Slow antegrade excitation and delayed retrograde activation through an 'inexcitable zone': A basis for arrhythmia formation in infarcted myocardium ex vivo
| Autor: | Eugene, Patterson, Benjamin J, Scherlag |
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| Rok vydání: | 2016 |
| Předmět: |
Male
Cardiac Complexes Premature Epinephrine Myocardial Infarction Lidocaine Arrhythmias Cardiac Ventricular Premature Complexes Electrophysiological Phenomena Electrocardiography Dogs Heart Conduction System Animals Anisotropy Tachycardia Atrioventricular Nodal Reentry Vasoconstrictor Agents Anti-Arrhythmia Agents Microelectrodes |
| Zdroj: | Journal of cardiovascular electrophysiology. 28(10) |
| ISSN: | 1540-8167 |
| Popis: | The electrophysiologic mechanism for rate-dependent PVBs associated with double potentials (DPs) was investigated in infarcted canine hearts using bipolar and intracellular microelectrode recordings.Dogs exhibiting rate-related ventricular ectopic beats (coupling interval, 390 ± 54 milliseconds) 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%) postcoronary 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%).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. |
| Databáze: | OpenAIRE |
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