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A Computational Test-Bed to Examine the Effects of Arterial Curvature and
Stenosis Severity on Coronary Stent Deployment
Claire Conway 1,2 , Patrick McGarry 1,2 , Peter McHugh 1,2
1. Department of Mechanical and Biomedical Engineering, National University of Ireland, Galway
2. National Centre for Biomedical Engineering Science, National University of Ireland, Galway
c.conway5@nuigalway.ie
Abstract
Stenting appears as a panacea for atherosclerosis,
however in-stent restenosis remains a problem for
clinicians. This work presents a geometrical test-bed
that examines the in-silico deployment behaviour of two
stent designs. Through greater knowledge of the
implantation process one can design for a better
performing stent in-vivo.
1. Introduction
The need for an improved coronary stent design is
clear from published reports on in-stent restenosis.
More comprehensive evaluation of stents in the design
phase is a step towards this goal. Current computational
stent models are primarily focused on evaluating stent
performance in patient-specific anatomical
environments. However, this work has the objective of
using finite element modelling to devise a geometrical
test bed which is capable of assessing stent performance
for a broad range of the population. Using a spectrum of
representative arterial geometries (encompassing a wide
range of tortuosity and stenosis) a comprehensive
evaluation of stent performance can be achieved.
2. Materials & Methods
3D finite element models representative of the
Cypher and Multi-Link stents were deployed, by
applying a pressure directly to the stent surface and
using a semi-compliant balloon, in straight and curved
three-layer unstenosed and stenosed arteries. The
inelastic constitutive model was described by a Von
Mises-Hill isotropic plasticity model. The Young’s
Modulus was 200GPa, the Poisson’s ratio 0.28 and the
yield strength 264MPa.
The anisotropic behaviour of each arterial layer was
described by an exponential hyperelastic constitutive
model as described in the work of Gasser et al 1 . The
lesion was modelled as a homogenous cellular isotropic
body governed by a third order hyperelastic strain
energy funtion 2 . Standard material properties from
literature were applied to the nitinol guidewire, nylon
balloon and HDPE catheter 3 .
3. Results
Straightening of all curved vessels was predicted after
implantation of the stent, for example see figure 1.
Results also indicate that the level of lumen gain is
affected by increasing level of stenosis and also the
level of recoil within the stent increases for increasing
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level of stenosis. Significant tissue damage was
predicted within all stenosed models. Explicit balloon
modelling was deemed be more appropriate in
accurately capturing the implantation process based on
the results of this study.
Figure 1. Stages of implantation of a Cypher stent in a
moderately curved three layer artery
4. Discussion & Conclusion
The application of this geometrical test-bed
successfully captured stent deployment in nine arterial
models. To the author's knowledge this study provides
the first comprehensive test-bed for stent design and
analysis. The proposed research methodology will offer
a novel insight into the optimisation of stent design for
specific arterial geometries and stenosis levels,
providing invaluable information for the design
engineer and clinician.
5. Acknowledgements
EMBARK Scholarship from the Irish Research Council
for Science Engineering and Technology
6. References
[1] Gasser et al, J. R. Soc. Interface (2006) 3:15-35.
[2] Pericevic et al, Med. Eng. & Phys. (2009) 31:428-433.
[3] Mortier et al, Ann. Biomed. Eng., (2010) 38:88-99.