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Background —The purpose of this study was to evaluate the safety and efficacy of a temperature-controlled radiofrequency catheter ablation system. Methods and Results —The patient population included 1050 patients who had undergone ablation of atrioventricular nodal reentrant tachycardia (AVNRT), an accessory pathway (AP), or the atrioventricular junction (AVJ). Ablation was successful in 996 patients. The probability of success was highest among patients who had undergone ablation of the AVJ, lowest in patients who had undergone ablation of an AP, and in between for patients who had undergone ablation of AVNRT. A major complication occurred in 32 patients. Four variables predicted ablation success (AVJ, AVNRT, or left free wall AP ablation and an experienced center). Four factors predicted arrhythmia recurrence (right free wall, posteroseptal, septal, and multiple APs). Two variables predicted development of a complication (structural heart disease and the presence of multiple targets), and 3 variables predicted an increased risk of death (heart disease, lower ejection fraction, and AVJ ablation). Conclusions —These findings may serve as a guide to clinicians considering therapeutic options in patients who are candidates for ablation.

Neurally mediated syncope is being recognized with increasing frequency in young adults and more recently in children.1–4 Most children undergoing formal orthostatic testing exhibit a vasodepressor or mixed response with a gradual onset of hypotension, often preceded by sinus tachycardia, followed by secondary bradycardia and syncope.1–3 Few of these patients have a dominant cardioinhibitory response exhibiting sudden onset of bradycardia and syncope without prior hypotension or tachycardia.1 Syncopal episodes in this group (unusual in the pediatric experience) may present more risk owing to the rapid onset of syncope, prolonged asystole and seizure activity often exhibited.4 This study reports on the incidence, clinical features, management and outcome of infants and children presenting with dominant Cardioinhibitory syncope.

Radiation exposure is an important risk during ablation (abl) procedures. To determine the relationship between the target arrhythmia, fluoroscopy time (fluoro), and the success of abl procedures we analyzed data from 450 patients in the Atakr multicenter clinical study(217 F, 233 M, 38 ± 21 yrs). Target arrhythmias included AVNRT (154 pts), the AV junction (54 pts, AVJ), and 241 accessory pathway (APs). Results Similar success was achieved during abl of APs, AVNRT. and the AVJ (93%, 98%, and 94% respectively, p g 0.1). In contrast, fluoro time was greater during abl of APs than during abl of AVNRT or the AVJ (62 ± 48, versus 31 ± 29 a 36 ± 24 min, p l 0.05). Cumulative success of catheter abl of APs rose rapidly during the first 90 min of fluoro exposure and then plateaued. In contrast. cumulative success during abl of the AVJ and AVNRT plateaued after 40 and 70 min. Concl Similar success can be achieved during abl of APs, AVNRT. and the AVJ, but greater fluoro is needed during abl of APs. Resultant radiation risk should be considered when determining an appropriate termination point. Download : Download high-res image (85KB) Download : Download full-size image