Imaging Sciences & Biomedical Engineering Division, St Thomas' Hospital, King's College London, SE1 7EH, UK.
J Biomech. 2012 Mar 15;45(5):850-5. doi: 10.1016/j.jbiomech.2011.11.026. Epub 2011 Dec 10.
The strong coupling between the flow in coronary vessels and the mechanical deformation of the myocardial tissue is a central feature of cardiac physiology and must therefore be accounted for by models of coronary perfusion. Currently available geometrically explicit vascular models fail to capture this interaction satisfactorily, are numerically intractable for whole organ simulations, and are difficult to parameterise in human contexts. To address these issues, in this study, a finite element formulation of an incompressible, poroelastic model of myocardial perfusion is presented. Using high-resolution ex vivo imaging data of the coronary tree, the permeability tensors of the porous medium were mapped onto a mesh of the corresponding left ventricular geometry. The resultant tensor field characterises not only the distinct perfusion regions that are observed in experimental data, but also the wide range of vascular length scales present in the coronary tree, through a multi-compartment porous model. Finite deformation mechanics are solved using a macroscopic constitutive law that defines the coupling between the fluid and solid phases of the porous medium. Results are presented for the perfusion of the left ventricle under passive inflation that show wall-stiffening associated with perfusion, and that show the significance of a non-hierarchical multi-compartment model within a particular perfusion territory.
冠状动脉内的流动与心肌组织的力学变形之间的强耦合是心脏生理学的一个核心特征，因此必须在冠状动脉灌注模型中加以考虑。目前可用的显式血管模型不能令人满意地捕捉到这种相互作用，对于整个器官模拟在数值上是难以处理的，并且在人体环境中难以参数化。为了解决这些问题，在本研究中，提出了心肌灌注不可压缩、多孔弹性模型的有限元公式。使用冠状动脉树的高分辨率离体成像数据，将多孔介质的渗透率张量映射到相应的左心室几何形状的网格上。所得张量场不仅描述了实验数据中观察到的不同灌注区域，而且通过多腔多孔模型描述了冠状动脉树中存在的广泛的血管长度尺度。使用宏观本构定律来求解有限变形力学，该定律定义了多孔介质的流体相与固相之间的耦合。给出了在被动膨胀下左心室灌注的结果，显示了与灌注相关的壁变硬，并且显示了特定灌注区域内非层次多腔模型的重要性。
