Photoplethysmography as a Potential Alternative to Electrocardiography for Recording Heart Rate Intervals Used in Variability Analysis

Rationale. This study investigates the use of photoplethysmography (PPG) as a comfortable alternative to electrocardiography (ECG) for heart rate variability (HRV) analysis. Although HRV is typically analyzed from an ECG trace, PPG poses a likely alternative, as arterial pulsations and peripheral tissue perfusion (as measured by PPG) are coupled with cardiac electrical activity (as measured by ECG). PPG may be more desirable in some clinical circumstances, as a fingertip optical sensor is more comfortable for patients than ECG electrodes, and can reduce waste by not needing to be disposed after each use. Objective. The aim of this study is to assess the efficacy of using PPG as an alternative to ECG for recording cardiac activity for HRV analysis by comparing HRV data obtained using both methods. Methods and results. The study was conducted on 10 healthy human subjects, aged 20 to 25 years (4 males, 6 females). Three lead ECG and fingertip PPG traces were simultaneously recorded with a two-channel analog-to-digital converter and HRV parameters were calculated from each data set. The two sets of HRV data simultaneously obtained from the same subjects were compared. The results showed a high correlation between ECG-derived and PPG-derived HRV data (R(2)>0.95). Time-domain parameters, frequency-domain parameters and Poincaré geometry and analysis showed no significant difference between HRV analyses using PPG as compared to ECG for heart beat detection. Discussion. The comparison between the two methods indicates that PPG is a reliable instrument to precisely assess HRV parameters, showing no statistically significant differences when compared to HRV assessments calculated using ECG.