The acute cardiac electrophysiological effects of intravenous sotalol hydrochloride

Abstract

The cardiac electrophysiological effects of sotalol were studied in ten patients (pts) aged 20-65 years undergoing intracardiac stimulation studies for palpitations (7 pts) or dizzy spells (3 pts). The following measurements were made: 1. basic sinus cycle length (SCL); 2. sinus node recovery time (SNRT) following overdrive pacing; 3. intra-atrial (PA), atrio-His (AH) and His-ventricular (HV) conduction intervals during regular atrial pacing; 4. effective refractory periods of the atria (AERP), AV node (AVERP) and ventricular myocardium (VERP). AV nodal functional refractoriness (AVFRP) was also determined. All measurements were repeated 10-15 min after i.v. administration of 0.4 mg/kg of sotalol. Results were analysed by the Wilcoxon Signed Rank test. Significant increases in SCL (p < 0.01), AH (p < 0.01), SNRT (p < 0.01), AVERP (p < 0.02) and AVFRP (p < 0.01) were observed. These effects are consistent with the beta-blocking action of sotalol. The acute increase in AERP (p < 0.01) is, however, not a common property of other betablockers and may be related to the ‘class III’ cellular effect of sotalol. These results are discussed in relationship to the electrophysiological effects of other beta-blocking drugs.