Influence Of Heat Irrigating Effect Of Radiofrequency Ablation On Regional Liver Tissue

Background and Objective: Heat irrigating effect of radiofrequency ablation(RFA) has been put forward for some time. However, there are few research on it. The preliminary study observed the existence of heat irrigating effect of radiofrequency ablation as long as there is large uncertainty. Besides, the specific effect on liver tissue is still unknown. This research explored the influence of heat irrigating effect of radio frequency ablation on liver tissue of Bama miniature pig.Methods: Eight Bama miniature pigs were randomly divided into observation group(group A)and control group(group B), four pigs per group. RFA electrode needle were implanted near(RFA electrode tips were 3-5mm far from the hepatic lobe portal venous) the hepatic lobe vascular under the guidance of ultrasound for group A, while RFA electrode needle were implanted far from(RFA electrode tips were 8-10mm far from the hepatic lobe portal venous)the hepatic lobe vascular under the guidance of ultrasound for group B. The left lateral lobe and right median lobe were chosen as RFA site for each pig. RFA was performed at each site on day one and day eight, respectively, lasting twelve minutes per ablation. The general situation and complications were observed during and after operation. The pigs were sacrificed and the livers were removed immediately after radiofrequency ablation at day eight.The samples was roughly checked up. HE staining, Ki67 staining and TUNEL detection were made with the tissue sections.Results: All the animals were successfully performed ultrasound guided radiofrequency ablation. No serious complications such as massive hemorrhage, biliary fistula, severe pleural effusion, hematopneumothorax, peripheral organ injury or renal failure occurred in all the animals during perioperative period. The radiofrequency ablation lesion was spherical. Liver tissue around the ablation portal vein and its distal area of Group A showed obvious change of thermal damage in HE staining. While Group B showed no obvious change of thermal damage in the same area. Difference of the Suzuki score of the above area between Group A and Group B was statistically significant (P<0.05). More apoptotic cells can be seen in liver tissue around the ablation portal vein and its distal area of Group A. While little apoptotic cells can be seen when it concerns to Group B in the same area. Difference of the apoptotic index of the above area between Group A and Group B was statistically significant (P<0.05).Ki67 staining positive cells can be seen in liver tissue around the ablation portal vein and its distal area of Group A. While no Ki67 staining positive cell can be seen in Group B.Difference of Ki67 staining positive index of the above area between Group A and Group B was statistically significant (P<0.05).Conclusion: When the radiofrequency ablation electrode tip is close to(<5mm) the portal vein, changes of thermal damage occur in the liver tissue around the ablation portal vein and its distal area because of heat irrigating effect.