Journal of Electrocardiology
Volume 43, Issue 3 , Pages 261-263, May 2010

Open-loop, clockwise QT-RR hysteresis immediately before the onset of torsades de pointes in type 2 long QT syndrome

  • Gen Nakaji, MD

      Affiliations

    • Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
    • ,
  • Masahiko Fujiwara, MD

      Affiliations

    • Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
    • ,
  • Mitsuhiro Fukata, MD

      Affiliations

    • Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
    • ,
  • Shioto Yasuda, MD

      Affiliations

    • Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
    • ,
  • Keita Odashiro, MD

      Affiliations

    • Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
    • ,
  • Toru Maruyama, MD

      Affiliations

    • Institute of Health Science, Kyushu University, Kasuga, Japan
    • Corresponding Author InformationCorresponding author. Institute of Health Science, Kyushu University, Kasuga 816-8580, Japan.
    • ,
  • Koichi Akashi, MD

      Affiliations

    • Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan

Received 2 October 2009 published online 18 January 2010.

Abstract 

Delay of QT interval adaptation to sudden heart rate change causes hysteresis in dynamic QT-RR relationship. We analyzed QT-RR plotting during and after exercise in a patient with genetically identified type 2 long QT syndrome before and after starting oral propranolol. Blunted QT shortening by exercise and augmented postexercise QT prolongation resulted in an open-loop, clockwise QT-RR hysteresis immediately before the onset of torsades de pointes before propranolol. However, this hysteresis was eliminated by propranolol. QT-RR analysis provided insight into the mechanisms of the onset of torsades de pointes at least in this case of type 2 long QT syndrome.

Keywords: Hysteresis, Long QT syndrome, QT-RR relation, Torsades de pointes

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PII: S0022-0736(09)00624-4

doi:10.1016/j.jelectrocard.2009.12.005

Journal of Electrocardiology
Volume 43, Issue 3 , Pages 261-263, May 2010

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