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A uni-extension study on the ultimate material strength and extreme extensibility of atherosclerotic tissue in human carotid plaques.


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Authors

Feng, Jiaxuan 
Zhang, Yongxue 
Sutcliffe, Michael PF 
Huang, Yuan 

Abstract

Atherosclerotic plaque rupture occurs when mechanical loading exceeds its material strength. Mechanical analysis has been shown to be complementary to the morphology and composition for assessing vulnerability. However, strength and stretch thresholds for mechanics-based assessment are currently lacking. This study aims to quantify the ultimate material strength and extreme extensibility of atherosclerotic components from human carotid plaques. Tissue strips of fibrous cap, media, lipid core and intraplaque hemorrhage/thrombus were obtained from 21 carotid endarterectomy samples of symptomatic patients. Uni-extension test with tissue strips was performed until they broke or slid. The Cauchy stress and stretch ratio at the peak loading of strips broken about 2mm away from the clamp were used to characterize their ultimate strength and extensibility. Results obtained indicated that ultimate strength of fibrous cap and media were 158.3 [72.1, 259.3] kPa (Median [Inter quartile range]) and 247.6 [169.0, 419.9] kPa, respectively; those of lipid and intraplaque hemorrhage/thrombus were 68.8 [48.5, 86.6] kPa and 83.0 [52.1, 124.9] kPa, respectively. The extensibility of each tissue type were: fibrous cap - 1.18 [1.10, 1.27]; media - 1.21 [1.17, 1.32]; lipid - 1.25 [1.11, 1.30] and intraplaque hemorrhage/thrombus - 1.20 [1.17, 1.44]. Overall, the strength of fibrous cap and media were comparable and so were lipid and intraplaque hemorrhage/thrombus. Both fibrous cap and media were significantly stronger than either lipid or intraplaque hemorrhage/thrombus. All atherosclerotic components had similar extensibility. Moreover, fibrous cap strength in the proximal region (closer to the heart) was lower than that of the distal. These results are helpful in understanding the material behavior of atherosclerotic plaques.

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Keywords

Atherosclerosis, Extensibility, Fibrous cap, Hemorrhage, Lipid core, Ultimate strength, Aged, Carotid Arteries, Endarterectomy, Carotid, Female, Fibrosis, Hemorrhage, Humans, Male, Materials Testing, Middle Aged, Plaque, Atherosclerotic

Journal Title

J Biomech

Conference Name

Journal ISSN

0021-9290
1873-2380

Volume Title

48

Publisher

Elsevier BV
Sponsorship
British Heart Foundation (None)
TCC (None)
British Heart Foundation (None)
European Commission (224297)
National Institute for Health and Care Research (NIHR/CS/009/011)
This research is supported by BHF PG/11/74/29100, HRUK RG2638/14/16, the NIHR Cambridge Biomedical Research Centre and National Natural Science Foundation of China (81170291).