title: Single cryothermia applications of less than five minutes produce permanent cavotricuspid isthmus block in humans.
abstract: OBJECTIVE
  The aim of this study was to compare single-3-minute (single-3) with double-3-minute (double-3) cryothermia applications for treatment of atrial flutter (AFL).
  
  
  BACKGROUND
  Previous animal studies have indicated the need for a double 5-minute cryothermal application to create large and permanent lesions.
  
  
  METHODS
  Forty patients (56 +/- 13 years old) with typical AFL (cycle length 229 +/- 35 ms) were randomized to single-3 (n = 20) or double-3 (n = 20) cryothermia applications at each site along the cavotricuspid isthmus (CTI). Cryoablation was performed with the CryoCor cryoablation system. A successful procedure was defined as noninducibility of AFL with the concomitant presence of bidirectional CTI conduction block under isoproterenol infusion.
  
  
  RESULTS
  All but 1 patient (95%) of the single-3 group and all patients (100%) of the double-3 group were successfully ablated. The number of sites needed to create isthmus conduction block was 9 +/- 4 (single-3) and 8 +/- 2 (double-3) (NS). Fluoroscopy time did not differ between the two groups (single-3: 31 +/- 14; double-3: 36 +/- 17 min, NS). The procedure time of the single-3 group was significantly shorter compared to the procedure time of the double-3 group (mean procedure duration 132 +/- 64 vs 159 +/- 50 min, P < .04). After a mean follow-up of 11.7 +/- 4.7 months, two recurrences of AFL occurred in the double-3 group.
  
  
  CONCLUSIONS
  Single cryothermia applications of 3 minutes produce permanent CTI conduction block in patients with typical AFL and significantly reduce procedure duration.
authors.affiliation: Department of Cardiology, Academic Hospital Maastricht, The Netherlands.
authors.forename: Randy
authors.initials: R
authors.lastname: Manusama
authors.forename: Carl
authors.initials: C
authors.lastname: Timmermans
authors.forename: Suzanne
authors.initials: S
authors.lastname: Philippens
authors.forename: Harry J G M
authors.initials: HJ
authors.lastname: Crijns
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Ayers
authors.forename: Luz-Maria
authors.initials: LM
authors.lastname: Rodriguez
mesh_terms: D001281:Atrial Fibrillation / Q000601:surgery; D001282:Atrial Flutter / Q000601:surgery*; D003452:Cryosurgery / Q000379:methods*; D004594:Electrophysiology; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014261:Tricuspid Valve / Q000503:physiopathology*; D014684:Venae Cavae / Q000503:physiopathology*