The changing electrical dynamics of ventricular fibrillation

The purpose of this study was to investigate the temporal evolution of ventricular fibrillation (VF) in vivo. Thirty continuous 1 minute recordings were obtained during electrically induced VF from the right and left ventricles in 3 dogs using epicardial arrays containing 5 electrodes. From these 5 unipolar recordings dV/dt, voltage gradient, and transmembrane current (I_m) were determined. Deflections with a -/+ I_m area of 0 (electrotonic deflections) were not analyzed. Analyses of the nonelectrotonic deflections showed that the electrophysiological parameters dV/dt and voltage gradient change significantly over 10 second intervals during the first minute of VF in vivo. The deflection to deflection interval initially speeds up then slows down as VF continues