Abstract
This paper is to design a new type of auxetic metamaterial-inspired structural architectures to innovate coronary stents under hemodynamics via a topological optimization method. The new architectures will low the occurrence of stent thrombosis (ST) and in-stent restenosis (ISR) associated with the mechanical factors and the adverse hemodynamics. A multiscale level-set approach with the numerical homogenization method and computational fluid dynamics is applied to implement auxetic microarchitectures and stenting structure. A homogenized effective modified fluid permeability (MFP) is proposed to efficiently connect design variables with motions of blood flow around the stent, and a Darcy-Stokes system is used to describe the coupling behavior of the stent structure and fluid. The optimization is formulated to include three objectives from different scales: MFP and auxetic property in the microscale and stenting stiffness in the macroscale. The design is numerically validated in the commercial software MATLAB and ANSYS, respectively. The simulation results show that the new design can not only supply desired auxetic behavior to benefit the deliverability and reduce incidence of the mechanical failure but also improve wall shear stress distribution to low the induced adverse hemodynamic changes. Hence, the proposed stenting architectures can help improve safety in stent implantation, to facilitate design of new generation of stents.
Highlights
Percutaneous coronary intervention (PCI) has been popular as a common treatment for coronary artery disease, but the risks of stent thrombosis (ST) and in-stent restenosis (ISR) still threaten the safety of stent implantation and represent a serious clinical shortfall
This paper has developed a family of auxetic architectures for stenting structures using a topological optimization approach and its associated numerical methods, which is especially beneficial to self-expanding stents
The new design combines the hemodynamic effect with auxetic structures to improve the stent performances from both mechanical and hemodynamic aspects
Summary
Percutaneous coronary intervention (PCI) has been popular as a common treatment for coronary artery disease, but the risks of stent thrombosis (ST) and in-stent restenosis (ISR) still threaten the safety of stent implantation and represent a serious clinical shortfall. Various reasons accounting for these adverse biological responses that have not been fully understood, the stent essentially serves as a mechanical structure and is believed to have a major effect on the ST and ISR complications. In our previous work (Xue et al, 2020), the self-expanding (SE) auxetic stent has been demonstrated to have capability in supplying adaptive deformation to help overcome the mechanical failures and low the incidence of the ST and ISR complications. The stent-induced hemodynamic changes will be combined into stents to further improve stenting performance from both mechanical and hemodynamic aspects, because the stenting structures are primally influenced by mechanical failure including inadequate expansion, fracture, malapposition, foreshortening and dogbone, and by the hemodynamic changes induced in stent implantation
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