Author + information
- Abraham R. Tzafriri1,
- Lynn Bailey1,
- John H. Keating1,
- Peter M. Markham1,
- David Prutchi2 and
- Elazer R. Edelman3
Clinical and preclinical studies suggest that the efficacy of RF renal denervation (RDN) increases with increasing number of treatments. We evaluated efficacy and safety of the 9-electrode, 5-Fr, over-the-wire, RF ‘basket’ catheter, along with simultaneous bipolar/unipolar therapy algorithm ReDy system (Renal Dynamics, NJ) in pigs. Two catheter configurations were contrasted, with and without a ‘basket’-covering membrane designed to minimize blood flow at the electrode/tissue interface thus minimizing shunting of RF power through blood.
Seven juvenile Yorkshire swine underwent bilateral temperature-controlled RDN using the ReDy system. A single catheter size was used on all arteries as the ReDy device accommodates artery diameters up to 6.5mm. Pigs were sacrificed 7-30d post treatment. Arteries were harvested for histopathology and kidneys processed for norepinephrine (NEPI) quantification.
There was no angiographic evidence of acute dissection, perforation, or occlusion at the time of the procedure. Macroscopic inspections of catheters post-removal showed no adherent thrombus. Angiographic assessments showed the lumens of all arteries were patent. Histologically, zones of treatment within arterial walls and surrounding adventitia were well-demarcated at 7d with resolution of tissue response over time. There was no evidence of any adverse effects on arteries or surrounding tissue, and all treated arterial sections exhibited advanced re-endothelialization.
The use of blood isolation membranes allowed for lower treatment powers (1.2±0.8 vs 1.4±0.2 W) and temperatures (63.6±6.3 vs 68±2.3 °C) while increasing ablation depth (5.0±2.6 vs 2.8±0.8 mm, p=0.025) and percentage of affected nerves (37 vs 21%, P=NS) at 7d, as estimated by histology and confirmed by a significant 60% reduction in NEPI (256±250 vs 634±250 ng/g, p=0.007). Tissue response was noted in all quadrants and ∼65% of the artery length. Though radial adventitial response was more compact at 30d, due to tissue repair, the percentage of affected nerves (35%) and NEPI levels (365±132 ng/g) were statistically equivalent to 7d values (p>0.46).
The Renal Dynamics ReDy system is safe and efficacious in a porcine RDN model. Utilization of non-occluding blood isolation membranes allowed for deep delivery of RF power into the tissue at relatively low treatment powers, at multiple axial and circumferential locations.