Studies on arterial flow patients - instantaneous velocity spectrums and their phasic changes - with directional ultrasonic Doppler technique.

Flow velocity spectra of main arteries in 24 healthy adult subjects and 21 healthy aged subjects were transcutaneously studied using the directional ultrasonic Doppler technique. I) The instantaneous flow velocity spectrum is continuous throughout a pulse cycle, and intensified near the instantaneous maximum velocity, especially in the earlypart ofa pulse cycle. 2) No reverse flow phase is observed in the common carotid artery except for a small momentary reverse component. A reverseflow phase is always exhibited in thefemoral artery and in many occasions in the other main arteries; it follows the systolic forward flow phase. After the reverse flow phase the diastolic forward flow phase appears. In some subjects a second reverseflow phase and thirdforwardflow phase are successively observed. 3) The arterial bloodflow almost looks like a propagation ofa damped longitudinal oscillation. 4) At the time of conversion between theforwardflow phase and the reverseflow phase, bothforward and