The biomechanical properties of blood clots, which are dictated by their compositions and micro-structures, play a critical role in determining their fates, i.e., occlusion, persistency, or embolization in the human circulatory system. While numerous constitutive models have emerged to describe the biomechanics of blood clots, most of these models have primarily focused on the macroscopic deformation of the clots and the resultant strain-stress correlations without depicting the microscopic contributions from their structural components, such as fibrin fibers, fibrin network and red blood cells. This work addresses the gap in current scientific understanding by quantifying how changes in the microstructure of blood clots affect its mechanical responses under different external stresses. We leverage our previous published work to develop a hyperelastic potential model for blood clots, which incorporates six distinct strain-energy components to describe the alignment of fibers, the entropic and enthalpic stretching of fibrin fibers, the buckling of these fibers, clot densification, and clot jamming. These strain-energy components are represented by a combination of simple harmonic oscillators, one-sided harmonic potentials, and a Gaussian potential. The proposed model, which is , , and continuous with a total of 13 parameters, has been validated against three datasets: 1) fibrin clot in tension, 2) blood clot in compression, and 3) blood clots in shear, demonstrating its robustness. Subsequent simulations of a microscopic blood clot model are performed to uncover mechanistic correlations for a majority of the hyperelastic potential's stiffness/strain parameters. Our results show that only one proposed term concerning fiber buckling needs further refinement, while the remaining five strain-energy terms appear to describe precisely what they were intended to. In summary, the proposed model provides insight into the behavior of thromboembolisms and assistance in computer-aided design of surgical tools and interventions such as thrombectomy.

中文翻译：

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血栓的超弹性：弥合微观尺度和连续尺度之间的差距


血凝块的生物力学特性由其成分和微观结构决定，在决定其命运（即人体循环系统中的闭塞、持续性或栓塞）方面发挥着关键作用。虽然已经出现了许多本构模型来描述血栓的生物力学，但大多数模型主要关注血栓的宏观变形以及由此产生的应变-应力相关性，而没有描述其结构成分（例如纤维蛋白纤维）的微观贡献。纤维蛋白网络和红细胞。这项工作通过量化血凝块微观结构的变化如何影响其在不同外部压力下的机械响应，弥补了当前科学理解的差距。我们利用之前发表的工作开发了血块的超弹性势模型，该模型包含六个不同的应变能分量来描述纤维的排列、纤维蛋白纤维的熵和热函拉伸、这些纤维的屈曲、血块致密化和血栓堵塞。这些应变能分量由简谐振子、单侧谐波势和高斯势的组合表示。所提出的模型为 、 、 和 连续型，共有 13 个参数，已针对三个数据集进行了验证：1) 张力下的纤维蛋白凝块，2) 压缩下的血凝块，3) 剪切下的血凝块，证明了其稳健性。随后对微观血凝块模型进行模拟，以揭示大多数超弹性势的刚度/应变参数的机械相关性。 我们的结果表明，只有一个关于纤维屈曲的拟议术语需要进一步细化，而其余五个应变能术语似乎准确地描述了它们的意图。总之，所提出的模型提供了对血栓栓塞行为的深入了解，并有助于计算机辅助设计手术工具和血栓切除术等干预措施。