Moderate stress by cardiac pacing may induce both short term and long term cardioprotection

László Szekeres, Julius Gy Papp, Zoltán Szilvássy, Éva Udvary, Ágnes Vegh

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Abstract

Objective: The aim was to investigate whether moderate ischaemic stress induced by brief periods of cardiac pacing to twice the normal heart rate protects the heart from the electrophysiological and haemodynamic consequences of subsequent periods of rapid pacing. Methods: Conscious rabbits with implanted right ventricular electrodes and a permanent catheter in the left ventricular cavity were studied. Hearts were paced at a rate of 500·min-1 for 5 min. The resulting transient ST segment elevation in the intracavital electrogram, the ventricular effective refractory period, and the left ventricular end diastolic pressure were measured. Results: After discontinuation of pacing, a shortlasting ST segment elevation appeared in the endocardial electrogram, together with a transient rise in left ventricular end diastolic pressure. These changes were significantly reduced after a second pacing, provided that this was applied not later than 30 min after the first pacing; maximum protection occurred when there was a 5 min interval between these pacing periods. Serial stimulation (10 pacing periods with a 5 min interval between each) gave a similar protection to that resulting from a single pacing period. The protection was lost after 1 h; however, 24 h and 48 h (but not 72 h) after the end of serial stimulation there was again a reduction in postpacing ST segment and left ventricular end diastolic pressure elevation. At these times the ventricular effective refractory period was prolonged. The cyclo-oxygenase inhibitor sodium meclofenamate (1-2 mg·kg-1) prevented the early protection. Conclusions: The results suggest that brief periods of rapid pacing induce both short term and long term cardioprotection, as shown by reduced electrophysiological and haemodynamic consequences of subsequent pacing periods. Endogenous prostanoids might play a role in the short term cardioprotection.Cardiovascular Research 1993;27:593-596.

Original languageEnglish
Pages (from-to)593-596
Number of pages4
JournalCardiovascular research
Volume27
Issue number4
DOIs
Publication statusPublished - Apr 1993

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Keywords

  • "Preconditioning"
  • Ischaemia
  • Long term cardioprotection
  • Short term cardioprotection
  • Ventricular overpacing

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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