title: Cooled needle catheter ablation creates deeper and wider lesions than irrigated tip catheter ablation.
abstract: OBJECTIVE
  To design and test a catheter that could create deeper ablation lesions.
  
  
  BACKGROUND
  Endocardial radiofrequency (RF) ablation is unable to reliably create transmural ventricular lesions. We designed an intramural needle ablation catheter with an internally cooled 1.1-mm diameter straight needle that could be advanced up to 14 mm into the myocardium. The prototype catheter was compared with an irrigated tip ablation catheter.
  
  
  METHODS
  Ablation lesions were created under general anesthesia in 14 male sheep (weight 44 +/- 7.3 kg) with fluoroscopic guidance. Each of the catheters was used to create two ablation lesions at randomly allocated positions within the left ventricle. The irrigation rate, target temperature, and maximum power were: 20 mL/min, 85 degrees C, 50 W for the intramural needle catheter and 20 mL/min, 50 degrees C, 50 W for the irrigated tip catheter, respectively. All ablations were performed for 2 minutes. After the last ablation, blue tetrazolium (12.5 mg/kg) was infused intravenously. The heart was removed via a left thoracotomy after monitoring the sheep for one hour.
  
  
  RESULTS
  There was no evidence of cardiac tamponade in any sheep. The intramural needle catheter lesions were significantly wider (10.9 +/- 2.8 mm vs 10.1 +/- 2.4 mm, P = 0.01), deeper (9.6 +/- 2.0 mm vs 7.0 +/- 1.3 mm, P = 0.01), and more likely to be transmural (38% vs 0%, P = 0.03).
  
  
  CONCLUSIONS
  Cooled intramural needle ablation creates lesions that are significantly deeper and wider than endocardial RF ablation using an irrigated tip catheter in sheep hearts. This technology may be useful in treating ventricular tachycardia resistant to conventional ablation techniques.
authors.affiliation: Department of Cardiology, Westmead Hospital, Westmead, NSW 2145, Australia. aravinda@westgate.wh.usyd.edu.au
authors.forename: Aravinda
authors.initials: A
authors.lastname: Thiagalingam
authors.forename: Jim
authors.initials: J
authors.lastname: Pouliopoulos
authors.forename: Michael Anthony
authors.initials: MA
authors.lastname: Barry
authors.forename: Anita C
authors.initials: AC
authors.lastname: Boyd
authors.forename: Vicki
authors.initials: V
authors.lastname: Eipper
authors.forename: Teresa
authors.initials: T
authors.lastname: Yung
authors.forename: David L
authors.initials: DL
authors.lastname: Ross
authors.forename: Pramesh
authors.initials: P
authors.lastname: Kovoor
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D003080:Cold Temperature; D004867:Equipment Design; D005471:Fluoroscopy; D008297:Male; D009206:Myocardium / Q000473:pathology*; D012756:Sheep