Phase 1B ventricular arrhythmia in the dog: localized reentry within the mid-myocardium.
Intramural and epicardial composite electrograms, signal-averaged orthogonal bipolar electrograms across the ischemic zone, and closely-spaced bipolar electrograms from subendocardium, mid-myocardium, and subepicardium were utilized to determine if phase 1B reentry resulted from localized reentry within ischemic mid-myocardium. During the first 10 minutes following coronary ligation, activation delays were largest in ischemic subepicardium, with continuous electrical activity in ischemic epicardium linking a ventricular extrasystole to the preceding beat. During the 15-30 minute period, activation delay observed in ischemic mid-myocardium exceeded activation delay on the epicardial surface. Ventricular extrasystoles were associated with mid-myocardial delays > 130 msec. With short-coupled extrasystoles (< 300 msec), electrical activity in ischemic mid-myocardium linked an extrasystole with the preceding beat. Although single extrasystoles with coupling intervals > 300 msec were also associated with mid-myocardial delays > 130 msec, most extrasystoles (68%) demonstrated an isoelectric gap > 20 msec. The data demonstrate an association between delayed activation within ischemic mid-myocardium and phase 1B arrhythmia resulting from (1) localized reentry in ischemic mid-myocardium and (2) a delay-dependent "non-reentrant" mechanism.
Patterson
E
E
Department of Pharmacology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA. EUGENE-PATTERSON@UOKHSC.EDU
Kalcich
M
M
Scherlag
B J
BJ
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000503:physiopathology; D001283:Atrioventricular Node / Q000503:physiopathology; D002036:Bundle of His / Q000503:physiopathology; D004285:Dogs; D004562:Electrocardiography; D004699:Endocardium / Q000503:physiopathology; D006327:Heart Block / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D017202:Myocardial Ischemia / Q000150:complications*; D010496:Pericardium / Q000503:physiopathology; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors; D014630:Vagus Nerve / Q000503:physiopathology; D018754:Ventricular Dysfunction / Q000209:etiology* / Q000503:physiopathology; D014693:Ventricular Fibrillation / Q000209:etiology / Q000503:physiopathology; D018879:Ventricular Premature Complexes / Q000209:etiology