Abstract 615: Renal Sympathetic Denervation: A Comparison Of Irrigated And Non-irrigated Radiofrequency Ablation In A Porcine Model

Abstract

Introduction: Renal artery sympathetic denervation using radiofrequency (RF) energy has recently been shown to reduce blood pressure in patients with hypertension. However arterial damage is required to achieve denervation, which has unknown long term consequences. Alternative techniques of denervation that minimize arterial wall damage are therefore preferable. We compared the ability of irrigated RF vs. non-irrigated RF to ablate the nerve fibers with respect to the degree of arterial wall sparing in an in vivo model.

METHODS: Percutaneous femoral arterial access was obtained in 14 adult

swine and renal angiography was performed to assess for stenosis at baseline and at time of sacrifice . Irrigated (3.5mm tip/30cc) and non-irrigated RF (3.5, 4mm and 2mm tips) energy was delivered bilaterally using custom catheters. All animals were then recovered and survived

for 30-90 days. Renal cortical tissue was collected from bilateral kidneys for norepinephrine levels prior to sacrifice.

Results: There was no significant interval renal artery stenosis. Arteries were sequentially sectioned, processed, cut at 4-6 μm and stained with hematoxylin&eosin and movat pentachrome. Arterial medial injury (percentage depth) and nerve injury were then scored on a incremental scale of 0-4. Medial injury was significantly less in the irrigated group vs. non-irrigated group (1.15vs 2.2 p<0.05). Nerve injury on the other hand was similar in both groups (1.75 vs. 1.24,p=0.24). Norepinephrine levels were obtained in 11/14 animals. In the irrigated and non-irrigated arms there was a 67% and 53% reduction of norepinephrine levels compared to that of controls.

Conclusions: Irrigated RF ablation is an efficacious and feasible means to achieve renal denervation. Although medial injury occurred in both groups, irrigated RF demonstrates a lower degree of medial injury for similar levels of nerve injury when compared to non-irrigated RF.