Loss of efficacy of flecainide in the Wolff-Parkinson-White syndrome after isoproterenol administration.

Although anterograde conduction through a Kent bundle with a short refractory period was suppressed by 300 mg of flecainide acetate, the infusion of small amounts of isoproterenol caused the reappearance of WPW and permitted the induction of an atrial tachycardia with 1/1 conduction through the accessory pathway at a rate of 260 beats min-1. This case shows that the effect of isoproterenol may be maintained after apparently successful flecainide therapy.

[Cardiac electrophysiologic effects of prostacyclin in man].

The electrophysiological effects of prostacyclin (PGI2) at increasing doses (2.5, 5 and 10 ng/kg/min) were assessed in 16 patients during classical investigations of sinus node function and atrioventricular conduction and during programmed atrial and right ventricular under basal conditions and during prostacyclin perfusion. Ten patients had normal sinus node function and atrioventricular conduction under basal conditions.

Proarrhythmic and antiarrhythmic effects of intravenous prostacyclin in man.

Prostacyclin (PGI2) has been shown to reduce the occurrence of experimental ventricular arrhythmias. To assess potential beneficial effects in man, the electrophysiological action of PGI2 was studied in 16 non medicated patients. The protocol used in incremental pacing and programmed stimulation in the right atrium and ventricle.