AJP - Heart and Circulatory Physiology, Vol 253, Issue 3 671-H679, Copyright © 1987 by American Physiological Society
Use of ultrasound for noninvasive study of blood vessel responsiveness
G. J. Stewart, M. C. Ziskin, R. G. Schaub, R. E. Cartee, C. M. Philips, E. A. Stone and D. W. Manuel
To provide a noninvasive means for studying individual macroscopic blood
vessels, an ultrasound scanner was modified to provide a recording of blood
vessel diameter. The instrument has A- and B-modes of signal display. The
B-mode is used to position the probe and the A-mode to measure vessel
diameter. The A-mode has two electronic gates for tracking the echo from
each of two structures, i.e., near and far wall of vessel. The front gate
was modified to pick up the falling rather than rising edge of a peak
generated by the vessel wall. An analog signal proportional to the distance
between gates was derived for recording with a strip-chart recorder. Probe
holders were constructed to optimize positioning and holding of probe.
Stability was excellent (reading varied 0.05 mm over 1 h). Axial resolution
was between 0.3 and 0.73 mm. Discrepancy of measurements of plastic tubing
made by ocular and ultrasound varied from 1.1 to 4.6%. Discrepancy with
lightly fixed vessels was 2.7-8.2%. Ex vivo measurements on vessels with
viable smooth muscle were more variable, perhaps because of actual change
during measurements. Changes in vessel diameter induced by change in
hydrostatic pressure and exposure to histamine were recorded.
