Heart Rhythm
Volume 9, Issue 1 , Pages 107-114, January 2012

Regional cooling facilitates termination of spiral-wave reentry through unpinning of rotors in rabbit hearts

  • Masatoshi Yamazaki, MD, PhD

      Affiliations

    • Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
    • Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan
    • ,
  • Haruo Honjo, MD, PhD

      Affiliations

    • Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
    • Corresponding Author InformationAddress reprint requests and correspondence: Dr. Haruo Honjo, Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
    • ,
  • Takashi Ashihara, MD, PhD

      Affiliations

    • Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
    • ,
  • Masahide Harada, MD, PhD

      Affiliations

    • Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
    • ,
  • Ichiro Sakuma, PhD

      Affiliations

    • Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
    • ,
  • Kazuo Nakazawa, PhD

      Affiliations

    • National Cardiovascular Center, Research Institute, Suita, Japan
    • ,
  • Natalia Trayanova, PhD, FHRS, FAHA

      Affiliations

    • Institute for Computational Medicine, Johns Hopkins University, Baltimore, Maryland
    • ,
  • Minoru Horie, MD, PhD

      Affiliations

    • Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Otsu, Japan
    • ,
  • Jérôme Kalifa, MD, PhD

      Affiliations

    • Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan
    • ,
  • José Jalife, MD, FHRS

      Affiliations

    • Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan
    • ,
  • Kaichiro Kamiya, MD, PhD

      Affiliations

    • Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
    • ,
  • Itsuo Kodama, MD, PhD

      Affiliations

    • Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan

published online 11 August 2011.

Background

Moderate global cooling of myocardial tissue was shown to destabilize 2-dimensional (2-D) reentry and facilitate its termination.

Objective

This study sought to test the hypothesis that regional cooling destabilizes rotors and facilitates termination of spontaneous and DC shock-induced subepicardial reentry in isolated, endocardially ablated rabbit hearts.

Methods

Fluorescent action potential signals were recorded from 2-D subepicardial ventricular myocardium of Langendorff-perfused rabbit hearts. Regional cooling (by 5.9°C ± 1.3°C) was applied to the left ventricular anterior wall using a transparent cooling device (10 mm in diameter).

Results

Regional cooling during constant stimulation (2.5 Hz) prolonged the action potential duration (by 36% ± 9%) and slightly reduced conduction velocity (by 4% ± 4%) in the cooled region. Ventricular tachycardias (VTs) induced during regional cooling terminated earlier than those without cooling (control): VTs lasting >30 seconds were reduced from 17 of 39 to 1 of 61. When regional cooling was applied during sustained VTs (>120 seconds), 16 of 33 (48%) sustained VTs self-terminated in 12.5 ± 5.1 seconds. VT termination was the result of rotor destabilization, which was characterized by unpinning, drift toward the periphery of the cooled region, and subsequent collision with boundaries. The DC shock intensity required for cardioversion of the sustained VTs decreased significantly by regional cooling (22.8 ± 4.1 V, n = 16, vs 40.5 ± 17.6 V, n = 21). The major mode of reentry termination by DC shocks was phase resetting in the absence of cooling, whereas it was unpinning in the presence of cooling.

Conclusion

Regional cooling facilitates termination of 2-D reentry through unpinning of rotors.

Keywords:  Spiral-wave reentry , Regional myocardial cooling , Unpinning , Optical mapping , Ventricular tachyarrhythmia

Abbreviations:  2-D, two-dimension, 3-D, three-dimension, APD, action potential duration, BCL, basic cycle length, BDM, 2,3-butandione monoxime, CV, conduction velocity, FBL, functional block line, ICD, implantable cardioverter-defibrillator, LV, left ventricle, PS, phase singularity, RC, regional cooling, SW, spiral wave, VF, ventricular fibrillation, VT, ventricular tachycardia

 

 This study was supported by Grant-in-Aid for Scientific Research (B) 19390210 and (C) 20590860 from the Japanese Society for Promotion of Sciences and Grant-in-Aid for Scientific Research on Innovative Area 22136010 from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

PII: S1547-5271(11)00919-2

doi:10.1016/j.hrthm.2011.08.013

Heart Rhythm
Volume 9, Issue 1 , Pages 107-114, January 2012

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