Mechanisms of termination of supraventricular tachycardias by intravenous class III antiarrhythmic agents. A comparison of amiodarone and sotalol.
The effects of amiodarone and sotalol were studied with programmed electrical stimulation of the heart in 19 patients with inducible tachycardia (AV nodal tachycardia: 10 cases, circus movement tachycardia: 9 cases). Amiodarone was administered intravenously at a dose of 300 mg over 2 min and sotalol at a dose of 1.5 mg kg-1 over 10 min. Both i.v. amiodarone and sotalol lengthened the transnodal conduction time, the effective refractory period of the AV node and the AV nodal Wenckebach cycle length. Only sotalol significantly lengthened the effective refractory periods of the right atrium and the right ventricle. Infused intravenously during tachycardia, amiodarone interrupted arrhythmia in five of six patients and sotalol in seven of ten cases. Tachycardia was stopped by blockade of the impulse into the AV node in three amiodarone patients and in five sotalol patients. In the remaining four cases, the weak link of the circuit was the accessory pathway. Thus i.v. sotalol exhibits electrophysiologic effects consistent with both class II and III activity, whereas the effects of i.v. amiodarone are the result of different activities throughout all areas of the cardiac tissue.
Waleffe
A
A
Department of Cardiology, Hôpital Universitaire, University of Liège, Belgium.
Nzayinambaho
K
K
Rodriguez
L M
LM
Dehareng
A
A
Kulbertus
H E
HE
D000293:Adolescent; D000328:Adult; D000638:Amiodarone / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D002648:Child; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D013015:Sotalol / Q000627:therapeutic use; D013617:Tachycardia, Supraventricular / Q000188:drug therapy*
D000889:Anti-Arrhythmia Agents; D013015:Sotalol; D000638:Amiodarone