Abstract 13198: Comparison of 12 and 56 Hole Open Irrigation Electrodes in Electrode Cooling, Radiofrequency Lesion Depth, and Thrombus
Introduction: During radiofrequency (RF) ablation, thrombus develops when the electrode-tissue interface (ETI) temperature exceeds 80°C. Open irrigated electrodes provide greater cooling of ETI to allow greater RF power with lower risk of thrombus. One limitation is the volume of saline delivered to the patient. The irrigation (IR) flow rate required to prevent thrombus may depend on the number, size and location of IR holes. We hypothesized that placing a larger number of smaller holes around the entire electrode would reduce the risk of thrombus formation and decrease the required IR flow rate.
Methods: In 4 dogs, the skin over the thigh muscle was incised and raised to form a cradle which was superfused with heparinized blood at 37°C. A catheter with 7F 4mm tip electrode and12 larger IR holes (diameter 0.015”, St. Jude Medical, Inc, Fig) or a catheter with 7.5F 3.5 mm tip electrode and 56 smaller holes (diameter 0.0035”, Biosense Webster, Inc, Fig) was held perpendicular or parallel to the thigh muscle at 10 g contact weight. RF was applied for 60 sec (n=96) at constant power of 30W (IR: 17 ml/min for 12 Holes or 8 ml/min for 56 Holes), 40 W or 50 W (IR: 17 ml/min for 12 Holes, 15 ml/min for 56 Holes) in low blood flow (<0.1 m/sec) to favor thrombus. Electrode temperature (ET), ETI temperature and tissue temperatures at 3 mm and 7 mm depths were measured. After each ablation, blood was removed from the cradle to examine for thrombus.
Results: Table. At 30W, 56 Holes with lower IR resulted in significantly lower ET and no thrombus (thrombus: 0/16 vs. 3/16 with 12 Holes). At 40 W and 50W, ET, ETI temperature and the incidence of thrombus were significantly lower with 56 Holes. Tissue temperatures and lesion size were similar between the two electrodes.
Conclusions: In the power range tested (30–50 W), lesion size was similar, but 56 Holes produced greater electrode and ETI cooling with lower irrigation flow rates and significantly decreased the incidence of thrombus.
- © 2010 by American Heart Association, Inc.