Development of android App for evaluating of the cardiac autonomic activity using a phase coupling of respiratory sinus arrhythmia

Abstract

Previous our study revealed that the degree of the phase coupling (λ) between respiratory sinus arrhythmia (RSA) and breathing showed a positive correlation with vagal index and a negative correlation with the sympathovagal balance of heart rate variability, suggesting that the λ could be used as a noninvasive measure for evaluating cardiac autonomic activity. In order to apply this finding to ambulatory monitoring, we developed a smartphone-based software named BiSync that enables to estimate cardiac autonomic profile using ECG signal. ECG was obtained from Shimmer via Bluetooth and the breathing was extracted using the amplitude modulation of ECG by respiratory movements. The analytic signals of RSA and breathing were constructed based on Hilbert-transform and then λ was computed from the phase difference between them. We examined the accuracy of λ by comparing actual measurement of breathing during mental stress condition. Results suggest that BiSync can be used for ambulatory monitoring.