title: [Enhancement of the antifibrillatory efficacy of quinidine in atrial fibrillation by verapamil (author's transl)].
abstract: We reported recently that in patients suffering from atrial fibrillation and being refractory to antifibrillatory therapy with quinidine conversion to sinus rhythm can often be achieved by additional doses of verapamil. To further evaluate the mechanism of this drug interaction, we studied the effects of quinidine, verapamil and combined quinidine-verapamil on the thresholds for electrically induced atrial repetitive extrasystoles (RET) and fibrillation (AFT). Comparative investigations were performed using the new calcium antagonist diltiazem. Our results show that verapamil provides protection against electrically induced atrial reentry arrhythmias only in combination with quinidine, but fails to exert a protective action when given alone. The increased success rate of conversion to sinus rhythm following combined quinidine-verapamil in patients with atrial fibrillation can be explained by an increase in the RET and AFT. The basic mechanism of this effect is supposed to be due to antiadrenergic properties of verapamil. In contrast to verapamil, diltiazen lacks the ability to increase RET and AFT in the presence of quinidine; diltiazen therefore cannot be expected to increase the antifibrillatory efficacy of quinidine in patients with atrial fibrillation.
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000188:drug therapy*; D005117:Cardiac Complexes, Premature / Q000188:drug therapy; D002304:Cardiac Pacing, Artificial; D004110:Diltiazem / Q000627:therapeutic use; D004285:Dogs; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D005260:Female; D008297:Male; D011802:Quinidine / Q000627:therapeutic use*; D014700:Verapamil / Q000627:therapeutic use*
chemical_list: D014700:Verapamil; D004110:Diltiazem; D011802:Quinidine
vernacular_title: Erhöhte antifibrillatorische Wirksamkeit von Chinidin bei Vorhofflimmern durch Verapamil).