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Med Eng Phys. 2015 Jan;37(1):23-33. doi: 10.1016/j.medengphy.2014.09.017. Epub 2014 Oct 22.

Morphological and stent design risk factors to prevent migration phenomena for a thoracic aneurysm: a numerical analysis.

Author information

1
Laboratoire de Mécanique des Contacts et des Structures, INSA de Lyon, 18-20 rue des Sciences, 69621 Villeurbanne, France. Electronic address: hussameddinaltnji86@gmail.com.
2
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.
3
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.

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.

KEYWORDS:

Aortic aneurysm; Finite element; Migration; Self-expanding stent; Type I endoleak

PMID:
25456396
DOI:
10.1016/j.medengphy.2014.09.017
[Indexed for MEDLINE]

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