RADIOFREQUENCY CATHETER ABLATION OF RIGHT-VENTRICULAR OUTFLOW TACHYCARDIA IN CHILDREN AND ADOLESCENTS

Objectives. The current study reviews the safety and efficacy of radio frequency catheter ablation for the treatment of right ventricular out flow tachycardia in children and adolescents and describes a modified method for mapping the tachycardia focus. Background. Although radiofr equency catheter ablation has proved highly effective for the treatmen t of supraventricular tachycardia during childhood and adolescence, it s application in children with idiopathic right ventricular outflow ta chycardia has been limited. Methods. Six children (mean [+/-SD] age 10 .6 +/- 2.4 years, range 6 to 16) with right ventricular outflow tachyc ardia underwent seven radiofrequency catheter ablation procedures. The mean tachycardia cycle length was 323 +/- 24 ms (range 300 to 360). T wo multipolar catheters were positioned in the right ventricular outfl ow tract to map the tachycardia focus. Results. Radiofrequency cathete r ablation was successful in five (83%) of the six children (95% confi dence interval 36% to 99%). At successful ablation sites, local endoca rdial activation times preceded the surface QRS onset by 46 +/- 5 ms ( range 37 to 57), and there was concordance of the 12-lead pace map and the electrocardiogram (EGG) in 11 (one patient) to 12 ECG leads (four patients). One patient developed complete right bundle branch block d uring radiofrequeucy catheter ablation. There were no additional compl ications and no clinical recurrences over a mean follow-up period of 1 2.7 +/- 3.8 months (range 9 to 22). Conclusions. These results suggest that radiofrequency catheter ablation is a safe and effective treatme nt for right ventricular outflow tachycardia during childhood and adol escence. In addition, tachycardia mapping may be enhanced by use of a multipolar right ventricular outflow catheter technique.