Karimi Alireza, Navidbakhsh Mahdi, Shojaei Ahmad
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.
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.
Tissue Cell. 2015 Apr;47(2):152-8. doi: 10.1016/j.tice.2015.01.004. Epub 2015 Jan 29.
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.
动脉粥样硬化被认为是心血管疾病最严重的形式，因为它会改变弹性蛋白和胶原蛋白的结构，进而改变动脉壁的力学性能。迄今为止，胶原纤维取向对健康和动脉粥样硬化的人类冠状动脉力学性能的作用尚未得到很好的确定。在本研究中，采用基于纤维族的本构方程，结合组织结构和单轴数据来研究健康和动脉粥样硬化的人类冠状动脉的力学行为。在尸检时切除一组6条健康和动脉粥样硬化的人类冠状动脉，并对每条动脉进行组织学分析，以确定胶原纤维的平均角度。然后对预处理后的动脉组织进行一系列准静态轴向和周向加载。纤维取向的关键作用被明确地纳入到一个提出的应变能密度函数中。采用约束非线性优化方法，根据动脉的轴向和周向伸长数据确定材料系数。冠状动脉的材料系数R(2)≥0.991。无论加载方向如何，结果显示与健康动脉相比，动脉粥样硬化动脉具有显著的承载能力和刚度(p<0.005)。优化后的纤维角度与实验组织学数据吻合良好，健康动脉和动脉粥样硬化动脉的差异分别仅为2.52%和10.10%。发现健康动脉的储能函数高于动脉粥样硬化动脉。这些发现有助于我们理解冠状动脉的定向力学性能，这可能对不同类型的干预和手术有影响，包括搭桥、支架置入和球囊血管成形术。
