High temporal resolution measurement of pulsatile red cell velocity in microvessels by a fiber-optic laser-Doppler anemometer microscope

Abstract

A fiber-optic laser-Doppler anemometer microscope (FLDAM) was developed for the measurement of microvascular red cell velocity and its applicability was examined in in vivo experiments with emphasis on the temporal resolution of the system. Red cell velocity measured with the time resolution up to about 10 ms clearly showed pulsation synchronous with the systemic arterial pressure in mesenteric microvessels of spontaneously hypertensive rats (SHR) with diameters from 5.8 to 88.9 μm. The amplitude of pulsation decreased with decreasing arteriolar diameter, and the time lag of red cell velocity relative to the systemic arterial pressure monotonically increased from large arterioles through small arterioles, capillaries, small venules to large venules. The propagation velocity of the pulse wave was also obtained in arterioles. Thus, the FLDAM was proved to have the temporal resolution sufficient for the analysis of the pulse wave propagation in microvasculature of small animals with high heart rates.