Navarrete Álvaro, Bezmalinovic Alejandro, Utrera Andrés, Álvarez-Carrasco Fabián, Herrera Emilio A, García-Herrera Claudio, Celentano Diego J
Departamento de Ingeniería Mecánica, Universidad de Santiago de Chile, USACH, Av. Bernardo O'Higgins 3363, Santiago de Chile, Chile.
Departamento de Ingeniería Mecánica, Universidad de Santiago de Chile, USACH, Av. Bernardo O'Higgins 3363, Santiago de Chile, Chile.
Comput Biol Med. 2025 Aug;194:110399. doi: 10.1016/j.compbiomed.2025.110399. Epub 2025 Jun 5.
The long-term effect of high altitude hypoxia (HAH) exposure is a relevant problem in cardiovascular biomechanics, that has not yet been fully assessed. Regarding this, the study examined the passive viscoelastic response of the descending thoracic aorta of individuals exposed to HAH.
Through a guinea-pig animal model, subjected to either normoxic-normobaric or HAH conditions (groups N and H, respectively), biaxial tensile and uniaxial stress relaxation tests were performed on artery samples. The experimental data obtained from these biomechanical tests allowed us to characterize an anisotropic quasi-linear viscoelastic model based on the Gasser-Holzapfel-Ogden (GHO) hyperelastic material.
Among the main results, biaxial tensile tests exhibited a trend towards a higher stiffness (at high stretch levels) in the hypoxic group. Results of stress relaxation tests revealed a similar behavior between groups, at both the initial, more pronounced stress-relaxation stage, attributed to the effect of elastin fibers, and at the second stage, with a less pronounced decrease in stress due to the role of collagen fibers.
Our study suggests that although HAH does not alter significantly the passive elastic and viscous properties of aortic tissue under ex-vivo conditions, there is a tendency to material stiffening to supra-physiological levels. Assessment of the biomechanical response is crucial to determine the pathophysiological effects in the cardiovascular system derived from exposure to HAH.
高原低氧（HAH）暴露的长期影响是心血管生物力学中的一个相关问题，尚未得到充分评估。关于此，本研究检测了暴露于HAH的个体降主动脉的被动粘弹性反应。
通过豚鼠动物模型，分别置于常氧常压或HAH条件下（分别为N组和H组），对动脉样本进行双轴拉伸和单轴应力松弛试验。从这些生物力学试验中获得的实验数据使我们能够基于加塞尔-霍尔扎佩尔-奥格登（GHO）超弹性材料表征一种各向异性准线性粘弹性模型。
在主要结果中，双轴拉伸试验显示低氧组在高拉伸水平下有更高硬度的趋势。应力松弛试验结果表明，在初始的、更明显的应力松弛阶段（归因于弹性纤维的作用）以及第二阶段（由于胶原纤维的作用应力下降不太明显），两组之间表现出相似的行为。
我们的研究表明，尽管在体外条件下HAH不会显著改变主动脉组织的被动弹性和粘性特性，但存在材料变硬至超生理水平的趋势。评估生物力学反应对于确定暴露于HAH对心血管系统的病理生理影响至关重要。
