Slow antegrade excitation and delayed retrograde activation through an 'inexcitable zone': A basis for arrhythmia formation in infarcted myocardium ex vivo

Autor: Benjamin J. Scherlag, Eugene Patterson
Rok vydání: 2017
Předmět:
Zdroj: Journal of Cardiovascular Electrophysiology. 28:1213-1222
ISSN: 1045-3873
DOI: 10.1111/jce.13268
Popis: Introduction : The electrophysiologic mechanism for rate-dependent premature ventricular beats associated with double potentials (DPs) was investigated in infarcted canine hearts using bipolar and intracellular microelectrode recordings. Methods and results : Dogs exhibiting rate-related ventricular ectopic beats (coupling interval, 390 ± 54 msec) during sinus rhythm or atrial pacing were studied 4–5 days (N = 63) or 25 days (N = 16) following anterior descending coronary artery ligation. Sites of DP and rate-dependent arrhythmia formation were identified in vivo using bipolar recordings for subsequent ex vivo studies. Rate-dependent conduction delays with increasing duration isoelectric intervals representing very slow conduction were observed at sites of DP formation, frequently provoking both manifest and concealed reentry (non-stimulated beats) over a narrow range of paced cycle lengths. Both slow antegrade and retrograde activation across an inexcitable gap (reflection) were integral components of extrasystole formation. Retrograde reflection to a region of very slow conduction (mid-potential) during antegrade activation was routinely observed at 4–5 days (42 of 63 preparations, 67%) and 25 days (22 of 26 preparations, 85%) post coronary artery ligation. Reflection and premature re-activation of the proximal site was then observed in 6 of 63, (9%), and 3 of 26 preparations, (12%). Conclusion : The present experiments demonstrate DP formation and rate-dependent constant-coupled late epicardial premature beats in infarcted dog hearts. Microelectrode recordings at DP sites demonstrating prolonged isoelectric intervals display very slow conduction preceding distal activation and “reentrant” re-activation of more proximal sites, representing reflection as an arrhythmia mechanism in ischemically-injured epicardium during subacute myocardial infarction. This article is protected by copyright. All rights reserved
Databáze: OpenAIRE
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