Abstract 290: Long Term Safety and Efficacy of Renal Nerve Ablation in Swine with the First Prototype of the Boston Scientific Renal Ablation System
Introduction: Early splanchnicectomy and radical sympathectomy research demonstrated that reducing sympathetic nerve activity achieved blood pressure reductions and improved long-term outcomes in hypertensive patients. These methods were abandoned due to high perioperative morbidity and mortality. A minimally invasive approach to inhibition of renal sympathetic nerves represents an attractive treatment of essential hypertension.
Methods: Swine were evaluated at 7, 30, 60, 90 or 180 days post treatment. At each time point, 4 animals treated with bilateral renal artery radiofrequency (RF) ablation and 3 sham treated animals were assessed. A single point ablation catheter was positioned within each renal artery of anesthetized animals and 4-6 ablations/artery were delivered in a spiral pattern. At baseline and termination, urinalysis, blood chemistry and QVA was performed. Right and left kidneys and renal arteries were harvested from all animals. Renal arteries were processed for histological evaluation. Kidneys were weighed, frozen, and used for the analysis of norepinephrine levels.
Results: No injuries were seen in tissues surrounding the renal arteries and no safety concerns were identified in the histological evaluation of the renal arteries. RF treated renal arteries showed segmental, transmural regions of minimal vessel wall injury with SMC loss. These regions showed progression of healing and complete recellularization by 60 days. All vessels had complete endothelial cell coverage at all timepoints. Minimal intimal hyperplasia was seen. There were no instances of EEL injury. Mural and adventitial inflammation were seen at 30 days, but both resolved by 60 days. No abnormalities in renal function were identified by urinalysis or serum chemistry. Efficacy of nerve ablation was determined by renal norepinephrine levels (pg/mg) and a significant decrease was seen in ablation groups relative to sham groups at every timepoint (7 days: 69% p< 0.0001, 30 days: 46% p =0.044; 60 days: 59% p<0.004; 90 days: 53% p< 0.0001; 180 days: 56% p<0.001).
Conclusions: Renal ablation with the BSC catheter in a healthy swine model demonstrated safety and efficacy as assessed by renal artery histology and renal norepinephrine levels out to 6 months.
- © 2012 by American Heart Association, Inc.