title: Effect of Irrigant Characteristics on Lesion Formation After Radiofrequency Energy Delivery Using Ablation Catheters with Actively Cooled Tips.
abstract: BACKGROUND
  The delivery of radiofrequency (RF) energy through irrigated ablation catheters may be affected by irrigant osmolarity and by catheter position. We sought to characterize lesion formation characteristics using different irrigants in both open and closed irrigated catheter.
  
  
  METHODS
  An ex vivo model consisting of viable bovine myocardium and a submersible load cell was assembled in a circulating saline bath at 37°C. An externally irrigated ablation catheter and a closed irrigated catheter were positioned with 10 g of force in both perpendicular and parallel positions. A series of ablation lesions using different irrigants were delivered using a constant rate of irrigation (30 cc/min) at 50 W. Potential clinical applicability was evaluated in vivo by targeting porcine epicardium with different irrigants during open irrigation ablation and assessing lesion sizes.
  
  
  RESULTS
  Ablation in the perpendicular position produced significantly larger lesions for all irrigants, compared to their respective parallel position ablation. For both open and closed irrigated ablation, half normal saline (HNS) ablation created larger lesions than normal saline (NS), and dextrose water (D5W) lesions were significantly larger than both HNS and NS lesions. Steam pops were mostly observed in the perpendicular position, and the rate of steam pops was statistically higher only for open irrigated D5W, but not for HNS, when compared to NS. Both open and closed irrigated ablation with D5W and HNS in the parallel position created larger lesions than parallel NS ablation without causing more steam pops. In an in vivo porcine model, open irrigated ablation with D5W created larger lesions compared to standard NS irrigation.
  
  
  CONCLUSIONS
  In ex vivo and in vivo models, decreased osmolarity and charge density increased RF energy delivery to tissue, resulting in larger lesions for both open and closed irrigated ablations. A perpendicular catheter position created larger lesions across all irrigants for both open and closed irrigation ablation. The incidence of steam pops was observed more frequently with high power open irrigated using D5W, especially if the catheter was in a perpendicular position. Further research is required to evaluate any clinical role for using different irrigants with an externally irrigated catheter.
authors: University of Colorado, Section of Cardiac Electrophysiology, Division of Cardiology, Aurora, Colorado, USA.
authors: Duy T
authors: DT
authors: Nguyen
authors: University of Colorado, Section of Cardiac Electrophysiology, Division of Cardiology, Aurora, Colorado, USA.
authors: Matthew
authors: M
authors: Olson
authors: University of Colorado, Section of Cardiac Electrophysiology, Division of Cardiology, Aurora, Colorado, USA.
authors: Lijun
authors: L
authors: Zheng
authors: University of Colorado, Section of Cardiac Electrophysiology, Division of Cardiology, Aurora, Colorado, USA.
authors: Waseem
authors: W
authors: Barham
authors: University of Chicago, Division of Cardiology, Chicago, Illinois, USA.
authors: Joshua D
authors: JD
authors: Moss
authors: University of Colorado, Section of Cardiac Electrophysiology, Division of Cardiology, Aurora, Colorado, USA.
authors: William H
authors: WH
authors: Sauer
mesh_terms: D000818:Animals; D006328:Cardiac Catheterization / Q000009:adverse effects / Q000295:instrumentation*; D062906:Cardiac Catheters; D017115:Catheter Ablation / Q000009:adverse effects / Q000295:instrumentation*; D002417:Cattle; D004867:Equipment Design; D005947:Glucose / Q000008:administration & dosage*; D066298:In Vitro Techniques; D009994:Osmolar Concentration; D010496:Pericardium / Q000473:pathology*; D012965:Sodium Chloride / Q000008:administration & dosage*; D013227:Steam; D013696:Temperature; D007507:Therapeutic Irrigation / Q000009:adverse effects / Q000295:instrumentation*
chemical_list: D013227:Steam; D012965:Sodium Chloride; D005947:Glucose
keywords: Smart Touch catheter; catheter ablation; contact force; experimental study; irrigated catheter tip; ventricular tachycardia