Experimental and theoretical analysis of phase singularity dynamics in cardiac tissue

Introduction: Quantitative analysis of complex self-excitatory wave pattern s, such as cardiac fibrillation and other high-order reentry, requires the development of new tools for identifying and tracking the most important fe atures of the activation, such as phase singularities. Methods and Results: Image processing operations can be used to detect the phase singularity at the tip of a spiral wave. The phase space behavior of a spatiotemporal sequence of data may be reconstructed using time-series an alysis. The phase singularities then are localized efficiently by computing the topologic charge density as the curl of the spatial phase gradient, We analyzed the singularity interaction dynamics of both experimentally obser ved and numerically simulated instances of quatrefoil reentry and found tha t the singularity behavior in the experimental preparations can be classifi ed into three categories on the basis of how their separation changes with time. Conclusion: Topologic charge densities can be calculated easily and efficie ntly to reveal phase singularity behavior. However, the differences between theoretical and experimental observations of singularity separation distan ces indicate the need for more sophisticated numerical models.