title: Cooled-tip ablation results in increased radiofrequency power delivery and lesion size in the canine heart: importance of catheter-tip temperature monitoring for prevention of popping and impedance rise.
abstract: Since myocardial lesion size during radio-frequency (RF) ablation is limited at high power by impedance rise when electrode tip temperature exceed 100 degrees C, controlling tip temperature by continuous intraelectrode saline infusion could permit generation of larger lesion. (1) Two dogs randomly received either standard or cooled tip RF ablation at 4 to 6 separate LV sites. Power output of 30 W was delivered via modified 7 Fr deflectable catheter with 4 mm tip for up to 120 sec or until impedance rise occurred. (2) Six dogs randomly received cooled tip RF ablation at power output of 20, 30, 40 W for 120 sec. (3) Three dogs randomly received cooled tip RF ablation using room temperature saline (21-25 degrees C) or chilled saline (1-4 degrees C) infusion.
  
  
  RESULTS
  Overall, peak tip temperature was lower for cooled vs standard RF deliveries (97 +/- 17 degrees C vs. 42 +/- 8 degrees C). Lesion depth and volume were significantly larger for cooled burns. Lesion depth and volume and the incidence of abrupt impedance rise/popping did not differ between room temperature saline and chilled saline infusion. The catheter-tip temperature at the onset of popping and abrupt impedance rise was 54 +/- 5 degrees C (48-60 degrees C) and 59 +/- 10 degrees C (50-75 degrees C).
  
  
  CONCLUSIONS
  Cooled tip RF current delivery at high power is associated with increased myocardial lesion size which may facilitate successful ablation of ventricular tachycardia associated with acquired structural heart disease. Catheter-tip temperature should be maintained below 45 degrees C to prevent popping and abrupt impedance rise during RF energy delivery.
authors.affiliation: The Second Department of Medicine, Nihon University School of Medicine, 30-1 Oyaguchi-kami, Itabashi-Ku, Tokyo, Japan 173-8610. iwatanab@med.nihon-u.ac.jp
authors.forename: Ichiro
authors.initials: I
authors.lastname: Watanabe
authors.forename: Riko
authors.initials: R
authors.lastname: Masaki
authors.forename: Nuo
authors.initials: N
authors.lastname: Min
authors.forename: Naohiro
authors.initials: N
authors.lastname: Oshikawa
authors.forename: Kimie
authors.initials: K
authors.lastname: Okubo
authors.forename: Hidezou
authors.initials: H
authors.lastname: Sugimura
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kojima
authors.forename: Satoshi
authors.initials: S
authors.lastname: Saito
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ozawa
authors.forename: Katsuo
authors.initials: K
authors.lastname: Kanmatsuse
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D003080:Cold Temperature; D004195:Disease Models, Animal; D004285:Dogs; D017097:Electric Impedance; D004566:Electrodes; D004869:Equipment Safety; D005260:Female; D008297:Male; D008991:Monitoring, Physiologic; D009206:Myocardium / Q000473:pathology; D011183:Postoperative Complications / Q000517:prevention & control*; D011336:Probability; D011897:Random Allocation; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D017180:Tachycardia, Ventricular / Q000473:pathology / Q000601:surgery*; D013696:Temperature