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Updated: Aug 19, 2026

A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts
Published on: February 17, 2023
Effects of transient myocardial ischemia on the ventricular defibrillation threshold
Maria I Anastasiou-Nana1, Eleftheria P Tsagalou, Christos Charitos
1Department of Clinical Therapeutics, University of Athens School of Medicine, Alexandra Hospital, Athens, Greece. jnanas@ath.forthnet.gr
Background:
Acute myocardial ischemia and the mode of ventricular fibrillation (VF) induction influence the ventricular defibrillation threshold (DFT).
Objectives:
The purpose of this study was to determine the effects of transient regional left ventricular (LV) ischemia on the DFT.
Methods:
Ventricular effective refractory period (ERP), ventricular fibrillation threshold (VFT), and DFT were measured under nonischemic conditions (control) in 26 pigs weighing 25-35 kg. Myocardial ischemia was then induced by occlusion of the mid left anterior descending coronary artery, and measurements of ERP and VFT were repeated after 2 minutes of occlusion. The coronary artery ligation was released immediately after the onset of VF and DFT was measured.
Results:
LV ERP was unchanged by ischemia (199 +/- 19 ms at control vs. 200 +/- 22 ms under ischemic conditions, P = 0.799), whereas VFT was significantly lower during coronary occlusion (10.7 +/- 5.4 mA vs. 37.7 +/- 13 mA, P = 0.000). Brief myocardial ischemia caused a significant increase in DFT (13.5 +/- 12.6 J after coronary occlusion vs. 6.8 +/- 6.8 J at control, P = 0.023). The duration of coronary occlusion was not correlated with the amounts of energy required to defibrillate (P = 0.526).
Conclusions:
This experimental study shows that transient myocardial ischemia markedly increases the DFT, suggesting that specific defibrillation algorithms should be designed for recipients of implantable defibrillators at risk of myocardial ischemia.
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