title: Effects of vascular perfusion on coagulation size in radiofrequency ablation of ex vivo perfused bovine livers.
abstract: OBJECTIVE
  A standardized perfused ex vivo bovine liver model was used to evaluate the effect of organ perfusion on coagulation size and energy deposition during radiofrequency ablation (RFA) procedures.
  
  
  METHODS
  Bovine livers were perfused in a tank after rinsing the prepared liver vessels with anticoagulants. Tyrode's solution, oxygenated and heated to 36.5 degrees C, was used as perfusion medium. A flow and pressure controlled pump regulated Portal vein circulation; a dialysis machine provided pulsatile arterial circulation. Impedance-guided radiofrequency ablations were performed with 4-cm LeVeen electrodes with and without underlying liver perfusion. Two-dimensional diameters (Dv, Dh) of each ablation area were measured after dissecting the livers.
  
  
  RESULTS
  In 4 bovine livers weighing 8.85 +/- 0.83 kg per organ (min, 7.7 kg; max, 9.7 kg) altogether 40 RF ablations were performed. A total of 20 ablations were generated with underlying liver perfusion (group 1) and 20 ablations with no liver perfusion (group 2). In group 1, Dv was 28.4 +/- 5.3 mm, Dh 38.6 +/- 7.8 mm, and energy deposition 36.9 +/- 18.0 kJ. The 20 ablation areas generated without liver perfusion displayed statistically significant differences, with Dv being 35.7 +/- 6.5 mm (P = 0.001), Dh 49.5 +/- 9.4 mm (P = 0.001), and energy deposition 25.5 +/- 13.0 kJ (P = 0.018).
  
  
  CONCLUSIONS
  The model reproduced the cooling effect of perfused tissue during RFA. The ablation areas produced under perfusion conditions had smaller diameters despite longer exposure times and higher energy deposition.
authors.affiliation: Department of Orthopaedics, University of Heidelberg, Germany.
authors.forename: Rudi Georg
authors.initials: RG
authors.lastname: Bitsch
authors.forename: Markus
authors.initials: M
authors.lastname: Düx
authors.forename: Thomas
authors.initials: T
authors.lastname: Helmberger
authors.forename: Andreas
authors.initials: A
authors.lastname: Lubienski
mesh_terms: D000818:Animals; D001777:Blood Coagulation; D017115:Catheter Ablation / Q000379:methods; D002417:Cattle; D066298:In Vitro Techniques; D008099:Liver / Q000473:pathology* / Q000601:surgery; D010477:Perfusion / Q000379:methods*