Abstract
Migration and endoleak phenomena are considered to be the principal reasons for Endovascular Aneurysm Repair failure. Wide differences of opinion exist regarding the nature of these critical complications. They occur when there is non-complete and ineffective contact between the endograft ends and the wall of the blood vessel. A major goal of present work is to investigate, using the Finite Element Method, the effect of nitinol stent design on the overall effectiveness of contact and radial force. The specific-patient aneurysmal thoracic aorta are challenging. The optimized stent results show better contact stability to resist the migration. They also show a good compromise of stent design requirements (flexibility and stiffness). Moreover, the new design can also prevent the risk of folding or the collapse of stent struts by mitigating the energy of eccentric deformation caused by high angulation and oversizing.
Highlights
The aneurysmal pathology is characterized by the aorta dilatation as a result of weakness in the aorta wall
This work demonstrated that stent graft dimensions are crucial factors to prevent migration and stent collapse in the case of a highly angulated proximal neck
The results showed that all the new designed stent 1 (NDSI) with 20%-25% oversizing: (NDSI: 1-23-4) oversized at both proximal and distal ends did not undergo migration failure even in the smoothest contact condition, and with severe angulation where the pullout forces can be high
Summary
The aneurysmal pathology is characterized by the aorta dilatation as a result of weakness in the aorta wall. Many clinical investigations were performed to investigate the origin of the ineffective contact interaction (device-aorta) which can be related to one or all of the following factors: endograft under sizing [2,3], high drag forces due to sever angulation [4,5], and insufficient length of proximal attachment site [6,7]. These factors have recently been evaluated using the finite element method (FEM) in the framework of classical continuum computational solid mechanics (CSM) [8]. We aim to investigate the effect of the stent design on the critical, conflicting, and required characteristics of the stent: flexibility and stiffness
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