Noninvasive renal sympathetic denervation by extracorporeal high-intensity focused ultrasound in a pre-clinical canine model.

OBJECTIVES: This study investigated the feasibility of noninvasive renal sympathetic denervation (RSD) by using the novel approach of extracorporeal high-intensity focused ultrasound (HIFU).

BACKGROUND: Catheter-based RSD has achieved promising clinical outcomes.

METHODS: Under the guidance of Doppler flow imaging, therapeutic ablations (250 W × 2 s) were performed by using extracorporeal HIFU on the bilateral renal nerves (36.3 ± 2.8 HIFU emissions in each animal) in a mean 27.4-min procedure in 18 healthy canines of the ablation group. Similar procedures without acoustic energy treatment were conducted in 5 canines of the sham group. The animals were killed on day 6 or 28. Blood pressure (BP), plasma noradrenaline (NA) level, and renal function were determined on days 0, 6, and 28. Pathological examinations were performed on all retrieved samples.

RESULTS: All of the animals survived the treatment. After ablation, BP and NA significantly decreased compared with the baseline values (BP changed -15.9/-13.6 mmHg, NA changed -55.4% [p < 0.001] 28 days after ablation]) and compared with the sham group on days 6 and 28. Ablation lesions around the renal artery adventitia were observed on day 6. A histological examination revealed the disruption of nerve fibers, necrosis of Schwann cells and neurons, and apparent denervation on day 28. No procedure-related complications were observed.

CONCLUSIONS: Effective RSD was successfully achieved by using the extracorporeal HIFU method in canines. Thus, noninvasive HIFU may be further explored as an important and novel strategy for RSD.