Abstract 20614: Evaluation of Ablation Catheter Technology: Comparison Between the Thigh Preparation Model and an In-Vivo Beating Heart

Background: An in-vivo animal thigh model is the standard technique for evaluation of ablation catheter technologies, including for prediction of ablation efficacy (lesion dimensions) and safety (cardiac tissue perforation and collateral damage). However, validation of this model with an in-vivo beating heart has not been performed. The purpose of this study was to prospectively compare these two methods. Methods: In 5 Yorkshire swine, radiofrequency ablation using a 3.5mm open irrigated catheter (Thermocool Smart Touch®) was performed sequentially in the thigh muscle and the beating ventricles. Ablation was performed in 2 settings: 30W for 40Ssec (low energy) and 40W for 60Sec (high energy) at similar tissue contact (8-14 grams). Tetrazolium chloride was injected 15 minutes prior to euthanasia and all tissue were fixed in formalin for ≥7 days. Ablation lesions were scanned in high-resolution and measured using electronic calipers. Results: A total of 114 RF ablation lesions were measured (57 for each method). In the low energy setting, lesion width was greater in the thigh model (8.37±1.5mm vs. 7.14±1.3mm; p=0.005) while lesion depth was greater in the beating heart (4.72±0.8mm vs. 4.2±0.6mm; p=0.016). The overall lesion volume was similar between the methods (thigh 27.8±7.1mm 2 vs. heart 26.9±7.9mm 2 ; p=0.74). In the high energy setting, lesion depth, width, and overall volume were greater in the thigh lesions (thigh 53.9±10.8mm 2 vs. heart 34.5±9.6mm 2 ; p=0.001). The thigh model demonstrated consistent and predictable lesions compared to the beating heart (r=0.75 vs r=0.53, respectively). There was no difference in steam pop incidence. Conclusion: The thigh model is a reasonable technique for evaluation of ablation catheter technology. The correlation of lesion dimensions between thigh model and beating heart is reasonable in low energy settings, however results in overestimation at higher energy setting. Caution should be taken before extrapolation of ablation data obtained using the thigh model technique to the beating heart physiology.