Analysis of hemodynamics in intramyocardial microcirculation using needle-probe fluorescent intravital microscope

为了显示心内膜下小动脉的血流速度，我们研制了一台高速CCD显微镜。血管图像通过针头聚焦在专用的ccd上，每隔5ms存储在数字存储器中(200图像/S)。视场大小为1×0.8 mm^2，空间分辨率小于4um。以光学闪光微球(MS)为光学标记物，显示微血管内血流速度。由苯乙烯单体与均匀分布的细颗粒重元素(0.2mumpi)聚合而成的光学标记器(mumpi为5-15mumpi)。根据MS每隔5ms的运动距离计算MS在心外膜下和心内膜下小动脉的运动速度。为了在监护仪上显示血流，将MS注入冠状动脉左前降支。首次通过的MS图像被记录在盒式录像机上。使用计算机系统测量MS在微血管中的位置。心内膜下小动脉舒张期为快进血流，收缩时为双峰型逆行血流。心外膜小动脉舒张期可见快进血流，与心内膜下血流相似。然而，在收缩期也观察到了大量的前向血流。这项研究的新成果是以高时间分辨率直接观察心动周期内膜下小动脉的血流。

To visualize the subendocardial arteriolar blood velocity, we have developed a high-speed CCD microscope. The vascular images, focused on the special CCD through a needle-probe, were stored on a digital memory every 5 ms (200images/s). A size of visual field is 1*0.8mm^2, and a spatial resolution is less than 4mum. The blood flow velocities in the microvessels were visualized with optically shinning microspheres (MS) as optical marker. The optical marker (5-15 mumphi) was prepared by polymerization of stirene monomer with homogeneously distributed fine particles of heavy elements (0.2 mumphi). Velocities of MS in the subepicardial and subendocardial arteriole were calculated by the movement distance of MS every 5 ms. To visualize flow on the monitor, the MS was injected into the left anterior descending coronary artery. The MS images of first-pass were recorded on a video-cassette recorder. Positions of MS in the microvessels were measured using a computer system. Velocities of MS in the subendocardial arteriole were calculated by frame-to-frame analysis from the movement distance of MS.In endocardial arterioles, fast forward flow was observed during diastole, while there was retrograde flow with two peaks during systole. In epicardial arterioles, fast forward flow was observed during diastole, similar to the subendocardial blood flow. However, a plenty of forward flow was also observed in systolic phase. The novel achievement in this study is the direct observation of subendocardial blood flow in arterioles during a cardiac cycles at highly temporal resolution.