Catheter ablation of accessory pathways in children

The efficacy and safety of catheter ablation of accessory pathways (AP) was studied in 79 children (age, 4–16 years), using DC shocks (n=25) or radiofrequency energy (n=54). All patients had docwnented arrhythimias including ventricular fibrillation in four. Organic heart disease was present in four patients. AP locations were left lateral (n=36), posteroseptal (n=36), right lateral (n=8), Mahaim fibres (n=2) and right anteroseptal (n=6). Seven patients had multiple AP. One patient had a preexcitation which appeared secondary to an atrio-infundibular connection (Fontan procedure). The ablation site of concealed or overt AP was identified by retrograde or anterograde conduction mapping, respectively. A mean of 2·6 ± 1 cathodal shocks (80–160 J) was delivered to 25 patients over 29 sessions, resulting in initial AP ablation in all. Fulguration was uncomplicated in all except in one patient (4%) who developed a secondary complete AV block post-ablation. During a follow-up period of 30–69 months, intermittent preexcitation recurred in two asymptomatic patients, but no significantly tachycardia was inducible at late electrophysiological study, including under isoproterenol infusion. Radiofrequency energy was applied to 54 patients during 62 sessions, using 20–40 watts for 30–60 s. AP ablation was initially achieved in all patients using a median of three impulses, without significantly immediate side-effects. Two patients (4%) developed a short episode of blurred vision possibly due to a microembolism. After discharge, the follow-up period was 10 ± 5 months (range 1 to 24). All patients but one (98%) were asymptomatic without any drug therapy. AP conduction and tachycardias recurred in one child, within one month after radiofrequency catheter ablation. Asymptomatic intermittent preexcitation recurred in another patient who had had three AP; a late study showed no inducible reciprocating tachycardia even wider isoproterenol infusion and a minimal preexcited RR interval of 350 ms during induced atrial fibrillation. It is concluded that catheter ablation is an effective and relatively safe method for ablation of AP in children.