Renal denervation using catheter-based radiofrequency ablation with temperature control: renovascular safety profile and underlying mechanisms in a hypertensive canine model.

Objective: Renal denervation is a novel method for hypertension treatment. In this study, we aimed to investigate the safety and efficacy of radiofrequency ablation (RFA) at ablation temperatures of 45 degrees C or 50 degrees C and its possible mechanisms. Methods: A hypertensive canine model was established by abdominal aortic constriction in 20 healthy hybrid dogs. These dogs were then randomly assigned to the treatment and the control groups, with dogs in the treatment group further randomly assigned to receive RFA at ablation temperatures of 45 degrees C or 50 degrees C. In the treatment group, RFA was performed at 1 month after modeling; renal angiography was performed at 2 months after ablation. The arterial vessels of the dogs were examined histologically with hematoxylin and eosin staining. Changes in blood pressure in the foreleg and whole-body norepinephrine spillover rate were also assessed. Results: No arterial stenosis, dissection, thrombosis or other abnormalities were detected in the treated vessels by renal angiography, yet histology results showed minimal to mild renal arterial injury. Renal denervation resulted in a marked decrease in the whole-body norepinephrine spillover rate (p < 0.05) in addition to significantly reducing blood pressure (p < 0.05), with no significant differences detected between the 45 degrees C and 50 degrees C subgroups for both (p > 0.05). Conclusion: Renal denervation can be performed without acute major adverse events, using catheter-based RFA with temperature control. The procedure was feasible in reducing blood pressure by at least partially inhibiting sympathetic drive and systemic sympathetic outflow.