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

stented case, corresponding to the area of the low TAWSS. This is because the
obstruction of implanted strut could retard the flow, leading to the local small regulation
at the strut interval. The regional slower flow would cause the non-unidirectional wall
shear stress, which is referred to the higher OSI in stented case, since OSI indicates the
directionality of the wall shear stress. In this aspect, these sites can be implied to a
higher risk of atherogenesis development after stent implantation.
Fig.3 Hemodynamic parameters, TAWSS between without and with stent.
Previous studies 1,2,3 have reported the higher exposed area to low TAWSS, i.e. 50%-
75%, but using different blood vessels geometries. In our case, flow pattern at carotid
bifurcation are strongly dominated by the curvature and non-uniform vessel geometry.
For this reason, the very low TAWSS (0-0.4 Pa), in both with and without stent, were
located at the ICA bulb due to the regional separation flow along the bifurcation shape 8 .
In the mean time, very high TAWSS were located close to the stagnation point. The
plaques are therefore normally accumulated at these regions. Even though the stent
would be eventually covered by plaque in this area, our simulation result has shown the
additional risky sites for re-stenosis, indicating by low TAWSS and high OSI near the
stent strut on CCA before bifurcation.
In this study, the elasticity of the arterial wall, the fluid-solid interaction between blood
flow and stent, and patient-specific geometry have not been taken into account. The
elasticity of the carotid artery could decrease the TAWSS, but no crucial differences
even in the patient-specific artery 8 . The simple assumptions are useful and less
computational expensive for hemodynamic parameter estimations.
5. CONCLUSIONS AND FUTURE WORKS
Low TAWSS and high OSI have indicated the high risk area for re-stenosis at carotid
bifurcation after stent implantation. Not only ICA bulb and bifurcation are covered by
plaque, the strut imprint on the CCA also provides the feasibility of atherogenesis