Abolition of Aorticorenal Ganglia Pacing Responses Improves Denervation Efficacy.

BACKGROUND

Transcatheter renal denervation (RDN) remains inconsistent despite developments in ablation technologies, due to the lack of an intraprocedural physiological end point. The aim of this study was to identify if aorticorenal ganglion (ARG) guided RDN using microwave (MW) catheter leads to more consistent denervation outcomes compared with empirical MW ablation.

METHODS

Pigs underwent sham procedure (n=8) or bilateral RDN using an in-house built open-irrigated MW catheter. Before denervation, ipsilateral ARG pacing was performed leading to renal artery vasoconstriction. MW ablation group (MW-group; n=7) received 1 ablation (100-120 W for 360 seconds) in the mid-main renal artery based on artery caliber. ARG-guided-MW ablation group (ARG-MW-group; n=7) was permitted an additional ablation more distally or at higher power until a vasoconstrictive response was abolished. Animals were euthanized at 4 to 5 weeks post-procedure.

RESULTS

ARG pacing caused an ipsilateral reduction in renal artery caliber from 4.67 to 4 mm; P=0.0006 in MW-group and 4.8 to 3.9 mm; P=0.001 in ARG-MW-group. Repeat ARG pacing at euthanasia led to a reduction in renal artery caliber in MW-group from 5.1 to 4.8 mm; P=0.006, but not in ARG-MW-group from 4.88 to 4.55 mm; P=0.08. There were no differences in ablation injury volumes between the groups. Compared with undenervated sham controls, ARG-MW-RDN versus MW-RDN caused median reductions in viable nerve area (antityrosine hydroxylase staining) at 4 to 5 weeks by 92.6% (interquartile range, 0.94-19.59%; P<0.0001) versus 55.02% (interquartile range, 15.87-75.11%; P=0.006) and median renal cortical norepinephrine content by 68.06% (interquartile range, 27.16-38.39%; P<0.0001) versus 25.25% (interquartile range, 56.97-157.7%; P=NS).

CONCLUSIONS

ARG pacing serves as a physiological procedural end point to guide MW denervation to improve denervation outcomes.