title: Bepridil versus nifedipine for ventricular tachycardia induced in the late postinfarction phase in conscious dogs.
abstract: The effects of the two calcium antagonists bepridil and nifedipine on induced ventricular tachyarrhythmias were studied by programmed electrical stimulation in 15 dogs, 4-8 days after myocardial infarction. Recordings from the infarcted and normal anterior wall of the left ventricle were obtained with an epicardial implanted 'composite' electrode. Bepridil (5 mg/kg) or nifedipine (0.025 mg/kg) were administered i.v. on different days and testing was repeated. Sustained ventricular tachycardia was prevented or significantly slowed by bepridil in 11/12 experiments compared with none of 9 experiments with nifedipine. Paradoxically, in 10/15 dogs nifedipine accelerated arrhythmias or even provoked ventricular fibrillation. Bepridil prolonged refractoriness of infarcted myocardium by 15 +/- 4% (mean +/- SD, p less than 0.01), which was greater than the increase it produced in the effective refractory period of normal tissue (9.0 +/- 3.8%) or QTc interval (11 +/- 5.5%). In contrast, nifedipine significantly shortened these parameters. Both drugs did not influence conduction in infarcted and normal zones as indicated by unchanged late potentials, QRS duration and normal-zone electrograms, respectively. The data indicate that the antiarrhythmic action of bepridil was predominantly related to the prolongation of ventricular refractoriness and repolarization (class III effects).
authors: Department of Cardiology, University of Heidelberg, FRG.
authors: J
authors: J
authors: Brachmann
authors: I
authors: I
authors: Aidonidis
authors: K
authors: K
authors: Dembowsky
authors: H
authors: H
authors: Seller
authors: W
authors: W
authors: Kuebler
mesh_terms: D000818:Animals; D015764:Bepridil; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D002304:Cardiac Pacing, Artificial; D003243:Consciousness; D004285:Dogs; D004562:Electrocardiography; D009203:Myocardial Infarction / Q000150:complications*; D009543:Nifedipine / Q000627:therapeutic use*; D011759:Pyrrolidines / Q000627:therapeutic use*; D013610:Tachycardia / Q000188:drug therapy* / Q000209:etiology
chemical_list: D002121:Calcium Channel Blockers; D011759:Pyrrolidines; D015764:Bepridil; D009543:Nifedipine