Background Aortic dissection (AD) is a common pathology and challenging clinical problem. A better understanding of the biomechanical effects preceding its initiation is essential for predicting adverse events on a patient-specific basis. Moreover, the predictability of patient-specific biomechanics-based computational models is hampered by uncertainty about boundary conditions and material properties. Objective Predisposition of thoracic aortic aneurysms (TAA) to ADs can be related to the degradation of biomechanically important constituents in the aortic wall of TAAs. The goal of the present study is to develop a new methodology to measure strain fields in aortic tissues subjected to radial tensile loading, combining optical coherence tomography (OCT) and digital image correlation (DIC). Methods Radial tensile tests are performed on 5 samples collected from a healthy porcine descending thoracic aorta and 2 samples collected from a human ascending thoracic aortic aneurysm. At each step of the radial tensile test, the OCT technique is used to acquire images of the sample presenting a speckle pattern generated by the optical signature of the tissue. The speckle pattern is used to quantify displacement and strain fields using DIC. Stress-strain data are also measured throughout the analyzed range. Results Results show that strain commonly localizes very early during tensile tests, at the location where the crack onset occurs. Aneurysm samples even show a sharper localization than healthy porcine tissues. Conclusion This suggests the importance of extending the analysis to a larger number of human samples using our new methodology to better identify the conditions predisposing aortas to dissection.

中文翻译：

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受径向张力作用的主动脉壁剥离前应变定位的体外测量

背景主动脉夹层 (AD) 是一种常见的病理和具有挑战性的临床问题。在开始之前更好地了解生物力学效应对于在特定患者的基础上预测不良事件至关重要。此外，基于患者特定生物力学的计算模型的可预测性受到边界条件和材料特性的不确定性的阻碍。目的胸主动脉瘤 (TAA) 对 AD 的易感性可能与 TAA 主动脉壁中生物力学重要成分的降解有关。本研究的目标是开发一种新的方法来测量受到径向拉伸载荷的主动脉组织中的应变场，结合光学相干断层扫描 (OCT) 和数字图像相关 (DIC)。方法对从健康猪胸降主动脉收集的5个样本和从人胸升主动脉瘤收集的2个样本进行径向拉伸试验。在径向拉伸测试的每个步骤中，OCT 技术用于获取样品的图像，该图像呈现由组织的光学特征生成的散斑图案。散斑图案用于使用 DIC 量化位移和应变场。还在整个分析范围内测量应力-应变数据。结果 结果表明，应变通常在拉伸试验中很早就出现，即出现裂纹的位置。动脉瘤样本甚至显示出比健康猪组织更清晰的定位。