We visualized subepicardial small veins (ID>100μm) and venules (ID<100μm) in a beating human heart using a needle-probe video-microscope with a CCD camera and examined the effects of nitroglycerin (NTG) on the vessels. In 9 patients who underwent cardiac surgery, we observed small veins (n＝12) and venules (n＝9). We carefully obtained access of the needle lens probe into the subepicardial small veins and venules. The microvascular diameter responses after superfusion of NTG were monitored for 5min. The diameter changes of the microvessels were analyzed at end diastole. In the control condition, the phasic diameter changes of both small veins and venules increased from end-diastole to end-systole and the diameter changes of the vessels during cardiac cycle reached almost 10%. Both small veins and venules started to dilate just after NTG. The dilation of small veins at 1min after NTG increased to 147±10μm from control values of 131±9μm (13.7±4.2%, p<0.01), whereas the diameters of venules increased to 65±9μm from 60±8μm (6.0±5.0％, p<0.05) at 1min. However, venules continued to dilate, reaching their maximum dilation at 2～3min. In conclusion, the human subepicardial microvessels were clearly visualized by the needle-probe videomicroscope. The degree of vasodilation in response to NTG in small veins and venules was about the same, at almost 10%, thereby reducing flow resistances.
ヒト冠細静脈 (human coronary venules)
心周期 (cardiac cycle)
拍動心 (beating heart)
ニードル型 CCD 生体顕微鏡 (needle-probe CCD videomicroscope)