Abstract 10794: Relationship Between Electrical Coupling Index, Contact Force, Impedance and Radiofrequency Lesion Size
Introduction: Electrical Coupling Index (ECI, EnSite ContactTM System, St. Jude Medical) has been used as a measure of electrode-tissue coupling for RF ablation. The purpose of this study was to compare the relationship of ECI to contact force (CF), initial impedance (Z) and RF lesion size between a 7F, 2.5 mm irrigated (Irg) electrode (Gen 2, St. Jude Medical) and a 7F, 4 mm Irg electrode (Therapy Cool FlexTM catheter, St Jude Medical) using a canine thigh muscle preparation.
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. The 2.5 mm and 4 mm Irrig electrodes were held perpendicular or parallel to thigh muscle at CF of 5, 20 or 40 grams. RF was applied for 60 sec at 20 W for the 2.5 mm electrode and 40 W for the 4mm electrode (both 17 ml/min). Initial ECI and Z were measured immediately before RF ablation. Dogs were sacrificed at 2 hours after ablation and lesion size was measured.
Results: Figs. There was a significant relationship between ECI and CF for both 2.5 mm and 4 mm electrodes (Figs A & B). At constant RF power and duration, lesion depth increased significantly with increasing CF and ECI for both 2.5 mm and 4 mm electrodes (Figs C-F). Compared to the 4 mm electrode, initial ECI and Z were significantly higher (and wider ranges of values) with the 2.5 mm electrode (p<0.01, Figs E-H). While ECI correlated well with lesion depth for both electrodes (Figs E & F), Z correlated poorly with lesion depth for both electrodes (Figs G & H).
Conclusions: ECI increased significantly with increasing CF. At constant RF power and duration, lesion depth increased strikingly with increasing CF and ECI for both 2.5 mm and 4 mm electrodes.
- © 2011 by American Heart Association, Inc.