[Electrophysiologic effects of isoproterenol in children with Wolff-Parkinson-White syndrome].

12 children with the Wolff-Parkinson-White (WPW) syndrome underwent electrophysiologic study before and after the intravenous administration of isoproterenol. Effective refractory period of the accessory pathway and shortest paced cycle length with 1:1 atrioventricular (A-V) conduction via the accessory pathway were shortened after intravenous isoproterenol in all patients. Orthodromic reciprocating tachycardia was induced after isoproterenol in one patient who did not documented tachycardia attack or palpitation before. Anterograde A-V conduction via A-V node and retrograde V-A conduction via accessory pathway were enhanced. Thus, tachycardia cycle length was shortened. Potential high risk group patient who develop hazardous atrial fibrillation during exercise in the WPW syndrome may be selected by isoproterenol infusion.