Preclinical evaluation of a novel cryo renal denervation system

Background The latest ESC guideline on hypertension mentioned catheter-based renal denervation (RDN) as a treatment option for patients with uncontrolled hypertension. Besides the radiofrequency and ultrasound RDN systems, cryoenergy using nitrous oxide (N2O) may become a valuable treatment as it can be applied with a single balloon inflation. Objectives The objective of this preclinical study was to demonstrate the safety and efficacy of the Cryo-RDN device in the porcine model. Methods The efficacy and safety were studied in 8 domestic swine which underwent unilateral (n=4) or bilateral (n=4) cryo-ablations. Efficacy outcomes at 7- and 28-day follow-ups, included the difference in renal tissue norepinephrine (NE) concentrations between treated and untreated renal arteries and histopathological assessment of nerve damage. The rates of procedural complications and renal artery damage were used as safety endpoints. Results All target renal arteries were successfully crossed with the guidewire-free Cryo-RDN catheter, achieving a procedural success rate of 100%. Successful ablation of the sympathetic nerves was demonstrated by reduced NE renal tissue concentration, which were highest after 28 days with -72.6% to -81.9% averaged over all cryo-times. Using various staining methods, nerve damage was most pronounced at 7 days and less pronounced at 28 days which suggests healing between 7 and 28 days. NE-reductions were strongest at 28 days demonstrating the highest efficacy. Conclusions Cryo-RDN using N2O was safe and effective in the swine model.