A Triphasic Change of Cardiac Autonomic Nervous System During Electroconvulsive Therapy

Dynamic autonomic activity changes have been repeatedly reported during electroconvulsive therapy (ECT). However, the specific timing of these changes remains unclear. To clarify whether sympathetic or parasympathetic nervous activity contributes separately to the second stage and the third stage during and after induced seizures by ECT, we examined heart rate (HR) and spectral analysis of variability (HRV) during ECT.

Seventeen patients with depression participated in the study and underwent ECT. The R-R intervals (RRI) were recorded and analyzed sequentially for the HRV indices high-frequency (HF) (an index of parasympathetic activity) and low-frequency (LF)/high-frequency (an index of sympathetic activity) for 4 minutes before and after stimulus onset by the maximum entropy method. Averaged HRs were compared between 3 heart beats prestimulus and poststimulus onset. The HRV power in the range of 30 to 80 and 80 to 130 seconds after a seizure was compared between the HF and LF/HF components.

There was a significant reduction of the averaged HR over 3 HRs just after stimulus onset, suggesting parasympathetic dominance in the first phase. The LF/HF power significantly increased in the 30 to 80 s range after stimulus onset, whereas the HF power significantly increased in the 80 to 130 s range after stimulus onset, reflecting sympathetic activation in the second phase and parasympathetic activation in the third phase, respectively.

The evaluation of HR and HRV revealed a triphasic change from parasympathetic to sympathetic to parasympathetic cardiac autonomic activity after ECT stimulus onset in depression patients.