Measurement of Local Pulse Wave Velocity: Agreement Among Various Methodologies

The local pulse wave velocity (PWV) is the velocity with which the arterial pulse wave travels from the left ventricle to the vascular bed. Local PWV is clinically significant as a prognostic indicator of vascular damage. The measurement of local PWV involves several direct and indirect methods. However, there are limited studies that compare agreement among different methodologies. In this work, we investigated the agreement among several methods of measurement of PWV, such as the haemodynamic loop-based, Bramwell-Hill, transit-time-based and computational models of PWV. A small cohort of 35 participants (21male/14 female) aged between 21 and 51 years was recruited on voluntary consent. The measurement setup included duplex mode recording of carotid diameter and flow velocity waveforms from an ultrasound machine and simultaneous acquisition of dual-diameter waveforms and tonometry waveforms using an in-house developed bi-modal arterial probe. The carotid pressure waveform, flow velocity and dual diameter waveforms for evaluating the various methods of PWV measurement were obtained from the data processing. The group average value of PWV were obtained between 3.07±1.17m/s to 5.02±1.00m/s for various methods. The lowest and the highest group average PWV was reported using the haemodynamics-loop-based methods. There exists a strong and statistically significant correlation among PWV obtained using Bramwell-Hill equations and computational models (r>0.91, p<0.001), whereas a moderate and statistically significant correlation was observed between Bramwell-Hill and transit-time-based methods (r=0.67, p<0.001). The correlation was poor between Bramwell-Hill and loop-based methods (r~0.2, p<0.001). The study confirms the variations in the measurements in PWV using different methods and suggests their interchangeable usage is not advised.