Time-frequency analysis of heart rate variability signals in patients with autonomic dysfunction

An imbalance in the autonomic nervous system has been suspected in patients with coronary artery disease during episodes of silent ischemia. Frequency analysis of the beat-to-beat heart rate variability (HRV) signals reveals a signature of autonomic regulation of the heart. We performed time-frequency analysis of HRV records containing silent ischemic episodes. In 14 out of 17 (82%) HRV data sets there was a loss of power during such intervals, as determined by S-T segment changes. Our studies suggest that if the frequency content of the signal is well preserved, there is less likelihood of ischemic events of any appreciable duration.