[Experimental study of the effect of radiofrequency ablation with series of WHK-3 conformable electrode in ex vivo ox liver].

Objective: To evaluate the conformablity and quantization controllability of multi-cluster conformable radiofrequency ablation electrode by ex vivo animal experiment.

Methods: The subject using in this experiment were fresh ex vivo ox liver. The electrode we used were the series of WHK-3 (including WHK-3 I and II), which were design and made by Welfare Electronic Technological Company (Beijing). Each electrode had 6 sub-electrode on opposite side (A and B). Both A and B side could separately in different length and radian so to form asymmetric shape. The difference between WHK-3 I and II were the shaft of I are electric conductive while it of WHK-3 II were inconductive by coating with insulant material. Our subject were divide into 3 group. In group 1 we do radiofrequency ablation in ex vivo ox liver with both sub-electrode (WHK-3 I and II) fully spread out symmetrically, then the diameter of 3D cross section in zone of melt necrosis between type I and II were compared. In group 2 we do radiofrequency ablation in ex vivo ox liver with WHK-3 I while the two side of sub-electrode were spread out asymmetrically in different shapes. Then the diameter of cross section which were parallel to the electrode shaft in zone of melt necrosis in different sub-electrode shape were compared. In group 3 we do the test same way as in group 2 on WHK-3 II electrode.

Results: In group 1, there had no significant different between the diameter of melt necrosis zone in ex vivo ox liver with WHK-3 I and II (average around 6 x 6 x 3 cm(3)) while sub-electrodes were fully spread out symmetrically. In group 2, while sub-electrode in A side were fully spread and sub-electrode in B side were half spread, WHK-3 I electrode could form an asymmetric melt necrosis zone. The diameter on A side were 3.24 + or - 0.32 cm and it on B side were 1.87 + or - 0.24 cm. While only A side sub-electrode were spread out, the diameter on A side were nearly the same and it on B side were decreased to 1.55 + or - 0.16 cm. In group 3, while sub-electrode in A side were fully spread and sub-electrode in B side were half spread, WHK-3 II electrode could form an asymmetric melt necrosis zone too. The diameter on A side were 3.27 + or - 0.35 cm and it on B side were 1.65 + or - 0.23 cm. While only A side sub-electrode were spread out, the diameter on A side were nearly the same and it on B side were decreased even to 0.90 + or - 0.18 cm.

Conclusions: The series of WHK-3 could form an asymmetric melt necrosis zone in ex vivo tissue, which were more suitable to clinical usage. And both of them had quantization controllability, especially in WHK-3 II.