Moderate hypothermia increases the chance of spiral wave collision in favor of self-termination of ventricular tachycardia/fibrillation

Masahide Harada, Haruo Honjo, Masatoshi Yamazaki, Harumichi Nakagawa, Yuko S. Ishiguro, Yusuke Okuno, Takashi Ashihara, Ichiro Sakuma, Kaichiro Kamiya, Itsuo Kodama

Research output: Contribution to journalArticle

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Abstract

In cardiac arrest due to ventricular fibrillation (VF), moderate hypothermia (MH, 33°C) has been shown to improve defibrillation success compared with normothermia (NR, 37°C) and severe hypothermia (SH, 30°C). The underlying mechanisms remain unclear. We hypothesized that MH might prevent reentrant excitations rotating around functional obstacles (rotors) that are responsible for the genesis of VF. In two-dimensional Langendorff-perfused rabbit hearts prepared by cryoablation (n = 13), action potential signals were recorded by a high-resolution optical mapping system. During basic stimulation (2.5-5.0 Hz), MH and SH caused significant prolongation of action potential duration and significant reduction of conduction velocity. Wavelength was unchanged at MH, whereas it was shortened significantly at SH at higher stimulation frequencies (4.0-5.0 Hz). The duration of direct current stimulation-induced ventricular tachycardia (VT)/VF was reduced dramatically at MH compared with NR and SH. The spiral wave (SW) excitations documented during VT at NR were by and large organized, whereas those during VT/VF at MH and SH were characterized by disorganization with frequent breakup. Phase maps during VT/VF at MH showed a higher incidence of SW collision (mutual annihilation or exit from the anatomical boundaries), which caused a temporal disappearance of phase singularity points (PS-0), compared with that at NR and SH. There was an inverse relation between PS-0 period in the observation area and VT/VF duration. MH data points were located in a longer PS-0 period and a shorter VT/VF duration zone compared with SH. MH causes a modification of SW dynamics, leading to an increase in the chance of SW collision in favor of self-termination of VT/VF.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume294
Issue number4
DOIs
Publication statusPublished - 01-04-2008

Fingerprint

Ventricular Fibrillation
Ventricular Tachycardia
Hypothermia
Action Potentials
Optical Devices
Cryosurgery
Heart Arrest
Observation
Rabbits
Incidence

All Science Journal Classification (ASJC) codes

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

Cite this

Harada, Masahide ; Honjo, Haruo ; Yamazaki, Masatoshi ; Nakagawa, Harumichi ; Ishiguro, Yuko S. ; Okuno, Yusuke ; Ashihara, Takashi ; Sakuma, Ichiro ; Kamiya, Kaichiro ; Kodama, Itsuo. / Moderate hypothermia increases the chance of spiral wave collision in favor of self-termination of ventricular tachycardia/fibrillation. In: American Journal of Physiology - Heart and Circulatory Physiology. 2008 ; Vol. 294, No. 4.
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abstract = "In cardiac arrest due to ventricular fibrillation (VF), moderate hypothermia (MH, 33°C) has been shown to improve defibrillation success compared with normothermia (NR, 37°C) and severe hypothermia (SH, 30°C). The underlying mechanisms remain unclear. We hypothesized that MH might prevent reentrant excitations rotating around functional obstacles (rotors) that are responsible for the genesis of VF. In two-dimensional Langendorff-perfused rabbit hearts prepared by cryoablation (n = 13), action potential signals were recorded by a high-resolution optical mapping system. During basic stimulation (2.5-5.0 Hz), MH and SH caused significant prolongation of action potential duration and significant reduction of conduction velocity. Wavelength was unchanged at MH, whereas it was shortened significantly at SH at higher stimulation frequencies (4.0-5.0 Hz). The duration of direct current stimulation-induced ventricular tachycardia (VT)/VF was reduced dramatically at MH compared with NR and SH. The spiral wave (SW) excitations documented during VT at NR were by and large organized, whereas those during VT/VF at MH and SH were characterized by disorganization with frequent breakup. Phase maps during VT/VF at MH showed a higher incidence of SW collision (mutual annihilation or exit from the anatomical boundaries), which caused a temporal disappearance of phase singularity points (PS-0), compared with that at NR and SH. There was an inverse relation between PS-0 period in the observation area and VT/VF duration. MH data points were located in a longer PS-0 period and a shorter VT/VF duration zone compared with SH. MH causes a modification of SW dynamics, leading to an increase in the chance of SW collision in favor of self-termination of VT/VF.",
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Moderate hypothermia increases the chance of spiral wave collision in favor of self-termination of ventricular tachycardia/fibrillation. / Harada, Masahide; Honjo, Haruo; Yamazaki, Masatoshi; Nakagawa, Harumichi; Ishiguro, Yuko S.; Okuno, Yusuke; Ashihara, Takashi; Sakuma, Ichiro; Kamiya, Kaichiro; Kodama, Itsuo.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 294, No. 4, 01.04.2008.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Moderate hypothermia increases the chance of spiral wave collision in favor of self-termination of ventricular tachycardia/fibrillation

AU - Harada, Masahide

AU - Honjo, Haruo

AU - Yamazaki, Masatoshi

AU - Nakagawa, Harumichi

AU - Ishiguro, Yuko S.

AU - Okuno, Yusuke

AU - Ashihara, Takashi

AU - Sakuma, Ichiro

AU - Kamiya, Kaichiro

AU - Kodama, Itsuo

PY - 2008/4/1

Y1 - 2008/4/1

N2 - In cardiac arrest due to ventricular fibrillation (VF), moderate hypothermia (MH, 33°C) has been shown to improve defibrillation success compared with normothermia (NR, 37°C) and severe hypothermia (SH, 30°C). The underlying mechanisms remain unclear. We hypothesized that MH might prevent reentrant excitations rotating around functional obstacles (rotors) that are responsible for the genesis of VF. In two-dimensional Langendorff-perfused rabbit hearts prepared by cryoablation (n = 13), action potential signals were recorded by a high-resolution optical mapping system. During basic stimulation (2.5-5.0 Hz), MH and SH caused significant prolongation of action potential duration and significant reduction of conduction velocity. Wavelength was unchanged at MH, whereas it was shortened significantly at SH at higher stimulation frequencies (4.0-5.0 Hz). The duration of direct current stimulation-induced ventricular tachycardia (VT)/VF was reduced dramatically at MH compared with NR and SH. The spiral wave (SW) excitations documented during VT at NR were by and large organized, whereas those during VT/VF at MH and SH were characterized by disorganization with frequent breakup. Phase maps during VT/VF at MH showed a higher incidence of SW collision (mutual annihilation or exit from the anatomical boundaries), which caused a temporal disappearance of phase singularity points (PS-0), compared with that at NR and SH. There was an inverse relation between PS-0 period in the observation area and VT/VF duration. MH data points were located in a longer PS-0 period and a shorter VT/VF duration zone compared with SH. MH causes a modification of SW dynamics, leading to an increase in the chance of SW collision in favor of self-termination of VT/VF.

AB - In cardiac arrest due to ventricular fibrillation (VF), moderate hypothermia (MH, 33°C) has been shown to improve defibrillation success compared with normothermia (NR, 37°C) and severe hypothermia (SH, 30°C). The underlying mechanisms remain unclear. We hypothesized that MH might prevent reentrant excitations rotating around functional obstacles (rotors) that are responsible for the genesis of VF. In two-dimensional Langendorff-perfused rabbit hearts prepared by cryoablation (n = 13), action potential signals were recorded by a high-resolution optical mapping system. During basic stimulation (2.5-5.0 Hz), MH and SH caused significant prolongation of action potential duration and significant reduction of conduction velocity. Wavelength was unchanged at MH, whereas it was shortened significantly at SH at higher stimulation frequencies (4.0-5.0 Hz). The duration of direct current stimulation-induced ventricular tachycardia (VT)/VF was reduced dramatically at MH compared with NR and SH. The spiral wave (SW) excitations documented during VT at NR were by and large organized, whereas those during VT/VF at MH and SH were characterized by disorganization with frequent breakup. Phase maps during VT/VF at MH showed a higher incidence of SW collision (mutual annihilation or exit from the anatomical boundaries), which caused a temporal disappearance of phase singularity points (PS-0), compared with that at NR and SH. There was an inverse relation between PS-0 period in the observation area and VT/VF duration. MH data points were located in a longer PS-0 period and a shorter VT/VF duration zone compared with SH. MH causes a modification of SW dynamics, leading to an increase in the chance of SW collision in favor of self-termination of VT/VF.

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