Zienkiewicz Centre for Computational Engineering, College of Engineering, Swansea University, Swansea, UK.
Data Science Building, Swansea University Medical School, Swansea University, Swansea, UK.
Biomech Model Mechanobiol. 2021 Aug;20(4):1231-1249. doi: 10.1007/s10237-021-01437-5. Epub 2021 Mar 8.
We present a novel framework for investigating the role of vascular structure on arterial haemodynamics in large vessels, with a special focus on the human common carotid artery (CCA). The analysis is carried out by adopting a three-dimensional (3D) derived, fibre-reinforced, hyperelastic structural model, which is coupled with an axisymmetric, reduced order model describing blood flow. The vessel transmural pressure and lumen area are related via a Holzapfel-Ogden type of law, and the residual stresses along the thickness and length of the vessel are also accounted for. After a structural characterization of the adopted hyperelastic model, we investigate the link underlying the vascular wall response and blood-flow dynamics by comparing the proposed framework results against a popular tube law. The comparison shows that the behaviour of the model can be captured by the simpler linear surrogate only if a representative value of compliance is applied. Sobol's multi-variable sensitivity analysis is then carried out in order to identify the extent to which the structural parameters have an impact on the CCA haemodynamics. In this case, the local pulse wave velocity (PWV) is used as index for representing the arterial transmission capacity of blood pressure waveforms. The sensitivity analysis suggests that some geometrical factors, such as the stress-free inner radius and opening angle, play a major role on the system's haemodynamics. Subsequently, we quantified the differences in haemodynamic variables obtained from different virtual CCAs, tube laws and flow conditions. Although each artery presents a distinct vascular response, the differences obtained across different flow regimes are not significant. As expected, the linear tube law is unable to accurately capture all the haemodynamic features characterizing the current model. The findings from the sensitivity analysis are further confirmed by investigating the axial stretching effect on the CCA fluid dynamics. This factor does not seem to alter the pressure and flow waveforms. On the contrary, it is shown that, for an axially stretched vessel, the vascular wall exhibits an attenuation in absolute distension and an increase in circumferential stress, corroborating the findings of previous studies. This analysis shows that the new model offers a good balance between computational complexity and physics captured, making it an ideal framework for studies aiming to investigate the profound link between vascular mechanobiology and blood flow.
我们提出了一种新的框架，用于研究大血管中血管结构对动脉血液动力学的作用，特别关注人类颈总动脉（CCA）。该分析通过采用三维（3D）衍生的、纤维增强的超弹性结构模型来进行，该模型与描述血流的轴对称简化模型相结合。血管壁的跨壁压力和管腔面积通过 Holzapfel-Ogden 型定律相关联，并且还考虑了血管厚度和长度上的残余应力。在对所采用的超弹性模型进行结构特征描述之后，我们通过将提出的框架结果与流行的管律进行比较，来研究血管壁响应和血流动力学之间的联系。比较表明，仅当应用代表顺应性的代表性值时，模型的行为才能通过更简单的线性替代来捕获。然后进行 Sobol 多变量敏感性分析，以确定结构参数对 CCA 血液动力学的影响程度。在这种情况下，局部脉搏波速度（PWV）用作表示血压波传输血液压力的动脉传输能力的指标。敏感性分析表明，一些几何因素，如无应力内半径和开口角，对系统的血液动力学起着重要作用。随后，我们量化了不同虚拟 CCA、管律和流动条件下获得的血液动力学变量之间的差异。尽管每条动脉都表现出独特的血管反应，但不同流动状态下获得的差异并不显著。正如预期的那样，线性管律无法准确捕获当前模型所具有的所有血液动力学特征。敏感性分析的结果通过研究 CCA 流动力学对轴向拉伸的影响得到进一步证实。该因素似乎不会改变压力和流动波形。相反，结果表明，对于轴向拉伸的血管，血管壁的绝对扩张会减弱，而周向应力会增加，这与先前研究的结果相符。该分析表明，新模型在计算复杂性和捕获的物理特性之间提供了良好的平衡，使其成为旨在研究血管力学生物学与血流之间深刻联系的理想框架。
