Development of 3-D Evaluation System of Microheterogeneity of Intramyocardial Flow Using Molecular Flow Tracers

越来越多的实验证据支持高风险冠状动脉微循环单位的概念，这是心肌缺血风险最大的。然而，心肌微循环血流的生理和病理生理调节存在许多不确定性。因此，在本项目中，为了评价心肌内微循环单位的解剖特征和功能特征，我们旨在利用分子流示踪剂建立心肌内血流微观异质性的三维评价系统。我们测量了心肌区大小为0.01-1.0 mm^2的麻醉兔左、右室局部心肌血流的层内分布。一种新的数字摄影方法结合氚标记去甲基米帕明沉积技术，使我们能够可视化心肌血流分布并计算局部心肌血流的变异系数。右室局部血流变异系数大于左室。左室心内膜下局部血流变异系数大于心外膜下局部血流变异系数，右室两心肌层间无显著差异。根据这些结果，我们认为较大的应力及其可能的左室心内膜下膜下组织的不均一性可能是导致营养血流在心内膜下层分布的更大微观异质性的原因。

Growing experimental evidence support for the concept of high risk coronary microcirculatory unit that is at greatest risk of ischemia in the myocardium. However, there are many uncertainties of physiological and pathophysiological regulation of the microcirculatory blood flow in the myocardium. Therefore, in this project, to evaluate the anatomical features and functional characteristics of the intramyocardial microcirculatory unit, we aimed to develop a three-dimensional evaluation system of microheterogeneity of intramyocardial flow using molecular flow tracers. We measured within-layr distribution of regional myocardial flows in the left and right ventricles of anesthetized rabbits with myocardial region sizes in the range of 0.01-1.0 mm^2. A novel method of digital radiography combined with the technique of tritium-labeled desmethylimipramine deposition enabled us to visualize the myocardial flow distribution and to compute the coefficient of variation of regional myocardial flows. The coefficient of variation of regional flows of the right ventricle was higher than that of the left ventricle. In left ventricle, coefficient of variation of regional flows was higher in the subendocardium than subepicardium, while there was no significant difference between the two myocardial layrs of the right ventricle. Based on these results it was suggested that greater stress and its possible heterogeneity of the subendocardium of the left ventricle may contribute to the greater microheterogeneity of the within-subendocardial layr distribution of the nutritious flow.