Analysis and Comparison of Heart Rate Variability Signals Derived from PPG and ECG Sensors

One of the methods of diagnosis and prevention of cardiovascular diseases is monitoring and analysis of heart rate variability (HRV). However, in order to accurately detect the RR intervals, the ECG signal must be acquired. The advances in optical sensors made photoplethysmography (PPG) to be considered as an alternative for heartbeat interval measurements as it is more convenient. The aim of this study is to compare the HRV signals calculated from ECG and PPG measurements based on the data from two Physionet datasets and assess the reliability and accuracy of time-domain, frequency-domain and nonlinear HRV parameters derived from the ECG and PPG signals. The results achieved suggest that the PRV can be used as an alternative for HRV analysis in static measurements, with significant correlation coefficient values above 98% for nonlinear, time and frequency features. In the dynamic measurements, performed during sports activities, especially nonlinear and frequency-domain parameters derived from PPG signals should be used with caution, as in some cases the correlation was inverse.