Adaptive time-frequency analysis of autonomic nervous system

Spectral analysis of heart rate variability (HRV) provides a noninvasive estimate of sympathetic and parasympathetic influences on heart rate. The Time-Frequency analysis was utilized to expand the concept of spectral analysis of HRV to describe changes in vagal tone as a function of time. A new adaptive methodology is now proposed to uncover the region of true parasympathetic activity. It is known that parasympathetic activity is highly correlated with the respiration frequency. This technique traces the respiration frequency and extracts the corresponding parasympathetic activity from the HRV signal by adaptive filtering