ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

studies provide evidence that the extent of NIH may be related to partial endothelial
denudation following stent expansion and decreased oxygen mass transfer resulting in
regions of hypoxia [4].
Use of computational fluid dynamics (CFD) allows quantitative study of the complex
environment of the fluid and mass transport within idealised and patient-specific stented
vessels. We have previously described [5] how micro-CT imaging in the detailed
reconstruction of stents deployed in real coronary arteries provides a basis for accurate
CFD simulations. Simultaneous availability of corresponding histological sections of
the stented arterial segment enables numerical results to be correlated with the NIH
response. It has been suggested that regions of low flow within the stented segment
affect the arterial response through an accumulation of inflammatory agents and a
decrease in the mass transfer of oxygen [6]. Furthermore, it has been reported that
supplemental supply of oxygen has been shown to decrease the NIH response to
vascular insult [7]. Better elucidation of the overall effects of the fluid environment on
the effective delivery of oxygen to the arterial wall following stent placement may lead
to improved options for clinical treatment. The aim of the current study is to employ a
simple model of blood flow and oxygen mass transport to investigate the distribution of
oxygen concentration at the wall of a realistic stented porcine coronary artery geometry.
3. MATERIALS AND METHODS
3.1 Computational model and domain
Geometric model. Three-dimensional micro-CT data sets of a BiodivYsio stent
(Biocompatibles International, UK) implanted into a porcine coronary artery were
obtained for the construction of the geometric surface mesh. Full details regarding the
protocol, histology, and 3D reconstruction methods are described elsewhere [5].
Structural model. Numerical analysis is performed using the full geometry of a right
porcine coronary artery (RCA) and deployed stent explanted at 14 days. The the first
two proximal repeating units of the stent were reported in a previous study [5]. The
computational domain is defined using the stent geometry obtained from the micro-CT
reconstruction. The vessel wall is not measured directly, instead a finite element code
(Abaqus Explicit, v6.10-EF1) is used to simulate the interaction of the stent/vessel.
The diameter of the structural model was 2.8mm, this was obtained from angiography,
the wall thickness is 100 µm; the length of the stent is 18 mm, with a vessel domain
(segment length) of 36 mm. The resulting finite element mesh was composed of
132,000 brick elements. Further details regarding the structural domain setup and
simulation is reported elsewhere [5].
Figure 1: A. Arterial and stent domain used for the numerical simulation with identification of three
locations (blue rings) along axial length. B. Tetrahedral mesh cross-section with close-up of wall detail.