The Mechanisms of Tachyarrhythmias in Infants with Structurally Normal Heart

Background and Objectives:The mechanisms of supraventricular tachycardia (SVT in children are known to have age-dependent distributions. However, the distribution of the mechanisms of tachyarrhythmia, as a whole, is not known in infants and children. The aim of this study was to evaluate the mechanisms of tachyarrhythmia in infants with a structurally normal heart. Subjects and Methods:We retrospectively reviewed the mechanisms of tachycardia in 56 children with structurally normal hearts, who had had a tachyarrhythmia in infancy. The mechanisms of tachycardia were confirmed in surface electrocardiogram and by transesophageal, or trans- venous, electrophysiological study. Results:The majority of tachycardia during infancy were SVT, in 50 of the 56 (89%. In the infants with SVT, 29 (58% had atrioventricular reentrant tachycardia using an accessory pathway, With a manifested accessory pathway were in 13 of the 29. Primary atrial tachycardia was found in 19 (38%:a chaotic atrial tachycardia in 10, an atrial flutter in 5 and an atrial ectopic tachycardia in 4. 6 (11% had a ventricular tachycardia, and of these 5 had a verapamil-sensitive idiopathic left ventricular tachycardia. The most infrequent tachycardia during infancy was an atrioventricular nodal reentrant tachycardia, which occurred in only 2 (4%. 39% of the tachycardia during infancy occurred in the neonatal period. Atrioventricular nodal reentrant and ventricular tachycardia were not found during the neonatal period. Conclusion:The most frequent mechanism of tachycardia during infancy was SVT related, with an accessory pathway. Primary atrial and ventricular tachycardia were also found in nearly half the infants, and these were sometimes difficult to manage without understanding their precise mechanism. ( ( ( (Korean Circulation J 2002;32( ( ((12 :1085-1090