title: High-volume lesions using a new second-generation open irrigation radiofrequency catheter are associated with the development of inhomogeneous lesions.
abstract: BACKGROUND
  After catheter ablation there is often a discrepancy between acute and chronic success rates. We aimed to evaluate major determinants for lesion quality and understand different manifestations of lesion structures.
  
  
  METHODS
  In a canine thigh muscle model radiofrequency (RF) current was delivered for 60 seconds at 30 W (n = 39) or 50 W (n = 18) with 15-g contact force. A second-generation 12-hole gold open irrigation catheter (SGIT) and a first-generation six-hole platinum-iridium catheter (FGIT; Biotronik, Berlin, Germany) were used. Electrode and tissue temperatures (at the surface and 3.5-mm and 7-mm depth) were recorded and lesion dimensions were measured. Lesions with steam pops were excluded. Histological examination was performed to evaluate homogeneity of the lesions. Inhomogeneity was defined as a visual multiband lesion pattern indicating different histological characteristics.
  
  
  RESULTS
  In total 57 lesions were created. Seventeen lesions were excluded (steam pops) and 40 lesions were analyzed. A total number of 11 homogeneous and 29 inhomogeneous lesions were identified. Using the SGIT catheter 16.7% of the lesions was homogeneous and 83.3% inhomogeneous; for FGIT it was 43.8% and 56.2% (P = 0.065), respectively. Homogeneous lesions had lower volumes as compared to inhomogeneous lesions (514.0 ± 198.8 vs 914.8 ± 399.1 mm, P = 0.003). Multiple logistic regression analysis indicated that the SGIT catheter is a significant predictor for inhomogeneous lesions (odds ratio 6.5, 95% confidence interval 1.1-38.8; P = 0.040) independent from power setting and flow rate.
  
  
  CONCLUSIONS
  The development of inhomogeneous lesions after acute RF ablation is associated with higher lesion volumes and the use of the second-generation irrigation gold-tip catheter.
authors.affiliation: Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Ferdi
authors.initials: F
authors.lastname: Akca
authors.forename: Martha
authors.initials: M
authors.lastname: Hubay
authors.forename: Endre
authors.initials: E
authors.lastname: Zima
authors.forename: Gábor
authors.initials: G
authors.lastname: Széplaki
authors.forename: Eszter M
authors.initials: EM
authors.lastname: Végh
authors.forename: Judit
authors.initials: J
authors.lastname: Skopál
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Lendvai
authors.forename: Dominic
authors.initials: D
authors.lastname: Theuns
authors.forename: Bela
authors.initials: B
authors.lastname: Merkely
authors.forename: Tamas
authors.initials: T
authors.lastname: Szili-Torok
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation* / Q000379:methods*; D057785:Catheters; D004285:Dogs; D004867:Equipment Design; D018482:Muscle, Skeletal / Q000473:pathology / Q000601:surgery; D007507:Therapeutic Irrigation
keywords: catheter ablation; gold-tip catheter; histology; lesion formation; platinum-iridium-tip catheter