Variations Among Heart Rate Varibility of Pulse Waves Simulataneously Measured at Different Sites

Although pulse wave (PW) is widely used for assessing heart rate variability (HRV) with wearable devices, the variations intrinsically existing in HRV assessment by this method are unknown. This study examined variations among HRV indices obtained from PWs simultaneously measured at four different sites (right and left wrists and forearms) and compared them with those assessed from R-R intervals of electrocardiogram (ECG). While mean interbeat intervals showed good consistency with small inter-site variation (coefficient of variation [CV], 0.8% and 0.5% for supine and sitting positions) and modest deviation from that assessed from ECG (coefficient of deviation [CD], 3.1 % and 2.0%), low and high frequency components of HRV showed non-negligible inconsistency with large inter-site variations (CV, 4.0% and 3.8% for supine and 3.6% and 4.7% for sitting) and deviations from those with ECG (CD, 29.3% and 51.3% for supine and 18.5% and 40.2% for sitting).