Mechanical simulation of the endovascular repair of abdominal aortic aneurysms
This thesis work is concerned with the simulation of the deployment of stent-graft (SG)  vascular prostheses in abdominal aortic aneurysms (AAA) during endovascular repair  (EVAR). This study is composed of three main parts: (i) mechanical tests in bending and  compression of frequently used SG (body and leg from Cook) as well as the numerical  simulation of these tests, (ii) development of a numerical AAA model, (iii) strategy of  simulation of SG deployment.  The finite element method is used. In a first step, a verification of the finite element  model (FEM) of SG is performed by comparison of the different load cases with their  experimental counterparts. Subsequently, the vascular FEM is also verified in terms of  maximal principal constraints in the wall against values available in the literature. Finally,  the deployment is investigated while taking the catheters into account.  The mechanical tests performed on the SG were simulated with a maximal difference  of 5.93%, while accounting for the pre-load in stents. The FEM of the vascular structure  showed maximal principal stresses that were 4.41% far from the ones found in the literature  for a similar model. Regarding the simulation of SG deployment, a complete set of SG  could be deployed with a good control of the relative and global position into a specific and  pre-deformed AAA, however, no intra-luminal thrombus (ILT) was included. The AAA  wall was modeled with an isotropic hyperelastic constitutive law.  In the clinical setting, the maximum tolerated difference between reality and simulation  is 5%, therefore, our approach seems acceptable, and could give rise to further developments.  However, the small amount of tested SG justifies a wide campaign of additional mechanical tests and simulations for the sake of validation.
Stent-graft Simulation Aneurysm Aorta Abdominal Stent-graft Deployment