Wang Chong, Garcia Marisa, Lu Xiao, Lanir Yoram, Kassab Ghassan S
Department of Mechanical and Aerospace Engineering, University of California, Irvine, 204 Rockwell Engineering Center, Irvine, CA 92697-2715, USA.
Am J Physiol Heart Circ Physiol. 2006 Sep;291(3):H1200-9. doi: 10.1152/ajpheart.01323.2005. Epub 2006 Mar 31.
The normal coronary artery consists of two mechanically distinct layers: intima-media and adventitia. The objective of this study is to establish a two-layer three-dimensional (3-D) stress-strain relation of porcine coronary arteries. Experimental measurements were made by a series of biaxial tests (inflation and axial extension) of intact coronary arteries and, subsequently, their corresponding intima-media or adventitia layer. The Fung-type exponential strain energy function was used to describe the 3-D strain-stress relation for each layer and the intact wall. A genetic algorithm was used to determine the material constants in the Fung-type constitutive equation by curve fitting the experimental data. Because one layer must be sacrificed before the other layer can be tested, the material property of the missing layer was computed from the material constants of the intact vessel and the tested layer. A total of 20 porcine hearts were used: one group of 10 hearts for the left anterior descending artery and another group of 10 hearts for the right coronary artery. Each group was further divided into two subgroups of five specimens tested for the intact wall and the intima-media layer and for the intact wall and the adventitia layer. Our results show statistically significant differences in the material properties of the two layers. The mathematical model was validated by experimental stress-strain data for individual layers. The validated 3-D constitutive model will serve as a foundation for formulation of layer-specific boundary value problems in coronary physiology and cardiology.
内膜-中膜层和外膜层。本研究的目的是建立猪冠状动脉的两层三维应力-应变关系。通过对完整冠状动脉及其相应的内膜-中膜层或外膜层进行一系列双轴试验（充气和轴向拉伸）来进行实验测量。采用冯氏指数应变能函数来描述各层和完整血管壁的三维应变-应力关系。通过对实验数据进行曲线拟合，采用遗传算法确定冯氏本构方程中的材料常数。由于在测试另一层之前必须牺牲一层，因此缺失层的材料特性是根据完整血管和已测试层的材料常数计算得出的。总共使用了20个猪心脏：一组10个心脏用于左前降支动脉，另一组10个心脏用于右冠状动脉。每组进一步分为两个亚组，每个亚组有5个标本，分别测试完整血管壁和内膜-中膜层以及完整血管壁和外膜层。我们的结果显示两层的材料特性存在统计学上的显著差异。该数学模型通过各层的实验应力-应变数据得到验证。经过验证的三维本构模型将为冠状动脉生理学和心脏病学中层特异性边界值问题的制定奠定基础。
