Bussemaker J, Groeneveld A B, Teerlink T, Hennekes M, Westerhof N, van Beek J H
Laboratory for Physiology Institute for Cardiovascular Research (ICaR-VU), Vrije Universiteit, Van der Boechorststraat 7, NL-1081 BT Amsterdam, The Netherlands.
Pflugers Arch. 1997 Nov;434(6):785-94. doi: 10.1007/s004240050466.
Myocardial perfusion is heterogeneous, even in the normal heart. It is unknown whether the resting normal blood flow level predicts the severity of mismatch between local blood flow and metabolism during acute ischaemia. In the present study local blood flow (measured with radioactively labelled microspheres) and metabolic indicators of ischaemia [tissue contents of lactate and inosine (INO), a breakdown product of adenosine triphosphate (ATP)] were determined in 84-102 simultaneously frozen samples (approximately 0.9 g) of normal (n = 7) and partially ischaemic (n = 4) porcine left ventricles. Ischaemia was induced for 20 min by partially occluding the left anterior descending artery to reduce perfusion pressure from 107 +/- 17 mm Hg to 39 +/- 10 mm Hg (mean +/- SD). Flow reduction in the ischaemic region was strongly variable, both within the subepicardium (range 6-66%, average 34%) and the subendocardium (range 33-84%, average 57%), indicating redistribution of blood flow inside transmural layers in addition to the well-known preferential decrease in subendocardial perfusion. The relative flow reduction during stenosis was not dependent on normal local perfusion level (Spearman rank correlation coefficient -0.002, P = 0.99). Samples with low or high myocardial blood flows before stenosis showed similar increases in lactate content and INO/ATP content ratio, as long as the percentage blood flow reduction was the same. It is concluded that regions with low and high resting flows in the normally perfused heart are equally susceptible to metabolism-perfusion mismatch resulting from coronary stenosis.
心肌灌注是不均匀的，即使在正常心脏中也是如此。静息时的正常血流水平是否能预测急性缺血期间局部血流与代谢之间不匹配的严重程度尚不清楚。在本研究中，对正常（n = 7）和部分缺血（n = 4）猪左心室的84 - 102个同时冷冻的样本（约0.9 g）测定了局部血流（用放射性标记微球测量）和缺血的代谢指标[乳酸和肌苷（INO，三磷酸腺苷（ATP）的分解产物）的组织含量]。通过部分阻断左前降支动脉20分钟，使灌注压从107±17 mmHg降至39±10 mmHg（平均值±标准差）来诱导缺血。缺血区域的血流减少差异很大，在心外膜下（范围6 - 66%，平均34%）和心内膜下（范围33 - 84%，平均57%）均如此，这表明除了心内膜下灌注众所周知的优先减少外，跨壁层内还存在血流重新分布。狭窄期间的相对血流减少不依赖于正常的局部灌注水平（斯皮尔曼等级相关系数 - 0.002，P = 0.99）。只要血流减少的百分比相同，狭窄前心肌血流低或高的样本显示出相似的乳酸含量和INO/ATP含量比增加。结论是，正常灌注心脏中静息血流低和高的区域对冠状动脉狭窄导致的代谢 - 灌注不匹配同样敏感。
