Design a bistable polymeric vascular stent (BPVS) and evaluate the biomechanical properties

Abstract

Background and objectives

Polymeric vascular stents generally have the disadvantages of poor biomechanical properties, which may not achieve the therapeutic purpose of supporting the blocked vascular vessels to restore normal blood flow. The bistable structure depending on the two stable configurations seems to improve the weak strength of stents. This paper mainly designs a polymeric vascular stent with bistable structure to enhance the radial force, and reduce the radial recoil and wall shear stress.

Methods

The bistable stents were derived from the bistable property of the tilted strut and the planar cell systematically. The mapping relationship between the tilted struts with different geometries and the bistable performance was revealed by finite element method, and then the bistable characteristics of the planar cells were further explored. Furthermore, the biomechanical performance involving radial force and radial recoil of bistable polymeric stents, and wall shear stress of vascular vessels were analyzed and evaluate by combining numerical simulation and experiments.

Results

The mapping relation between geometries and bistable properties of tilted struts was that the (t/L, θ) = (0.03, 10° ∼ 60°), and (t/L, θ) = (0.03 ∼ 0.1, 30° ∼ 40°) were the widest ranges of optional parameters. When the bistable evaluation factor B = T/t ≥ 4, the BREH cells had outstanding bistable properties. The finite element results of polymeric stents indicated that the bistable structure obviously greatened the radial force (2.52 N), and lessened the radial recoil (1.69 %) of the polymeric stent. Besides, the bistable structure minified the wall shear stress of vascular vessels to 0.04177 MPa.

Conclusions

It could be concluded that the bistable structure not only endowed polymeric stents with strong biomechanical properties, but also reduces the risk of secondary injury after its being implanted into vascular vessels. The bistable polymeric stents have the potential to support the blocked vessels and restore the blood flow.