Sympathetic Vasomotion Reflects Catheter-based Radiofrequency Renal Denervation

The field of renal denervation remains challenged by the inability to confirm successful ablation of the targeted renal sympathetic nerves. The availability of technology to measure regional blood flow in real time makes sympathetic control of the renal vasculature a logical endpoint to assess effective renal denervation, but autoregulatory mechanisms mask effects on mean renal blood flow. We hypothesized that renal sympathetic vasomotion, a novel marker of rhythmic sympathetic control, reflects successive rounds of catheter-based radiofrequency renal denervation. To test this, ten pigs underwent unilateral surgical renal denervation, recovered for at least seven days, and then underwent four successive rounds of catheter-based radiofrequency denervation of the contralateral kidney. Bilateral renal blood flow velocity and abdominal aortic pressure were measured before and after ablations to assess renal vasomotion. Prior to catheter-based denervation, the renal vasomotion profiles of the innervated and surgically denervated kidneys differed significantly (P < 0.005). Ablation of the largest renal branch artery reduced renal sympathetic vasomotion by 52%. Ablation of the remaining renal branch arteries reduced sympathetic vasomotion 95% from baseline and eliminated the statistical differences between surgically and catheter denervated kidneys. Two additional rounds of catheter denervation of the main renal artery did not consistently decrease renal sympathetic vasomotion magnitude any further. These results indicate that renal sympathetic vasomotion could provide intraprocedural feedback for interventionalists performing catheter-based renal denervation and thereby improve the efficacy, safety, and consistency of this antihypertensive intervention.