Cardiac electrophysiologic effects of intravenous ketanserin in humans.

The hypotensive effects of ketanserin, a selective blocker of 5-hydroxytryptamine2, are well defined, but its electrophysiologic effects in humans are not. Intravenous ketanserin (0.15 mg/kg) was therefore given to 10 patients undergoing electrophysiologic evaluation, and data were obtained before and after drug administration. The mean ketanserin plasma level was 389 +/- 211 ng/ml. Ketanserin decreased systolic and diastolic blood pressure, but the change did not reach statistical significance. Ketanserin increased the QTc interval by 3% (p less than 0.01), without effect on QRS or the HV intervals. Ketanserin exerted no effect on ventricular effective refractory period (ERP) but decreased the atrial ERP by 6% (p less than 0.01); the decrease in atrioventricular (AV) nodal ERP and in the AV nodal Wenkebach cycle length did not reach statistical significance. The sinus node recovery time and intranodal conduction time were shortened significantly by ketanserin. The data indicate that ketanserin has a modest effect in prolonging ventricular repolarization without influencing the fast sodium channel. Its effect on atrial refractoriness and on sinus and AV-nodal function suggests a complex interaction with the autonomic nervous system in producing its net cardiac electrophysiologic actions.