Intrahepatische Ablation: Radiofrequenzablation versus Elektrochemische Lyse

Background:Radio frequency ablation (RFA) and electrochemical treatment (ECT) are competing methods of intrahepatic ablation. We compared RFA and ECT in a perfusion model and in vivo in pigs. Material and Methods:Twenty-seven fresh porcine livers were obtained from a slaughterhouse and placed ex vivo into a perfusion model. RFA or ECT electrodes were inserted under ultrasound guidance in perivascular locations at a distance of 10mm from a portal vessel. A total of 83areas of ablation were created. In vivo ablations were performed at perivascular sites in 10 laparotomised pigs. Four areas of ablation were created per liver using RFA or ECL. Inflammatory parameters, liver values and cytokine levels were determined before and after surgery and on days1, 3 and 7 after surgery. On day7, the livers were harvested and specimens were analysed histologically by independent experts. Results:In 29% of 59ex vivo RFA ablations, the target temperature was not reached and the procedure was discontinued. Intact hepatocytes were detected in close proximity to 70% of the vesselswithin necrotic areas. In 24ECT applications, treatment time depended on the charge delivered and ranged between 50min at 150coulombs (C) and 200min at 600C. The pH level was 0.9 at the anode and 12.2 at the cathode. ECT always led to complete perivascular necrosis and vessel wall destruction. The animals had an in vivo median weight of 39.5kg. Neither RFA nor ECT caused major complications such as bleeding, bile leaks or abscesses. Treatment time was 67min (200C) for ECT and 12.4min for RFA. In 73% of the cases, RFA led to incomplete perivascular areas of necrosis. ECT induced complete perivascular necrosis and vessel wall destruction. On day1 after surgery, both ECT and RFA were associated with a significant increase in monocyte, C-reactive protein and aspartate aminotransferase levels. Leukocyte counts were elevated only after ECT, bilirubin levels only after RFA. There were no significant differences in interleukin-6 (IL-6), tumour necrosis factor- (TNF-) and IL-1. Conclusion:Both RFA and ECL are safe methods of intrahepatic ablation. As a result of a heat sink effect of blood flow in nearby vessels, RFA leads to incomplete necrosis in perivascular sites both ex vivo and in vivo. ECT has the disadvantage of long treatment times but the advantage of lower costs since the platinum electrodes are reusable. Without a reduction in liver perfusion, the central application of RFA in close proximity to vessels should be considered problematic.