title: Morphological and stent design risk factors to prevent migration phenomena for a thoracic aneurysm: a numerical analysis.
abstract: The primary mechanically related problems of endovascular aneurysm repair are migration and type Ia endoleaks. They occur when there is no effective seal between the proximal end of the stent-graft and the vessel. In this work, we have developed several deployment simulations of parameterized stents using the finite element method (FEM) to investigate the contact stiffness of a nitinol stent in a realistic Thoracic Aortic Aneurysm (TAA). Therefore, we evaluated the following factors associated with these complications: (1) Proximal Attachment Site Length (PASL), (2) stent oversizing value (O%), (3) different friction conditions of the stent/aorta contact, and (4) proximal neck angulation α. The simulation results show that PASL>18 mm is a crucial factor to prevent migration at a neck angle of 60°, and the smoothest contact condition with low friction coefficient (μ=0.05). The increase in O% ranging from 10% to 20% improved the fixation strength. However, O%≥25% at 60° caused eccentric deformation and stent collapse. Higher coefficient of friction μ>0.01 considerably increased the migration risk when PASL=18 mm. No migration was found in an idealized aorta model with a neck angle of 0°, PASL=18 mm and μ=0.05. Our results suggest carefully considering the stent length and oversizing value in this neck morphology to strengthen the contact and prevent migration.
authors.affiliation: Laboratoire de Mécanique des Contacts et des Structures, INSA de Lyon, 18-20 rue des Sciences, 69621 Villeurbanne, France. Electronic address: hussameddinaltnji86@gmail.com.
authors.forename: H-E
authors.initials: HE
authors.lastname: Altnji
authors.affiliation: Laboratoire de Mécanique des Contacts et des Structures, INSA de Lyon, 18-20 rue des Sciences, 69621 Villeurbanne, France. Electronic address: benyebka.bou-said@insa-lyon.fr.
authors.forename: B
authors.initials: B
authors.lastname: Bou-Saïd
authors.affiliation: Laboratoire de Mécanique des Contacts et des Structures, INSA de Lyon, 18-20 rue des Sciences, 69621 Villeurbanne, France. Electronic address: helene.walter-le-berre@insa-lyon.fr.
authors.forename: H
authors.initials: H
authors.lastname: Walter-Le Berre
mesh_terms: D000497:Alloys; D017545:Aortic Aneurysm, Thoracic / Q000473:pathology* / Q000628:therapy*; D001807:Blood Vessel Prosthesis; D003198:Computer Simulation; D004548:Elasticity; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D017276:Friction; D021621:Imaging, Three-Dimensional; D008955:Models, Cardiovascular; D011312:Pressure; D011474:Prosthesis Design; D012307:Risk Factors; D015607:Stents; D013314:Stress, Mechanical
chemical_list: D000497:Alloys; C013616:nitinol
keywords: Aortic aneurysm; Finite element; Migration; Self-expanding stent; Type I endoleak