Reflection effects of vaso-active drugs on arterial pulse propagation velocities measured in-vivo in a dog.

Blood-flow velocity signals have been recorded simultaneously at the proximal and distal sites of four arterial segments in an anaesthetized dog under two vaso-active conditions (vaso-dilation and vaso-constriction) using a continuous wave Doppler-shift ultrasonic technique. Spectral analysis produced sonograms of these signals. Phase delays between flow pulses in each segment were obtained from the sonograms and the variation of the resulting phase velocities with frequency has been discussed. Foot-to-foot transit time of the sonogram waveforms for each segment also gave an apparent pulse wave velocity, PWVff (Pulse wave velocity foot-to-foot) and this has been compared with the corresponding phase velocity of the higher harmonics, PWVhh in determining the true or characteristic pulse propagation velocity in the arterial pathways.