Copyright © 1991 by the European Society of Cardiology.
© 1991 The European Society of Cardiology
The electrophysiological effects of flosequinan
Department of Cardiological Sciences, St George's Hospital Medical School London, U.K.
Received 24 July 1990; revised 21 November 1990; .
Correspondence: Dr Y. Bashir, Department of Cardiological Sciences, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, U.K.
Abstract
We have evaluated the acute electrophysiological effects of flosequinan in 18 patients with normal ventricular function. Following intravenous infusion of flosequinan 100 mg over 1 h, mean (SD) systolic blood pressure fell from 131 ± 19 to 120±22mmHg (P<0·02) and there was significant shortening of sinus cycle length (732±151 to 575±93 ms, P<0·001), AH interval (110±45 to 71±19 ms, P<0·01) QRS duration (98±28 to 91±26 ms, P<0·02) and QT interval (373±47 to 337±35 ms, P<0·001 but no change in sinus node recovery time, intra-atrial conduction time, HV interval or the corrected QTc interval. There was a reduction in both anterograde atrioventricular Wenckebach cycle length (299±53 to 259 ±52 ms, P<0·01) and retrograde ventriculoatrial Wenckebach cycle length (375 ± 77 to 300 ± 56 ms, P<0·01). There was no change in atrial or ventricular effective refractory period (ERP) but atrial functional refractory period (FRP) shortened (233 ± 31 to 212 ± 24 ms, P=007) as did ventricular FRP (249 ± 24 to 234 ± 21 ms, P<0·01). Patients received an oral dose of flosequinan 50 mg 12 h later. By 24 h, sinus cycle length, QRS duration and the QT interval had all returned towards baseline values, but ventricular ERP had lengthened (199±22 to 215±26 ms, P<0·06). Programmed ventricular stimulation did not result in any sustained arrhythmias before or after flosequinan. The observed electrophysiological effects of flosequinan infusion are consistent with reflex sympathetic activation. There was no conclusive evidence for any direct electrophysiological effect or for contraction-excitation feedback. No proarrhythmic effects were observed.
Key Words: Flosequinan vasodilators electrophysiology