Cooled needle catheter ablation creates deeper and wider lesions than irrigated tip catheter ablation.
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.
Thiagalingam
Aravinda
A
Department of Cardiology, Westmead Hospital, Westmead, NSW 2145, Australia. aravinda@westgate.wh.usyd.edu.au
Pouliopoulos
Jim
J
Barry
Michael Anthony
MA
Boyd
Anita C
AC
Eipper
Vicki
V
Yung
Teresa
T
Ross
David L
DL
Kovoor
Pramesh
P
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