Correlating Geometric Features with Stress Distributions in Pressurized Anisotropic Aortas to Study the Mechanics of Aortic Diseases

Aortic dissections originate with a tear in the inner layer of the aortic wall, which comprises its integrity and creates a mechanically unstable system prone to fracture. Such fractures are often seen to propagate from the descending aorta to the ascending aorta. The mechanism by which this occurs is unclear but is strongly influenced by the aorta’s geometric complexity (composed of a hyperbolic section and a cylindrical section) and anisotropic fiber-reinforced composition. As such, the ability to link stress information from finite element analysis (FEA) with purely geometric information can help improve understanding of dissection transitions. Here, we seek to develop this linkage by studying a patient model with a dissection propagation from the descending to ascending aorta. We performed FEA to model the aorta as a pressurized curved shell made of an anisotropic elastic material (using the Ogden-Gasser-Holzapfel constitutive model). From this, we can calculate both the curvature tensor and the stress tensor and correlate them. In particular, we concentrate on the hyperbolic lesser aortic arch, where double curvature strongly influences the stress field. Further establishing this link between biomechanical stress and geometry may help improve treatment for these diseases.