School of Engineering, University of Aberdeen, Aberdeen, UK.
Microvasc Res. 2010 Jul;80(1):99-109. doi: 10.1016/j.mvr.2010.02.005. Epub 2010 Feb 13.
This paper presents the results of a circulation analysis using an image based network model of a murine retinal vasculature, which closely represents the 3D vascular distribution of the retina. The uneven distribution of the red blood cells at vascular network bifurcations (i.e., plasma skimming effect), the microvascular diameter effect (i.e., Fahraeus-Lindqvist effect) and the role of endothelium surface layer (i.e., in vivo viscosity) were considered in determining the viscosity of the blood in the retinal vessel segments. The study yielded detailed distributions of the hemodynamic quantities in the arterial and venous trees shown in various anatomical based contour plots. Quantitative analysis was also carried out based on statistical distributions. The analysis shows that the distribution of the blood hematocrit (H(D)) in the retinal network is very non-uniform, with lower values at the pre-equator region (near the optic disc) and higher values in the equator region of the retina. This has significant influence on the distribution of apparent viscosity, pressure and wall shear stress (WSS) in the vasculature. The viscosity is generally higher in smaller vessels (i.e., pre-capillary vessels) but exceptions occur in some vessels where the H(D) is small. WSS is greater in smaller vessels located near the optic disc than that in the mainstream retinal vessels. The results presented can be directly useful to ophthalmologists and researchers working with retinal vasculature.
本文介绍了一种基于图像的鼠视网膜血管网络模型的循环分析结果,该模型紧密代表了视网膜的 3D 血管分布。在确定视网膜血管段血液的粘度时,考虑了红细胞在血管网络分支处的不均匀分布(即血浆撇除效应)、微血管直径效应(即 Fahraeus-Lindqvist 效应)和内皮表面层的作用(即体内粘度)。研究得到了动脉和静脉树中各种基于解剖学的等高线图中血液动力学量的详细分布。还根据统计分布进行了定量分析。分析表明,视网膜网络中血液的血细胞比容(H(D))分布非常不均匀,在赤道前区域(靠近视盘)的值较低,而在视网膜赤道区域的值较高。这对血管中表观粘度、压力和壁面切应力(WSS)的分布有重大影响。粘度通常在较小的血管(即毛细血管前血管)中较高,但在某些 H(D)较小的血管中存在例外。位于视盘附近的较小血管中的 WSS大于主流视网膜血管中的 WSS。所呈现的结果可以直接对眼科医生和研究视网膜血管的研究人员有用。