Abstract 14611: Defibrillation Threshold Varies Over the Duration of Ventricular Fibrillation in Canine Hearts
Introduction: Recent studies have shown that short duration ventricular fibrillation (SDVF) and long duration ventricular fibrillation (LDVF) are maintained by different mechanisms. But little research has been performed to evaluate how the defibrillation threshold (DFT) alters over the duration of fibrillation.
Methods: Two 64 electrodes basket catheters used to global endocardium electrical mapping were deployed into the LV and RV respectively. Internal defibrillation with biphasic shock was performed in 10 canines which were randomly divided into 2 groups (Group A, n=5, and Group B,n=5). DFTs of SDVF were measured with the shock given 20 s after VF induction in both groups. DFTs of LDVF were determined 1-3 min (Group A) and 5-7 min (Group B) respectively after VF induction.
Results: Between 3 and 7 min of LDVF in Group B, endocardial activations became more highly organized than that within 1 to 3 min of LDVF in Group A. LDVF-DFT in Group A was significantly higher than LDVF-DFT in Group B. (670±60 vs 304±66 V, p<0.01). (Figure)
Conclusions: After 3 min, VF can exhibit highly organized activation patterns, which might contribute to the decreased LDVF-DFT. The results of this study indicate that DFT may be affected differently as VF progresses.
- © 2011 by American Heart Association, Inc.