Finite Element Simulations of the ID Venous System to Treat Venous Compression Disorders: From Model Validation to Realistic Implant Prediction

Abstract

The ID Venous System is an innovative device proposed by ID NEST MEDICAL to treat venous compression disorders that involve bifurcations, such as the May-Thurner syndrome. The system consists of two components, ID Cav and ID Branch, combined through a specific connection that prevents the migration acting locally on the pathological region, thereby preserving the surrounding healthy tissues. Preliminary trials are required to ensure the safety and efficacy of the device, including numerical simulations. In-silico models are intended to corroborate experimental data, providing additional local information not acquirable by other means. The present work outlines the finite element model implementation and illustrates a sequential validation process, involving seven tests of increasing complexity to assess the impact of each numerical uncertainty separately. Following the standard ASME V&V40, the computational results were compared with experimental data in terms of force-displacement curves and deformed configurations, testing the model reliability for the intended context of use (differences < 10%). The deployment in a realistic geometry confirmed the feasibility of the implant procedure, without risk of rupture or plasticity of the components, highlighting the potential of the present technology.

Analytical methods for braided stents design and comparison with FEA

“…The validation was performed comparing the results of the analytical formulae with output of numerical simulations performed in Abaqus/Explicit 2019 (Dassault Systemes Simulia, Providence, RI, USA). Four braided models were built, using 3D parametric equations (Zaccaria et al, 2020b) and starting from the geometrical and material properties of the braided component of the ID Venous System (ID NEST MEDICAL, Strasbourg, FR), named ID Branch, that was deeply analyzed and validated with respect to experimental tests in previous works (Zaccaria et al, 2020a): a cylindrical braided stent, a braided stent with one looped end, the ID Branch design (involving one looped end and five double twist layers), the ID Branch design with triple and quadruple twists instead of double twists.…”

“…The general contact algorithm was exploited to describe the interaction among the wires (Zaccaria et al, 2020b), imposing a friction coefficient of 0.2 (Kelly et al, 2019;Ma et al, 2012). Concerning the material model, the original stent is made of Nitinol, a super-elastic material whose properties were extracted from experimental tests on wire samples at both 25°C and 37°C (Zaccaria et al, 2020a). However, for the purpose of this study, only the austenite behavior, defining the stress-strain relationship for low deformations, was considered.…”

“…Concerning the double twist feature, the ID Branch original design, previously validated through the comparison with experimental tests (Zaccaria et al, 2020a), was used to assess the accuracy of the analytical predictions (Fig. 7 "Double twist").…”

“…This work focuses on braided stents, self-expandable endoprosthesis consisting of interlaced wires, and featuring great flexibility and kinking resistance, which make them suitable for several applications (Bishu and Armstrong, 2015;Cremonesi et al, 2015;Madhkour et al, 2019;Seigerman et al, 2019;Subramaniam et al, 2019). The numerical or experimental studies available in the literature on braided stent behavior are very few and very recent (Zaccaria et al, 2020a, Shanahan et al, 2017, McKenna and Vaughan, 2020, McKenna and Vaughan, 2021. In this context, the prediction of mechanical properties through analytical models is not trivial.…”

“…In this paper, approximated analytical formulae for the prediction of the radial strength of different braided structures are presented and compared with a numerical model validated in a previous work (Zaccaria et al, 2020a). Moreover, equations based on the braided geometrical parameters to obtain the minimum and maximum diameter are illustrated and validated comparing with numerical simulations on a repetitive braided unit.…”