title: Cryoablation for accessory pathways located near normal conduction tissues or within the coronary venous system in children and young adults.
abstract: BACKGROUND
  Cryoablation may offer advantages over radiofrequency (RF) ablation for certain arrhythmia substrates, such as septal accessory pathways (APs). Data for young patients, especially regarding recurrence risk, require expansion.
  
  
  OBJECTIVE
  The purpose of this study was to study institutional outcomes for cryoablation of APs located in potentially difficult septal regions for children and young adults.
  
  
  METHODS
  Cryoablation was attempted in 35 young patients (mean age 15.6 years) with 37 APs that were either close to normal conduction tissues or inside the coronary venous system. Outcomes were compared with previously published institutional data for RF ablation at these same locations.
  
  
  RESULTS
  Acute cryoablation success was achieved for 29 (78%) of 37 APs. Apart from permanent PR prolongation in one case and right bundle branch block in one other, there were no detrimental effects on normal conduction. At median follow-up of 207 days (range 2-695 days), AP conduction recurred for 13 (45%) of 29 ablated APs. Younger patient age and midseptal AP location correlated with higher likelihood of recurrence. Acute success rates for cryoablation were similar to RF ablation in our laboratory, but recurrence rates were significantly higher (P <.001).
  
  
  CONCLUSIONS
  Cryoablation yields acute success rates comparable with RF ablation for difficult septal APs in young patients. The risk of AP recurrence appears higher after cryoablation, although safety benefits may provide suitable compensation for this deficiency. Methods for creating more effective cryoablation lesions need to be explored.
authors.affiliation: Electrophysiology Division, Department of Cardiology, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Bar-Cohen
authors.forename: Frank
authors.initials: F
authors.lastname: Cecchin
authors.forename: Mark E
authors.initials: ME
authors.lastname: Alexander
authors.forename: Charles I
authors.initials: CI
authors.lastname: Berul
authors.forename: John K
authors.initials: JK
authors.lastname: Triedman
authors.forename: Edward P
authors.initials: EP
authors.lastname: Walsh
mesh_terms: D000293:Adolescent; D000328:Adult; D017115:Catheter Ablation / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D003331:Coronary Vessels / Q000294:innervation / Q000601:surgery*; D003452:Cryosurgery / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000601:surgery*; D006346:Heart Septum / Q000294:innervation / Q000601:surgery*; D006801:Humans; D008297:Male; D012008:Recurrence; D013617:Tachycardia, Supraventricular / Q000601:surgery*; D016896:Treatment Outcome