Heart Rate Variability and the Acceleration Plethysmogram signals measured at rest

It is well-known that the electrocardiogram (ECG) is a non-invasive method that can be used to measure heart rate variability (HRV). Photoplethysmogram (PPG) signals also reflect the cardiac rhythm since the mechanical activity of the heart is coupled to its electrical activity. Photoplethysmography is a non-invasive, safe, and easy-to-use technique that has been developed for experimental use in vascular disease. A useful algorithm for a-wave detection in the acceleration plethysmogram (APG, the second derivative of the PPG) is introduced to determine the interval between successive heartbeats and heart rate variability. In this study, finger-tip PPG signals were recorded for twenty seconds from 27 healthy subjects measured at rest. The use of the aa interval in APG signals showed very promising results in calculating the HRV statistical indices, SDNN and rMSSD.