Comparison of Wet Radiofrequency Ablation with Dry Radiofrequency Ablation and Radiofrequency Ablation Using Hypertonic Saline Preinjection: Ex Vivo Bovine Liver

Abstract

ObjectiveWe wished to compare the in-vitro efficiency of wet radiofrequency (RF) ablation with the efficiency of dry RF ablation and RF ablation with preinjection of NaCl solutions using excised bovine liver.Materials and MethodsRadiofrequency was applied to excised bovine livers in a monopolar mode for 10 minutes using a 200 W generator and a perfused-cooled electrode with or without injection or slow infusion of NaCl solutions. After placing the perfused-cooled electrode in the explanted liver, 50 ablation zones were created with five different regimens: group A; standard dry RF ablation, group B; RF ablation with 11 mL of 5% NaCl solution preinjection, group C; RF ablation with infusion of 11 mL of 5% NaCl solution at a rate of 1 mL/min, group D; RFA with 6 mL of 36% NaCl solution preinjection, group E; RF ablation with infusion of 6 mL of 36% NaCl solution at a rate of 0.5 mL/min. In groups C and E, infusion of the NaCl solutions was started 1 min before RF ablation and then maintained during RF ablation (wet RF ablation). During RF ablation, we measured the tissue temperature at 15 mm from the electrode. The dimensions of the ablation zones and changes in impedance, current and liver temperature during RF ablation were then compared between the groups.ResultsWith injection or infusion of NaCl solutions, the mean initial tissue impedance prior to RF ablation was significantly less in groups B, C, D, and E (43-75 Ω) than for group A (80 Ω) (p < 0.05). During RF ablation, the tissue impedance was well controlled in groups C and E, but it was often rapidly increased to more than 200 Ω in groups A and B. In group D, the impedance was well controlled in six of ten trials but it was increased in four trials (40%) 7 min after starting RF ablation. As consequences, the mean current was higher for groups C, D, and E than for the other groups: 401 ± 145 mA in group A, 287 ± 32 mA in group B, 1907 ± 96 mA in group C, 1649 ± 514 mA in group D, and 1968 ± 108 mA in group E (p < 0.05). In addition, the volumes of RF-induced coagulation necrosis were greater in groups C and E than in group D, which was greater than in groups A and B than in group E (p < 0.05); 14.3 ± 3.0 cm3 in group A; 12.4 ± 3.8 cm3 in group B; 80.9 ± 9.9 cm3 in group C; 45.3 ± 11.3 cm3 in group D and 81.6 ± 8.6 cm3 in group E. The tissue temperature measured at 15 mm from the electrode was higher in groups C, D and E than other groups (p < 0.05): 53 ± 12℃ in group A, 42 ± 2℃ in group B, 93 ± 8℃ in group C; 79 ± 12℃ in group D and 83 ± 8℃ in group E.ConclusionWet RF ablation with 5% or 36% NaCl solutions shows better efficiency in creating a large ablation zone than does dry RF ablation or RF ablation with preinjection of NaCl solutions.

Expansion of radiofrequency ablation volume by saturated NaCL saline injection in the area of vaporization

“…In addition, the technique described in the present study would be safer than the previously described method that involves continuous infusion of saline during RF application using open-perfused electrodes (8).…”

Think Before You Inject

“…In the fields of cardiology and radiology, fluid preinjection has been studied with cooled RF technology, and in these models, specific fluids have been shown to significantly influence final lesion size. [12][13][14][15] Goldberg et al 12 demonstrated that preinjection of sodium chloride (NaCl) solution before RF ablation increases energy deposition, tissue heating, and lesion size. However, Goldberg et al 12 also revealed that there is a limit to size enhancement.…”

Bimodal Electric Tissue Ablation-Modified Radiofrequency Ablation with a Le Veen Electrode in a Pig Model

“…It is hypothesized that if desiccation and charring could be prevented or at least delayed, the size of the ablation zone could be increased. Experiments with preinjecting the tissue to be ablated with hypertonic saline and the development of perfusion needle electrodes that allow infusion of saline through them into the tissues have shown modest improvements in the size of the ablative zones [20,21].…”