Observation of a Period Doubling Bifurcation During Onset of Human Ventricular Fibrillation

We find evidence of a period doubling bifurcation and transition from pseudo-periodic chaos to a stable limit cycle during onset of ventricular fibrillation (VF) in humans. Novel radial basis modeling techniques are applied to time series of spontaneous VF to estimate time dependent changes in the dynamics. Furthermore, we show that the spectral power content may be used as a surrogate for the underlying bifurcation parameter. With this spectral power measure we demonstrate a characteristic transition from pseudo-periodic chaos to a second pseudo-periodic chaotic regime. The methods described in this paper are generic and applicable to any time series data.