The Specific Electrophysiologic Characteristics in Children with the Atypical Forms of Atrioventricular Nodal Reentrant Tachycardia

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is well known to be one of the most common supraventricular tachycardias in childhood. However, information about the atypical forms of AVNRT in childhood is limited. The purpose of this retrospective study was to investigate the clinical and electrophysiologic characteristics in pediatric patients with the atypical forms of AVNRT. METHODS: One hundred and three pediatric patients with AVNRT were included (aged 8-18 years; 44 male, 59 female). There were 10 (9.7%) children with the atypical forms (group 1), 86 (83.4%) with the slow-fast form (group 2) and 7 (6.9%) with the fast-slow form of AVNRT (group 3). The electrophysiologic characteristics and results of the radiofrequency catheter ablation were compared among these 3 groups. RESULTS: Group 2 patients were associated with an older age when compared with the other two groups. A significantly higher incidence of retrograde dual atrioventricular nodal pathways and a higher percentage of ventricular pacing- and extrastimulation-induced AVNRT were demonstrated in the children with the fast-slow form of AVNRT. The children with the atypical forms of AVNRT had a greater difference in the antegrade 1:1 conduction (100 +/- 73 vs. 52 +/- 41 vs. 35 +/- 26 ms, p = 0.003). Furthermore, the children with the slow-fast form of AVNRT had a greater difference in the retrograde 1:1 conduction (125 +/- 97 vs. 42 +/- 35 vs. 65 +/- 79 ms, p = 0.012). CONCLUSION: This study demonstrated that the pediatric patients with the atypical forms of AVNRT had different electrophysiologic characteristics than those with the slow-fast or fast-slow forms of AVNRT. The results of radiofrequency catheter ablation were similar for all children with the slow-fast, fast-slow and atypical forms of AVNRT.