title: Clinical evaluation of a novel bipolar radiofrequency ablation system for renal masses.
abstract: What's known on the subject? and What does the study add? With the advancement of minimally invasive surgery, the management of small renal masses (SRM) has dramatically changed. Ablative technology such as radiofrequency ablation (RFA) and cryoablation have emerged as viable alternative modalities to extirpative surgery. RFA is one of the most studied and applied energy-based, needle-ablative treatment modalities, with encouraging mid- and long-term oncological outcomes. Monopolar devices have several shortcomings. The electrodes are susceptible to the cooling effect of nearby blood vessels that act as a 'heat sink', limiting the extent of tissue ablation and forming lesions with asymmetric borders and 'skip lesions'. Therefore, it is difficult to monitor and accurately predict the size of ablated lesions. A novel bipolar radiofrequency ablation (BRFA) device has been recently developed to address concerns with monopolar systems (Trod Medical, Paris, France). The BRFA system addresses the limitations of monopolar RFA, in terms of lesion size, targeting, consistency and concerns about cell death in the ablated area. We evaluated the BRFA device in 10 patients undergoing laparoscopic partial or radical nephrectomy. The present study demonstrates the safety and efficacy of a novel BRFA device. A BRFA device can produce a defined reproducible lesion with a precise transition zone to normal tissue. The area of ablated tissue exhibited completely devitalized cells and precise transition zone. With these characteristics, the potential advantages of this new technology during RFA ablation of SRM include less collateral damage and more complete ablation without skip lesions. This has the potential to lower rates of local recurrence and reduce incidence of skin burns. Further follow-up studies are necessary to determine its oncological efficacy.
  
  
  OBJECTIVE
  To evaluate a novel bipolar radiofrequency ablation (BRFA) system for the destruction of kidney tumours in patients.
  
  
  METHODS
  Bipolar radiofrequency ablation (BRFA) was used to ablate renal masses in 10 patients undergoing laparoscopic radical or partial nephrectomy. The probe was placed percutaneously and laparoscopically guided into the tumour after routine laparoscopic exposure. The electrical current was continuously adjusted by the generator to overcome disruption from increasing impedance created from desiccated tissue. The specimens were then excised in routine fashion and analysed by a single pathologist. Lesion size and shape, and size of the transition zone to viable tissue were measured via nicotinamide adenine dinucleotide (NADH) staining.
  
  
  RESULTS
  Ablation was successful in all 10 tumours. Mean time to set up and place the probe was between 2 and 4 min. Duration of ablation was 200 s. None of the ablated tissue showed signs of viable cells by histological examination and NADH staining. The mean size of the ablation zone was 6.26 cm(3), with regular borders and a tapered cylindrical shape similar to the shape of the outer coil. The width of the transition zone, or area spanning complete tissue ablation to the first viable cells, ranged from 10 to 60 µm. There were no complications noted due to the ablation.
  
  
  CONCLUSIONS
  A BRFA device can produce a defined reproducible lesion with a precise transition zone to normal tissue. The area of ablated tissue exhibited completely devitalized cells and precise transition zone.
authors.affiliation: The Arthur Smith Institute for Urology, New Hyde Park, NY, USA.
authors.forename: Zhamshid
authors.initials: Z
authors.lastname: Okhunov
authors.forename: Ornob
authors.initials: O
authors.lastname: Roy
authors.forename: Brian
authors.initials: B
authors.lastname: Duty
authors.forename: Nikhil
authors.initials: N
authors.lastname: Waingankar
authors.forename: Amin
authors.initials: A
authors.lastname: Herati
authors.forename: Nora
authors.initials: N
authors.lastname: Morgenstern
authors.forename: Silvat
authors.initials: S
authors.lastname: Sheikh-Fayyaz
authors.forename: Louis R
authors.initials: LR
authors.lastname: Kavoussi
mesh_terms: D018249:Adenoma, Oxyphilic / Q000601:surgery*; D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000601:surgery*; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D007680:Kidney Neoplasms / Q000601:surgery*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control