Abstract 13874: The Comparison of Defibrillation Threshold and the Incidence of Refibrillation Following Long Duration Ventricular Fibrillation in Dogs with and without Pacing-Induced Heart Failure
Introduction: Recent studies have shown that defibrillation threshold (DFT) varies during short duration ventricular fibrillation (SDVF; VF duration < 1min) and long duration ventricular fibrillation (LDVF; VF duration > 1min), and refibrillation is common following LDVF in normal dogs hearts. The purpose of this study was to determine whether the SDVF and LDVF DFTs and the incidence of refibrillation were higher in heart failure (HF) than normal dogs.
Methods: VF was electrically induced in six normal dogs (control group) and six ones with right ventricular pacing-induced congestive HF (HF group). Two 64-electrodes basket catheters deployed into the left and right ventricles were used to global endocardium electrical mapping. The DFTs of 20 sec-SDVF and 7 min-LDVF were determined respectively in these two groups. Basket electrode recordings were made for 20 min after successful defibrillation to observe any episodes of refibrillation.
Results: In the control group, the DFT of 7 min-LDVF was lower than that of 20 sec-SDVF (Figure). The DFTs of 20 sec-SDVF and 7 min-LDVF in the HF group were both significantly higher than control group (Figure). No episode of refibrillation after SDVF was observed in each group. The number of refibrillation episodes per animal in failing hearts did not differ from that of normal hearts (2.8±2.0 vs 2.3±1.9, P>0.05).
Conclusions: The SDVF and LDVF DFTs were both higher in the HF than control animals. The incidence of refibrillation following successful defibrillation for LDVF was not higher in HF than control dogs, which indicated that LDVF itself can cause refibrillation without preexisting cardiac dysfunction.
- © 2012 by American Heart Association, Inc.