Studies on arterial flow patterns - Instantaneous velocity spectrums and their phasic changes - With directional ultrasonic Doppler technique

Abstract

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. The instantaneous flow velocity spectrum is continuous throughout a pulse cycle, and intensified near the instantaneous maximum velocity, especially in the early part ofa pulse cycle. No reverse flow phase is observed in the common carotid artery except for a small momentary reverse component. A reverse flow phase is always exhibited in the femoral 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. The arterial bloodflow almost looks like a propagation of a damped longitudinal oscillation. At the time of conversion between the forwardflow phase and the reverse flow phase, both forward and reverse components simultaneously coexist in a cross-section of the vessel. The arterialflow pattern is easily changeable in the arteries of the extremities, especially in the brachial artery. Such an easy changeability is the essentialfeature of the arterial bloodflow. The propagation velocity of the flow velocity wave is more rapid in elderly subjects than in other adult subjects. The reverse flow phase of the arterial flow pattern in the extrermties is more often observed in elderly subjects than in adult subjects. In the common carotid artery of elderly subjects the peak velocity is reduced so that the systolic rapidforward phase looks like a plateau.