Applications of FSI for Cardiovascular Haemodynamics - Computational Hemodynamics: Theory, Modelling and Applications - page 257

Fig. 8.23 Comparison of first principal stress at peak systole ( t = 1�95 s ). LM , left main stem;
LAD , left anterior descending; LCx , left circumflex
the idealized ( θ = 90°) and the image-based models at peak systole phase. For the
idealized model, high first principal stress concentrates at the bifurcation area.
A maximum value of 0.28 MPa occurs at the bifurcation apex, followed by the
bifurcation shoulders on LCx side (0.22 MPa) and LAD side (0.15 MPa) respec-
tively. Similarly, the first principal stress distribution of the image-based model
shows a similar result when compared with the idealized model ( θ = 90°). Due to
its irregular vascular luminal shape, a fraction of the luminal left main stem (LM)
region experiences stronger stress values than their corresponding locations on the
idealized model.
The influence of bifurcation angulation on stress distribution is shown through
the variations of first principal stress at the LAD side bifurcation shoulder (Fig. 8.24 )
the bifurcation apex (Fig. 8.25 ), and the LCx side bifurcation shoulder (Fig. 8.25 ).
In general, the first principal stress shows a similar profile with aortic pressure,
which demonstrates the stress variation mainly driven by the pulsatile aortic pres-
sure. Since the angle formed by LM and LAD is kept constant (159°), the stress
variation profiles at the LAD side bifurcation shoulder are similar for all models
(Fig. 8.24 ), and hence the bifurcation angle variation does not affect the stress dis-
tribution in this region.
Figure 8.25 depicts the stress variation at the bifurcation apex, where the bifurca-
tion angle correlates negatively with the first principal stress value. For the narrowest
idealized model ( θ = 70°), the maximum stress σ max = 0.41 MPa occurs at peak sys-
tole, while the widest idealized model ( θ = 110°) experiences σ max = 0.24 MPa at
the same time. This represents a value reduction of 41.5 % due to bifurcation angle
increase.
In contrast, a positive correlation is found between the first principal stress at
the LCx bifurcation shoulder and the bifurcation angle (Fig. 8.26 ). As the angle
increases, the maximum stress also increases 50 % from 0.18 MPa ( θ = 70°) to