Applications of FSI for Cardiovascular Haemodynamics - Computational Hemodynamics: Theory, Modelling and Applications - page 262

8.5 Analysis of Calcified Plaque

8.5.1 Calcified Plaque Models

8.5.1.1 Plaque Composite Model

We assess stress on a plaque that comprises four main tissue types: the lipid ( lp ),
the fibrous cap ( fc ), the calcium agglomerate ( cag ), the non-diseased wall ( ndw ).
The morphological configuration of these components is of critical importance in
the quantification of plaque vulnerability. The properties of these tissues are vari-
able and integration of these various components into a plaque structure produces
different stress effects.
In calcified plaques, agglomeration of microcalcification clusters is aligned in a
crescent within the lipid and acts as a buoyant support to the rupture of the fibrous
cap. Calcification clusters may be eccentrically shaped or positioned distantly from
the lumen such that higher stress or tension may be localized at the fibrous cap
(Wong et al. 2012a). This causes an increase in plaque vulnerability as the calcifica-
tion configuration tends to shift all the stress onto a focal point.
The composites' elastic behaviour is modelled by using stress-plane analysis on
an idealistic model (Fig. 8.29 ). The peripheral arterial internal diameter (3.6 mm)
and external diameter (4.0 mm) are fixed. The presence of the fibrous cap and lipid
within a diseased artery causes the protrusion of the arterial wall into the lumen.

Fig. 8.29 Plaque configuration in atherosclerotic artery. a The morphological configuration of
these plaque composites is idealized schematically to facilitate geometrical modelling for valida-
tion. b The definition of a calcification gap is based on distance between the calcification agglom-
erate and the fibrous cap