Comparison of Radio Frequency Current and Microwave Energy for Transcatheter Renal Denervation

Transcatheter renal denervation (RDN) is a catheter-based procedure for resistant hypertension treatment using radio frequency (RF) ablation. However, RF ablation is proven to have an inconsistent result of reducing hypertension, for the reason that it has a limited heating capability. We present the feasibility of using microwave energy as a different energy source for RDN ablation treatment, by comparing to RF current energy source. In this paper, we designed a coaxial-slot antenna for microwave (2.45 GHz) and an electrode for RF current (500 kHz), with phantoms that match human muscle dielectric properties at each respective working frequency. Both phantoms thermal properties and material density were measured, and then used in simulation. A total of 10 ablation experiments were conducted to validate the numerical simulation results. Each temperature points of the experiments were measured at 1 mm interval between thermometer probes. The results of the experiment temperature distributions agree well with the simulation results, RF achieved 5-6 mm while microwave achieved 7-8 mm. Additionally, numerical calculations with different input power were conducted to understand the temperature characteristics of both energy source. Microwave energy offers higher input power for a more profound and broader ablation area as opposed to RF current.