title: In vitro evaluation of ice-cold saline irrigation during catheter radiofrequency ablation.
abstract: BACKGROUND
  Irrigated radiofrequency (RF) catheters allow tissue-electrode interface cooling, decreasing thrombus risk while enabling higher RF power delivery. The impact of irrigation with ice-cold saline (ICS) instead of conventional ambient-temperature saline (ATS) on lesion formation is unknown.
  
  
  RESULTS
  We performed 120 RF ablations in vitro on porcine left ventricles, using ICS (<5 °C) or ATS (21 °C) irrigation. For ICS irrigation, the irrigation circuit was cooled externally to maintain delivery of cooled saline at the catheter's tip. We applied 20 g of contact force, and delivered 20 W (irrigation 8 or 17 mL/min) or 30 W (irrigation 17 or 30 mL/min) RF power. Temperatures at tissue-electrode interface and 3-mm depth were assessed by fluoroptic probes. Lesion dimensions were assessed. ICS irrigation cooled the tissue-electrode interface better than ATS (53.9 ± 9.6 °C vs. 63 ± 11.4 °C, P < 0.001). Temperatures at 3-mm depth were similar at 30 W using ICS and ATS (104.2 ± 9.3 °C vs. 105.8 ± 7.3 °C, P = 0.5), but were cooler at 20 W using ICS (71.3 ± 11.6 °C vs. 100.2 ± 11.9 °C, P < 0.001). This translated into smaller lesions at 20 W with ICS versus ATS. At 30 W with 17 mL/min flow rate, lesions had the same depth with ICS and ATS (4.9 ± 0.8 mm vs. 5.4 ± 0.7 mm, P = 0.13) but were narrower with ICS (7.7 ± 0.8 mm vs. 9.3 ± 1.2 mm, P = 0.001). At 30 mL/min, lesions had the same dimensions. Steam pop rate was similar using ICS or ATS irrigation.
  
  
  CONCLUSIONS
  ICS irrigation more effectively cools tissue-electrode interface than ATS. This may improve RF safety by potentially decreasing thrombus formation, thus facilitating safe ablation at a low saline volume load. However at lower RF power, ICS reduced lesion size compared to ATS.
authors.affiliation: Department of Cardiology, Pasteur University Hospital, Nice, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Squara
authors.forename: Shingo
authors.initials: S
authors.lastname: Maeda
authors.forename: Bashar
authors.initials: B
authors.lastname: Aldhoon
authors.forename: Julie
authors.initials: J
authors.lastname: Marginiere
authors.forename: Pasquale
authors.initials: P
authors.lastname: Santangeli
authors.forename: William W
authors.initials: WW
authors.lastname: Chik
authors.forename: John
authors.initials: J
authors.lastname: Michele
authors.forename: Erica
authors.initials: E
authors.lastname: Zado
authors.forename: Francis E
authors.initials: FE
authors.lastname: Marchlinski
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D017115:Catheter Ablation / Q000379:methods*; D003131:Combined Modality Therapy / Q000379:methods; D017679:Cryotherapy / Q000379:methods*; D006352:Heart Ventricles / Q000601:surgery*; D007053:Ice; D066298:In Vitro Techniques; D012965:Sodium Chloride / Q000627:therapeutic use; D013552:Swine; D013696:Temperature; D007507:Therapeutic Irrigation / Q000379:methods*; D016277:Ventricular Function, Left / Q000502:physiology*
chemical_list: D007053:Ice; D012965:Sodium Chloride
keywords: catheter ablation; contact force; irrigated-tip catheter; thrombus formation; ventricles