Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands.
Biomech Model Mechanobiol. 2012 Mar;11(3-4):533-42. doi: 10.1007/s10237-011-0331-1. Epub 2011 Jul 13.
A patient-specific mechanical description of the coronary arterial wall is indispensable for individualized diagnosis and treatment of coronary artery disease. A way to determine the artery's mechanical properties is to fit the parameters of a constitutive model to patient-specific experimental data. Clinical data, however, essentially lack information about the stress-free geometry of an artery, which is necessary for constitutive modeling. In previous research, it has been shown that a way to circumvent this problem is to impose extra modeling constraints on the parameter estimation procedure. In this study, we propose a new modeling constraint concerning the in-situ fiber orientation (β (phys)). β (phys), which is a major contributor to the arterial stress-strain behavior, was determined for porcine and human coronary arteries using a mixed numerical-experimental method. The in-situ situation was mimicked using in-vitro experiments at a physiological axial pre-stretch, in which pressure-radius and pressure-axial force were measured. A single-layered, hyperelastic, thick-walled, two-fiber material model was accurately fitted to the experimental data, enabling the computation of stress, strain, and fiber orientation. β (phys) was found to be almost equal for all vessels measured (36.4 ± 0.3)°, which theoretically can be explained using netting analysis. In further research, this finding can be used as an extra modeling constraint in parameter estimation from clinical data.
为了实现冠状动脉疾病的个体化诊断和治疗，对冠状动脉壁进行特定于患者的力学描述是必不可少的。确定动脉力学特性的一种方法是将本构模型的参数拟合到特定于患者的实验数据。然而，临床数据基本上缺乏动脉无应力几何形状的信息，这对于本构建模是必要的。在以前的研究中，已经表明一种规避这个问题的方法是在参数估计过程中施加额外的建模约束。在这项研究中，我们提出了一个关于原位纤维取向（β（phys））的新建模约束。β（phys）是动脉应力-应变行为的主要贡献者，我们使用混合数值-实验方法确定了猪和人冠状动脉的β（phys）。通过在生理轴向预拉伸下进行的体外实验模拟原位情况，测量了压力-半径和压力-轴向力。单层超弹性厚壁双纤维材料模型准确地拟合了实验数据，从而能够计算出应力、应变和纤维取向。测量的所有血管的β（phys）几乎相等（36.4±0.3）°，这可以使用网眼分析理论上进行解释。在进一步的研究中，这一发现可以作为从临床数据进行参数估计的额外建模约束。
