Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States.
Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States; Center for Vascular Remodeling and Regeneration, University of Pittsburgh, Pittsburgh, PA, United States; McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, United States.
J Biomech. 2014 Mar 21;47(5):981-8. doi: 10.1016/j.jbiomech.2014.01.005. Epub 2014 Jan 14.
Aortic dissection (AoD) is a common condition that often leads to life-threatening cardiovascular emergency. From a biomechanics viewpoint, AoD involves failure of load-bearing microstructural components of the aortic wall, mainly elastin and collagen fibers. Delamination strength of the aortic wall depends on the load-bearing capacity and local micro-architecture of these fibers, which may vary with age, disease and aortic location. Therefore, quantifying the role of fiber micro-architecture on the delamination strength of the aortic wall may lead to improved understanding of AoD. We present an experimentally-driven modeling paradigm towards this goal. Specifically, we utilize collagen fiber micro-architecture, obtained in a parallel study from multi-photon microscopy, in a predictive mechanistic framework to characterize the delamination strength. We then validate our model against peel test experiments on human aortic strips and utilize the model to predict the delamination strength of separate aortic strips and compare with experimental findings. We observe that the number density and failure energy of the radially-running collagen fibers control the peel strength. Furthermore, our model suggests that the lower delamination strength previously found for the circumferential direction in human aorta is related to a lower number density of radially-running collagen fibers in that direction. Our model sets the stage for an expanded future study that could predict AoD propagation in patient-specific aortic geometries and better understand factors that may influence propensity for occurrence.
主动脉夹层（AoD）是一种常见的病症，常导致危及生命的心血管急症。从生物力学的角度来看，AoD 涉及主动脉壁承载微观结构组件的失效，主要是弹性蛋白和胶原蛋白纤维。主动脉壁的分层强度取决于这些纤维的承载能力和局部微观结构，而这些纤维的承载能力和局部微观结构可能随年龄、疾病和主动脉位置而变化。因此，定量分析纤维微观结构对主动脉壁分层强度的作用可能有助于深入了解 AoD。我们提出了一种基于实验的建模范例来实现这一目标。具体来说，我们利用从多光子显微镜获得的胶原蛋白纤维微观结构，在一个预测性的力学框架中，对分层强度进行特征化。然后，我们将我们的模型与人体主动脉条的剥离测试实验进行比较，并利用模型预测不同主动脉条的分层强度，并与实验结果进行比较。我们观察到，径向运行的胶原蛋白纤维的数量密度和失效能控制着剥离强度。此外，我们的模型表明，先前在人体主动脉中发现的圆周方向的较低分层强度与该方向上径向运行的胶原蛋白纤维数量密度较低有关。我们的模型为未来的研究奠定了基础，该研究可以预测特定患者的主动脉几何形状中的 AoD 传播，并更好地理解可能影响发生倾向的因素。
