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Evaluation of myocardial blood flow heterogeneity by using molecular deposition technique and fractal analysis

分子沉积技术和分形分析评价心肌血流异质性

基本信息

批准号：
05680768
负责人：
OGASAWARA Yasuo
金额：
$ 1.34万
依托单位：
Kawasaki Medical School
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

The goal of this study was to evaluate microheterogeneity of myocardial blood flow and a functional zone of vascular control, and their dependency on arterial oxygen tension (PO_2). We introduced a new method of imaging myocardial blood flow with highest spatial resolution so far, and succeeded to visualize regional blood flow of the rabbit left ventricle during normoxic and hypoxic states. We injected ^3H-labeled desmethylimipramine into the left ventricle of the anesthetized rabbit heart (n=12) , and imaged myocardial blood flow distribution using digital-radiography with highest resolution of 0.01 mm^2. The image was quantitated ; we computed the coefficient of variation (CV) and the correlation between adjacent regional fows (C_A). CV was resolution dependent ; with increasing resolution ranging from 0.01 mm^2 to 1 mm^2, CV increased in both normoxic and hypoxic states (p<0.001). At all resolution, CV was larger during normoxia(PO_2=97<plus-minus>20 mmHg)than hypoxia (PO_2=26<plus-minus>5 mmHg)(p<0.001) , while C_A was smaller in normoxia than in hypoxia(p<0.001). In the normoxic state, C_A of the deep myocardial layr is larger than that of superficial myocardial layr (p<0.001). The hypoxic perfusion resulted in no difference in C_A between the myocardial layrs. We conclude as followings : 1) The heterogeneity of myocardial blood flow increased with measurement resolution, and there is surprising microheterogeneity at resolution of 0.01 mm^2.2) In response to decreased arterial PO_2, the heterogeneity of blood flow decreased regardless of spatial resolution, and the functional zone of vascular control enlaged as evaluated by C_A. The latter suggests that the main site of vascular control shifts toward larger arteriole during the hypoxic state.

本研究的目的是评价心肌血流和血管控制功能区的微观异质性及其对动脉血氧压（PO_2）的依赖性。我们介绍了一种迄今为止空间分辨率最高的心肌血流成像新方法，成功地显示了兔左心室在常氧和缺氧状态下的局部血流。我们将^ 3h标记的去甲基咪帕明注射到麻醉的兔心脏左心室（n=12），并使用最高分辨率为0.01 mm^2的数字x线摄影成像心肌血流分布。对图像进行定量；我们计算了变异系数（CV）和相邻区域流量之间的相关性（C_A）。CV依赖于分辨率；随着分辨率从0.01 mm^2到1 mm^2的增加，CV在常氧和缺氧状态下都增加（p<0.001）。在所有分辨率下，常氧条件下CV （PO_2=97<正负>20 mmHg）均大于缺氧条件下CV (PO_2=26<正负>5 mmHg)(p<0.001)，而C_A在常氧条件下均小于缺氧条件下（p<0.001）。常氧状态下，心肌深层C_A大于浅层C_A （p<0.001）。低氧灌注导致心肌各层间C_A无差异。结果表明：1)心肌血流的异质性随测量分辨率的增加而增加，在0.01 mm^2.2分辨率下存在显著的微观异质性。随着动脉PO_2的降低，血流的异质性随空间分辨率的降低而降低，C_A评价的血管控制功能区扩大。后者表明，在缺氧状态下，血管的主要控制部位向大动脉转移。