A Pilot Study of Perioperative External Circumferential Cryoablation of Human Renal Arteries for Sympathetic Denervation

Cryoablation, which induces cellular death without extensive tissue damage, has been extensively used to denervate the myocardium. However, periadventitial external circumferential application of cryotherapy to denervate the renal artery sympathetic nerves has, to our knowledge, never been tested in humans. The main aim of this study was to examine the safety and potential effects of cryotherapy on ambulatory blood pressure levels and other outcomes that are indirectly related to sympathetic tone, including pulse-wave velocity, central pulse pressure, and glucose levels.

Five patients who underwent the denervation of the renal arteries during open surgery of the abdominal aortic aneurysm and four controls who did not undergo denervation during the surgery were enrolled. An argonpowered cryotherapy catheter (Cardioblate; Medtronic Inc., USA) was applied periadventitially to each renal artery in the five patients and then activated by infusion with liquid nitrogen for 1 minute.

No cryoablation-related complications occurred in the five consecutive patients. Their ambulatory blood pressures 3 to 5 months after surgery did not demonstrate any general blood pressure-reducing effects, but two patients responded favorably with the reduction of antihypertensive medication and decreased 24-hour blood pressure. The patients' mean HbA1C levels decreased from 5.9±0.78% to 5.6±0.71% (P=0.042).

This pilot study suggests that periadventitial cryoablation during open surgery can be used in the study of renal denervation in humans, as it had no complications in five patients in this study. The effectiveness of cryoablation for treating hypertension should be proven in a phase II clinical trial.