title: Spiral wave control by a localized stimulus: a bidomain model study.
abstract: BACKGROUND
  It has been reported that electrical stimulation can control spiral wave (SW) reentry. However, previous research does not account for the effects of stimulus-induced virtual electrode polarization (VEP) and the ensuing cathode-break (CB) excitation. The aim of the present study was to examine the interaction of VEP with SW reentry in a bidomain model of electrical stimulation and thus provide insight into the mechanistic basis of SW control.
  
  
  RESULTS
  We conducted 3,168 simulations of localized stimulation during SW reentry in an anisotropic bidomain sheet. Unipolar cathodal 2-ms stimuli of strengths 4, 8, 16, and 24 mA were delivered at 99 locations in the sheet. The interaction between stimulus-induced VEP and SW reentry resulted in 1 of 3 possible outcomes: SW shift, SW breakup, or no effect. SW shift, which could be instrumental in SW termination at an anatomic or functional line of block, resulted from CB rather than cathode-make excitation. Stimulus timing, site, and strength all were important factors in VEP-mediated SW control. Furthermore, we found that the number of episodes of SW shift across the fibers was more sensitive to stimulus strength than that of SW shift along the fibers. SW shift can be explained by the interaction between the four VEP-induced wavebreaks and the wavebreak of the SW, ultimately resulting in termination of the original SW and the survival of one of the VEP-induced wavebreaks. This establishes a new SW reentry.
  
  
  CONCLUSIONS
  This study provides new mechanistic insight into SW control.
authors.affiliation: Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118, USA. tashihar@tulane.edu
authors.forename: Takashi
authors.initials: T
authors.lastname: Ashihara
authors.forename: Tsunetoyo
authors.initials: T
authors.lastname: Namba
authors.forename: Makoto
authors.initials: M
authors.lastname: Ito
authors.forename: Takanori
authors.initials: T
authors.lastname: Ikeda
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nakazawa
authors.forename: Natalia
authors.initials: N
authors.lastname: Trayanova
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology; D003198:Computer Simulation; D004056:Differential Threshold; D004553:Electric Conductivity; D004558:Electric Stimulation; D004566:Electrodes; D022062:Electrophysiologic Techniques, Cardiac; D005071:Evoked Potentials / Q000502:physiology; D006321:Heart / Q000502:physiology*; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008564:Membrane Potentials / Q000502:physiology; D008955:Models, Cardiovascular; D009206:Myocardium / Q000737:chemistry; D013997:Time Factors