Abstract 16002: Transmurality Achieved With Bipolar Irrigated Radiofrequency Ablation: An in vitro Comparison to Sequential Unipolar Ablation
Introduction: Bipolar RF has been proposed as a treatment option for deep intramural ventricular tachycardias that are often refractory to unipolar radiofrequency (RF) ablation. We compare the ability of bipolar vs. sequential unipolar ablation to achieve lesion transmurality using irrigated RF in an in vitro setting.
Methods: Porcine left ventricular tissue was immersed into an isotonic saline bath at 37ºC. In the bipolar arm, ablation was performed between the distal poles of two irrigated catheters (Thermocool Celsius) positioned on opposing aspects of the tissue. Both catheters were connected to the RF generator (Stockert), allowing one catheter to be the active and the other the return electrode. In the unipolar arm, irrigated RF was sequentially delivered on both sides of the tissue. Ablation in both groups was performed using power titrated up to a max of 50 W, targeting an impedance drop of >10-15 ohms but limiting temperature to <45°C for a duration of 120 seconds with contact force of 20 gms and 30 cc irrigation for all lesions.
Results: A total of 28 bipolar and 15 pairs of sequential unipolar lesions were compared. There was no statistical significant differences between the thickness of tissue ablated in the bipolar vs. unipolar arm (17.3±3.3mm vs. 15.6±5.2mm, p=0.18). Transmurality was achieved in 82% of all lesions created with bipolar RF as compared to 33% of paired unipolar RF lesions. Amongst the transmural lesions created in both groups, tissue thickness in the bipolar arm (16.5±2.8mm, range: 11.3-22.4mm) was greater (p<0.05) than the tissue thickness in the unipolar (10±3.3mm, range: 6.5-14.2mm) arm.
Conclusions: Lesion transmurality is more readily achieved and at greater tissue thickness when using bipolar RF compared to sequential unipolar RF ablation. Bipolar RF therefore may have a role when attempting to target deep intramural circuits in the clinical setting.
- © 2011 by American Heart Association, Inc.