Electrophysiologic effect of sotalol in supraventricular tachycardias

The electrophysiological effects of sotalol, a beta-blocking drug with class III antiarrhythmic properties were assessed in 20 patients (mean age 33 +/- 14.3 years) with supraventricular tachycardias. Sixteen patients had Wolff-Parkinson-White syndrome (overt n = 9, concealed n = 7), three patients AV-nodal reentrant tachycardias and another patient atrial tachycardias. Sotalol was administered intravenously (n = 16) in a dose of 1.5 mg/kg over 15 min. The effects of 320 to 480 mg/day oral sotalol were assessed in 7 patients. By intravenous and oral application of sotalol a significant increase in the AH interval, the refractory periods of the atrium and ventricle as well as a decrease of the antegrade and retrograde conduction capacity of the AV node or the accessory pathway were observed. The mean R-R interval during induced atrial fibrillation increased significantly in patients with Wolff-Parkinson-White syndrome from 224 +/- 52 ms to 277 +/- 59 ms (p less than 0.05). In 10 patients, sotalol was administered during supraventricular reentrant tachycardia. The cycle length of supraventricular tachycardia increased from 276 +/- 90 ms to 358 +/- 25 ms (p less than 0.01). The tachycardia terminated in 7 patients: in 5 patients block was observed in the AV node, while in another 2 patients tachycardia terminated retrogradely. After intravenous application supraventricular arrhythmias were no longer inducible in 5 of 12 patients. In a further 4 patients only non-sustained supraventricular tachycardias (4-20 QRS complexes) were inducible. In 2 patients the supraventricular tachycardia terminated distal to the His bundle.(ABSTRACT TRUNCATED AT 250 WORDS)