Hemodynamic factors changing blood flow velocity waveform and profile in normal human brachial artery.

We have investigated the influence of changes of perfusion pressure and local peripheral resistance on blood flow velocity waveform and profile in normal human peripheral arteries. Blood flow velocity and profile were recorded from the distal end of the left brachial artery in ten normal subjects by means of an ultrasonic device. The records were obtained in basal conditions and after blood pressure in the brachial artery and local peripheral vascular resistance were changed, separately or together, by progressive inflation of two arm cuffs, one encircling the proximal half of the left arm and the other the middle part of the left forearm. Both blood flow velocity waveform and profile were shown to be markedly modified by changes in perfusion pressure and local peripheral vascular resistance. Reduction of perfusion pressure decreased both forward and reverse peak velocities, but had the largest effect upon reverse velocity. The upslope and the downslope of the forward velocity wave were left unchanged. Increase in local peripheral vascular resistance markedly augmented reverse peak velocity, whether perfusion pressure was normal or reduced. Increased resistance only slightly influenced peak forward velocity.

In vivo recording of blood velocity profiles and studies in vitro of profile alterations induced by known stenoses.

Recordings of blood velocity profiles and their behavior in the time domain in some peripheral human vessels (carotid arteries and limb vessels) are reported. Measurements have been obtained with a pulsed ultrasonic instrument based on the analysis of the cross-correlation function of blood-diffused echoes. The alterations of blood velocity profiles and of the velocity in the time domain, induced by known stenosis, have been studied in vitro as a function of the distance between stenosis and measuring point, and the position of the sample volume along the diameter. These studies may be useful for a better comprehension of blood velocity measurements made with ultrasound equipment for clinical noninvasive diagnostic purposes.