title: Large hepatic ablation with bipolar saline-enhanced radiofrequency: an experimental study in in vivo porcine liver with a novel approach.
abstract: BACKGROUND
  Radiofrequency ablation (RFA) is a relatively new technology for the local destruction of liver tumors. Development of recent devices has enabled the creation of larger lesions. Nevertheless, treating liver tumors larger than 2.5 cm in diameter often requires multiple overlapping ablations to encompass the tumor and the surrounding healthy tissue rim with an increasing risk of local recurrence.
  
  
  METHODS
  RFA (480 kHz) of the liver using our method was undertaken on a total number of 15 healthy farm pigs with (Group B, n = 8) or without (Group A, n = 5) the Pringle maneuver via laparotomy. The pigs were followed and euthanized on the seventh day of the experiment. Livers were removed for histological assessment. Time of the procedure, impedance, current, power output, energy output, temperatures in the liver, central temperature of the animal, volume size of the lesion, and delivered energy per lesion volume were determined and compared among groups. Additionally a regularity ratio (RR) was determined by gross examination of the specimen and scored (0-3) taking into account regularity and predictability of the ablation with pathologic assessment.
  
  
  RESULTS
  With both methods, ellipsoid lesions were created between the two probes. In both groups tissue impedance fell with time (r = -0.47, P < 0.01 and r = -0.34, P < 0.05, in Groups A and B, respectively). The mean lesion size achieved with the Pringle maneuver was the largest lesion size described in the literature for any RFA method in vivo and was greater in Group B than in Group A (123.22 cm(3) +/- 49.62 and 52.40 cm(3) +/- 23.59, respectively, P < 0.05). A better regularity and predictability evaluated by RR was observed in Group B compared to Group A (1.88 +/- 1.35 and 0.40 +/- 0.55, respectively, P < 0.05). Five major complications were described and attributed primarily to failure in isolation from hypertermic lesions.
  
  
  CONCLUSIONS
  Our new bipolar saline-enhanced electrode with Pringle maneuver achieves large hepatic ablations in in vivo pig liver. These large lesions are well-tolerated by the animal when thermal injuries to adjacent structures are avoided.
authors.affiliation: Department of Surgery A, Hospital Cli;nico Universitario Lozano Blesa, Zaragoza, Spain. fburdio@comll.es <fburdio@comll.es>
authors.forename: Fernando
authors.initials: F
authors.lastname: Burdío
authors.forename: Antonio
authors.initials: A
authors.lastname: Güemes
authors.forename: José M
authors.initials: JM
authors.lastname: Burdío
authors.forename: Ana
authors.initials: A
authors.lastname: Navarro
authors.forename: Ramón
authors.initials: R
authors.lastname: Sousa
authors.forename: Tomás
authors.initials: T
authors.lastname: Castiella
authors.forename: Ignacio
authors.initials: I
authors.lastname: Cruz
authors.forename: Olga
authors.initials: O
authors.lastname: Burzaco
authors.forename: Xavier
authors.initials: X
authors.lastname: Guirao
authors.forename: Ricardo
authors.initials: R
authors.lastname: Lozano
mesh_terms: D000818:Animals; D004566:Electrodes; D006498:Hepatectomy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D008099:Liver / Q000473:pathology; D016634:Radiosurgery / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D012965:Sodium Chloride / Q000627:therapeutic use*; D013552:Swine
chemical_list: D012965:Sodium Chloride