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

为了了解心内膜下对缺血易感性的基础，我们使用带有电荷耦合装置(CCD)摄像机的便携式针状探头视频显微镜评估了心内膜下微血管的行为及其血流。将针尖从跳动犬心脏的左心房送入左室腔内，观察心内膜下小动脉和小静脉。为了突出小血管图像，我们采用了：1)绿色滤光片，2)冠状动脉内注射FITC-葡聚糖，以及3)冠状动脉内或静脉注射吲哚青绿。利用这些技术，可以容易地识别动脉和静脉微血管，并可以评估血管内径的变化。我们评价了甘油对冠状动脉微血管的影响。研究表明，硝酸甘油扩张心外膜下和心内膜下小动脉。硝酸甘油对心内膜下小动脉的扩张作用因血管大小而异。硝酸甘油使直径大于100微米的较大小动脉扩张，而直径小于100微米的微动脉扩张。硝酸甘油增加心内膜下小动脉的搏动幅度。还发现硝酸甘油有扩张冠状动脉小静脉的趋势。硝酸甘油对静脉心肌血管的影响还有待进一步研究。使用高对比度血流标志物印度墨水，不仅可以追踪心肌内的血流，还可以追踪从心肌到脑室腔的血流，即西贝斯静脉血流。

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.