title: Open-irrigated laser catheter ablation produces flow-dependent sizes of lesions.
abstract: BACKGROUND
  Growth and sizes of lesions produced during catheter ablation is difficult to control. Laser lesion formation was evaluated during various flow rates and energy settings by using an open-irrigated laser catheter on a thigh-muscle dog model.
  
  
  METHODS
  Laser radiation at 15 W or 20 W was applied in blood for 10 seconds, 20 seconds, 30 seconds, 40 seconds, and 50 seconds during an irrigation flow of 16 mL/min or 35 mL/min, in direct contact, and in a noncontact mode of laser application. Lesions were evaluated morphometrically.
  
  
  RESULTS
  There was a linear increase of lesions with the increase of the level of energy applied. Maximal depth of lesions achieved during a flow rate of 16 mL/min at 15 W/50 seconds increased significantly from 9.9 ± 0.3 mm to 12.1 ± 0.5 mm, and at 20 W/50 seconds from 11.1 ± 0.55 mm to 12.4 ± 0.26 mm, when irrigation flow was 35 mL/min (P < 0.5). However, difference of lesion increase between 15 W and 20 W was not significant (P = 0.30). Lesions were achieved also in a noncontact mode of radiation at a distance of 1-2 mm, but not at 5 mm away. Radiation at 20 W > 40 seconds and a flow rate of 35 mL/min may cause steam pop with intramural cavitation.
  
  
  CONCLUSIONS
  By using an open-irrigated laser catheter augmentation of catheter flow increases lesion sizes. Lesions can be achieved also in a noncontact mode of radiation. In order to avoid unwanted effects the level of energy applied must be limited.
authors.affiliation: CCEP Center Taufkirchen, Taufkirchen, Germany.
authors.forename: Helmut P
authors.initials: HP
authors.lastname: Weber
authors.forename: Michaela
authors.initials: M
authors.lastname: Sagerer-Gerhardt
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization / Q000379:methods*; D004285:Dogs; D004307:Dose-Response Relationship, Radiation; D053685:Laser Therapy / Q000379:methods*; D018482:Muscle, Skeletal / Q000473:pathology* / Q000601:surgery*; D011829:Radiation Dosage; D007507:Therapeutic Irrigation
keywords: contact pressure; energy settings; irrigation flow; open-irrigated laser catheter