Virtual electrode-induced phase singularity in a rabbit model of chronic myocardial infarction

Y. Cheng*, S. Zhuang, V. Nikolski, I. R. Efimov, D. W. Wallick

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


Shock-induced vulnerability and defibrillation have been mostly studied in a structurally normal heart, rarely the case in clinical settings. Increased vulnerability has been reported during ischemia, which is likely to contribute to defibrillation failure. The purpose of this study is to examine the mechanism of increased vulnerability after myocardial infraction (MI). Methods: Ligation of marginal branch of left circumflex artery in rabbits was done 1-6 weeks before acute experiments. Epicardial electrical activity of Langendorff-perfused hearts (n=4) was optically mapped before, during and after 8-ms monophasic shocks (150 microF) applied during T-wave from a right ventricular lead. Results: Histology revealed that ligation consistently resulted in a discrete left ventricular apical infraction with a border zone (BZ) characterized by action potential shortening. Cathodal shocks produced the virtual electrode polarization pattern with an area of a positive polarization near the shock lead and adjacent area of negative polarization (de-excitation area). Maximum transmembrane voltage gradient was located in the BZ. The resulting postshock break-excitation wavefronts consistently originated at this gradient and propagated toward the base, forming a sustained reentrant arrhythmia. Conclusion: Regional MI provides the substrate for increased vulnerability via virtual electrode-induced phase singularity, which originates in the BZ. This may contribute to defibrillation failure.

Original languageEnglish (US)
Pages (from-to)1430-1431
Number of pages2
JournalAnnual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings
StatePublished - 2002
EventProceedings of the 2002 IEEE Engineering in Medicine and Biology 24th Annual Conference and the 2002 Fall Meeting of the Biomedical Engineering Society (BMES / EMBS) - Houston, TX, United States
Duration: Oct 23 2002Oct 26 2002


  • Defibrillation
  • Myocardial infraction
  • Optical mapping
  • Vulnerability

ASJC Scopus subject areas

  • Signal Processing
  • Biomedical Engineering
  • Computer Vision and Pattern Recognition
  • Health Informatics


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