Estimate of electromotive surface dimension during ventricular fibrillation

The accurate identification of local activation from extracellular recording electrodes attached to the beating heart is critical for the development of a mechanistic understanding of serious cardiac rhythm disturbances in both experimental animals and man. One of the most complex of these rhythm disturbances is ventricular fibrillation, a common cause of sudden cardiac death in man. When using bipolar extracellular recording electrodes to detect local activation, the spatial extent of the upstroke of the action potentials that generate the extracellular waveform determines the optimal interelectrode distances for the bipolar electrodes. This spatial length has been well characterized for normal cardiac conduction at around 1.0 mm on the epicardial surface. We found that for many of the activations occurring during early ventricular fibrillation this length is similarly around 1.0 mm.