Noninvasive measurement of local arterial pulse wave velocity in humans by ultrasound

An improved method for noninvasive measurement of the local velocity of arterial pulse wave propagation by an echo-tracking-based ultrasound system is described. A data acquisition image interface was programmed in the ultrasound machine simultaneously to record M-mode ultrasound signals at two locations of a given distance apart along an artery. The selections of measurement sites, separation, and time resolution were performed on the control interface. The temporal sampling frequency could be as high as 10 kHz. The displacements of the blood vessel wall along the time axis were calculated from the M-mode signals by cross-correlation of the radio-frequency data and the distension waveforms were obtained. The temporal separation of the feet of the distension curves from the two measurement locations was derived to give the travel time of the pulse wave. Measurements were made in vivo on human carotid arteries. The pulse wave velocities measured from four volunteers were from 4.1 to 7.2 m/s with coefficients of variation from 5.9 to 29.5%. Some of the factors contributing to the variation in measured values of the velocity are discussed. The method is simple to implement and should be suitable for clinical research into local pulse wave velocity.