<p>Influence of Stent Flexibility on Artery Wall Stress and Wall Shear Stress in Bifurcation Lesions</p>

Abstract

Purpose Stent flexibility can influence clinical outcome, especially in bifurcation lesions. For instance, an overly rigid stent can impose mechanical stress on the artery at the stent edges and alter both arterial geometry and blood flow dynamics in bifurcations. This study investigated the influence of stent flexibility on vessel geometry, histology, wall stress, and blood flow dynamics in arterial bifurcations. Materials and Methods We compared arterial angulation, stenosis, histopathology, simulated wall shear stress (WSS), and simulated blood flow velocity distribution in swine coronary artery bifurcations following placement of the less flexible Multi-link 8 or more flexible Kaname stent (4.1 ± 0.5 vs 1.5 ± 0.1 mN, p < 0.05, t -test). Stents were implanted into six coronary artery bifurcations each using the single-stent crossover technique without side branch strut dilatation. Outcomes were examined after 28 days. Results Implantation of both stents significantly increased site angulation (Multi-link 8: 148° ± 8° to 172° ± 2°, p < 0.05, paired t -test; Kaname: 152° ± 5° to 164° ± 4°, p < 0.05, paired t -test), but the change tended to be greater after Multi-link 8 stent implantation (24° ± 15° vs 11° ± 7°, p = 0.1, t -test), suggesting greater straightening of the bifurcation. The Multi-link 8 stent induced greater neointimal thickness than the Kaname stent (0.53 ± 0.3 mm vs 0.26 ± 0.1 mm, p < 0.05, t -test). The distribution of neointimal hyperplasia following stent implantation as revealed by longitudinal histopathology matched the distribution of WSS simulated using computational fluid dynamics (CFD). The endothelium at low WSS areas exhibited aberrant cell morphology and leukocyte adhesion. A CFD model of a curved bifurcation suggested that the region of low WSS is expanded by artery straightening. Conclusion In bifurcated lesions, stent flexibility influences not only mechanical stress on the artery but also WSS, which may induce local neointimal hyperplasia.

A 3D Bioprinted In Vitro Model of Pulmonary Artery Atresia to Evaluate Endothelial Cell Response to Microenvironment

“…Otherwise, the recanalized connection may lose its patency over time or worse, can promote stenosis in the once healthy vascular segment. [47][48][49][50][51] For instance, low velocity, oscillatory flow patterns have been shown to correlate with arterial stenosis and thus should be avoided via proper anastomotic geometry and angle of placement, all of which are better modelled prior to the procedure. Evaluating a variety of connection designs and angles in silico and via techniques, such as ultrasound or laser PIV, would allow us to avoid pathologic turbulent flows that will eventually result in restenosis of the reestablish vascular tree.…”

Corroded iron stent increases fibrin deposition and promotes endothelialization after stenting

“…Clinical observations have indicated that the rate of endothelialization is delayed when the stent is implanted at the artery bifurcation. This is due to the dramatic change in the direction of blood flow in the artery bifurcations, leading to a much higher shear stress on the vessel wall and insufficient endothelialization 21,22 . To further address the role of fibrin deposition in artery bifurcation endothelialization, we implanted a corroded iron stent in the iliac artery bifurcation (Figure 4a,b).…”

“…This is due to the dramatic change in the direction of blood flow in the artery bifurcations, leading to a much higher shear stress on the vessel wall and insufficient endothelialization. 21 , 22 To further address the role of fibrin deposition in artery bifurcation endothelialization, we implanted a corroded iron stent in the iliac artery bifurcation (Figure 4a,b ). The fibrin‐coated iron stent and the S316L stent were used as controls.…”

Design and Shape Optimization of a Biodegradable Polymeric Stent for Curved Arteries Using FEM

“…Their results showed that the Palmaz-Schatz-shaped stent had the greatest maximum plastic strain and the largest diameter change but the highest maximum von Mises stress on plaque and arterial intima and media (Wei et al, 2019). Saito et al's investigation revealed that stent flexibility influences not only mechanical stress on the artery but also wall shear stress (WSS), which may induce local neointimal hyperplasia (Saito et al, 2020). Perrin et al's report revealed that increasing vessel curvature leads to stent graft kinks and inadequate apposition against the arterial wall (Perrin et al, 2015).…”