Background Coronary artery stenting is commonly used for the treatment of coronary atherosclerosis,but it causes serious clinical complications,such as the in-stent restenosis(ISR).The main reason leading to ISR is the neointimal hyperplasia(NH),which is related to the stresses of plaque and artery,and to the altered local hemodynamic environment due to the presence of stents.Different stent structures indeed have various impacts on the stresses of plaque and artery,and the local hemodynamic environment,such as the wall shear stress(WSS),average WSS(AWSS),and WSS gradient(WSSG).Thus,it is important to evaluate the performance of stents with different structures by the mechanical factors after coronary stenting.Methods Six stents implanted into a stenotic curved coronary artery were treated separately,and they included three typical commercial stents(Palmaz-Schatz,Xience,and Cypher)and three author-developed stents,which were constructed by reducing the numbers of link(C-Rlink)and crown(C-Rcrown),and aligning the strut(C-Astrut)of the commercial Cypher Solid mechanical analyses of the balloon-stent-plaque-artery system in Abaqus were first performed to assess the performance of different stent structures and provide the deformed boundary of lumen for the subsequent hemodynamic analysis.With the deformed boundary,then hemodynamic analyses in Ansys were conducted to quanti-fy the hemodynamic parameters induced by different stent structures.Combining the solid mechanical and hemodynamic analyses,the performance of the six stents was evaluated.Results The results show that among the three commercial stents,the Palmaz-Schatz stent has the least stent dogboning and recoiling,which corresponds to the greatest maximum plastic strain as well as the largest diameter.However,it induces the greatest maximum stress of plaque,intima,and media.From the viewpoint of hemodynamics,the Palmaz-Schatz stent also performs better and it has smaller areas of adverse low WSS(<0.5 Pa),high WSS(>15 Pa),low AWSS(<0.5 Pa),and high WSSG(>5 000
Combining the elastica theory, finite element(FE)analysis, and a geometrical topological experiment, we studied the mechanical behavior of a ring subjected to multi-pairs of evenly distributed equal radial forces by looking at its seven distinct states. The results showed that the theoretical predictions of the ring deformation and strain energy matched the FE results very well, and that the ring deformations were comparable to the topological experiment. Moreover, no matter whether the ring was compressed or tensioned by N-pairs of forces, the ring always tended to be regular polygons with 2N sides as the force increased, and a proper compressive force deformed the ring into exquisite flower-like patterns.The present study solves a basic mechanical problem of a ring subjected to lateral forces,which can be useful for studying the relevant mechanical behavior of ring structures from the nano-to the macro-scale.
Introduction Stroke or heart attack,the leading cause of death and disability worldwide,is usually caused by rupture of atheromatous plaque.Therefore,the identification of vulnerable atheroma pre rupture has become extremely important for patient risk stratification.Previous studies have shown that the vulnerable plaque,i.e.one that is prone to rupture with thromboembolic complications,is often associated with a thin fibrous cap,a large lipid core and a high inflammatory burden.The mechanism of plaque rupture is not entirely clear but is thought to be a multi-factorial process involving thinning and weakening of the fibrous cap by enzymes secreted by activa-
