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 mm vs heart 43.1 ± 16.1 mm; P <.001). At the high-energy setting, lesion depth, width, and area were all greater in the thigh model (thigh 91.5 ± 16.8 mm vs heart 56.0 ± 15.5 mm; 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.