CHARACTERISTICS, MANAGEMENT, AND MIDTERM OUTCOME IN INFANTS WITH ATRIOVENTRICULAR NODAL REENTRY TACHYCARDIA

Atrioventricular nodal reentry is a commonly recognized mechanism of s upraventricular tachycardia (SVT) in adults, but is only rarely docume nted in the first year of life. The aim of this study was to elucidate characteristics, management, and outcome in infants with atrioventric ular nodal reentrant tachycardia (AVNRT), Electrophysiologic studies p erformed between January 1988 and June 1996 were reviewed. Fifteen inf ants with AVNRT at 58 +/- 27 days (mean +/- SEM) were identified. Five had AVNRT detected following palliation of structural cardiac anomali es, including 4 with critical obstructions to left ventricular outflow . Typical AVNRT (ventriculoatrial interval 49 +/- 5 ms) was observed i n 14 of 15 patients and atypical AVNRT (ventriculoatrial interval 191 +/- 22 ms) in 4 of 15, All patients received long-term therapy, beginn ing with digoxin in 13. Eight had symptomatic recurrences on digoxin a nd 6 of these were given beta blockers, with satisfactory control in 4 , Three patients were controlled with class III agents, and 2 underwen t slow pathway radiofrequency modification at ages 4.1 and 6.7 years, respectively. AVNRT was still inducible in 6 of 6 asymptomatic patient s who underwent follow-up atrial stimulation studies after discontinua tion of medical therapy. All 15 patients were alive with either absent or well-controlled AVNRT at age 45 +/- 7 months, We conclude that the course and outcome of AVNRT diagnosed in the first year of life are g enerally benign, but that a minority of patients have symptoms persist ing beyond infancy. Digoxin is of questionable benefit in long-term co ntrol. AVNRT often remains inducible in asymptomatic patients, althoug h the significance of this finding remains to be determined by longter m follow-up. (C) 1998 by Excerpta Medica, Inc.