Study on the peak interval variability of photoplethysmogtaphic signals

Heart rate variability (HRV) is concerned with the analysis of the intervals between heartbeats. ECG R-R interval variability is the commonly used measure of HRV. In this study, the peak interval variability and successive interval difference variability of photoplethysmographic signals were analyzed for HRV estimation instead of using the ECG R-R interval. The experiments were conducted under three different physiological conditions: rest, immediate post-exercise, and recovery from exercise on 16 subjects. Comparison with HRV estimated by R-R intervals indicated that a reasonably accurate HRV estimation could be achieved from photoplethysmographic signals at rest. With the error of 2.6% for overall HRV and 2.1% for short term HRV, the preliminary results showed that it is possible to analyze the HRV using photoplethysmographic signal when subjects are in stationary cardiovascular condition.