Date

9-2014

Document Type

Dissertation

Degree Name

Ph.D.

Department

Dept. of Biomedical Engineering

Institution

Oregon Health & Science University

Abstract

An abdominal aortic aneurysm (AAA) is a pathological dilation of the abdominal aorta, which carries a high mortality rate if ruptured. The most commonly used surrogate marker of rupture risk in clinical practice is the maximal transverse diameter of the aneurysm. More recent studies suggest that wall stress derived from models of patient-specific aneurysm geometries extracted, for instance, from computed tomography images is a better predictor of rupture risk and an important factor in AAA size progression. However, quantification of wall stress is currently computationally intensive and time-consuming, mainly because AAA walls are modeled with nonlinear mechanical properties. This has limited the potential of computational models in clinical practice. To facilitate computation of wall stresses, we propose to use a linear approach that ensures equilibrium of wall stresses in the aneurysm. This proposed linear model is easy to implement and eliminates the burden of nonlinear computations. To assess the potential of our proposed approach for predicting patient wall stresses, results from both idealized and patient-specific model simulations were compared to those obtained using conventional approaches and to those of a hypothetical, reference abdominal aortic aneurysm model in which wall mechanical properties and the initial unloaded and unstressed configuration were assumed to be known. Our linear approach closely approximated the reference wall stresses for varying model geometries and wall material properties. Our findings suggest that the linear approach could be used as an effective, efficient, and easy-to-use clinical tool to estimate patient-specific wall stresses and ultimately identify AAAs with high rupture risk.

Identifier

doi:10.6083/M4W37V1C

School

School of Medicine

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