Hepatic lesion ablation with bipolar saline-enhanced radiofrequency in the audible spectrum

The authors' purpose was to create larger and more regular liver lesions in vitro by testing a new hyperthermia approach that uses a bipolar salineenhanced electrode for radiofrequency (RF) in the audible spectrum and a greater power supply. The authors' hyperthermia approach (group A, n = 23) was used in excised porcine livers, and the results were compared with those of a previously described monopolar saline-enhanced electrode procedure (group B, n = 23). In each set of experiments, RF in the audible spectrum current (50 Hz) was provided for 15 minutes with a similar ablation protocol. Electrical variables (impedance, current, voltage, power, and energy), temperatures in the lesions, volume size, regularity ratio of the lesion, and microscopic findings were measured. In group A, the mean volume size and the mean regularity ratio values were 144.8 cm 3 ± 59.8 and 0.78 ± 0.1, respectively. In group B, the mean volume size and regularity ratio values were 62.1 cm 3 ± 36.4 and 0.62 ± 0.1, respectively. The values in group B were thus significantly lower than those in group A ( P < .01). The lesions in group A were also more homogeneous. No significant differences were found in electrical variables. The new bipolar saline-enhanced electrode produced larger, more regular, and more homogeneous lesions ex vivo than the previously used monopolar saline-enhanced electrode method. Using a greater power supply increased the amount of coagulative necrosis.