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DETERMINANTS OF REPERFUSION ARRHYTHMIAS: ACTION POTENTIAL DURATION VS DISPERSION OF REPOLARIZATION
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  • Olesya Bernikova,
  • Alexandra Durkina,
  • Ksenia Sedova,
  • Jan Azarov
Olesya Bernikova
Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences

Corresponding Author:[email protected]

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Alexandra Durkina
Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences
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Ksenia Sedova
Czech Technical University in Prague
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Jan Azarov
Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences
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Abstract

Introduction. The role of a border zone in arrhythmogenesis is not fully understood. In this study we evaluated independent contributions of action potential duration (APD) and dispersion of repolarization (DOR) across the normal/ischemic border to the development of ventricular tachycardia and/or fibrillation (VT/VF). Methods. Ischemia-reperfusion episodes were induced in anesthetized rats by transient coronary occlusion. Unipolar electrograms were recorded from ischemic and perfused areas using a 64-lead array to obtain activation times (ATs), repolarization times (RTs), activation-repolarization intervals (ARIs, a surrogate for APD) and dispersion of repolarization (DOR, as a difference between the earliest and latest RTs). Pinacidil (0.3 mg/kg) and glibenclamide (2 mg/kg) were applied to reduce DOR and to clamp APD at a lower and upper levels, respectively. Results. In the control animals, APD shortened in the ischemic zone, DOR increased to 9±3 ms, and VT/VF developed at reperfusion (6 out of 10). Pre-occlusion application of glibenclamide prolonged APD in the ischemic and perfused zones, decreased DOR to 5±2 ms and did not affect VT/VF development (4 out of 11). Post-occlusion infusion of pinacidil shortened APD in the perfused zone, decreased DOR to 6±3 ms and VT/VF incidence (2 out of 11). Extrasystolic burden at reperfusion was associated with VT/VF incidence in logistic regression analysis (β=1.182, 95%CI 1.008-1.386, p=0.04) and was lesser (p<0.01) in the pinacidil group as compared to the control and glibenclamide groups. Conclusion. The APDs in the perfused zone were a superior arrhythmogenic factor in respect to DOR in the present ischemia-reperfusion model.