Advancing the Local Pulse Wave Velocity Measurement–Wave Confluence Decomposition Using a Double Gaussian Propagation Model

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 (PWV
$_{\sf DGPM}$
) and compare it against conventional spatiotemporal PWV (PWV
$_{\sf ST}$
), with Bramwell-Hill PWV (PWV
$_{\sf BH}$
) 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 PWV
$_{\sf ST}$
was computed from linear fittings of respective feature timings and distances. Regression analyses were conducted with PWV
$_{\sf DGPM}$
and PWV
$_{\sf ST}$
as predictors, and various PWV and BP measures as response variables.
Results
Whereas PWV
$_{\sf ST}$
correlations were insignificant, PWV
$_{\sf DGPM}$
estimated the reference PWV
$_{\sf BH}$
with a significant reduction in errors (P < 0.001), explained up to 65% PWV
$_{\sf BH}$
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 PWV
$_{\sf DGPM}$
outperforms the conventional PWV
$_{\sf ST}$
in all investigated respects, potentially enabling PWV assessment in routine clinical practice.