aortic valve function more than morphology seems to be more important in affecting ascending aorta hemodynamics. Changes in distribution of wall shear stress and related descriptors may provide further insights in aneurysms development and progression and could in the future help clinicians in assessing the risk of dissection.