Cardiac effects of repeated focal seizures in rats induced by intrahippocampal tetanus toxin: bradyarrhythmias, tachycardias and prolonged interictal QT interval

John G.R. Jefferys*, Alexander Ashby-Lumsden, Thelma A Lovick

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

Objective: To determine electrical changes in the heart in a chronic, non-status model of epilepsy.
Methods: Electrocorticogram (ECoG) and electrocardiogram (ECG) of 9 animals (5 made epileptic by intrahippocampal injection of tetanus neurotoxin (TeNT) and 4 control), are monitored continuously by radiotelemetry for up to 7 weeks.
Results: Epileptic animals develop a median of 168 seizures, with postictal tachycardias reaching a mean of 487 beats/min and lasting a mean of 661 seconds. Ictal changes in heartrate include tachycardia and in the case of convulsive seizures, bradyarrhythmias resembling Mobitz type 1 second degree atrioventricular block; notably the P-R interval increased before block. Postictally the amplitude of T wave increases. Interictally, QT dependence on RR is modest and conventional QT corrections prove ineffective. Interictal QT intervals, measured at a heartrate of 400 bpm, increased from 65 ms to 75 ms, an increase
dependent on seizure incidence over the preceding 10-14 days.
Significance: Repeated seizures induce a sustained tachycardia and increase in QT interval of the ECG and evoke arrhythmias including periods of atrioventricular block during Racine Type 4 and 5 seizures. These changes in cardiac function may predispose to development in fatal arrhythmias and sudden death in humans with epilepsy.
Original languageEnglish
JournalEpilepsia
DOIs
Publication statusPublished - 22 Mar 2020

Keywords

  • Cardiac dysfunction
  • QT correction
  • QT prolongation
  • cardiac arrhythmia
  • autonomic

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