title: Effects of temporal application parameters on lesion dimensions during transvenous catheter cryoablation.
abstract: Lesion dimension of cryoablation.
  
  
  BACKGROUND
  Transvenous catheter cryoablation is a novel technique for treating cardiac arrhythmias. However, the relative importance of temporal application parameters on lesion dimension and clinical efficacy has not been studied.
  
  
  RESULTS
  We investigated the effects of (1) application duration: single 2.5 (2.5x1) versus single 5 versus double 2.5 (2.5x2) versus double 5 (5x2) minutes, (2) number of freeze-thaw cycles: single versus double, and (3) electrode contact area: horizontal versus vertical orientation, on the lesion diameter and depth during catheter cryoablation (10F, 6.5-mm tip-electrode, CryoCor, San Diego) in a thigh muscle preparation. A total of 175 lesions (horizontal=90, vertical=85) were created in thigh muscle preparations on 10 swine. The lesion diameter and depth were significantly greater using 2.5x2 and 5x2 application modes as compared with 2.5x1 applications (P<0.05). Horizontal tip-electrode orientation produced larger lesion diameter (P<0.05), but not lesion depth as compared with vertical orientation. Multivariate analysis demonstrated that both tip-electrode orientation and duration of freeze >2.5 minutes were independent predictors for lesion diameter (P<0.001). However, only duration of freeze >2.5 minutes was an independent predictor for lesion depth (P<0.001).
  
  
  CONCLUSIONS
  The dimensions of lesions created by catheter cryoablation are affected by mode of cryoablation application and electrode orientation. Increasing the duration of application, employing multiple freeze-thaw cycles at shorter cycle durations, and orienting the catheter to enhance/increase tissue contact can create a larger lesion.
authors.affiliation: Cardiology Division, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong. hftse@hkucc.hku.hk
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Ripley
authors.forename: Kathy L F
authors.initials: KL
authors.lastname: Lee
authors.forename: Chung-Wah
authors.initials: CW
authors.lastname: Siu
authors.forename: John F
authors.initials: JF
authors.lastname: Van Vleet
authors.forename: William L
authors.initials: WL
authors.lastname: Pelkey
authors.forename: Chu-Pak
authors.initials: CP
authors.lastname: Lau
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D003452:Cryosurgery / Q000379:methods*; D004566:Electrodes; D015999:Multivariate Analysis; D009132:Muscles / Q000473:pathology; D013552:Swine; D013997:Time Factors