Smalling R W, Ekas R D, Felli P R, Binion L, Desmond J
J Am Coll Cardiol. 1986 Jun;7(6):1335-46. doi: 10.1016/s0735-1097(86)80155-3.
The mechanism of the increase in function in myocardial segments adjacent to those subjected to regional ischemia is not known. To investigate the hypothesis that changes in regional loading are an important causative factor of this phenomenon, 17 dogs were instrumented with segmental shortening sonomicrometers in the left anterior descending and circumflex artery distributions, circumflex coronary flow probes and cuff occluders, as well as circumflex coronary pressure catheters. Additionally, the animals had aortic pressure catheters and ventricular pressure micromanometers. This animal model allowed modulation of regional inotropic state with regional ischemia or isoproterenol administration. With circumflex coronary bed ischemia, segmental shortening in the circumflex distribution decreased from 11.9 to 6.3% (p = 0.001) whereas left anterior descending regional shortening increased from 11.6 to 13.4% (p less than 0.001). These reciprocal changes occurred in the absence of changes in global afterload or heart rate. Systemic beta-receptor blockade did not change this response, suggesting that it was not reflex- or catecholamine-mediated. Infusing isoproterenol into the circumflex coronary artery resulted in an increase in circumflex regional shortening from 12.5 to 17.4% (p less than 0.02) whereas left anterior descending regional shortening decreased from 13.5 to 8.3% (p less than 0.001), again without change in heart rate or left ventricular or aortic pressure. These data suggest that reciprocal functional interaction between adjacent myocardial segments is a result of changes in regional afterload for the most part, with changes in local preload and timing of ejection also contributing to the observed effect.
与局部缺血心肌节段相邻的心肌节段功能增强的机制尚不清楚。为了研究局部负荷变化是这一现象的重要致病因素这一假说，对17只犬进行了如下仪器植入：在左前降支和左旋支动脉分布区域植入节段缩短声测微计、左旋支冠状动脉血流探头和袖带阻塞器，以及左旋支冠状动脉压力导管。此外，这些动物还植入了主动脉压力导管和心室压力微测压计。该动物模型允许通过局部缺血或给予异丙肾上腺素来调节局部心肌收缩状态。左旋支冠状动脉床缺血时，左旋支分布区域的节段缩短率从11.9%降至6.3%（p = 0.001），而左前降支区域的节段缩短率从11.6%增至13.4%（p < 0.001）。这些相反的变化发生在整体后负荷或心率无变化的情况下。全身性β受体阻滞剂并未改变这种反应，表明其不是由反射或儿茶酚胺介导的。向左旋支冠状动脉内注入异丙肾上腺素导致左旋支区域节段缩短率从12.5%增至17.4%（p < 0.02），而左前降支区域节段缩短率从13.5%降至8.3%（p < 0.001），心率、左心室或主动脉压力同样没有变化。这些数据表明，相邻心肌节段之间的反向功能相互作用在很大程度上是局部后负荷变化的结果，局部前负荷变化和射血时间也对观察到的效应有贡献。
