CAROTID-FEMORAL PULSE WAVE VELOCITY VARIABILITY: BEAT-TO-BEAT ASSESSMENT

Abstract

Objective: Variability of carotid pulse wave velocity (CFPWV) measurements may be related to measurement errors, but also to physiological beat-to-beat variations in pulse transit time (TT). We aimed to 1) evaluate beat-to-beat variability of CFPWV on simultaneous non-invasive carotid and femoral waveforms without signal artefacts, and 2) explore its clinical and hemodynamic determinants. Design and method: In 44 adult patients (47±18 years; 50% men; 32% hypertensive, 27% with chronic kidney disease, 9% diabetic and 5% with cardiovascular disease), three 10 seconds-long acquisitions of carotid and femoral pressure waveforms were performed using Complior Analyse. Raw data of the three recordings were extracted, checked to be artefact-free, concatenated, and subjected to a custom 2nd derivative-based foot detection algorithm. Mean, beat-to-beat standard deviation (SD), and coefficient of variation (CV) of CFPWV (80% of direct distance) and heart rate were determined. Regression analysis was used to identify determinants of CV of CFPWV. Results: 44 ± 3 (mean ± SD) beats per individual were analysed, and the mean CFPWV was 7.7±2.6 m/s. The SD and CV of CFPWV were 1.2±0.8 m/s and 13.9±6.5%, respectively. In multivariable regression analysis, age (standardized ß = 0.470, p<0.001) and intra-individual SD of heart rate (ß = 0.430, p<0.001) explained 63% of changes in CV of CFPWV. Systolic/diastolic blood pressures were not significant determinants of CV of CFPWV. Conclusions: There is a variability in beat-to-beat pulse transit time that is not explained by poor signal quality, but by higher physiological variations of beat-to-beat transit time, which is explained by advancing age and beat-to-beat heart rate variability.