Considerations for analysis of endothelial shear stress and strain in FSI models of atherosclerosis

Miten Patel, Fotios Savvopoulos, Caleb C. Berggren, Lydia Aslanidou, Lucas H. Timmins, Ranil de Silva, Ryan M. Pedrigi, Rob Krams

Research output: Contribution to journalArticlepeer-review

Abstract

Atherosclerosis is a lipid driven chronic inflammatory disease that is characterized by the formation of plaques at predilection sites. These predilection sites (side branches, curved segments, and bifurcations) have often been associated with disturbed shear stress profiles. However, in addition to shear stress, endothelial cells also experience artery wall strain that could contribute to atherosclerosis progression. Herein, we describe a method to accurately obtain these shear stress and strain profiles. We developed a fluid–structure interaction (FSI) framework for modelling arteries within a commercially available package (Abaqus, version 6.12) that included known prestresses (circumferential, axial and pressure associated). In addition, we co-registered 3D histology to a micro-CT-derived 3D reconstruction of an atherosclerotic carotid artery from a cholesterol-fed ApoE−/− mouse to include the spatial distribution of lipids within a subject-specific model. The FSI model also incorporated a nonlinear hyperelastic material model with regionally-varying properties that distinguished between healthy vessel wall and plaque. FSI predicted a lower shear stress than CFD (~−12%), but further decreases in plaque regions with softer properties (~-24%) were dependent on the approach used to implement the prestresses in the artery wall. When implemented with our new hybrid approach (zero prestresses in regions of lipid deposition), there was significant heterogeneity in endothelial shear stress in the atherosclerotic artery due to variations in stiffness and, in turn, wall strain. In conclusion, when obtaining endothelial shear stress and strain in diseased arteries, a careful consideration of prestresses is necessary. This paper offers a way to implement them.

Original languageEnglish (US)
Article number110720
JournalJournal of Biomechanics
Volume128
DOIs
StatePublished - Nov 9 2021

Keywords

  • Atherosclerotic plaques
  • Backward incremental method
  • Computational fluid dynamics
  • Endothelial strain
  • Fluid-structure interaction
  • Mechanical modelling
  • Murine carotid artery
  • Residual stress
  • Wall shear stress

ASJC Scopus subject areas

  • Biophysics
  • Biomedical Engineering
  • Orthopedics and Sports Medicine
  • Rehabilitation

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