Abstract 15777: Controlling Lesion Size and Incidence of Steam Pop by Controlling Contact Force and Radiofrequency Power in Canine Beating Heart
Introduction: During radiofrequency (RF) ablation at constant power, lesion size and incidence of steam pop increase strikingly with increasing contact force (CF). Catheter systems to measure CF are now under development. A novel 7.5F CF sensing catheter (ThermoCool SmartTouch, Biosense Webster, Inc) has a tiny spring connecting a 3.5mm irrigated tip electrode to the shaft. CF (resolution <1 g in bench tests) and direction is measured by the degree of spring bending, using a magnetic transmitter (tip) and 3 location sensors (shaft). CF is measured every 50 ms. A continuous 1 sec average CF is displayed on the 3D map (CARTO XP). The purpose of this study was to determine whether controlling RF power based on CF (ie, high CF with low power and low CF with high power) can produce equivalent sized lesions and same incidence of steam pop in the beating canine heart.
Methods: 14 dogs (29–47 kg) were studied closed chest under pentobarbital anesthesia. The saline irrigated CF ablation catheter was positioned in RV and LV under fluoroscopy. RF was delivered for 60 sec to 3 RV sites and 3 LV sites in each dog. RF Power was modulated based on CF. RV ablation: 1) 40 W at Low CF (4–9 g, median 6 g); 2) 25 W at Moderate CF (15–26 g, median 15.5 g); and 3) 10 W at High CF (40–54 g, median 42 g). LV ablation: 1) 50 W at Low CF (6–10 g, median 9.5 g); 2) 40 W at Moderate CF (20–25 g, median 21 g); and 3) 25 W at High CF (40–57 g, median 44 g). Dogs were sacrificed at 2 hours and RF lesion size was measured using triphenyl tetrazolium chloride staining.
Results: Figs A, B, C and D. Lesion depth and diameter and incidence of steam pop were similar between Low CF - 40W, Moderate CF - 25W and High CF - 10W in RV (depth 5.0 – 5.2 mm, Fig A), and between Low CF - 50W, Moderate CF - 40W and High CF - 25W in LV (depth 8.0 – 8.6 mm, Fig C).
Conclusions: Modulating RF power for low, moderate and high CF may control RF lesion depth (5 mm or 8 mm) and incidence of steam pop.
- Ablation, radiofrequency
- Atrial arrhythmias
- Ventricular arrhythmia
- Catheter ablation
- Atrial fibrillation
- © 2010 by American Heart Association, Inc.