The combination of radiofrequency ablation (RFA) with direct current (DC) is a promising strategy to improve the efficiency of RFA. However, DC-enhanced monopolar RFA is limited by electrolytic injury at the positive-electrode site. The aim of this study was to investigate the feasibility of the DC-enhanced bipolar RFA. To obviate the need for the subcutaneous positive electrode, the DC circuit was combined with a commercially available bipolar RFA system, in which both poles of the DC circuit are connected to a single RF probe. DC was applied for 15 min and followed by RFA in bovine livers using the following various DC currents: (1) no DC (control), (2) 3V continued until the end of RFA, (3) 5V continued until the end of RFA, (4) 10V continued until the end of RFA, (5) 5V continued in the circuit with reversed pole, (6) 3V stopped after initiation of RFA, and (7) 5V stopped. Coagulation volume, temperatures at a distance of 5, 10, and 15 mm from the RF probe, mean amperage, ablation duration, applied energy, minimum impedance, and degree of tissue charring were assessed and compared (analysis of variance, Student–Newman–Keuls test). All combined DC and RFA groups did increase coagulation volume. The 10V continued group showed significantly lower applied energy, shortest ablation duration, highest minimum impedance, and highest degree of charring with the lowest coagulation volume (p < 0.05). DC-enhanced bipolar RFA with both poles of the DC circuit on a single probe appears to be ineffective.
Radiofrequency ablation Liver tumor Direct current
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The authors acknowledge the excellent technical support of So-Hyun Park and Dennis Faßbänder.
Pereira PL, Trübenbach J, Schenk M et al (2004) Radiofrequency ablation: in vivo comparison of four commercially available devices in pig livers. Radiology 232:482–490PubMedCrossRefGoogle Scholar
Bruners P, Jochen P, Kazim RM et al (2007) A newly developed perfused umbrella electrode for radiofrequency ablation: an ex vivo evaluation study in bovine liver. Cardiovasc Intervent Radiol 30:992–998PubMedCrossRefGoogle Scholar
Tacke J, Mahnken A, Roggan A et al (2004) Multipolar radiofrequency ablation: first clinical results. Rofo 176:324–329PubMedGoogle Scholar
Bruners P, Schmitz-Rode T, Günther RW et al (2008) Multipolar hepatic radiofrequency ablation using up to six applicators: preliminary results. Rofo 180:216–222PubMedGoogle Scholar
Dobbins C, Wemyss-Holden SA, Cockburn J et al (2008) Bimodal electric tissue ablation―modified radiofrequency ablation with a Le Veen electrode in a pig model. J Surg Res 144:111–116PubMedCrossRefGoogle Scholar
Dobbins C, Brennan C, Wemyss-Holden SA et al (2008) Bimodal electric tissue ablation―long-term studies of morbidity and pathological change. J Surg Res 148:251–259PubMedCrossRefGoogle Scholar
Cockbum JF, Wemyss-Holden SA (2005) Initial results of a method of increasing the cytocidal radius of radiofrequency ablation needles. CIRSE Book of Abstracts 22.5.7Google Scholar
Cockburn JF, Maddern GJ, Wemyss-Holden SA (2007) Bimodal electric tissue ablation (BETA)―in vivo evaluation of the effect of applying direct current before and during radiofrequency ablation of porcine liver. Clin Radiol 62:213–220PubMedCrossRefGoogle Scholar
Tanaka T, Isfort P, Bruners P, et al. (2010) Optimization of direct current-enhanced radiofrequency ablation: an ex vivo study. Cardiovasc Intervent Radiol, doi:10.1007/s00270-010-9797-y
Wemyss-Holder SA, Dennison AR, Finch GJ et al (2002) Electrolytic ablation as an adjunct to liver resection: experimental studies of predictability and safety. Br J Surg 89:579–585CrossRefGoogle Scholar
Dobbins C, Brennan C, Simon A et al (2008) Bimodal electric tissue ablation: positive electrode studies. ANZ J Surg 78:568–572PubMedCrossRefGoogle Scholar
Bruners P, Mueller R, Guenther RW et al (2008) Fluid-modulated bipolar radiofrequency ablation: an ex-vivo evaluation study. Acta Radiol 49:258–266PubMedCrossRefGoogle Scholar
Bruners P, Lipka J, Guenther RW et al (2008) Bipolar radiofrequency ablation: is the shape of the coagulation volume different in comparison to monopolar RF-ablation using variable active tip lengths? Minim Invasive Ther Allied Technol 17:267–274PubMedCrossRefGoogle Scholar
Lee JM, Han JK, Kim SH (2005) Bipolar radiofrequency ablation using wet-cooled electrodes: an in vitro experimental study in bovine liver. AJR Am J Roentgenol 184:391–397PubMedGoogle Scholar
Lee JM, Han JK, Kim SH (2003) A comparative experimental study of the in vitro efficiency of hypertonic saline-enhanced hepatic bipolar and monopolar radiofrequency ablation. Korean J Radiol 4(3):163–169PubMedCrossRefGoogle Scholar
Roberge PR (2000) High-temperature corrosion: oxidation. In: Handbook of corrosion engineering. McGraw-Hill, New York, pp 238–245Google Scholar