Comparison of internally cooled wet electrode and hepatic vascular inflow occlusion method for hepatic radiofrequency ablation

Abstract

Background/aims: Various strategies to expand the ablation zone have been attempted using hepatic radiofrequency ablation (RFA). The optimal strategy, however, is unknown. We compared hepatic RFA with an internally cooled wet (ICW) electrode and vascular inflow occlusion.

Methods: EIGHT DOGS WERE ASSIGNED TO ONE OF THREE GROUPS: only RFA using an internally cooled electrode (group A), RFA using an ICW electrode (group B), and RFA using an internally cooled electrode with the Pringle maneuver (group C). The ablation zone diameters were measured on the gross specimens, and the volume of the ablation zone was calculated.

Results: The ablation zone volume was greatest in group B (1.82±1.23 cm(3)), followed by group C (1.22±0.47 cm(3)), and then group A (0.48±0.33 cm(3)). The volumes for group B were significantly larger than the volumes for group A (p=0.030). There was no significant difference in the volumes between groups A and C (p=0.079) and between groups B and C (p=0.827).

Conclusions: Both the usage of an ICW electrode and hepatic vascular occlusion effectively expanded the ablation zone. The use of an ICW electrode induced a larger ablation zone with easy handling compared with using hepatic vascular occlusion, although this difference was not statistically significant.

Keywords: Catheter ablation; Liver.

Fig. 1

The radiofrequency needle electrode system. (A) Diagram of the internally cooled electrode system. Chilled saline is circulated during ablation for internal cooling. The arrows indicate the direction of the saline flow. (B) Diagram of the internally cooled wet (ICW) electrode system. The microhole on the needle surface allows the saline to be infused into the tissue (dotted line). (C) Photograph showing an 18-gauge ICW electrode with a 1-cm active tip and a microhole on the needle electrode (Jet tip®) with a saline jet through the microhole.

Fig. 2

Comparison of the radiofrequency ablation (RFA) zone volume between the groups. There were significant differences in the RFA zone volumes between groups A and B (p=0.030). There were no significant differences between groups B and C (p=0.827) or between groups A and C (p=0.079). The volume of the RFA zone in group B showed more variation compared with the volume of group C.