Study on the subendocardial ischemia using a high resolution needle-probe video-microscope with a CCD camera

为了了解动脉内膜下易缺血的基础，我们使用带有电荷耦合器件（CCD）摄像机的便携式针探针视频显微镜评价了动脉内膜下微血管及其血流的行为。将探针针尖从左心房插入左心室腔，观察心内膜下的小动脉和小静脉。为了突出小血管图像，我们采用：1）绿色（红色的互补色）滤光片，2）冠状动脉内注射FITC-葡聚糖，3）冠状动脉内或静脉内注射吲哚菁绿色。利用这些技术，可以很容易地识别动脉和静脉微血管，并可以评估直径的变化。研究表明，硝酸甘油扩张了心外膜下和心内膜下小动脉。硝酸甘油对血管内膜下小动脉的舒张作用因血管的大小而异。与直径小于100 μ m的小动脉相比，直径大于100 μ m的小动脉扩张较大。硝酸甘油增加内膜下小动脉的搏动幅度。同时发现硝酸甘油有扩张冠状小静脉的趋势。硝酸甘油对静脉心肌血管的影响还需进一步研究。使用高对比度血流标记物印度墨水，不仅心肌中的血流，而且从心肌到心室腔的血流，即，Thebesian静脉血流，可以追踪到。

To understand the basis of the subendocardial vulnerability to ischemia, we evaluated the behavior of the microvessels and their blood flows in the subendocardium using a portable needle-probe video-microscope with a charge-coupled device (CCD) camera. The tip of the needle-probe was introduced into the left ventticular cavity from the left atrium of the beating canine hearts and observed the subendocardial arterioles and venules. To accentuate the small vascular images, we employed : 1) a green (complimentary color of red) filter, 2) an intracoronary injection of FITC-dextran, and 3) an intracoronary or intravenous injection of indocyanine green. Using these techniques, the arterial and venous microvessels could be identified easily, and the diameter changes could be evaluated.We evaluated the effects of ninoglycerin on the coronary microvessels. The study showed that nitroglycerin dilated both subepicardial and subendocardial arterioles. The vasodilatory effects of nitroglycerin on the subendocardial arterioles were different depending on the sizes of the vessels. Nitroglycerin dilated larger arterioles with diameters greater than 100 mum compared to those with diameters smaller than 100 mum. Nitroglycerin increased the pulsation amplitude of the subendocardial arterioles. It was also found that nitroglycerin tended to dilate the coronary venules. Further investigation will be needed to understand the effects of nitroglycerin on the venous myocardial vessels.Using a high-contrast blood flow marker, India ink, not only the blood flow in the myocardium but also that from the myocardium to the ventricular cavity, i.e., Thebesian venous blood flow, could be traced.