Contact Sensing Provides a Highly Accurate Means to Titrate Radiofrequency Ablation Lesion Depth

RF Ablation Lesion Depth Estimation Using Contact Sensing. Background: Transmural lesions are essential for efficacious ablation. There are, however, no accurate means to estimate lesion depth. Objective: Explore use of the electrical coupling index (ECI) from the En Site Contact (TM) System as a potential variable for lesion depth estimation. Methods: Radiofrequency (RF) ablation lesions were created in atria and the thighs of swine using an irrigated RF catheter. Power was 30 W for 20 or 30 seconds intracardiac and 30-50 W for 10-60 seconds for the thigh. Intracardiac, the percentage change in ECI during ablation was compared with transmurality and collateral damage occurrence. For the thigh model, an algorithm estimating lesion depth was derived. Factors included: power, duration, and change in the ECI subcomponents (Delta ECI+) during ablation. The Delta ECI+ algorithm was compared to one using power and duration (PD) alone. Results: Intracardiac, lesions with >= 12% reduction in ECI were more likely to be transmural (92.3% vs. 59.4%, P < 0.001). Twenty-second lesions were less likely to cause collateral damage compared to 30 seconds (33% vs. 70%, P = 0.003), while transmurality was similar. With the thigh model, Delta ECI+ had a better correlation than the PD algorithm (P < 0.01). Accuracy of the Delta ECI+ algorithm was unimproved with inclusion of tip orientation, while PD improved (R(2) = 0.64). Discussion: Change in ECI provides evidence of transmural versus nontransmural swine intracardiac atrial lesions. A lesion depth estimation algorithm using ECI subcomponents is unaffected by tip orientation and is more accurate than using PD alone. Conclusion: Use of ECI as a factor in a lesion depth algorithm may provide clinically valuable information regarding the efficacy of intracardiac RF ablation lesions. (J Cardiovasc Electrophysiol, Vol. 22, pp. 684-690, June 2011)