3.8: Implementing Fluid-Structure Interaction Computational and Empirical Techniques to assess Hemodynamics of Abdominal Aortic Aneurysms

Abstract

An Abdominal Aortic Aneurysm (AAA) represents a degenerative disease process of the abdominal aorta that leads to a focal dilation and irreversible remodeling of the arterial wall [1].

The reliable assessment of AAA rupture risk in a clinical setting is crucial in decreasing related mortality without needlessly increasing the rate of surgical repair. Currently there is no accepted technique to quantify the risk of rupture for individual AAAs. Elective repair decisions are generally founded on the “maximum diameter criterion” [2].

A multi-disciplinary approach including constitutive modeling and vascular biomechanics is required to increase the effectiveness in assessing and treating the disease.

Guidelines for treatment of AAAs from the Society for Vascular Surgery indicate computationally acquired rupture predictors need additional validation prior to their implementation in clinics. For this purpose, silicone replicas of anatomically realistic geometries of AAAs are fabricated and the flow field in the aneurysmal region is experimentally measured in vitro, using time-resolved volumetric Particle Image Velocimetry (PIV) [3–4]. Furthermore, the experimental setup allows for strain measurements of the aneurysmal wall to be taken simultaneously using Digital Image Correlation (DIC). These data are used to validate concurrent computational simulation results and FSI analyses. The results demonstrate that the FSI computational approach can predict the patterns of flow from the PIV measurements, which arise from the geometry of the AAA. This work highlights that empirical and computational modelling can complement each other to investigate AAA development towards our goal of producing validated computational simulations that can be used for diagnostic purposes.