Optical mapping of ventricular defibrillation in isolated swine right ventricles

Demonstration of a postshock isoelectric window after near-threshold defibrillation shocks

Nina C. Wang, Moon Hyoung Lee, Toshihiko Ohara, Yuji Okuyama, Gregory A. Fishbein, Shien-Fong Lin, Hrayr S. Karagueuzian, Peng-Sheng Chen

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

Background - Investigators who studied ventricular defibrillation by use of optical mapping techniques failed to observe an initial defibrillation event (isoelectric window or quiescent period) shown by electrode mapping studies. This discrepancy has important implications for the mechanisms of defibrillation. The purpose of the present study was to demonstrate an optical equivalent of an isoelectric window after a near-threshold defibrillation shock. Methods and Results - We studied 10 isolated, perfused swine right ventricles. Upper limit of vulnerability was determined by shocks on T waves. A 50% probability of successful defibrillation (DFT50) was determined with an up-down algorithm. Immediately after unsuccessful defibrillation shock, new wavefronts were generated. When the shock strength was low, immediate reinitiation of reentry and ventricular fibrillation might occur without a postshock isoelectric window. However, if the shock strength was within 50 V of DFT50 (near-threshold), a synchronized activation occurred, followed by organized repolarization that ended 64±18 ms after shock. After a period of quiescence (18±24 ms), activation recurred 83±33 ms after shock and reinitiated ventricular fibrillation. Similar patterns of activation, including a quiescent period, were observed after shock was applied on the T wave of the paced beat that induced ventricular fibrillation. Upper limit of vulnerability correlated well with DFT50. Conclusions - In isolated swine right ventricles, an optical equivalent of an isoelectric window exists after near-threshold defibrillation shocks. These findings support the idea that a near-threshold defibrillation shock terminates all activation wavefronts but fails to halt ventricular fibrillation because the same shock reinitiates ventricular fibrillation after an isoelectric window.

Original languageEnglish (US)
Pages (from-to)227-233
Number of pages7
JournalCirculation
Volume104
Issue number2
StatePublished - Jul 10 2001
Externally publishedYes

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Heart Ventricles
Shock
Swine
Ventricular Fibrillation
Electrodes
Research Personnel

Keywords

  • Action potentials
  • Death, sudden
  • Electrical stimulation
  • Electrophysiology
  • Mapping

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Optical mapping of ventricular defibrillation in isolated swine right ventricles : Demonstration of a postshock isoelectric window after near-threshold defibrillation shocks. / Wang, Nina C.; Lee, Moon Hyoung; Ohara, Toshihiko; Okuyama, Yuji; Fishbein, Gregory A.; Lin, Shien-Fong; Karagueuzian, Hrayr S.; Chen, Peng-Sheng.

In: Circulation, Vol. 104, No. 2, 10.07.2001, p. 227-233.

Research output: Contribution to journalArticle

Wang, Nina C. ; Lee, Moon Hyoung ; Ohara, Toshihiko ; Okuyama, Yuji ; Fishbein, Gregory A. ; Lin, Shien-Fong ; Karagueuzian, Hrayr S. ; Chen, Peng-Sheng. / Optical mapping of ventricular defibrillation in isolated swine right ventricles : Demonstration of a postshock isoelectric window after near-threshold defibrillation shocks. In: Circulation. 2001 ; Vol. 104, No. 2. pp. 227-233.
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abstract = "Background - Investigators who studied ventricular defibrillation by use of optical mapping techniques failed to observe an initial defibrillation event (isoelectric window or quiescent period) shown by electrode mapping studies. This discrepancy has important implications for the mechanisms of defibrillation. The purpose of the present study was to demonstrate an optical equivalent of an isoelectric window after a near-threshold defibrillation shock. Methods and Results - We studied 10 isolated, perfused swine right ventricles. Upper limit of vulnerability was determined by shocks on T waves. A 50{\%} probability of successful defibrillation (DFT50) was determined with an up-down algorithm. Immediately after unsuccessful defibrillation shock, new wavefronts were generated. When the shock strength was low, immediate reinitiation of reentry and ventricular fibrillation might occur without a postshock isoelectric window. However, if the shock strength was within 50 V of DFT50 (near-threshold), a synchronized activation occurred, followed by organized repolarization that ended 64±18 ms after shock. After a period of quiescence (18±24 ms), activation recurred 83±33 ms after shock and reinitiated ventricular fibrillation. Similar patterns of activation, including a quiescent period, were observed after shock was applied on the T wave of the paced beat that induced ventricular fibrillation. Upper limit of vulnerability correlated well with DFT50. Conclusions - In isolated swine right ventricles, an optical equivalent of an isoelectric window exists after near-threshold defibrillation shocks. These findings support the idea that a near-threshold defibrillation shock terminates all activation wavefronts but fails to halt ventricular fibrillation because the same shock reinitiates ventricular fibrillation after an isoelectric window.",
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T2 - Demonstration of a postshock isoelectric window after near-threshold defibrillation shocks

AU - Wang, Nina C.

AU - Lee, Moon Hyoung

AU - Ohara, Toshihiko

AU - Okuyama, Yuji

AU - Fishbein, Gregory A.

AU - Lin, Shien-Fong

AU - Karagueuzian, Hrayr S.

AU - Chen, Peng-Sheng

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N2 - Background - Investigators who studied ventricular defibrillation by use of optical mapping techniques failed to observe an initial defibrillation event (isoelectric window or quiescent period) shown by electrode mapping studies. This discrepancy has important implications for the mechanisms of defibrillation. The purpose of the present study was to demonstrate an optical equivalent of an isoelectric window after a near-threshold defibrillation shock. Methods and Results - We studied 10 isolated, perfused swine right ventricles. Upper limit of vulnerability was determined by shocks on T waves. A 50% probability of successful defibrillation (DFT50) was determined with an up-down algorithm. Immediately after unsuccessful defibrillation shock, new wavefronts were generated. When the shock strength was low, immediate reinitiation of reentry and ventricular fibrillation might occur without a postshock isoelectric window. However, if the shock strength was within 50 V of DFT50 (near-threshold), a synchronized activation occurred, followed by organized repolarization that ended 64±18 ms after shock. After a period of quiescence (18±24 ms), activation recurred 83±33 ms after shock and reinitiated ventricular fibrillation. Similar patterns of activation, including a quiescent period, were observed after shock was applied on the T wave of the paced beat that induced ventricular fibrillation. Upper limit of vulnerability correlated well with DFT50. Conclusions - In isolated swine right ventricles, an optical equivalent of an isoelectric window exists after near-threshold defibrillation shocks. These findings support the idea that a near-threshold defibrillation shock terminates all activation wavefronts but fails to halt ventricular fibrillation because the same shock reinitiates ventricular fibrillation after an isoelectric window.

AB - Background - Investigators who studied ventricular defibrillation by use of optical mapping techniques failed to observe an initial defibrillation event (isoelectric window or quiescent period) shown by electrode mapping studies. This discrepancy has important implications for the mechanisms of defibrillation. The purpose of the present study was to demonstrate an optical equivalent of an isoelectric window after a near-threshold defibrillation shock. Methods and Results - We studied 10 isolated, perfused swine right ventricles. Upper limit of vulnerability was determined by shocks on T waves. A 50% probability of successful defibrillation (DFT50) was determined with an up-down algorithm. Immediately after unsuccessful defibrillation shock, new wavefronts were generated. When the shock strength was low, immediate reinitiation of reentry and ventricular fibrillation might occur without a postshock isoelectric window. However, if the shock strength was within 50 V of DFT50 (near-threshold), a synchronized activation occurred, followed by organized repolarization that ended 64±18 ms after shock. After a period of quiescence (18±24 ms), activation recurred 83±33 ms after shock and reinitiated ventricular fibrillation. Similar patterns of activation, including a quiescent period, were observed after shock was applied on the T wave of the paced beat that induced ventricular fibrillation. Upper limit of vulnerability correlated well with DFT50. Conclusions - In isolated swine right ventricles, an optical equivalent of an isoelectric window exists after near-threshold defibrillation shocks. These findings support the idea that a near-threshold defibrillation shock terminates all activation wavefronts but fails to halt ventricular fibrillation because the same shock reinitiates ventricular fibrillation after an isoelectric window.

KW - Action potentials

KW - Death, sudden

KW - Electrical stimulation

KW - Electrophysiology

KW - Mapping

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