Abstract 15841: Contact Force-Time Integral Predicts Radiofrequency Lesion Size and Incidence of Steam Pop in the Canine Beating Heart
Introduction: During radiofrequency (RF) ablation at constant power, the lesion size and incidence of steam pop increase strikingly with increasing contact force (CF) and RF application time. An RF ablation catheter has been developed to measure real time contact force (Endosense SA), using 3 optical fibers to measure micro-deformation of the catheter tip. Contact force is calculated every 100 ms (sensitivity <1 gram in bench testing). The area under the CF vs Time curve (Force-Time Integral, FTI) can be measured and displayed in real-time during RF delivery. The purpose of this study was to determine the relationship between FTI, lesion size and incidence of steam pop in the canine beating heart.
Methods: 5 dogs (27-33 kg) were studied closed chest under pentobarbital anesthesia. The 7F CF catheter with 3.5 mm saline irrigated electrode was positioned in RV and LV under fluoroscopic guidance. RF applications were delivered at 25 W (17 ml/min irrigation) to 39 RV sites and at 40 W (30 ml/min irrigation) to 42 LV sites, using 3 ranges of CF: low (5-14g, median 9 g), moderate (16-25g, median 21 g) and high CF (33-45g, median 40 g) and 3 RF durations (15, 30 and 60 sec) to obtain a wide range of FTI (68-1350 gram-seconds). Dogs were sacrificed at 2 hours and lesion size was measured using TTC staining.
Results: At constant RF power (25W or 40 W), lesion depth increased significantly with increasing FTI in both RV (R=0.784, p<0.001, Fig A) and LV (R=0.781, p<0.001, Fig B). Steam pop occurred only at 40W with FTI >478.
Conclusions: In the canine beating heart, RF lesion size correlates highly with FTI. Real-time measurement of FTI can predict lesion size and risk of steam pop.
- © 2012 by American Heart Association, Inc.