Structure-based mechanical properties of human carotid arteries and their effect on stress-strain response

Abstract

Mechanical properties and structure of components of an atherosclerotic arterial wall are important for computational prediction of atheroma vulnerability. In this study, a total of 36 specimens harvested during standard carotid endarterectomies were tested under uniaxial tension, followed by histological examination to distinguish their tissue types. The structural composition of the specimens was found to have a significant impact on their mechanical properties, more specifically the extensibility. Specimens with severe atherosclerotic changes exhibited lower extensibility compared with those less impacted by the disease (p-value < 0.005), while no difference was observed in strength. These findings suggest that deformation-related parameters (strains) may be more sensitive to tissue-level disease changes than stress-based measures. A total of 64 computational simulations was performed using patient-specific geometry with isotropic and anisotropic models of individual arterial layers. These models demonstrate that local collagen fibre distribution in the fibrous cap where rupture can occur, is necessary for accurate assessment of strains and stresses. In contrast, population-specific data, such as those obtained in this study, may be sufficient for modelling the outer artery layers where the collagen fibre orientation did not have a significant impact on the strains and stresses in the fibrous cap.