Cohen M V, Steingart R M
Circulation. 1985 Oct;72(4):881-91. doi: 10.1161/01.cir.72.4.881.
To examine the effects of coronary collateral development on thallium-201 (201Tl) distribution the left circumflex coronary artery was ligated in eight dogs. Three days later these animals ran on a treadmill, and 201-thallous chloride was injected into the right atrium at peak exercise. Scintigraphic scanning was begun within 10 min and continued for 3 hr. Scanning was repeated weekly for 6 weeks. In the last week radioactive microspheres were injected into the left atrium at peak exercise to measure regional myocardial blood flow. The scintigraphically determined disparity between perfusion of the ischemic and normal myocardium was most marked at 3 days after ligation. This difference gradually lessened over the first 4 weeks until there was no difference in 201Tl distribution to normally perfused myocardium and tissue distal to the ligation. Concomitant with the improvement in the scintigrams, exercise hemodynamics also improved over this 4 week period with significant increases in cardiac output and decreases in left atrial pressure. Serial coronary angiographic studies in two animals demonstrated the appearance of collaterals in the initial weeks after coronary occlusion, and by 4 weeks the left circumflex artery distal to the obstruction was completely opacified by collateral flow. The ratio of directly measured exercise blood flow to the left circumflex and normally perfused tissues was 0.89 +/- 0.08 at 6 weeks after ligation. Scintigraphic 201Tl redistribution after 3 hr also changed over the weeks after ligation. Three days after ligation washout from the ischemic area was significantly slower than that from the normal myocardium. By 6 weeks loss of 201Tl from the two regions occurred at nearly equal rates. Thus myocardial perfusion and function during exercise after coronary occlusion are dynamic events that change with time. It is likely that coronary collateral development is responsible for these phenomena. Therefore coronary collaterals do have salutary effects in the dog.
为研究冠状动脉侧支循环发育对铊-201（²⁰¹Tl）分布的影响，对8只犬结扎左旋冠状动脉。3天后，这些动物在跑步机上运动，在运动高峰时将氯化亚铊注入右心房。在10分钟内开始进行闪烁扫描，并持续3小时。每周重复扫描，共进行6周。在最后一周，在运动高峰时将放射性微球注入左心房以测量局部心肌血流量。闪烁扫描测定的缺血心肌与正常心肌灌注差异在结扎后3天最为明显。在最初4周内，这种差异逐渐减小，直到²⁰¹Tl在正常灌注心肌和结扎远端组织中的分布没有差异。与闪烁扫描图像的改善同时，在这4周内运动血流动力学也有所改善，心输出量显著增加，左心房压力降低。对2只动物进行的系列冠状动脉造影研究表明，冠状动脉闭塞后的最初几周出现了侧支循环，到4周时，阻塞远端的左旋冠状动脉完全被侧支血流充盈。结扎后6周，直接测量的左旋冠状动脉和正常灌注组织的运动血流比值为0.89±0.08。结扎后数周，3小时后的²⁰¹Tl闪烁扫描再分布也发生了变化。结扎后3天，缺血区的洗脱明显慢于正常心肌。到6周时，两个区域的²⁰¹Tl丢失率几乎相等。因此，冠状动脉闭塞后运动时的心肌灌注和功能是随时间变化的动态事件。冠状动脉侧支循环发育可能是这些现象的原因。因此，冠状动脉侧支循环在犬中确实具有有益作用。
