Cardiovascular dysautonomia after seizures induced by maximal electroshock in Wistar rats

BACKGROUND Cardiac dysfunction is one of the possible causes of sudden unexpected death in epilepsy (SUDEP). Therefore, it was the objective of this study to evaluate the cardiac and electrocardiographic parameters after seizures induced by maximal electroshock (MES) in Wistar rats. METHODS Electroshock seizures were induced in Wistar rats through a pair of ear-clip electrodes (10 mA at a frequency of 60 Hz applied for one second). In vivo electrocardiography (ECG) was performed in awake animals for analysis of heart rate variability (HRV) and cardiac rhythm. Ex vivo the Langendorff technique was used to analyze cardiac function and observe the incidence and severity of reperfusion arrhythmias. RESULTS Convulsive seizures triggered by MES induced profound abnormalities in cardiac rhythm with serious electrocardiographic changes including ST-elevation, bundle branch block, atrioventricular nodal escape rhythm and premature ventricular contractions. ECG analysis demonstrated a consistent period of postictal bradyarrhythmia resulting in a transiently irregular cardiac rhythm with highly variable and prolonged QRS complexes and RR, PR, QT and QTc intervals. HRV evaluation revealed an increase in the high-frequency range of the power, suggesting an imbalance in the autonomic control of the heart with a postictal enhancement of parasympathetic tone. In addition, we observed in isolated heart a decrease in systolic tone and an increase in the coronary flow, heart rate and incidence/duration of ischemia-reperfusion arrhythmias. CONCLUSION The present study supports a relationship betweem seizures, cardiac dysfunction and cardiac arrhythmias. This relationship may partially account for the occurrence of SUDEP.