Finite Element Modeling of A Novel Self-Expanding Endovascular Stent Method in Treatment of Aortic Aneurysms

Abstract

A novel large self-expanding endovascular stent was designed with strut thickness of 70 μm × 70 μm width. The method was developed and investigated to identify a novel simpler technique in aortic aneurysm therapy. Stage 1 analysis was performed after deploying it in a virtual aneurysm model of 6 cm wide × 6 cm long fusiform hyper-elastic anisotropic design. At cell width of 9 mm, there was no buckling or migration of the stent at 180 Hg. Radial force of the stents was estimated after parametric variations. In stage 2 analysis, a prototype 300 μm × 150 μm stent with a cell width of 9 mm was chosen, and it was evaluated similarly after embedding in the aortic wall, and also with a tissue overgrowth of 1 mm over the stent. The 300/150 μm stent reduced the peak wall stress by 70% in the aneurysm and 50% reduction in compliance after embedding. Stage 3 analysis was performed to study the efficacy of stents with struts (thickness/width) 70/70, 180/100 and 300/150 μm after embedding and tissue overgrowth. The adjacent wall stresses were very minimal in stents with 180/100 and 70/70 μm struts after embedding. There is potential for a novel stent method in aortic aneurysm therapy.

Validated Computational Model to Compute Re-apposition Pressures for Treating Type-B Aortic Dissections

“…The development of effective mechanical devices for endovascular grafting requires the use of computational techniques such as Finite Element Analysis (FEA) to analyze the structural interaction between the rigid stents (usually composed of Stainless steel or Nitinol alloy) and different tissue segments of the dissected aorta (i.e., intimal flap, FL wall, and true lumen [TL] wall). FEA has been used in the past to compute radial forces and improve stent designs being deployed for treatment of stenosed valves ( Kumar and Mathew, 2010 ), atherosclerotic coronary arteries ( Eshghi et al, 2011 ) and aortic aneurysms ( Arokiaraj et al, 2014 ). The present study utilized FEA utilized to develop a bench-validated computational model based on contact mechanics to quantify the radial pressures required to reconstitute the aorta from dissection and promote remodeling, without exerting undue strains on the vessel wall.…”

Deployment of a Bulk Metallic Glass-Based Self-Expandable Stent in a Patient-Specific Descending Aorta

“…Currently, a variety of computational techniques are available such as boundary element method (BEM), finite volume method (FVM), finite difference method (FDM), and finite element method (FEM). As the specific application of these techniques, BEM is predominantly used for sound propagation analysis and electromagnetics, , FVM is used in computational fluid dynamics, and FDM is used for certain case-based specific problems. , Besides, FEM has proven to be a formidable tool that can be used to analyze ubiquitous biomechanical problems including stent applications and to explore the effects of design parameters on the mechanical performance of stents and their resulting stress distributions on the artery wall. − Hence, because of its solid theoretical foundation and computational efficiency, most of the stent-related theoretical work available in the literature has used FEM to conduct stent structural analyses, which have also been experimentally confirmed in a variety of cases. ,− Our FE analyses are also based on the available documentations provided by the U.S. Food and Drug Administration (FDA or USFDA) on stent analysis…”

A Numerical Study on the Hemodynamic and Shear Stress of Double Aneurysm Through S-Shaped Vessel

“…18 AAA is a signi¯cant health risk in older populations, representing the 14th leading cause of death for the 60 to 85 years old age group in the United States. 47 Sadasivan et al investigated an in vitro study to develop a method for quanti¯cation of the void size distribution in an experimental aneurysm that was coiled both by balloon-assist and stent-assist techniques. Budwig et al determined the pressure and shear stress on the AAA walls during laminar°ow.…”