Biomedical Engineering Reference
In-Depth Information
parison with a FSI model. Furthermore, using pressure as the prescribed inlet bound-
ary condition allows a more realistic haemodynamic simulation of stenotic arteries.
8.2.5
Closure
Different degrees of stenosis have a significant influence on three basic characteris-
tics of atherosclerosis. Firstly, the presence of severe stenosis can dramatically alter
the blood flow pattern. Flow reversal is smaller at advanced stages of the disease.
This leads to diminishing low wall shear stress in the stenotic region. Secondly, the
stenosis apex experiences compressive stresses which intensify as it grows. This
explains why plaque can still grow at advanced stages when the wall shear stress
is higher. Finally, the relationship among pulse pressure, maximum displacement,
and maximum principal stress suggests that elevated heart rates can lead to a higher
risk of stroke due to longer exposure to high vessel wall displacement and stresses.
Furthermore, the relationship between stenosis with recirculation length, wall dis-
placement, and effective wall shear stress can be established. These results can be
used as a platform for future work in atherosclerotic research aiming for improved
understanding of the complicated process of the disease.
8.3
Flow in a Realistic Carotid Artery Bifurcation
In this example we present an FSI simulation of a realistic carotid artery bifurcation
model which is patient-specific and realistic unlike the ideal case presented in the
previous section. Studies on the pathophysiology of vascular disease have shown
that atherosclerotic plaque is closely related to wall shear stress (Wong et al. 2013b)
due to blood flow inside the blood vessel (Cunningham and Gotlieb 2005; Malek
et al. 1999). For regular vascular functioning, the endothelial cells located in the
blood vessels must experience the appropriate wall shear stress. Under a low shear
stress condition, generation and growth of atherosclerotic plaque can unofrunately
progress easily.
Medical imaging diagnosis using CT or MR mainly focus on the geometrical oc-
clusion of the arterial vessel, and lacks the detailed blood flow information such as
a local wall shear stress distribution. This has limitations in the use for the clinical
diagnosis and treatment of cerebral vascular diseases. To predict the evolution of
atherosclerotic plaques related to vascular disease, the haemodynamic blood flow
and arterial deformation inside patient-specific carotid artery bifurcation models
have to be investigated.
The arterial model was reconstructed from the CT images and a fully coupled
FSI simulation performed based on this model by imposing physiologically reason-
able flow boundary conditions. The differences between rigid wall and elastic wall
approaches were addressed, and detailed blood flow information inside a compliant
Search WWH ::
Custom Search