Transesophageal electropharmacologic test in a newborn with familial Wolff-Parkinson-White syndrome.

A newborn infant with familial Wolff-Parkinson-White (WPW) syndrome presented with a supraventricular tachycardia of 300 beats/min, refractory to digoxin and flecainide administration. Serial electropharmacologic tests were performed via the esophagus before and during oral therapy with verapamil at 40, 80, and 60 mg daily. Before treatment, tachycardia could be induced with programmed stimulation. A regimen of verapamil at 60 mg daily, which resulted in the initiation of nonsustained (less than 10 s) reciprocating tachycardia only, without clinical recurrences, was identified as suitable long-term oral therapy. The efficacy of this drug regimen in preventing episodes of tachycardia was confirmed during a 1-month follow-up period. It is concluded that transesophageal atrial pacing is a useful, noninvasive means of selecting treatment in neonates with supraventricular tachycardia, when nonconventional drugs are considered for prophylaxis.