Developement of side-on typed needle-probe for CCD microscope

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To evaluate the effect of cardiac contraction on intramyocardial microvessels, we measured the phasic change in the diameter of the intramural arterioles and venules of beating dog hearts using a needle-probe video-microscope with a CCD camera. We also compared the result with that of the epicardial microvessels and the endocardial microvessels. In 12 open-chest anesthetized dogs, the needle-probe was inserted 3-6 mm into the myocardium from myocardial surface. The probe tip was pulled several tens micrometers away from the microvessels to avoid direct compression of the vessels after obtaining clear image of the intramural vessels. The observation of microvessels was performed for a short time and was discontinued immediately when the microvessels had a hemorrhage. The diameter was measured for the vascular segment showing a relative uniform diameter change. the phasic diameter change in the intramural arterioles was from 130<plus-minus>79mum in end-diastole to 118<plus-minus>72mum (mean<plus-minus>SD) in end-systole (p<0.001, n=21, 10<plus-minus>6% change) and that in venules from 8544mum to 8642mum (not significant, n=15, 2<plus-minus>6%). In contrast, the diameter of the endocardial arterioles and venules decreased by 10<plus-minus>8% (p<0.001) and 12<plus-minus>10% (p<0.001) from end-diastole to end-systole, respectively. The diameter of the epicardial arterioles was almost unchanged during cardiac cycle and venular diameter increased by 9<plus-minus>8% (P<0.01) from end-diastole to end-systole. We conclusion, the diameter of the intramural arterioles decreased from end-diastole to end-systole in a similar way to subendocardial arterioles, but that of subepicardial arterioles changed very little. On the other hand, the diameter of the intramural venules was almost unchanged from end-diastole to end-systole, while the diameter of subendocardial venules decreased and that of subepicardial ve