Effect Of Plaque Composition On Biomechanical Performance Of A Carotid Stent: Computational Study
Published 2018 · Mathematics
Clinical application of bare metal stents is constrained by the occurrence of instent restenosis, mainly due to the complex biomechanical environment in the body. Numerical simulation method was used to evaluate the effect of plaque composition on stent performance in a carotid artery. CT angiography (CTA) data were used as a reference, and zero-load state of the carotid artery was used to establish a 3D stenotic artery model. Different plaque compositions, calcified and hypo-cellular were defined in Model 1 and Model 2, respectively. Interactions between the stents and arterial tissues within the stent crimping-expansion process were analyzed to explore the effects of plaque composition on the mechanical parameters of carotid stents. Goodman diagram and fatigue safety factor (FSF) were analyzed to explore the effects of plaque composition on fatigue performance of a carotid stent in the stent service process. In the stent crimping-expansion process, the von Mises stress in the stent and the dog-boning ratio in Model 1 were higher than that in Model 2. The calcified plaque prevented the stent from expanding the stenotic vessel to a pre-set diameter. Thus, the risk of rupture in the calcified plaque was higher than that in the hypo-cellular plaque. Plaque also affected the stress/strain in the vessel wall, which was observed to be lower in Model 1 than in Model 2. This indicated that calcified plaque could decrease the stress-induced injury of arterial tissues. Within the stent service process, the stents used in these two models were predicted to not fail under fatigue rupture as calculated by the Goodman diagram. Additionally, the points closer to the fatigue limit were generally observed at the inner bend of the stent crowns. The FSF of the stent in Model 1 was lower than that in Model 2. The stent operating in the presence of calcified plaques suffered high risk of fractures. Reliability and fatigue performance of the stent were found to be associated with plaque composition. Hence, this study may provide stent designers an approach toward enhancing the mechanical reliability of a stent.