Abstract
Finite element analyses have been carried out to investigate the effects of plaque thickness, plaque asymmetry and artery curvature on stent deployment in stenotic arteries. The Xience stent, one of the latest commercial metallic stents, was considered and its expansion was controlled by the inflation of a folded balloon. Results showed that it became a challenge to open arteries with thick plaque via stent expansion, as stresses and recoiling increased considerably with the increasing level of stenosis. Asymmetric plaque caused non-uniform stent expansion and uneven dogboning effect, with considerably high levels of vessel wall stresses developed in the regions covered by relatively thin layer of plaque. In a curved artery, a reduction in stent expansion was observed with the increase of artery curvature, accompanied by an elevation of stresses in the plaque and arterial layers. Consequently, particular care should be taken when implanting stents in diseased arteries with severe stenosis, unevenly distributed plaque layer and sharp curvature, as tissue damage might occur due to non-uniform expansion of the system.
Highlights
Angioplasty and stenting are predominantly used to treat cardiovascular disease such as coronary stenosis, a leading cause of heart attack
The results showed that, in addition to stent design, plaque composition and non-uniform thickness due to its asymmetry significantly affect the stresses in the artery induced by stent deployment
Schiavone A (2015) The importance of vessel factors for stent deployment in diseased arteries might affect the results by over-predicting stent recoil and vessel stress due to the stiffer stress-strain curve developed for the vessel wall and hard plaques at later stage (~20% strain) [5,16,17]
Summary
Angioplasty and stenting are predominantly used to treat cardiovascular disease such as coronary stenosis, a leading cause of heart attack. Simulation of stent expansion was performed by Imani et al [6] to study the effects of stent designs on arterial wall stresses and restenosis rate. At a given deployment pressure, more severe deformation, stronger dogboning/ recoiling effects and considerably reduced residual stresses were observed for stents made of materials with lower yield stress and weaker strain hardening. The model simulated the expansion of the stent inside the artery (with and without calcification) and post-deployment deformation subjected to cyclic blood pressure and wall movement. Their results showed that plaque calcification can be associated with an increased risk of stent fracture due to the increased stress on the stent mainly caused by the heterogeneity of the partially calcified plaque
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