title: The duration of coronary occlusion influences adrenergic contributions to reperfusion ventricular arrhythmias.
abstract: To study the role of the adrenergic nervous system in the genesis of nonlethal reperfusion arrhythmias, the proximal left anterior descending coronary artery was occluded for either 1 or 3 hours in 48 open-chest dogs anesthetized with alpha-chloralose. Heart rate was controlled (90 to 110 beats/min) by bilateral vagotomy and continuous right vagal stimulation. Dogs were treated with either saline, timolol (0.1 mg/kg), or prazosin (0.5 mg/kg) 15 minutes prior to reperfusion. Reperfusion after 1 hour of occlusion in saline-treated dogs evoked sustained polymorphic ventricular tachycardia (204 +/- 9 beats/min) that reverted to sinus rhythm by 15 minutes of reperfusion. The maximum rate of ventricular tachycardia was significantly reduced by both prazosin and timolol. Both drugs also caused about a 50% reduction in the total number of ectopic beats in the first 10 minutes of reperfusion. With a 3-hour occlusion, reperfusion in saline-treated dogs caused sustained polymorphic ventricular tachycardia (135 +/- 15 beats/min) which persisted for several hours. Neither timolol nor prazosin significantly altered the ventricular ectopic rate in these dogs. Furthermore, bilateral stellate transection, left stellate stimulation, isoproterenol (0.5 mg/kg), or methoxamine (100 ug/kg) all failed to alter the ventricular ectopic rate in the saline-treated dogs. Ventricular ectopy induced by reperfusion after a 1- or 3-hour occlusion was overdriven in all dogs by rapid atrial pacing. The results suggest that the nature of reperfusion-induced ventricular ectopy is highly dependent upon the preceeding duration of coronary occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, Loyola University Medical Center, Maywood, Illinois 60153.
authors.forename: D E
authors.initials: DE
authors.lastname: Euler
authors.forename: P J
authors.initials: PJ
authors.lastname: Scanlon
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000503:physiopathology*; D003327:Coronary Disease / Q000503:physiopathology*; D004285:Dogs; D006352:Heart Ventricles / Q000503:physiopathology; D015425:Myocardial Reperfusion; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013997:Time Factors