engleski

Finite Element Growth Model of Abdominal Aortic Aneurysm

Computational models of the abdominal aortic aneurysm (AAA) growth are important because they can broaden our understanding of disease formation and development. Additionally, they can be used to analyze the influence of risk factors, test different hypotheses about AAA growth, and eventually, predict the rupture risk. In this work, a 3D finite element growth and remodeling (G&R) model of AAA is presented. The constrained mixture G&R model is implemented into finite element analysis program FEAP via subroutines for the user defined material model. In order to enforce incompressibility, the Augmented Lagrange method was used. Using this model, we can simulate formation and growth of clinically observed aneurysm types, i.e. a fusiform and a saccular aneurysm. Starting from the idealized cylindrical geometry of a healthy aorta, and by employing spatio-temporal elastin degradation functions, the formation of different aneurysms is induced. Modeling and tracking changes in the axial, circumferential and radial direction of an aneurysm was enabled by 3D hexahedral elements. Different clinically observed aneurysm outcomes (e.g. continuous growth, stabilization, rupture, and discontinuous growth) can be achieved numerically, depending on production and degradation of constituents in the aortic wall (elastin, collagen, and smooth muscle cells). Furthermore, a method for adding additional finite elements of ILT in the aneurysm model was implemented in FEAP to simulate thrombus deposition. We also show that ILT mechanically shields the aneuryms, and can lead to stabilization of an aneurism that would otherwise rupture.

Abdominal Aortic Aneurysm ; Growth ; FEM ; Intraluminal Thrombus

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