title: Evaluation of renal nerve morphological changes and norepinephrine levels following treatment with novel bipolar radiofrequency delivery systems in a porcine model.
abstract: OBJECTIVE
  To evaluate the safety and effectiveness of different bipolar radiofrequency system algorithms in interrupting the renal sympathetic nerves and reducing renal norepinephrine in a healthy porcine model.
  
  
  METHODS
  A porcine model (N = 46) was used to investigate renal norepinephrine levels and changes to renal artery tissues and nerves following percutaneous renal denervation with radiofrequency bipolar electrodes mounted on a balloon catheter. Parameters of the radiofrequency system (i.e. electrode length and energy delivery algorithm), and the effects of single and longitudinal treatments along the artery were studied with a 7-day model in which swine received unilateral radiofrequency treatments. Additional sets of animals were used to examine norepinephrine and histological changes 28 days following bilateral percutaneous radiofrequency treatment or surgical denervation; untreated swine were used for comparison of renal norepinephrine levels.
  
  
  RESULTS
  Seven days postprocedure, norepinephrine concentrations decreased proportionally to electrode length, with 81, 60 and 38% reductions (vs. contralateral control) using 16, 4 and 2-mm electrodes, respectively. Applying a temperature-control algorithm with the 4-mm electrodes increased efficacy, with a mean 89.5% norepinephrine reduction following a 30-s treatment at 68°C. Applying this treatment along the entire artery length affected more nerves vs. a single treatment, resulting in superior norepinephrine reduction 28 days following bilateral treatment.
  
  
  CONCLUSIONS
  Percutaneous renal artery application of bipolar radiofrequency energy demonstrated safety and resulted in a significant renal norepinephrine content reduction and renal nerve injury compared with untreated controls in porcine models.
authors.affiliation: aVessix Vascular and Boston Scientific Corporation, Laguna Hills, California bCBSET Inc., Department of Science Services, Lexington, Massachusetts cCenter for Interventional Hypertension Therapies, Cardiology PC, Birmingham, Alabama dPrairie Heart Institute at St. John's Hospital, Springfield, Illinois, USA.
authors.forename: Meital
authors.initials: M
authors.lastname: Cohen-Mazor
authors.forename: Prabodh
authors.initials: P
authors.lastname: Mathur
authors.forename: James R L
authors.initials: JR
authors.lastname: Stanley
authors.forename: Farrell O
authors.initials: FO
authors.lastname: Mendelsohn
authors.forename: Henry
authors.initials: H
authors.lastname: Lee
authors.forename: Rose
authors.initials: R
authors.lastname: Baird
authors.forename: Brett G
authors.initials: BG
authors.lastname: Zani
authors.forename: Peter M
authors.initials: PM
authors.lastname: Markham
authors.forename: Krishna
authors.initials: K
authors.lastname: Rocha-Singh
mesh_terms: D000818:Animals; D001794:Blood Pressure; D017115:Catheter Ablation / Q000379:methods*; D003404:Creatinine / Q000097:blood; D006339:Heart Rate; D007668:Kidney / Q000737:chemistry / Q000294:innervation; D023421:Models, Animal; D009638:Norepinephrine / Q000032:analysis*; D012077:Renal Artery / Q000294:innervation* / Q000473:pathology; D013552:Swine; D013562:Sympathectomy / Q000379:methods*; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis
chemical_list: D003404:Creatinine; D014446:Tyrosine 3-Monooxygenase; D009638:Norepinephrine