Changing Views of the Biomechanics of Vulnerable Plaque Rupture: A Review

Abstract

This review examines changing perspectives on the biomechanics of vulnerable plaque rupture over the past 25 years from the first FEA showing that the presence of a lipid pool significantly increases the local tissue stress in the atheroma cap to the latest imaging and 3D FEA studies revealing numerous microcalcifications in the cap proper and a new paradigm for cap rupture. The first part of the review summarizes studies describing the role of the fibrous cap thickness, tissue properties and lesion geometry as main determinants of the risk of rupture. Advantages and limitations of current imaging technologies for assessment of vulnerable plaques are also discussed. However, the basic paradoxes as to why ruptures frequently did not coincide with location of PCS and why caps > 65 μm thickness could rupture at tissue stresses significantly below the 300 kPa critical threshold still remained unresolved. The second part of the review describes recent studies in the role of microcalcifications, their origin, shape and clustering in explaining these unresolved issues including the actual mechanism of rupture due to the explosive growth of tiny voids (cavitation) in locals regions of high stress concentration between closely spaced microinclusions oriented along their tensile axis.

Image-based modeling for better understanding and assessment of atherosclerotic plaque progression and vulnerability: Data, modeling, validation, uncertainty and predictions

“…Vengrenyuk et al (2006, 2008), Bluestein et al (2008), Maldonado et al (2012), Cardoso and Weinbaum (2013), and Kelly-Arnold et al (2013) demonstrated that plaque cap with micro-calcification inclusions are associated with elevated stress levels and may be related to plaque rupture. Gao et al (2011) studied carotid plaques and found that critical stress values from symptomatic patients were higher that from asymptomatic patients.…”

Effect of tissue properties, shape and orientation of microcalcifications on vulnerable cap stability using different hyperelastic constitutive models

“…This basic hypothesis was subsequently explored by numerous investigators using 2D and 3D finite element analysis (FEA) and fluid structure interaction numerical models in which various aspects of plaque morphology, tissue properties, residual and fluid shear stress are examined (Cheng et al, 1993; Finet et al, 2004; Tang et al, 2005; Vengrenyuk et al, 2008; Akyildiz et al, 2011; Speelman et al, 2011; Rambhia et al, 2012). These and related studies are described in more detail in a recent review by Cardoso and Weinbaum (2013).…”

Effects of severity and location of stenosis on the hemodynamics in human aorta and its branches

“…Previous hemodynamic studies have not investigated the magnitude and distribution of the wall shear stress in severely stenosed aortic arch and its branches. However, the role of high wall shear stresses on the plaque rupture and atherothrombosis has been widely accepted [3,4,12,29]. Accurate knowledge of stresses developed in both healthy and diseased vessels is critical in analyzing biomechanical determinants of plaque rupture [3,29,42].…”