TITLE:
A parameterized analysis of the mechanical stress for co-ronary plaque fibrous caps
AUTHORS:
Ramses Galaz, Catherine Pagiatakis, Emmanuel Gaillard, Rosaire Mongrain
KEYWORDS:
Coronary Atherosclerotic Plaque; Fibrous Cap; Stenosis Severity; Lipid Core; Fluid-Structure Interaction
JOURNAL NAME:
Journal of Biomedical Science and Engineering,
Vol.6 No.12A,
December
17,
2013
ABSTRACT: The
fibrous cap is a protective layer of connective tissue that covers the core of an
atherosclerotic plaque. The rupture of this layer has been commonly associated
with acute myocardial infarctions. The thickness of the fibrous cap, the
percentage of stenosed area, and the stiffness of the core were studied
(commonly associated with vulnerable plaque characteristics) to quantify their
effects on the cap’s mechanical stress state by performing analyses using
computational fluid-structure interaction (FSI) methods. The mechanical stress
levels are significantly increased within the fibrous cap structure at the upstream
side of the plaque. As expected, the highest stresses occurred for a severe
stenosis and a thin fibrous cap. Interestingly, a weak structural support such
as a soft lipid pool beneath the fibrous cap allowed for the hemodynamic
pressure gradient forces to displace the fibrous cap in the direction of the
flow, resulting in higher strains and thus higher mechanical stresses in the
upstream portion of the plaque cap, potentially increasing the risk of cap
rupture. The peak stress behavior of the most critical cases (thin fibrous cap
and soft lipid core) at various degrees of stenosis was analyzed. For mid-range
stenosis from 43% to 75%, there was a plateau region revealing that mild and
moderate plaques were quickly exposed to the high stress condition of severe
plaques. In conclusion, the particular combination of a mild to severe stenosis,
a thin fibrous cap and a soft lipid core resulted in the highest mechanical
stresses calculated at the proximal side of the plaque. Mild and moderate plaques
can be subjected to stresses similar to severe plaques, possibly contributing
to their rupture.