Our group is developing novel preferential covered carotid stents aimed at preventing
friable parts from atherosclerotic plaques from dislodging into the cerebral
blood flow, and also preserving external carotid artery (ECA) perfusion
through slits on the membrane. Enhanced ECA flow rates can be achieved by
designing bare metal stents with larger cells that can accommodate more slits
for enhanced blood flow to the ECA where the stents have fewer crowns
in the circumferential direction. The general perception is that the stent
stiffness and thereby the crush resistance will decrease with fewer crowns in the
circumferential direction. However, we observed the opposite effect. To study the
effect of crown number on crush resistance of stents, finite element analysis
(FEA) was used to evaluate the crush resistance of open-cell stent designs by
varying the number of crowns. From FEA simulation results, it was found that
the crush resistance of the open-cell stent design actually increases with
fewer crowns. To verify this effect, three stent designs with different crown
numbers were fabricated and subjected to crush resistance experimental
testing. The experimental testing further confirmed the effect observed by
FEA. Finally, a simplified analytical model was proposed to explain why
the crush resistance of stent increases with a reduction in the number of
stent crowns. From this study, we can infer that the stent’s crush resistance
increases with reduction in the number of stent crowns in the circumferential
direction.