Alternans of action potential duration and amplitude in rabbits with left ventricular dysfunction following myocardial infarction

Myles, R. , Burton, F.L., Cobbe, S. and Smith, G.L. (2011) Alternans of action potential duration and amplitude in rabbits with left ventricular dysfunction following myocardial infarction. Journal of Molecular and Cellular Cardiology, 50(3), pp. 510-512. (doi:10.1016/j.yjmcc.2010.11.019)

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Abstract

T-wave alternans may predict the occurrence of ventricular arrhythmias in patients with left ventricular dysfunction and experimental work has linked discordant repolarization alternans to the induction of re-entry. The aim of this study was to examine the occurrence of transmural repolarization alternans and to investigate the link between alternans and ventricular arrhythmia in rabbits with left ventricular dysfunction following myocardial infarction. Optical mapping was used to record action potentials from the transmural surface of left ventricular wedge preparations from normal and post-infarction hearts during a progressive reduction in pacing cycle length at 30 and 37 degrees C. Data were analyzed using custom software, including spectral analysis. There were no significant differences in baseline transmural electrophysiology between the groups. Post-infarction hearts had a lower threshold for both repolarization alternans (286 vs. 333 bpm, p<0.05) and ventricular arrhythmias (79 vs. 19%, p<0.01) during rapid pacing, which was not accounted for by increased transmural discordant alternans. In VF-prone hearts, alternans in optical action potential amplitude was observed and increased until 2:1 block occurred. The degree of optical action potential amplitude alternans (12.0 +/- 7.0 vs. 1.8 +/- 0.3, p<0.05), but not APD(90) alternans (1.4 +/- 0.6 vs. 1.1 +/- 0.1, p>0.05) was associated with VF inducibility during rapid pacing. Post-infarction hearts are more vulnerable to transmural alternans and ventricular arrhythmias at rapid rates. Alternans in optical action potential amplitude was associated with conduction block and VF. The data suggest that changes in optical action potential amplitude may underlie a mechanism for alternans-associated ventricular arrhythmia in left ventricular dysfunction.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Smith, Professor Godfrey and Myles, Dr Rachel and Burton, Dr Francis and Cobbe, Professor Stuart
Authors: Myles, R., Burton, F.L., Cobbe, S., and Smith, G.L.
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Journal Name:Journal of Molecular and Cellular Cardiology
Publisher:Elsevier
ISSN:0022-2828
ISSN (Online):1095-8584

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
430871The role of repolarisation alternans in ventricular arrhythmia in a rabbit model of heart failureStuart CobbeBritish Heart Foundation (BHF)FS/06/037School of Medicine