Advancing the Local Pulse Wave Velocity Measurement - Wave Confluence Decomposition using a Double Gaussian Propagation Model.

Abstract

Background Pulse wave velocity (PWV) is a marker of arterial stiffness and local measurements could facilitate its widescale clinical use. However, confluence of incident and early reflected waves leads to biased spatiotemporal PWV estimates. Objective We introduce the Double Gaussian Propagation Model (DGPM) to measure local PWV in consideration of wave confluence (PWVDGPM) and compare it against conventional spatiotemporal PWV (PWVST), with Bramwell-Hill PWV (PWVBH) and blood pressure (BP) as reference measures. Methods Ten subjects ranging from normotension to hypertension were repeatedly measured at rest and with induced PWV changes. Carotid distension waveforms over a 19 mm wide segment were acquired from ultrasonography, simultaneously with noninvasive continuous BP. Per cardiac cycle, the 8-parameter DGPM (amplitude, centroid, width, and velocity, respectively of forward and backward propagating wave) was fitted to the distension waveforms' systolic foot and dicrotic notch complexes. Corresponding PWVST was computed from linear fittings of respective feature timings and distances. Regression analyses were conducted with PWVDGPM and PWVST as predictors, and various PWV and BP measures as response variables. Results Whereas PWVST correlations were insignificant, PWVDGPM estimated the reference PWVBH with a significant reduction in errors (P<0.001), explained up to 65% PWVBH variability at rest, demonstrated higher intra-method consistency and correlated significantly with all BP measures (P<0.001). Conclusion The proposed DGPM measures local carotid PWV in consideration of wave confluence, showing significant correlations with Bramwell-Hill PWV and BP at two distinct waveform complexes. Thereby PWVDGPM outperforms the conventional PWVST in all investigated respects, potentially enabling PWV assessment in routine clinical practice.