title: Effect of plunge electrodes in active cardiac tissue with curving fibers.
abstract: OBJECTIVE
  Our goal is to determine if plunge electrodes change how the heart responds to electrical stimulation.
  
  
  BACKGROUND
  Several experiments designed to study the induction of a rotor in cardiac tissue have used plunge electrodes to measure the transmural potential. It is our hypothesis that these electrodes may have affected the electrical response of the tissue to a shock.
  
  
  METHODS
  We previously have shown that a single plunge electrode in two-dimensional, passive cardiac tissue induces a significant transmembrane potential when stimulated by a large shock. In this study, we expand our simulation to include an array of nine electrodes in active tissue with curving fibers. We compare the thresholds for rotor induction in tissue with and without electrodes by initiating a planar S1 wavefront and then stimulating the tissue at different intervals with a uniform S2 electric field perpendicular to S1. In tissue without plunge electrodes, virtual electrode polarization due to the curving fibers is generally widespread over the entire tissue, whereas polarization tends to be localized around the electrodes in tissue including them.
  
  
  RESULTS
  Our results show that at some S1-S2 intervals, the presence of plunge electrodes can result in reentry when it otherwise would not be possible. For other S1-S2 intervals, such as during the vulnerable period when the reentry threshold is at a minimum, the induction of reentry is unaffected by the presence of plunge electrodes.
  
  
  CONCLUSIONS
  Plunge electrodes can play an important role during the stimulation of cardiac tissue, but this is highly dependent on the chosen S1-S2 interval.
authors.affiliation: Department of Physics, Oakland University, Rochester, Michigan 48309, USA.
authors.forename: Deborah Langrill
authors.initials: DL
authors.lastname: Beaudoin
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Roth
mesh_terms: D016477:Artifacts; D004558:Electric Stimulation / Q000295:instrumentation*; D004566:Electrodes; D022062:Electrophysiologic Techniques, Cardiac; D006321:Heart / Q000502:physiology*; D006801:Humans; D008564:Membrane Potentials / Q000502:physiology*; D008955:Models, Cardiovascular; D009206:Myocardium / Q000473:pathology*