Renal Artery Vasodilation May Be An Indicator of Successful Sympathetic Nerve Damage During Renal Denervation Procedure

Abstract

Autonomic nervous system plays a crucial role in maintaining and regulating vessel tension. Renal denervation (RDN) may induce renal artery vasodilation by damaging renal sympathetic fibers. We conducted this animal study to evaluate whether renal artery vasodilation could be a direct indicator of successful RDN. Twenty-eight Chinese Kunming dogs were randomly assigned into three groups and underwent RDN utilizing temperature-controlled catheter (group A, n = 11) or saline-irrigated catheter (group B, n = 11) or sham procedure (group C, n = 6). Renal angiography, blood pressure (BP) and renal artery vasodilation measurements were performed at baseline, 30-minute, 1-month, and 3-month after interventions. Plasma norepinephrine concentrations were tested at baseline and 3-month after intervention. Results showed that, in addition to significant BP reduction, RDN induced significant renal artery vasodilation. Correlation analyses showed that the induced renal artery vasodilation positively correlated with SBP reduction and plasma norepinephrine reduction over 3 months after ablation. Post hoc analyses showed that saline-irrigated catheter was superior to TC catheter in renal artery vasodilation, especially for the acute dilatation of renal artery at 30-minute after RDN. In conclusion, renal artery vasodilation, induced by RDN, may be a possible indicator of successful renal nerve damage and a predictor of blood pressure response to RDN.

Figure 1. Angiograms before and after ablation.

Baseline (A) 30-minute (B) and 1-month(C) renal artery angiograms were from a group B dog. The diameter of renal artery underwent renal nerve ablation via saline-irrigated catheter was markedly increased than that at baseline. Baseline (D) 30-minute (E) And 1-month (F) renal artery angiograms were from a group A dog. Similar changes were showed, but the vessel spasm caused by renal nerve ablation using temperature-controlled catheter made the observation difficult. Angiograms were calibrated using a 6 F JR4 Judkins catheter with an inner diameter of 2 mm as reference (denoted with white arrow heads).

Figure 2. The multiple comparisons of the differences in changes of renal artery diameter among groups during 30 minutes to 3 months follow up after interventions.

Renal artery vasodilation was observed in RDN groups (group A and group B), but not in the sham procedure group (group C) during the 30 minutes to 3 months follow up after interventions. Saline-irrigated catheter is superior to TC catheter in renal artery vasodilation, especially for the acute dilatation of renal artery at 30-minute after RDN. The different lowercase letters show significant differences among groups of the variable at 30-minute/1-month/3-month follow up after interventions (LSD post-hoc test at p < 0.05), while the same lowercase letter show no significant differences among groups of the variable (LSD post-hoc test at p > 0.05). R-RA =  diameter of right renal artery; L-RA =  diameter of left renal artery; M-RA = mean diameter of renal artery.

Figure 3. The multiple comparisons of the differences in changes of blood pressure among groups during 30 minutes to 3 months follow up after interventions.

Systolic/diastolic blood pressure in RDN groups (group A and group B) was significantly decreased after RDN while no significant changes were observed in sham procedure group (group C). The different lowercase letters show significant differences among groups of the variable at 30-minute/1-month/3-month follow up after interventions (LSD post-hoc test at p < 0.05), while the same lowercase letter show no significant differences among groups of the variable (LSD post-hoc test at p > 0.05). SBP = systolic blood pressure; DBP = diastolic blood pressure.