Inter-Electrode Pulse Wave Velocity: A Direct Method for Maternal Arterial Stiffness Assessment During Pregnancy Using Multi-Channel ECG

TL;DR

This study validates a new inter-electrode pulse wave velocity method using multi-channel ECG to assess maternal arterial stiffness during pregnancy, demonstrating its stability, physiological plausibility, and potential clinical utility.

Contribution

The paper introduces a direct inter-electrode PWV measurement technique that does not require LVET estimation, showing robustness and physiological validity in pregnant women.

Findings

PWV values aligned with known aortic PWV (5-10 m/s).

PWV stabilized within 5 minutes with low variability.

Preliminary group differences suggest potential for monitoring pregnancy-related arterial changes.

Abstract

Objective: To validate a novel inter-electrode pulse wave velocity (PWV) method that measures pulse propagation between ECG electrodes without left ventricular ejection time (LVET) estimation. Methods: We analyzed 43 three-channel ECG recordings (1000 Hz) from the FELICITy 2 cohort (approximately 19 and 35 weeks gestation). R-peaks were independently detected per channel using an ensemble approach. Time lags (Delta t) between matched R-peaks across electrode pairs were used to compute PWV as PWV = L / Delta t, where L is effective inter-electrode distance. Three channel pairs yielded independent PWV estimates. Temporal stability was assessed using sliding windows (1-15 minutes). To test whether Delta t reflects morphology or vascular propagation, we evaluated three QRS fiducials (R-peak, QRS onset, maximum dV/dt) and two bandpass filters (0.5-40 and 0.5-100 Hz). Longitudinal changes were compared between control (n=24) and yoga (n=20) groups. Results: PWV values were physiologically plausible and consistent with aortic PWV (5-10 m/s): control 7.40 +/- 1.51 vs 6.98 +/- 1.63 m/s; yoga 7.10 +/- 2.15 vs 8.16 +/- 0.91 m/s (early vs late pregnancy). PWV stabilized at 5 minutes (coefficient of variation 12.3 percent), with 2.6- to 5.2-fold lower variability than heart rate and heart rate variability. Inter-electrode delays (15-27 ms) persisted across fiducials and were minimally affected by filter settings (change -8.5 percent, not significant), arguing against purely morphological distortion; PWV remained within 6.8-9.1 m/s. Preliminary group trends differed (control -5.7 percent, yoga +14.9 percent; interaction p=0.07). Conclusions: Inter-electrode PWV enables direct spatial assessment of pulse propagation with physiologically valid values, is robust to fiducial and filtering choices, and shows promise for pregnancy-related arterial stiffness assessment with standard multi-channel ECG.