title: Bipolar radiofrequency ablation: development of a new expandable device.
abstract: OBJECTIVE
  To test the performance of an expandable bipolar probe as a simple technical solution for extending the coagulation volume.
  
  
  METHODS
  On the basis of a commercially available monopolar radiofrequency (RF) probe (LeVeen), an expandable bipolar RF probe was developed by integrating a second electrode into the probe shaft. The influence of length on the second electrode, and the distance between both electrodes and generator output was investigated by performing ten ablations for each condition on a freshly excised bovine liver. Macroscopically quantified coagulation volumes, lesion shape characteristics, and procedure durations were recorded. Results of the prototype featuring the optimal configuration were compared to the original LeVeen probe and commonly used bipolar RF probe (CelonLabPower).
  
  
  RESULTS
  Extension of the shaft electrode length, increasing distance between the shaft electrode and the tip electrode, and reduction of generator output resulted in increasing coagulation volumes. The coagulation volumes the prototype generated were significantly smaller and more elliptically shaped than the monopolar probe (9.4 ± 1.5 cm(3) vs. 12.1 ± 1.6 cm(3)), but were larger than the commercially available bipolar RF probe (vs. 7.3 ± 0.5). The procedure duration of the prototype was comparable to the monopolar probe (467 ± 31 s vs. 464 ± 17 s) and shorter than the bipolar probe (vs. 2009 ± 444 s). In comparison to the commercially available bipolar system, the developed prototype exhibited favorable results.
  
  
  CONCLUSIONS
  The first benchmark testing of the developed bipolar prototype had promising results. However, further optimization of the applicator design and ablation protocol is needed to enlarge the achievable coagulation volume.
authors.affiliation: Department for Diagnostic Radiology, RWTH Aachen University, Aachen, Germany, nobutake@rad.med.keio.ac.jp.
authors.forename: Nobutake
authors.initials: N
authors.lastname: Ito
authors.forename: Jochen
authors.initials: J
authors.lastname: Pfeffer
authors.forename: Peter
authors.initials: P
authors.lastname: Isfort
authors.forename: Tobias
authors.initials: T
authors.lastname: Penzkofer
authors.forename: Christiane K
authors.initials: CK
authors.lastname: Kuhl
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Mahnken
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmitz-Rode
authors.forename: Philipp
authors.initials: P
authors.lastname: Bruners
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D002417:Cattle; D004867:Equipment Design; D066298:In Vitro Techniques; D008099:Liver / Q000601:surgery*; D011846:Radio Waves