猪降主动脉环向力学性质的实验研究

目的 研究猪降主动脉的力学特性。方法 猪降主动脉按照距心脏距离分成5组，各组由左右两侧组织、腹侧面组织构成。使用单轴拉伸方法拉伸组织，获得应力与伸张比曲线。采用经典数学模型分析5个部位（位置1～5）弹性、胶原纤维模量以及胶原纤维激活参数等特征，并对比腹侧面与两侧组织之间的力学差异。结果 在环向上，胶原纤维模量随着远离心脏的方向逐渐增长，而弹性纤维模量位置1～4随着距心脏的距离增加而逐渐增大，位置5的弹性纤维模量减小，且位置5两侧的环向弹性纤维模量小于腹侧面约19%；在轴向上，弹性纤维模量小于腹侧面约37%，位置5腹侧面的弹性纤维模量相比于位置4差异不大（均值差异约5%）。在整个降主动脉中，侧面环向胶原纤维模量大于腹侧面约26%，环向弹性纤维模量在靠近心脏的四部分侧面高于腹侧面约16%。结论 猪胸主动脉的环向力学特性和位置有关，最远端的部分在低应力下表现出较软特点。研究结果有助于科研人员更好理解主动脉的力学特征以及开展更细致的计算机建模。
Objective To study the mechanical properties of porcine descending aorta. Methods The porcine descending aortas were divided into 5 groups by the distance from the heart, and tissues in each group were subdivided into ventral-quadrant part and lateral-quadrant part. Stress-stretch curves were obtained by using uniaxial tension test. The moduli of elastic and collagen fiber and collagen fiber recruitment parameter of tissues in 5 groups (Position 1-5) were first analyzed by a classical mathematical model. Then the mechanical differences between tissues of ventral quadrant and lateral quadrant were compared. Results The modulus of circumferential collagen fibers increased gradually away from the heart. The modulus of circumferential elastic fibers had the same trend except for tissues at Position 5 (the most distal one). The elastic fibers modulus of tissues decreased at Position 5. At the most distal position, the circumferential and axial elastic fiber modulus of the lateral quadrant was lower than that of ventral quadrant by 19% and 33%, respectively. The axial and the elastic fiber modulus of the ventral quadrant was similar with that of tissues at Position 4 and 5. For the whole descending aorta, the circumferential collagen fiber modulus of the lateral quadrant was higher than that of ventral quadrant by 26% and the circumferential elastic fiber modulus of the lateral quadrant was higher than that of ventral quadrant by 16% at the proximal 4 positions. Conclusions The circumferential mechanical properties of porcine descending aorta were related with regions. The ventral quadrant of the most distal aorta showed abnormally soft trend. The research findings can be used to better understand the mechanism of aorta and improve the spatial accuracy of computer models.