Evaluation of ablation catheter technology: Comparison between 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 efficacy and safety of ablation. However, the biophysics of ablation in a thigh model may not be similar to a beating heart. Objective The purpose of this study was to compare efficacy and safety of ablation between a thigh preparation model and a beating heart. Methods In 7 swine, radiofrequency ablation using a 3.5-mm open irrigated catheter (ThermoCool Smart Touch) was performed sequentially in a thigh muscle and in vivo beating ventricles. Ablation was performed at low (30 W for 40 s) and high (40 W for 60 s) energy settings and at similar contact force. Ablation lesions were scanned in high resolution and measured using electronic calipers. Results A total of 152 radiofrequency ablation lesions were measured (86 thigh and 66 heart). At low energy, lesion width was greater in the thigh model (12.19 ± 1.8 mm vs 8.99 ± 2.1 mm; P <.001), whereas lesion depth was similar between the thigh and heart (5.71 ± 0.8 mm vs 5.95 ± 1.3 mm, respectively; P =.18). The planar cross-sectional lesion area was greater in the thigh model (thigh 54.8 ± 10.8 mm² vs heart 43.1 ± 16.1 mm²; P <.001). At the high-energy setting, lesion depth, width, and area were all greater in the thigh model (thigh 91.5 ± 16.8 mm² vs heart 56.0 ± 15.5 mm²; P <.001). The incidence of steam pop and char formation was similar between the models. Conclusion The thigh preparation model is a reasonable technique for evaluation of ablation catheter technology; however it often results in overestimation of lesion size, especially at higher energy settings.