Early and late postictal cardiac electrophysiological changes associated with low, moderate, and high dose electroconvulsive shocks.

BACKGROUND: Studies have examined the effects of electroconvulsive therapy (ECT) on human cardiac electrophysiology. However, no study has so far examined whether these effects vary with the magnitude of the electrical dose used to elicit the seizure. Because the benefits and adverse effects of the ECT seizure are dose-dependent, we examined the effects of different electrical doses of electroconvulsive shocks (ECS) on cardiac electrophysiology in an animal model with a view to determine whether cardiac electrophysiology could be a useful proxy to evaluate the quality of the ECT seizure. METHODS: Adult female Wistar rats (n = 20/group) received sham, low dose (10 mC), moderate dose (18 mC), or high dose (25 mC) ECS. The electrocardiogram (ECG) was recorded and was analyzed for time and frequency domain variables in 30 s epochs in preictal (30 s before ECS), early postictal (starting 15 s after stimulation) and late postictal (5 h after ECS) periods. RESULTS: ECS was associated with substantial changes in most time and frequency domain measures during the early postictal period; a strong parasympathetic effect was observed. However, the effects of different ECS doses did not differ for any variable. All changes returned to levels that were similar to those of the sham controls in the late postictal period. CONCLUSIONS: The effect of ECS on time and frequency domain cardiac electrophysiological measures was not dose-dependent. This suggests that if higher electrical doses are associated with stronger central seizures, ECG-derived variables may not be useful proxies for the quality of the central seizure. The generalization of this conclusion from animal to clinical contexts requires study.