Analysis on myocardial ischemia by observation of NADH fluorescence/oxygen partial pressure phosphorescence using an intra-vital needle microscope

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We made in-vivo analysis on images of metabolic function and oxygen partial pressures in endocardial microcirculation where is the most frequent site of myocardial ischaemia. The purpose of the present study was to elucidate coronary microcirculation pathophysiologically. We achieved ;1) development of needle lens2) development of an NADH excitor and its fluorescence observer(excitation at 370 nm, fluorescence at 460 mm)3) development of Pd-porphine excitor and its fluorescence observer(excitation at 545 nm, fluorescence at 610 nm)4) development of micro-circulation image observer(wave length : 545 nm)With these developments, we confirmed that myocardial metabolism imaging was made possible.After evaluating the performance of the developed intra-vital needle microscope, we firstly applied this system to porcine and canine experiments. Obtaining metabolism images by NADH fluorescence, capillary blood flow distribution of digital radiogram was measured by perfusing molecular blood flow tracers, which specifically bind to α2 receptors of capillary endothelial cells.Secondly, we performed metabolism imaging at the region of endocardial microcirculation under the conditions of control and myocardial ischaemia. We compared NADH fluorescence intensity, coronary micro-vascular diameters and blood flow distribution under the control condition of 100 mmHg perfusion pressure and under the ischaemic condition of low perfusion pressure at 40 and 60 mmHg. There was heterogeneity with patchy pattern in NADH fluorescence distribution during reperfusion and hypoxic perfusion.. The sizes of patchy area in both images are about several hundred microns. In summary, there is a significant correlation between NADH fluorescence and blood flow distribution, indicating the similarity between metabolic function distribution and blood flow distribution.