Mechanisms of AV Node Reentrant Tachycardia in Young Patients With and Without Dual AV Node Physiology

Recent advances in electrophysiological mapping and radiofrequency catheter ablation have demonstrated the participation of perinodal atrial tissue or pathways in atrioventricular node reentrant tachycardia (AVNRT). Current concepts of the role of these pathways in the genesis of the various forms of AVNRT continue to evolve. In view of these recent advances, this study investigated the electrophysiology of AVNRT in young patients, and factors potentially associated with variant forms of this arrhythmia. Detailed programmed stimulation and catheter mapping were performed in 35 consecutive young patients with AVNRT. This group consisted of 15 male and 20 female patients, with a mean age of 12.1 ± 4.2 years (range 3–18 years). Of the 35 patients, 23 demonstrated dual AV node physiology, either in response to a critically timed extrastimulus (n = 17) or to rapid pacing (n = 6). The common form (antegrade slow‐retrograde fast) of AVNHT was demonstrated in 21 of these 23 patients. Antegrade fast‐retrograde slow (n = 1) and antegrade slow‐retrograde slow (n = 1) forms of AVNRT were identified in the 2 other patients. In contrast, only 5 of the 12 patients who did not demonstrate dual AV node physiology had the common form of AVNRT (P = 0.03). Eive of these patients also had the slow‐slow form of AVNRT, while 1 patient each had a fast‐slow and fast‐fast form of AVNRT. Patients with dual AV node physiology were older (14.2 ± 2.0 years) and more likely to be female (16 of 23) than patients in whom dual A V node physiology was not identified, where the mean age was 10.6 ± 4.2 years and only 4 of 12 patients were female (P = 0.02 for age and P = 0.07 for gender). These observations suggest that the physiology of AV node reentry may evolve as a function of age, with slow‐fast AVNRT prevalent in adolescents. However, absence of dual AV node physiology should not preclude diagnosis of AVNRT in young patients with supraventricular tachycardia, in whom atypical forms of AVNRT may be common.