Department of Management and Manufacturing Engineering, Faculty of Engineering and Architecture University of Zaragoza, Spain.
Aragón Institute of Engineering Research (I3A), Mechanical Engineering Department University of Zaragoza, Spain.
J Mech Behav Biomed Mater. 2018 Jan;77:434-445. doi: 10.1016/j.jmbbm.2017.10.007. Epub 2017 Oct 4.
In this paper, we hypothesize that the biaxial mechanical properties of the aorta may be dependent on arterial location. To demonstrate any possible position-related difference, our study analyzed and compared the biaxial mechanical properties of the ascending thoracic aorta, descending thoracic aorta and infrarenal abdominal aorta stemming from the same porcine subjects, and reported values of constitutive parameters for well-known strain energy functions, showing how these mechanical properties are affected by location along the aorta. When comparing ascending thoracic aorta, descending thoracic aorta and infrarenal abdominal aorta, abdominal tissues were found to be stiffer and highly anisotropic. We found that the aorta changed from a more isotropic to a more anisotropic tissue and became progressively less compliant and stiffer with the distance to the heart. We observed substantial differences in the anisotropy parameter between aortic samples where abdominal samples were more anisotropic and nonlinear than the thoracic samples. The phenomenological model was not able to capture the passive biaxial properties of each specific porcine aorta over a wide range of biaxial deformations, showing the best prediction root mean square error ε=0.2621 for ascending thoracic samples and, especially, the worst for the infrarenal abdominal samples ε=0.3780. The micro-structured model with Bingham orientation density function was able to better predict biaxial deformations (ε=0.1372 for ascending thoracic aorta samples). The root mean square error of the micro-structural model and the micro-structured model with von Mises orientation density function were similar for all positions.
在本文中，我们假设主动脉的双轴力学性能可能取决于动脉的位置。为了证明任何可能存在的位置相关差异，我们的研究分析和比较了来自同一头猪的升主动脉、降主动脉和肾下腹部主动脉的双轴力学性能，并报告了知名应变能函数的本构参数值，展示了这些力学性能如何受到沿主动脉位置的影响。在比较升主动脉、降主动脉和肾下腹部主动脉时，发现腹部组织更硬且各向异性更强。我们发现，随着与心脏距离的增加，主动脉从更各向同性组织变为更各向异性组织，并且顺应性和刚性逐渐降低。我们观察到主动脉样本之间各向异性参数存在显著差异，其中腹部样本比胸部样本更各向异性和非线性。在宽范围的双轴变形下，现象模型无法捕捉每个特定猪主动脉的被动双轴特性，对于升主动脉样本，表现出最佳的预测均方根误差 ε=0.2621，特别是对于肾下腹部样本，预测效果最差，ε=0.3780。具有宾汉定向密度函数的微观结构模型能够更好地预测双轴变形（对于升主动脉样本，ε=0.1372）。微观结构模型和具有冯·米塞斯定向密度函数的微观结构模型的均方根误差对于所有位置都相似。
