Submitted on April 21, 2003
Accepted on July 28, 2003
Synchronization of ventricular fibrillation with real-time feedback pacing: Implication to low-energy defibrillation
Hui-Nam Pak1, Yen-Bin Liu1, Hideki Hayashi1, Yuji Okuyama1, Peng-Sheng Chen1, and Shien-Fong Lin1*
1 Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center and David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
* To whom correspondence should be addressed. E-mail: Linsf{at}cshs.org.
Wavefront synchronization is an important aspect preceding the termination of ventricular fibrillation (VF). We evaluated the defibrillation efficacy of a novel multi-site pacing algorithm using optical recording-guided, synchronized pacing (SyncP) in the excitable gaps. We compared the effects of SyncP with the traditional overdrive pacing (ODP) at 90% of VF cycle length (VFCL) and high frequency pacing (HFP, 43-215 Hz) on spontaneous VF termination in isolated rabbit hearts. For SyncP, the pacing current was triggered by the activation of a reference site and was delivered when the optical potential of the pacing site was in an excitable gap. We measured VFCL and spatial dispersion of VFCL (SDCL) from 5 points (3 in paced area, 2 in non-paced area) and the distribution of phase singularities during the pre-pacing, pacing, and post-pacing periods. The results showed that 1) the VF termination rate of SyncP (16.0%, n=106) was higher than that of ODP (2.1%, n=48, p<0.01) or HFP (1.6%, n=129, p<0.0001). 2) Energy consumption for SyncP (7.6±9.3mJ) was significantly lower than that of ODP (14.0±14.8 mJ, p<0.0001). 3) Sync P, but not ODP or HFP, decreased SDCL in the paced area during pacing (p<0.01) and post-pacing (p<0.05) periods compared to the pre-pacing period. We conclude that SyncP is effective in inducing wavefront synchronization and is more effective at facilitating spontaneous VF termination than non-synchronized pacing.
