Abstract 12104: Prospective Study Using a New Formula Incorporating Contact Force, Radiofrequency Power and Application Time (Force-Power-Time Index) for Quantifying Lesion Formation to Guide Long Continuous Atrial lesions in the Beating Canine Heart
Introduction: In a previous study on radiofrequency (RF) ablation in the canine right and left ventricle, we found that lesion depth was predicted accurately (± 1mm) by a logarithmic function of contact force (CF), RF power and application time (Force-Power-Time Index, FPTI). The purpose of this study was to test prospectively whether the FPTI formula would guide RF linear lesions to be created at depths of 3 or 5 mm in the beating canine right and left atrium (RA and LA).
Methods: 8 anesthetized dogs were studied closed chest. A 7.5F irrigated CF catheter (ThermoCool SmartTouch, Biosense Webster, Inc) was positioned in the RA and LA under fluoroscopy. RF was delivered point-by-point between the superior vena cava and inferior vena cava (intercaval lesion) in RA at 25W or 35W and between the right superior pulmonary vein ostium and LA appendage (roof line) in LA at 25W or 35W in each dog. Each RF application was terminated when the FPTI formula reached a predicted depth of 3mm (3 dogs: 3 RA and 3 LA Linear lesions) or 5mm (5 dogs: 5 RA and 5 LA linear lesions). Lesions were placed 2.5 - 3.0 mm apart (center-to-center) for 3 mm predicted depth and 3.5 mm - 4.0 mm apart for 5 mm predicated depth (Fig A): The dogs were sacrificed 2 hours after ablation. RF lesion size was measured using TTC staining.
Results: For 5 mm predicted depth, long continuous lesions were obtained in 5/5 RA lines (48 - 70 mm in length) and in 4/5 LA lines (30 - 47 mm in length). For 3 mm predicted depth, long continuous lesions were obtained in 3/3 RA lines (49 - 60 mm in length) and in 1/3 LA lines (30 mm in length). Actual lesion depth ranged 4.0 - 6.4 mm (median 5.7 mm) for 5 mm predicated depth and ranged 3.8 - 4.2 mm (median 4.0 mm) for 3 mm predicted lesion depth. All 3 LA gaps were small (≤3 mm) and located at sites where the catheter could be positioned (due to a LA ridge, Fig B ).
Conclusions: The FPTI formula successfully guided continuous atrial lesions with accurately predicted lesion depth of 3 mm or 5 mm. Continuous overlapping RF lesions are required.
- © 2013 by American Heart Association, Inc.