Consideration of stiffness of wall layers is decisive for patient-specific analysis of carotid artery with atheroma.

Ondřej Lisický,Aneta Malá,Jiří Burša,Zdeněk Bednařík,Tomáš Novotný,Fang-Bao Tian

doi:10.1371/journal.pone.0239447

Abstract

The paper deals with the impact of chosen geometric and material factors on maximal stresses in carotid atherosclerotic plaque calculated using patient-specific finite element models. These stresses are believed to be decisive for the plaque vulnerability but all applied models suffer from inaccuracy of input data, especially when obtained in vivo only. One hundred computational models based on ex vivo MRI are used to investigate the impact of wall thickness, MRI slice thickness, lipid core and fibrous tissue stiffness, and media anisotropy on the calculated peak plaque and peak cap stresses. The investigated factors are taken as continuous in the range based on published experimental results, only the impact of anisotropy is evaluated by comparison with a corresponding isotropic model. Design of Experiment concept is applied to assess the statistical significance of these investigated factors representing uncertainties in the input data of the model. The results show that consideration of realistic properties of arterial wall in the model is decisive for the stress evaluation; assignment of properties of fibrous tissue even to media and adventitia layers as done in some studies may induce up to eightfold overestimation of peak stress. The impact of MRI slice thickness may play a key role when local thin fibrous cap is present. Anisotropy of media layer is insignificant, and the stiffness of fibrous tissue and lipid core may become significant in some combinations.

Highlights

Atherosclerosis is a cardiovascular disease causing local intimal thickening of artery wall and plaque formation
We focused on consideration of material properties of the vessel wall along with those of the atheroma; we used 3D PS computational models and the design of experiment (DoE) strategy to investigate their influence on peak cap stress (PCS) and peak plaque stress (PPS)
The fibrous tissue (FT) extreme experimental responses selected for this study show only low strain stiffening which was captured by the second parameter of the used Yeoh strain-energy density function (SEDF)

Summary

Introduction

Atherosclerosis is a cardiovascular disease causing local intimal thickening of artery wall and plaque formation. Vulnerable atherosclerotic plaques, characterized by lipid accumulation under a thin fibrous cap (FC), have attracted attention of researchers for more than two decades [1, 2]. A rupture of the plaque may cause blood clot formation and leads to the stroke in case of carotid arteries [3]. The rupture occurs when stresses induced by mechanical loading. Stiffness of wall layers is decisive for the atheroma stresses

Results

Discussion

Conclusion