title: Experimental and theoretical analysis of phase singularity dynamics in cardiac tissue.
abstract: BACKGROUND
  Quantitative analysis of complex self-excitatory wave patterns, such as cardiac fibrillation and other high-order reentry, requires the development of new tools for identifying and tracking the most important features of the activation, such as phase singularities.
  
  
  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 analysis. 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 observed and numerically simulated instances of quatrefoil reentry and found that the singularity behavior in the experimental preparations can be classified into three categories on the basis of how their separation changes with time.
  
  
  CONCLUSIONS
  Topologic charge densities can be calculated easily and efficiently to reveal phase singularity behavior. However, the differences between theoretical and experimental observations of singularity separation distances indicate the need for more sophisticated numerical models.
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA. mark.bray@vanderbilt.edu
authors.forename: M A
authors.initials: MA
authors.lastname: Bray
authors.forename: S F
authors.initials: SF
authors.lastname: Lin
authors.forename: R R
authors.initials: RR
authors.lastname: Aliev
authors.forename: B J
authors.initials: BJ
authors.lastname: Roth
authors.forename: J P
authors.initials: JP
authors.lastname: Wikswo
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D004562:Electrocardiography; D006321:Heart / Q000502:physiology* / Q000503:physiopathology; D008564:Membrane Potentials / Q000502:physiology; D017711:Nonlinear Dynamics