PURPOSE: The objective of this study was to optimize the least invasive technique of radiofrequency ablation (RFA) for the degenerated renal parenchyma and to develop a novel RFA system. MATERIALS AND METHODS: Tissue temperature and pathological degeneration were investigated at regular time intervals and distances from the RFA needle electrode in the renal parenchyma of the pig kidney. We also examined whether interruption of the renal artery or irrigation in the renal pelvis had an influence on the therapeutic effects. RESULTS: Pathological investigations showed a core necrotic area surrounded by an ischemic layer around the needle electrode. Interestingly, interruption of the renal artery and irrigation in the renal pelvis markedly enhanced the degeneration of the parenchyma. Especially the electric conductivity of irrigation solutions in the renal pelvis influenced the therapeutic effect. In this novel system which retains the flow of electricity between the 2 electrodes and maintains the electric power at a constant wattage, a marked therapeutic effect was observed between the 2 electrodes rather than on their outsides, and this was not influenced by renal artery interruption and/or renal parenchyma cooling. CONCLUSIONS: This novel RFA system may contribute to more effective and highly reproducible therapeutic results.
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