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INTRODUCTION: A multicenter prospective study was designed and implemented to assess the short- and longer-term results and risks associated with radiofrequency (RF) ablation in children. METHODS AND RESULTS: Patients recruited for the study were aged 0 to 16 years with supraventricular tachycardia due to accessory pathways or AV nodal reentrant tachycardia (AVNRT), excluding patients with nontrivial congenital heart disease. A national registry also was established, and contributing centers were encouraged to enroll all pediatric patients, aged 0 to 21 years, undergoing ablation at their center. This report summarizes acute results of these procedures. For analysis, subjects were divided into three groups: the prospective cohort (n = 481), cohort-eligible registry participants (n = 504), and not cohort eligible registry participants (n = 1,776). Prospectively enrolled cohort patients were similar to cohort-eligible patients in terms of demographic and other patient characteristics. Overall success rates for RF ablation were high (95.7%), with higher success rates for left-sided and particularly left free-wall pathways (97.8%) than right free-wall pathways (90.8%). Complications of both electrophysiologic study and RF ablation were infrequent (4.2% and 4.0%, respectively), and there were no deaths. AV block was uncommon overall (1.2%) and was limited to ablation in AVNRT (2.1%) and septal accessory pathways (3.0%). CONCLUSION: Despite the multicenter and prospective design, the study demonstrates high success rates and low complication rates, which are comparable to prior single-center retrospective studies. These results may serve as the current best benchmark for expected results in the pediatric population, aged 0 to 16 years, both in terms of acute success rates and the occurrence of complications. [ABSTRACT FROM AUTHOR]

Introduction: Fasciculoventricular connections are the rarest form of accessory pathways leading to preexcitation. Electrophysiologic characteristics of these pathways include ventricular preexcitation with normal PR and AH intervals and short HV intervals during sinus rhythm. In addition, atrial overdrive pacing prolongs the PR interval without affecting the HV interval or the degree of preexcitation. Methods and Results: From March 1994 through February 1997, 3 of 59 pediatric patients referred for electrophysiologic study for preexcitation on surface ECGs were found to have iasciculoventricular pathways. Two patients had no inducible supraventricular tachycardia. One patient had successful ablation of both a left lateral pathway and a concealed anterolateral pathway that had facilitated antidromic and orthodromic supraventricular tachycardias, respectively. Conclusion: Children often manifest minimal preexcitation via accessory AV pathways due to rapid AV conduction and/or left lateral pathway location. Fasciculoventricular pathways may masquerade as Wolff-Parkinson-White syndrome. Separation of the two diagnoses depends on the demonstration of specific electrophysiologic criteria. [ABSTRACT FROM AUTHOR]