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Aims: In the current literature, results of the low-voltage bridge (LVB) ablation strategy for the definitive treatment of atrioventricular nodal re-entry tachycardia (AVNRT) seem to be encouraging also in children. The aims of this study were (i) to prospectively evaluate the mid-term efficacy of LVB ablation in a very large cohort of children with AVNRT, and (ii) to identify electrophysiological factors associated with recurrence., Methods and Results: One hundred and eighty-four children (42% male, mean age 13 ± 4 years) with AVNRT underwent transcatheter cryoablation guided by voltage mapping of the Koch's triangle. Acute procedural success was 99.2% in children showing AVNRT inducibility at the electrophysiological study. The overall recurrence rate was 2.7%. The presence of two LVBs, a longer fluoroscopy time and the presence of both typical and atypical AVNRT, were found to be significantly associated with an increased recurrence rate during mid-term follow-up. Conversely, there was no significant association between recurrences and patient's age, type of LVB, lesion length, number of cryolesions or catheter tip size., Conclusion: The LVB ablation strategy is very effective in AVNRT treatment in children. Recurrences are related to the complexity of the arrhythmogenic substrate., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: journals.permissions@oup.com.)

Aims: Recently, voltage gradient mapping of Koch's triangle to find low-voltage connections, or 'voltage bridges', corresponding to the anatomic position of the slow pathway, has been introduced as a method to ablate atrioventricular nodal reentry tachycardia (AVNRT) in children. Thus, we aimed to assess the effectiveness of voltage mapping of Koch's triangle, combined with the search for the slow potential signal in 'low-voltage bridges', to guide cryoablation of AVNRT in children., Methods and Results: From June 2015 to May 2016, 35 consecutive paediatric patients (mean age 12.1 ± 4.5 years) underwent 3D-guided cryoablation of AVNRT at our Institution. Fifteen children were enrolled as control group (mean age 14 ± 4 years). A voltage gradient mapping of Koch's triangle was obtained in all patients, showing low-voltage connections in all children with AVNRT but not in controls. Prior to performing cryoablation, we looked for the typical 'hump and spike' electrogram, generally considered to be representative of slow pathway potential within a low-voltage bridge. In all patients the 'hump and spike' electrogram was found inside bridges of low voltage. Focal or high-density linear lesions, extended or not, were delivered guided by low-voltage bridge visualization. Acute success rate was 100%, and no recurrence was reported at a mean follow-up of 8 ± 3 months., Conclusions: Voltage gradient mapping of Koch's triangle, combined with the search for the slow potential signal in low-voltage bridges, is effective in guiding cryoablation of AVNRT in paediatric patients, with a complete acute success rate and no AVNRT recurrences at mid-term follow-up.

Background: Transcatheter cryoablation is a well-established technique for the treatment of atrioventricular nodal reentry tachycardia (AVNRT) in children. Nevertheless, atrioventricular nodal slow-pathway conduction may recur after an acutely successful procedure. The aim of this study was to evaluate the long-term outcome of acutely successful AVNRT cryoablations in pediatric patients in case of focal cryolesion and in case of need for High-Density Linear Lesion (HDLL) cryoablation due to focal failure., Methods: Sixty-nine consecutive pediatric patients (30 males, mean age 12.4 ± 3.2 years; range: 5.4-18.0 years) underwent 3D-guided cryoablation for AVNRT at our institution from July 2013 to November 2014. When a focal cryoablation was acutely unsuccessful, a 3D-guided HDLL was created delivering multiple overlapping cryolesions/cryoenergy applications from the ventricular side of the tricuspid annulus to the atrial side, including the site of focal cryoablation if transiently successful., Results: No permanent cryoablation-related complications occurred. Acute success rate was 98.5% (68 out of 69): in 55.9% (38 out of 68) with focal-lesion and in 44.1% (30 out of 68) with HDLL. Mean follow-up was 25.3 months and AVNRT recurrence rate was 13.2% (nine out of 68): 5.2% (two out of 38) with focal lesion and 23.3% (seven out of 30) with HDLL (P = 0.036)., Conclusions: In cryoablation of AVNRT in children, the need for a more aggressive protocol (HDLL), due to the failure of focal ablation, is strictly related to higher recurrence rates. Indeed, AVNRT recurrences after cryoablation in children seem to be due to a larger and deeper substrate rather than due to the type of energy used., (© 2016 Wiley Periodicals, Inc.)