Moderate hypothermia (33 °c) decreases the susceptibility to pacing-induced ventricular fibrillation compared with severe hypothermia (30 °c) by attenuating spatially discordant alternans in isolated rabbit hearts

Yu Cheng Hsieh, Shien Fong Lin, Jin Long Huang, Chen Ying Hung, Jiunn Cherng Lin, Ying Chieh Liao, Chu Pin Lo, Kuo Yang Wang, Tsu Juey Wu

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Methods: Using an optical mapping system, action potential duration (APD)/conduction velocity restitutions and thresholds of APD alternans were determined by S1 pacing in Langendorff-perfused isolated rabbit hearts. In the MHgroup (n = 7), S1 pacing was performed at baseline (37 °C), after 5-minMH, and after 5-min rewarming (37 °C). In the SH group (n = 9), pacing was also performed at baseline (37 °C), after 5-min SH, and after 5-min rewarming (37 °C). The thresholds of APD alternans were defined as the longest S1 pacing cycle length at which APD alternans were detected.

Results: Although the thresholds of APD alternans were not different between the MH (273 ± 46 ms) and the SH (300 ± 35 ms) (p = 0.281) groups, SDA threshold was shorter (at a faster heart rate) during MH (228 ± 33 ms) than that during SH (289 ± 42 ms) (p = 0.028). At APD alternans threshold, SH hearts showedmore SDA than that during MH (SH: 7 hearts, MH: 2 hearts, p = 0.049). SDA could be induced in all 9 SH hearts (100%), while only 4 MH hearts (57%) had SDA (p = 0.029). The PIVF inducibility during SH (44 ± 53%) was higher than that during MH (0%) (p = 0.043).

Conclusions: Compared with SH, the MH group showed greater attenuation of SDA and decreased the susceptibility of PIVF. Therefore,MH is safer as a procedural guideline for use in clinical therapeutic hypothermia than SH.

Background: Severe hypothermia (SH, 30 °C) increases the risk of pacing-induced ventricular fibrillation (PIVF) by enhancing spatially discordant alternans (SDA). Whether moderate hypothermia (MH, 33 °C), which is clinically used for therapeutic hypothermia, also facilitates SDA remains unclear.We hypothesized thatMH attenuates SDA occurrence compared with that achieved by SH, and decreases the susceptibility of PIVF.

Original languageEnglish (US)
Pages (from-to)455-465
Number of pages11
JournalActa Cardiologica Sinica
Volume30
Issue number5
StatePublished - Sep 1 2014

Keywords

  • Cardiac alternans
  • Conduction velocity
  • Hypothermia
  • Optical mapping

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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