Self-expanding stent modelling and radial force accuracy

Abstract

Computational simulations using finite element analysis are a tool commonly used to analyse stent designs, deployment geometries and interactions between stent struts and arterial tissue. Such studies require large computational models and efforts are often made to simplify models in order to reduce computational time while maintaining reasonable accuracy. The objective of the study is focused on computational modelling and specifically aims to investigate how different methods of modelling stent-artery interactions can affect the results, computational time taken and computational size of the model. Various different models, each with increasing levels of complexity, are used to simulate this analysis, representing the many assumptions and simplifications used in other similar studies in order to determine what level of simplification will still allow for an accurate representation of stent radial force and resulting stress concentrations on the inner lining of the vessel during self-expanding stent deployment. The main conclusions of the study are that methods used in stent crimping impact on the resulting predicted radial force of the stent; that accurate representation of stent-artery interactions can only be made when modelling the full length of the stent due to the incorporation of end effects; and that modelling self-contact of the stent struts greatly impacts on the resulting stress concentrations within the stent, but that the effect of this on the unloading behaviour and resulting radial force of the stent is negligible.

Effect of Self-Expanding Carotid Stents on Plaque Thickness and Vessel Diameter

“…Our major findings were as follows: (1) self-expanding nitinol stents alter the baseline ventral and dorsal plaque thickness to a significant degree, while not significantly affecting the native arterial wall; and (2) stenting appears to impact the ventral and dorsal components of the plaque equally, which would be expected given their radial expansion. 13,14 Our results suggest that an increase in luminal diameter is achieved by a process of plaque remodeling and is not accompanied by native arterial expansion. The radial outward force produced by a self-expanding stent compresses the plaque component in all directions in a similar manner, but this force is not enough to produce a dilatation of the arterial wall, avoiding the risk of vessel rupture.…”

Effect of Stent Radial Force on Stress Pattern After Deployment: A Finite Element Study

“…In the current work, a simplified method was used to quantify radial stiffness, which was previously used in other works (Ref 9, 25). Such method assumes a simplified configuration which does not reflect the in vivo configuration of the stent and fails to catch localized behavior such as stent detachment (Fig.…”

“…In conclusion, the calculation of RF yields information on the interaction between the stent and the artery but it is not sufficient for understanding the localized effects of the deployment in the case of shape memory alloy stents. In the current work, a simplified method was used to quantify radial stiffness, which was previously used in other works (Ref 9 , 25 ). Such method assumes a simplified configuration which does not reflect the in vivo configuration of the stent and fails to catch localized behavior such as stent detachment (Fig.…”

“…9 , 10 ). The calculation of radial stiffness with another method (such as rigid body crimp) may yield better results, however, it was shown how—at low RFs—such two methods are equivalent (Ref 25 ).…”

Interactive virtual stent planning for the treatment of coarctation of the aorta

“…Finite element (FEM) simulations are commonly used to analyze different stent designs, the deployment process or the interaction between stent and vessel wall [11]. These simulations allow for a detailed exploration of various effects, e.g., local wall shear stress at the struts [12] or the relation between local flow patterns and strut design [13].…”