title: Catheter-based cryoablation produces permanent bidirectional cavotricuspid isthmus conduction block in dogs.
abstract: BACKGROUND
  Catheter-based cryoablation has been shown to produce punctate and effective cardiac lesions to treat focal targets. However, sequential applications are required to produce a continuous linear lesion needed to cure macroreentrant arrhythmias with large critical isthmuses. The purpose of this study was to compare and contrast linear cardiac lesions produced with sequential applications using a novel cryoablation system to those produced using radiofrequency (RF) energy.
  
  
  RESULTS
  Seven mongrel dogs were prepared for femoral venous insertion of the ablation catheter (either a 10-French, 6-mm tipped, bipolar cryoablation catheter (N = 5, cryo group) or a 7-French, 4-mm tipped, bipolar RF ablation catheter (N = 2, RF group)). Ablation of the cavotricuspid isthmus was performed by delivering applications at sequential locations across the isthmus. The cryo group received 6 to 10 (mean 8 +/- 1.4), 5-minute applications at 3 to 5 separate sites with a mean nadir temperature of -74.5 +/- 1.6 degrees C. Each dog in the RF group received 9, 90-second applications with a mean temperature and power of 62 +/- 0 degrees C and 32 +/- 3.6 W. No acute or chronic complications were associated with either form of ablation. Immediately and six weeks after the index procedure, electroanatomical mapping showed the presence of bidirectional isthmus conduction block in all dogs. Gross and histopathologic examination revealed the presence of linear lesions, which were continuous and transmural.
  
  
  CONCLUSIONS
  Similar to RF ablation, catheter-based cryoablation can produce linear, transmural lesions in the cavotricuspid isthmus resulting in permanent bidirectional isthmus conduction block.
authors.affiliation: Department of Cardiology, Academic Hospital Maastricht, Maastricht, The Netherlands. C.Timmermans@cardio.azm.nl
authors.forename: Carl
authors.initials: C
authors.lastname: Timmermans
authors.forename: Luz-Maria
authors.initials: LM
authors.lastname: Rodriguez
authors.forename: Robert Jan
authors.initials: RJ
authors.lastname: Van Suylen
authors.forename: Jet
authors.initials: J
authors.lastname: Leunissen
authors.forename: Marc
authors.initials: M
authors.lastname: Vos
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Ayers
authors.forename: Harry J G M
authors.initials: HJ
authors.lastname: Crijns
authors.forename: Hein J J
authors.initials: HJ
authors.lastname: Wellens
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D003452:Cryosurgery / Q000379:methods*; D004285:Dogs; D005240:Feasibility Studies; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D008297:Male; D014261:Tricuspid Valve / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D014684:Venae Cavae / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*