Reliability and reproducibility of piezoelectric-derived local brachial pulse wave velocity measurement and pressure normalization

BACKGROUND: Local pulse wave velocity (PWV) is an emerging non-invasive marker of arterial stiffness that enables site-specific evaluation of vascular health and early detection of localized vessel stiffening associated with cardiovascular risk. METHODS:In this study, local brachial PWV was measured using two piezoelectric sensors placed proximally and distally along the brachial artery to determine intra- and inter-rater reliability and compare the results with standard ultrasound-derived PWV. The brachial artery was chosen for its accessibility, consistent geometry, and physiological relevance as a peripheral muscular artery sensitive to early vascular changes. Thirty-five healthy participants (17M:18F) underwent local brachial PWV measurements in a controlled environment. Measurements were repeated within the same day (intra- and inter-rater), across different days, and at a six-month follow-up to evaluate temporal reproducibility. Additionally, blood pressure was estimated from the piezoelectric pulse signals, and PWV was normalized to mean arterial pressure (MAP) to examine whether normalization improved repeatability. RESULTS:Intra-rater reliability was excellent (ICC = 0.94 [0.91-0.97], CV = 3.0%), while inter-rater reliability was good (ICC = 0.82 [0.76-0.87], CV = 6.0%). Between-day reproducibility remained high (ICC = 0.87 [0.82-0.91]). PWV correlated strongly with ultrasound-derived PWV (R² = 0.79, p < 0.001). Measurements at six-month follow-up demonstrated good temporal reproducibility (ICC = 0.71 [0.67-0.79]). Normalization of PWV to MAP reduced measurement variability. CONCLUSION: Local brachial PWV measurements exhibit high reliability, strong agreement with ultrasound PWV, and consistent temporal reproducibility, particularly when normalized to mean arterial pressure. These findings support the methodological validity and reproducibility of local brachial PWV assessment and provide a foundation for future standardization and clinical evaluation.