title: Action of sotalol on potential reentrant pathways and ventricular tachyarrhythmias in conscious dogs in the late postmyocardial infarction phase.
abstract: Sotalol is a beta-adrenergic blocker that also prolongs action potential duration and myocardial refractoriness over the short term (class III effect). Its short-term antiarrhythmic effects were compared with those of metoprolol, which has neither short-term class III nor membrane-stabilizing action, on reentrant ventricular arrhythmias produced by programmed stimulation in 17 conscious dogs 3 to 8 days after myocardial infarction. Ventricular arrhythmias were prevented or significantly slowed by sotalol in 11 of 19 studies (58%) compared with in one of 14 (7%) studies with metoprolol. Sotalol prolonged refractoriness in the infarct zone, measured from an implanted "composite" electrode, by 41 +/- 45% (mean +/- SD, p less than .01), which was significantly greater than the increases it produced in effective refractory period of the normal ventricle (14.0 +/- 5.5%) or QT interval (12.5 +/- 7.8%). Metoprolol had no effect on infarct-zone refractoriness. Sotalol differentially increases refractoriness in potential reentry circuits in ischemic myocardium. Its antiarrhythmic effect in this model is not due to beta-blockade, and is presumably related to prolongation of action potential duration.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003243:Consciousness; D004285:Dogs; D004562:Electrocardiography; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology; D008790:Metoprolol / Q000627:therapeutic use; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy*; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D013015:Sotalol / Q000627:therapeutic use*; D013610:Tachycardia / Q000209:etiology / Q000517:prevention & control*; D013997:Time Factors
chemical_list: D013015:Sotalol; D008790:Metoprolol