Risk of Rupture in Abdominal Aortic Aneurysms and Vulnerable Plaques: A Patient Based Fluid Structure Interaction Approach

Abstract

In this study we performed two separate fluid structure interaction (FSI) simulations. A patient-specific Abdominal Aortic Aneurysm (AAA) geometry, and coronary vulnerable plaque (VP) geometry in idealized and in patient based geometries reconstructed from intravascular (IVUS) measurements. The patient specific AAA FSI simulations were carried out with both isotropic and anisotropic wall properties. An orthotropic material model was used to describe wall properties, closely approximating experimental results of AAA specimens [1]. The results predict larger deformations and stress values for the anisotropic material model as compared to the isotropic one. This difference indicates that the isotropic formulation may underestimate the risk of rupture. The ability to quantify stresses developing within the aneurysm wall based on FSI simulations will help clinicians to reach informed decisions in determining rupture risk of AAA and the need for surgical intervention. The risk of rupture of vulnerable plaques was studied in both idealized and patient specific geometries using FSI simulations. The idealized model included vessel wall, fibrous cap, and a lipid core. Regions susceptible to failure and the contribution of the various components were studied. The upstream side of the vulnerable plaque fibrous cap had the highest stresses. The presence of a calcified spot embedded within the fibrous cap proper was studied, and was demonstrated to enhance stresses within the fibrous cap, significantly contributing to its risk of rupture.