Virtual electrode polarization in the far field: Implications for external defibrillation

Igor R. Efimov*, Felipe Aguel, Yuanna Cheng, Brian Wollenzier, Natalia Trayanova

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

107 Scopus citations

Abstract

We recently suggested that failure of implantable defibrillation therapy may be explained by the virtual electrode-induced phase singularity mechanism. The goal of this study was to identify possible mechanisms of vulnerability and defibrillation by externally applied shocks in vitro. We used bidomain simulations of realistic rabbit heart fibrous geometry to predict the passive polarization throughout the heart induced by external shocks. We also used optical mapping to assess anterior epicardium electrical activity during shocks in Langendorff-perfused rabbit hearts (n = 7). Monophasic shocks of either polarity (10-260 V, 8 ms, 150 μF) were applied during the T wave from a pair of mesh electrodes. Postshock epicardial virtual electrode polarization was observed after all 162 applied shocks, with positive polarization facing the cathode and negative polarization facing the anode, as predicted by the bidomain simulations. During arrhythmogenesis, a new wave front was induced at the boundary between the two regions near the apex but not at the base. It spread across the negatively polarized area toward the base of the heart and reentered on the other side while simultaneously spreading into the depth of the wall. Thus a scroll wave with a ribbon-shaped filament was formed during external shock-induced arrhythmia. Fluorescent imaging and passive bidomain simulations demonstrated that virtual electrode polarization induced scroll waves underlie mechanisms of shock-induced vulnerability and failure of external defibrillation.

Original languageEnglish (US)
Pages (from-to)H1055-H1070
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume279
Issue number3 48-3
DOIs
StatePublished - 2000

Keywords

  • Bidomain simulations
  • External shock
  • Optical mapping
  • Sudden cardiac death
  • Ventricular fibrillation

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)
  • Physiology

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