Sriram Krishna, Intaglietta Marcos, Tartakovsky Daniel M
Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California; and.
Department of Bioengineering, University of California, San Diego, La Jolla, California.
Am J Physiol Heart Circ Physiol. 2014 Dec 1;307(11):H1576-86. doi: 10.1152/ajpheart.00283.2014. Epub 2014 Sep 12.
Quantitative modeling of physiological processes in vasculatures requires an accurate representation of network topology, including vessel branching. We propose a new approach for reconstruction of vascular network, which determines how vessel bifurcations distribute red blood cells (RBC) in the microcirculation. Our method follows the foundational premise of Murray's law in postulating the existence of functional optimality of such networks. It accounts for the non-Newtonian behavior of blood by allowing the apparent blood viscosity to vary with discharge hematocrit and vessel radius. The optimality criterion adopted in our approach is the physiological cost of supplying oxygen to the tissue surrounding a blood vessel. Bifurcation asymmetry is expressed in terms of the amount of oxygen consumption associated with the respective tissue volumes being supplied by each daughter vessel. The vascular networks constructed with our approach capture a number of physiological characteristics observed in in vivo studies. These include the nonuniformity of wall shear stress in the microcirculation, the significant increase in pressure gradients in the terminal sections of the network, the nonuniformity of both the hematocrit partitioning at vessel bifurcations and hematocrit across the capillary bed, and the linear relationship between the RBC flux fraction and the blood flow fraction at bifurcations.
血管系统中生理过程的定量建模需要准确表示网络拓扑结构，包括血管分支。我们提出了一种新的血管网络重建方法，该方法确定血管分叉如何在微循环中分配红细胞（RBC）。我们的方法遵循默里定律的基本前提，即假设此类网络存在功能最优性。它通过允许表观血液粘度随排出血细胞比容和血管半径变化来考虑血液的非牛顿行为。我们方法中采用的最优性标准是向血管周围组织供应氧气的生理成本。分叉不对称性通过与每个子血管所供应的相应组织体积相关的氧气消耗量来表示。用我们的方法构建的血管网络捕捉了体内研究中观察到的许多生理特征。这些特征包括微循环中壁面剪应力的不均匀性、网络末端部分压力梯度的显著增加、血管分叉处血细胞比容分配和整个毛细血管床血细胞比容的不均匀性，以及分叉处红细胞通量分数与血流分数之间的线性关系。
