Austin R E, Aldea G S, Coggins D L, Flynn A E, Hoffman J I
Cardiovascular Research Institute, University of California, San Francisco 94143.
Circ Res. 1990 Aug;67(2):319-31. doi: 10.1161/01.res.67.2.319.
We examined the ability of individual regions of the canine left ventricle to increase blood flow relative to baseline rates of perfusion. Regional coronary flow was measured by injecting radioactive microspheres over 90 seconds in seven anesthetized mongrel dogs. Preliminary experiments demonstrated a correlation between the regional distributions of blood flow during asphyxia and pharmacological vasodilatation with adenosine (mean r = 0.75; 192 regions in each of two dogs), both of which resulted in increased coronary flow. Subsequent experiments, during which coronary perfusion pressure was held constant at 80 mm Hg, examined the pattern of blood flow in 384 regions (mean weight, 106 mg) of the left ventricular free wall during resting flow and during maximal coronary flow effected by intracoronary adenosine infusion. We found that resting and maximal flow patterns were completely uncorrelated to each other in a given dog (mean r = 0.06, p = NS; n = 3 dogs). Furthermore, regional coronary reserve, defined as the ratio of maximal to resting flow, ranged from 1.75 (i.e., resting flow was 57% of maximum) to 21.9 (resting flow was 4.5% of maximum). Thus, coronary reserve is spatially heterogeneous and determined by two distinct perfusion patterns: the resting (control) pattern and the maximal perfusion pattern. Normal hearts, therefore, contain small regions that may be relatively more vulnerable to ischemia. This may explain the patchy nature of infarction with hypoxia and at reduced perfusion pressures as well as the difficulty of using global parameters to predict regional ischemia. Despite the wide dispersion of coronary reserve, we found, by autocorrelation analysis, that reserve in neighboring regions (even when separated by a distance of several tissue samples) was significantly correlated. This also applied to patterns of resting myocardial flow. Thus, both resting coronary blood flow and reserve appear to be locally continuous and may define functional zones of vascular control and vulnerability, respectively.
我们研究了犬左心室各个区域相对于基础灌注率增加血流的能力。通过在7只麻醉的杂种犬身上于90秒内注射放射性微球来测量局部冠状动脉血流。初步实验表明，窒息期间的血流区域分布与用腺苷进行的药理血管舒张之间存在相关性（平均r = 0.75；两只犬各192个区域），这两种情况均导致冠状动脉血流增加。随后的实验中，冠状动脉灌注压力维持在80 mmHg恒定，研究了左心室游离壁384个区域（平均重量106 mg）在静息血流以及冠状动脉内注入腺苷实现最大冠状动脉血流时的血流模式。我们发现，在给定的犬中，静息和最大血流模式彼此完全不相关（平均r = 0.06，p =无显著性差异；n = 3只犬）。此外，局部冠状动脉储备定义为最大血流与静息血流之比，范围从1.75（即静息血流为最大值的57%）到21.9（静息血流为最大值的4.5%）。因此，冠状动脉储备在空间上是异质性的，由两种不同的灌注模式决定：静息（对照）模式和最大灌注模式。因此，正常心脏包含一些可能相对更易发生缺血的小区域。这可能解释了缺氧和灌注压力降低时梗死的片状性质，以及使用整体参数预测局部缺血的困难。尽管冠状动脉储备差异很大，但通过自相关分析我们发现，相邻区域的储备（即使相隔几个组织样本的距离）显著相关。这也适用于静息心肌血流模式。因此，静息冠状动脉血流和储备似乎在局部都是连续的，并且可能分别定义血管控制和易损性的功能区。
