Indolfi C, Guth B D, Miyazaki S, Miura T, Schulz R, Ross J
Department of Medicine, University of California, San Diego, La Jolla 92093.
Am J Physiol. 1991 Sep;261(3 Pt 2):H910-7. doi: 10.1152/ajpheart.1991.261.3.H910.
Regional myocardial blood flow (MBF) distribution and function upon slowing the heart rate (HR) during ischemia were studied in anesthetized swine, a species without coronary collaterals. Perfusion of the left anterior descending artery by a pump allowed controlled production of regional ischemia. Slowing tachycardia by electrical pacing (127 to 87 beats/min) caused marked improvement of regional dysfunction [% wall thickening (WTh) from 9 to 27%] and increased subendocardial MBF [from 0.31 to 0.55 ml.min-1.g-1 (P less than 0.001)] without change of subepicardial MBF. Total left ventricular (LV) MBF increased, whereas right ventricular (RV) MBF fell by 18% (P less than 0.02). The mechanism of MBF changes during slowed HR was assessed by surgically excluding the RV and comparing findings with previous experiments with RV intact when HR was slowed from 96 to 60 beats/min. A similar improvement of regional LV function occurred (8% vs. 30% WTh) with the RV excluded, but without a change in total flow to the LV bed, whereas subendocardial MBF increased and subepicardial MBF fell, indicating transmural redistribution only. These findings show that the RV vascular bed can contribute to LV perfusion in swine during ischemia, and they document the potential for "reverse RV steal" during slowed heart rate in this setting.
在无冠状动脉侧支循环的麻醉猪身上，研究了缺血期间心率减慢时局部心肌血流量（MBF）分布及功能。通过泵灌注左前降支动脉可控制局部缺血的产生。通过电起搏使心动过速减慢（从127次/分钟降至87次/分钟），导致局部功能显著改善（%室壁增厚（WTh）从9%增至27%），心内膜下MBF增加（从0.31增至0.55毫升·分钟-1·克-1，P<0.001），而心外膜下MBF无变化。左心室（LV）总MBF增加，而右心室（RV）MBF下降18%（P<0.02）。通过手术切除右心室并将结果与之前右心室完整时心率从96次/分钟降至60次/分钟的实验结果进行比较，评估心率减慢期间MBF变化的机制。切除右心室时，左心室局部功能出现类似改善（WTh从8%增至30%），但左心室床总血流量无变化，而心内膜下MBF增加，心外膜下MBF下降，仅表明存在跨壁血流重新分布。这些发现表明，在缺血期间，猪的右心室血管床可对左心室灌注有贡献，并且证明了在这种情况下心率减慢时“反向右心室窃血”的可能性。
