title: Low recurrence rate in treating atrioventricular nodal reentrant tachycardia with triple freeze-thaw cycles.
abstract: BACKGROUND
  Cryoablation is an alternative to radiofrequency ablation in treating atrioventricular nodal reentrant tachycardia (AVNRT). However, its long-term effectiveness is in question when compared to radiofrequency ablation. We reviewed the results of cryoablation in children with AVNRT at our institute.
  
  
  METHODS
  We performed a retrospective single-center chart review of consecutive patients ≤18 years of age with AVNRT who underwent cryoablation between January 2007 and August 2009. During cryoablation, a 6-mm-tip cryocatheter was used with temperature set to -80°C. Test lesions were performed at the presumed slow pathway location based on combined anatomic and electrophysiologic approach. If successful, ablation was then continued with triple freeze-thaw cycles (FTC) of 4 minutes each.
  
  
  RESULTS
  A total of 53 patients (age range: 6.1-18.4 years, mean: 13.6 years, median: 13.2 years) underwent slow pathway modification with cryoablation. Acute success was achieved in 51 (96.2%) cases. Transient atrioventricular block was seen in 19 cases. The block occurred during FTC in eight patients (15%). The number of FTC was three in 47 (92.2%) patients. Less than three FTC were given in two patients due to transient heart block and four FTC were given in two patients with suspected catheter movement. Procedure duration was 177 ± 56 minutes; fluoroscopic time was 14 ± 11 minutes. Mean follow-up was 30.7 ± 10 (range 12-52, median 31) months. Recurrence of supraventricular tachycardia was seen in only one (1.96%) patient.
  
  
  CONCLUSIONS
  Triple FTC cryoablation lesions resulted in a low recurrence rate comparable to RF ablation in treating AVNRT without increased complications.
authors.affiliation: Department of Pediatrics, Division of Pediatric Cardiology, University of Miami, Miami, Florida.
authors.forename: Muhammad Y
authors.initials: MY
authors.lastname: Qureshi
authors.forename: Christopher
authors.initials: C
authors.lastname: Ratnasamy
authors.forename: Mary
authors.initials: M
authors.lastname: Sokoloski
authors.forename: Ming-Lon
authors.initials: ML
authors.lastname: Young
mesh_terms: D000293:Adolescent; D002648:Child; D017679:Cryotherapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D055502:Secondary Prevention; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000628:therapy*