title: A combination of histological analyses and uniaxial tensile tests to determine the material coefficients of the healthy and atherosclerotic human coronary arteries.
abstract: Atherosclerosis is considered as the most severe form of cardiovascular diseases as it alters the structure of the elastin and collagen and, consequently, the mechanical properties of the artery wall. The role of collagen fibers orientations in the mechanical properties of the healthy and atherosclerotic human coronary arteries so far has not been well determined. In this study, a fiber family based constitutive equation was employed to address the mechanical behavior of healthy and atherosclerotic human coronary arteries using the combination of histostructural and uniaxial data. A group of six healthy and atherosclerotic human coronary arteries was excised at autopsy and histological analyses were performed on each artery to determine the mean angle of collagen fibers. The preconditioned arterial tissues were then subjected to a series of quasi-static axial and circumferential loadings. The key role of fiber orientation was explicitly added into a proposed strain energy density function. The constrained nonlinear optimization method was used to determine the material coefficients based on the axial and circumferential extension data of the arteries. The material coefficients of coronary arteries were given with R(2)≥0.991. The results regardless of loading direction revealed a significant load-bearing capacity and stiffness of atherosclerotic arteries compared to the healthy ones (p<0.005). The optimized fiber angles were in good agreement with the experimental histological data as only 2.52% and 10.10% differences were observed for the healthy and atherosclerotic arteries, respectively. The stored energy function of the healthy arteries was found to be higher than that of atherosclerotic ones. These findings help us to understand the directional mechanical properties of coronary arteries which may have implications for different types of interventions and surgeries, including bypass, stenting, and balloon-angioplasty.
authors.affiliation: School of Mechanical Engineering, Iran University of Science and Technology, Tehran 16846, Iran; Tissue Engineering and Biological Systems Research Laboratory, School of Mechanical Engineering, Iran University of Science and Technology, Tehran 16887, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Karimi
authors.affiliation: School of Mechanical Engineering, Iran University of Science and Technology, Tehran 16846, Iran; Tissue Engineering and Biological Systems Research Laboratory, School of Mechanical Engineering, Iran University of Science and Technology, Tehran 16887, Iran. Electronic address: mnavid@iust.ac.ir.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Navidbakhsh
authors.affiliation: Department of Ophthalmology, Baqiyatallah University of Medical Sciences, Tehran 14155, Iran; Research Department, Basir Eye Center, Tehran 14186, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Shojaei
mesh_terms: D003324:Coronary Artery Disease / Q000503:physiopathology*; D003331:Coronary Vessels / Q000503:physiopathology*; D004548:Elasticity / Q000502:physiology*; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology
keywords: Atherosclerosis; Coronary artery; Histological structure; Strain-energy density function; Uniaxial extension