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

Abstract

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