Background:
The safety and efficacy of catheter-based radio frequency (RF) renal denervation (RDN) have been demonstrated in randomized, sham-controlled trials. Long-term durability of blood pressure reduction following RDN has also been demonstrated by all-comer registries, although published pre-clinical reports of functional renal nerve regrowth are not consistent. We quantified the processes that support RDN procedural durability utilizing animal models.
Methods:
Animal studies were conducted in accordance with published guidelines. RDN was performed (4 lesions in the main renal artery) in normotensive swine using the Symplicity Spyral™ RDN system (Medtronic, Santa Rosa, CA, USA). Two additional groups not undergoing RDN served as control. Serial histological tissue samples were obtained in separate groups at 7 (n=12/group) and 180 (N=16/group) days post-procedure in all animals followed by bioanalytical quantification of cortical norepinephrine (NE) levels and immunohistochemical analysis of renal cortical axon density in matched samples.
Results:
Renal cortical axon density and NE levels were significantly reduced at 7 days and persisted through 180 days following RDN compared with control (
Figure
). Nerve fibrosis and necrosis were observed in the region of ablation, while nerve body atrophy was apparent distal to ablation location at 180 days.
Conclusions:
Reductions in both NE and renal cortical axon density were sustained at 7 and 180 days post-RDN procedure using RF renal denervation in a normotensive swine model. These data confirm and extend other pre-clinical and clinical evidence of long-term durability of the RDN procedure using RF energy.
TCT-19 Durability of Radio-Frequency Catheter-Based Renal Denervation Associated With Lack of Functional Nerve Recovery at 6 Months in Normotensive Swine Model
