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Arrhythmogenicity of hypothermia - a large animal model of hypothermia

journal contribution
posted on 2023-05-18, 05:10 authored by Bassin, L, Yong, AC, David KilpatrickDavid Kilpatrick, Hunyor, SN
Therapeutic hypothermia (TH) is used to mitigate cerebral injury after an out of hospital cardiac arrest. There is a perceived risk of increased arrhythmias with temperatures lower than the current target of 32-34°C for TH. This study sought to develop and investigate the electrophysiological changes in a sheep model of systemic hypothermia regarding the susceptibility to ventricular arrhythmias.

Methods: Ten sheep underwent systemic hypothermia using a venous-venous extra-corporeal circuit whilst instrumented with a 12 lead ECG. An epicardial sock recorded potentials to 30°C (n = 10) or 26°C (n = 6). Activation times (AT) and Activation Recovery Intervals (ARI) were calculated using custom software.

Results: The AT and ARI were significantly prolonged with increased heterogeneity during hypothermia. This effect was most pronounced between normothermia and 34°C during sinus rhythm (SR). For ventricular pacing (VP) however heterogeneity continued to increase with progressive hypothermia.

Conclusions: Hypothermia causes a significant increase in the heterogeneity of depolarisation and repolarisation. There is evidence to suggest that SR is protective with most of the increase in heterogeneity occurring with cooling to 34°C. This raises the possibility that the current target temperatures for therapeutic hypothermia may be safely lowered to provide a gain in cerebral protection.

History

Publication title

Heart, Lung and Circulation

Volume

23

Pagination

82-87

ISSN

1443-9506

Department/School

Tasmanian School of Medicine

Publisher

Elsevier Australia

Place of publication

Australia

Rights statement

Copyright 2014 Elsevier

Repository Status

  • Restricted

Socio-economic Objectives

Other health not elsewhere classified

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