Chiral constrained stent: Effect of structural design on the mechanical and intravascular stent deployment performances

Abstract

The high mortality of atherosclerosis-caused cardiovascular disease has promoted the requirement of designing novel intravascular stents with comprehensive robust mechanical performances, which is critical for re-constructing the blocked artery and recovering the biomechanical functions of artery vessels during vascular interventional therapy procedures. In this study, a chiral constrained structure with zero/negative Poisson's ratio and robust expansion transformation ability is proposed through combining the axial constraint effect of tetrachiral element and the good stretchability of oscillating wave element along circumferential direction. Afterwards, through applying the theoretical prediction, experimental tests and finite element analysis, the mechanical properties and stenting performances of the chiral constrained structure are explored. The modified tetrachiral topology shows strong orthotropic after integration of oscillating wave strut profile, indicating its capability of handling radial loads without great longitudinal recoil (foreshortening). Finally, stent deployment performances have been evaluated through a highly nonlinear coupling analysis of the stenosed vessels system, in terms of transformation characteristics, dogboning, radial recoil, foreshortening, and plaque prolapse ratio, etc. Especially, remarkable non-conventional performances of anti-dogboning and anti-foreshortening are identified in chiral constrained stent. Synthetically index is generated to compensate the competing behaviors among the above terms, and to improve the comprehensive mechanical performances of chiral constrained stent. These results show the potential in generating a new family of the intravascular stent with chiral mechanical metamaterials and provide a promising clinical application in curing atherosclerosis.