Evaluation of lesion and thermodynamic characteristics of Symplicity and EnligHTN renal denervation systems in a phantom renal artery model

Aims: Radiofrequency renal artery denervation has been used effectively to treat resistant hypertension. However, comparison of lesion and thermodynamic characteristics for different systems has not been previously described. We aimed to assess spatiotemporal lesion growth and ablation characteristics of Symplicity and EnligHTN systems. Methods and results: A total of 39 ablations were performed in a phantom renal artery model using Symplicity (n=17) and EnligHTN (n=22) systems. The phantom model consisted of a hollowed gel block surrounding a thermochromic liquid crystal (TLC) film, exhibiting temperature sensitivity of 50-78 degrees C. Flow was simulated using 37 degrees C normal saline with impedance equal to blood. Radiofrequency ablations with each system were delivered with direct electrode tip contact to the TLC. Lesion size was interpreted from the TLC as the maximum dimensions of the 51 degrees C isotherm. Mean lesion depth was 3.82 mm+/-0.04 versus 3.44 mm+/-0.03 (p<0.001) for Symplicity and EnligHTN, respectively. Mean width was 7.17 mm+/-0.08 versus 6.23 mm+/-0.07 (p<0.001), respectively. With EnligHTN, steady state temperature was achieved 20 sec earlier, and was 15 degrees C higher than Symplicity. Conclusions: In this phantom model, Symplicity formed larger lesions compared to EnligHTN with lower catheter-tip temperature. The clinical significance of our findings needs to be explored further.