Mechanisms of unpinning and termination of ventricular tachycardia

Crystal M. Ripplinger, Valentin I. Krinsky, Vladimir P. Nikolski, Igor R. Efimov*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


High-energy defibrillation shock is the only therapy for ventricular tachyarrhythmias. However, because of adverse side effects, lowering defibrillation energy is desirable. We investigated mechanisms of unpinning, destabilization, and termination of ventricular tachycardia (VT) by low-energy shocks in isolated rabbit right ventricular preparations (n = 22). Stable VT was initiated with burst pacing and was optically mapped. Monophasic "unpinning" shocks (10 ms) of different strengths were applied at various phases throughout the reentry cycle. In 8 of 22 preparations, antitachycardia pacing (ATP: 8-20 pulses, 50-105% of period, 0.8-10 mA) was also applied. Termination of reentry by ATP was achieved in only 5 of 8 preparations. Termination by unpinning occurred in all 22 preparations. Rayleigh's test showed a statistically significant unpinning phase window, during which reentry could be unpinned and subsequently terminated with E 80 (magnitude at which 80% of reentries were unpinned) = 1.2 V/cm. All reentries were unpinned with field strengths ≤2.4 V/cm. Unpinning was achieved by inducing virtual electrode polarization and secondary sources of excitation at the core of reentry. Optical mapping revealed the mechanisms of phase-dependent unpinning of reentry. These results suggest that a 20-fold reduction in energy could be achieved compared with conventional high-energy defibrillation and that the unpinning method may be more effective than ATP for terminating stable, pinned reentry in this experimental model.

Original languageEnglish (US)
Pages (from-to)H184-H192
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number1
StatePublished - 2006


  • Antitachycardia pacing
  • Defibrillation
  • Optical mapping
  • Reentry

ASJC Scopus subject areas

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


Dive into the research topics of 'Mechanisms of unpinning and termination of ventricular tachycardia'. Together they form a unique fingerprint.

Cite this