title: Cryo-ablation for septal tachycardia substrates in pediatric patients: mid-term results.
abstract: OBJECTIVE
  The aim of this study was to evaluate the efficacy and safety of catheter-based cryo-therapy for septal tachycardia substrates in pediatric patients.
  
  
  BACKGROUND
  Cryo-therapy may be particularly useful for ablation of septal tachycardias, including atrioventricular nodal re-entry tachycardia (AVNRT), atrioventricular reciprocating tachycardia (AVRT), and ventricular tachycardia (VT) originating high in the conduction system.
  
  
  METHODS
  Thirty-one pediatric patients (median = 13.7 years, range 5.3 to 19.6 years) with septal tachycardia substrates underwent cryo-ablation (CA). Twenty-two had AVNRT, 8 AVRT, and 1 VT. Applications were considered cryo-maps (CMs) if the temperature set-point was -35 degrees C or the application time was <120 s. Other lesions were considered CAs.
  
  
  RESULTS
  A total of 242 CMs (4 per patient, range 0 to 40 CMs) and 89 CAs (2 per patient, range 1 to 8 CMs) were performed, for a total cryo-therapy time of 689 s/patient (range 158 to 3,300 s). Procedural success with cryo-therapy was achieved in 27 of 31 patients (87.1%), including two procedures with a His potential at the CA location and three performed in tachycardia. The success rate for AVNRT was higher than for AVRT (95.5% vs. 62.5%, p < 0.05). For AVRT, a sustained effect on accessory pathway conduction occurred -3.3 +/- 4.9 s after reaching -25 degrees C, whereas for those sites at which the effect was transient, the effect took 24.8 +/- 25.5 s (p = 0.07). Transient atrioventricular (AV) block occurred during eight cryo-applications (1 CA, 7 CMs) with immediate return of normal AV conduction upon cessation of application. There were no other complications.
  
  
  CONCLUSIONS
  Cryo-therapy was used to effectively and safely ablate septal tachycardias in this group of 31 pediatric patients. Cryo-therapy may be more effective for AVNRT than septal AVRT.
authors.affiliation: The Children's Heart Program of South Carolina-Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors.forename: Aya
authors.initials: A
authors.lastname: Miyazaki
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Blaufox
authors.forename: David L
authors.initials: DL
authors.lastname: Fairbrother
authors.forename: J Philip
authors.initials: JP
authors.lastname: Saul
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003452:Cryosurgery / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000601:surgery*; D017180:Tachycardia, Ventricular / Q000601:surgery*; D013997:Time Factors