Abstract 14079: Value of Magnetic Field Direction for Percutaneous Epicardial RF Ablation Using Magnetic Maneuvering System
Introduction: Percutaneous epicardial RF ablation is performed within the narrow pericardial space. The effect of electrode-tissue contact within the pericardial space on RF lesion size has not been examined. We hypothesized that directing magnetic force toward the epicardium would produce deeper RF lesions for epicardial ablation using a magnetic catheter maneuvering system (Niobe II, Stereotaxis).
Methods: 5 anesthetized dogs were studied. Pericardial access was obtained through a subxyphoid incision. A flexible 7F ablation catheter (location sensor and 3 magnets, ThermoCool-RMT, Biosense Webster) was placed into the pericardial space. Epicardial LV/RV mapping was performed remotely by changing the magnetic field vector (CARTO-RMT). RF (40 W, 60 sec, saline irrigation 10 ml/min) was delivered with magnetic vector toward (Toward EPI, n=12) or away from epicardium (Away EPI, n=18). Dogs were sacrificed at 2 hours. Lesion size was measured using TTC staining.
Results: Lesion depths were significantly greater for RFs directed Toward EPI (5.3 - 9.9, median 6.3 mm) than RFs directed Away EPI (0 - 6.1, median 4.0 mm, p<0.01, Fig). 4/18 Away EPI sites showed no epicardial lesion. Steam pop occurred 2/12 Toward EPI and 1/18 Away EPI (p=NS). Shallow lung lesions were present 6/12 Toward EPI and 9/18 Away EPI sites.
Conclusions: Deep epi-myocardial lesions are consistently produced by percutaneous epicardial ablation using a magnetic maneuvering system with magnetic vector directed Toward EPI. Small or no epicardial lesions result when magnetic vector is directed Away EPI.
- © 2011 by American Heart Association, Inc.