Biomedical Engineering Reference
In-Depth Information
Fig. 7.20  Time-averaged WSS distribution of carotid bifurcations
growth of lesion will lead to stenosis at the artery wall, and further narrowing down-
stream of the blood vessel will occur. Therefore, this is one of the key parameters
that will be used for examination of diseased carotid bifurcations.
Contour maps of the predicted maximum wall shear stress at peak pressure for
each of the ten case studies are given in Fig. 7.20 . In all models, the maximum wall
shear stress (WSS max ) shows peak values on the inner ICA and ECA walls near
the bifurcation points; and significantly elevated values spiralling around the larger
angular branch (either the ICA or ECA) from the inner walls along the superior
orientation. The maximum WSS value appeared at the stenosed section due to ves-
sel tapering. For example, the ICA branch on cases (1/L), (1/R), (4/R), (2/L) exhibit
maximum wall shear stress.
Low wall shear stress was seen primarily at the roots and along the outer walls
of the sinus bulbs. Nevertheless, the shape and location of the wall surface subject
to low wall shear stress differ from subject to subject. For all cases, the low WSS
zone starts from the CCA and extends asymmetrically to the posterior and anterior
aspects, with more pronounced coverage on the ECA walls in subjects (1/L), (1/R),
(2/L), (2/R), (4/R) and (3). However, this pattern is reversed in cases (5/L), (5/R)
and (6). For subject (4/L), the low WSS zone starts from CCA, and then terminates
at the stenosed area, which is located at the CCA just before the bifurcation, and
then appears again on the outer wall of ICA branch. WSS max values are presented
by Table 7.5 for ten cases.
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