Pillalamarri N R, Patnaik S S, Piskin S, Gueldner P, Finol E A
University of Texas at San Antonio, Department of Mechanical Engineering, San Antonio, TX.
Istinye University, Department of Mechanical Engineering, Zeytinburnu, Istanbul, Turkey.
Exp Mech. 2021 Jan;61(1):285-303. doi: 10.1007/s11340-020-00678-2. Epub 2021 Jan 7.
Regional mechanical characterization of pulmonary arteries can be useful in the development of computational models of pulmonary arterial mechanics.
We performed a biomechanical and microstructural characterization study of porcine pulmonary arteries, inclusive of the main, left, and right pulmonary arteries (MPA, LPA, and RPA, respectively).
The specimens were initially stored at -20°C and allowed to thaw for 12-24 hours prior to testing. Each artery was further subdivided into proximal, middle, and distal regions, leading to ten location-based experimental groups. Planar equibiaxial tensile testing was performed to evaluate the mechanical behavior of the specimens, from which we calculated the stress at the maximum strain ( ), tensile modulus (TM), anisotropy index (AI), and strain energy in terms of area under the stress-strain curve (AUC). Histological quantification was performed to evaluate the area fraction of elastin and collagen content, intima-media thickness (IMT), and adventitial thickness (AT). The constitutive material behavior of each group was represented by a five-constant Holzapfel-Gasser-Ogden model.
The specimens exhibited non-linear stress-strain characteristics across all groups. The MPA exhibited the highest mean wall stress and TM in the longitudinal and circumferential directions, while the bifurcation region yielded the highest values of AI and AUC. All regions revealed a higher stiffness in the longitudinal direction compared to the circumferential direction, suggesting a degree of anisotropy that is believed to be within the margin of experimental uncertainty. Collagen content was found to be the highest in the MPA and decreased significantly at the bifurcation, LPA and RPA. Elastin content did not yield such significant differences amongst the ten groups. The MPA had the highest IMT, which decreased concomitantly to the distal LPA and RPA. No significant differences were found in the AT amongst the ten groups.
The mechanical properties of porcine pulmonary arteries exhibit strong regional dissimilarities, which can be used to inform future studies of high fidelity finite element models.
肺动脉的区域力学特性对于肺动脉力学计算模型的开发可能有用。
我们对猪肺动脉进行了生物力学和微观结构特性研究，包括主肺动脉、左肺动脉和右肺动脉（分别为MPA、LPA和RPA）。
标本最初储存在-20°C，在测试前解冻12 - 24小时。每条动脉进一步细分为近端、中间和远端区域，形成十个基于位置的实验组。进行平面等双轴拉伸试验以评估标本的力学行为，由此我们计算了最大应变时的应力（ ）、拉伸模量（TM）、各向异性指数（AI）以及应力 - 应变曲线下面积（AUC）表示的应变能。进行组织学定量分析以评估弹性蛋白和胶原蛋白含量的面积分数、内膜 - 中膜厚度（IMT）和外膜厚度（AT）。每组的本构材料行为由五常数霍尔扎佩尔 - 加塞尔 - 奥格登模型表示。
所有组的标本均表现出非线性应力 - 应变特性。MPA在纵向和圆周方向上表现出最高的平均壁应力和TM，而分叉区域产生最高的AI和AUC值。与圆周方向相比，所有区域在纵向方向上显示出更高的刚度，表明各向异性程度被认为在实验不确定性范围内。发现胶原蛋白含量在MPA中最高，在分叉处、LPA和RPA处显著降低。弹性蛋白含量在这十个组之间没有产生如此显著的差异。MPA的IMT最高，向远端LPA和RPA逐渐降低。十个组之间的AT没有发现显著差异。
猪肺动脉的力学性能表现出强烈的区域差异，这可用于为未来高保真有限元模型的研究提供信息。
