The influence of strut-connectors in stented vessels: a comparison of pulsatile flow through five coronary stents

Abstract

The design of coronary stents has evolved significantly
over the past two decades. However, they still face the
problem of in-stent restenosis, formation of neointima within
12 months of the implant. The biological response after stent
implantation depends on various factors including the stent
geometry which alters the hemodynamics. This study takes
five different coronary stent designs, used in clinical practice,
and explores the hemodynamic differences arising due to the
difference in their design. Of particular interest is the design
of the segments (connectors) that connect two struts.
Pulsatile blood flow analysis is performed for each stent,
using 3-D computational fluid dynamics (CFD), and various
flow features viz. recirculation zones, velocity profiles, wall
shear stress (WSS) patterns, and oscillatory shear indices are
extracted for comparison. Vessel wall regions with abnormal
flow features, particularly low, reverse, and oscillating WSS,
are usually more susceptible to restenosis. Unlike previous
studies, which have tried to study the effect of design
parameters such as strut thickness and strut spacing on
hemodynamics, this work investigates the differences in the
flow arising purely due to differences in stent-shape, other
parameters being similar. Two factors, the length of the
connectors in the cross-flow direction and their alignment
with the main flow, are found to affect the hemodynamic
performance. This study also formulates a design index
(varying from 18.81% to 24.91% for stents used in this
study) that quantifies the flow features that could affect
restenosis rates and which, in future, could be used for
optimization studies.

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Identifiers

ORCID for Nick Curzen: orcid.org/0000-0001-9651-7829

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