Analysis of the Phenomenon of Endoleak of Type I A: Influence of the Mechanical Characterization of the Aorta

Models of the mechanical behaviour of arterial walls are required for mechanical applications in cardiovascular disease treatments, such as Endovascular Aneurysm Repair (EVAR) in particular, to contribute to the ability to predict type IA endoleak. In this work, an explicit finite-element in-house code was used to evaluate the stresses generated by the blood flow in a whole system consisting of the endograft, plaque, and aneurysmal aorta. The developed numerical model was modified to take into account the effect of anisotropy using a method of homogenization. A comparison of simulation results on the occurrence of Type IA endoleak between the aorta composed of a single layer and a true aorta, involving all three layers, was performed. In considering the anisotropy effect, the results showed the existence of two Young's moduli in the radial and longitudinal directions for the media, which is the middle layer of the aorta. Additionally, the simulations showed a significant difference in displacement and stress distribution in the true aorta composed of three layers when compared to simulations of the simplified aorta made up of one layer.