The evaluation of different techniques of hepatic ablation in an ex-vivo perfused porcine liver model

Background: Electrolytic ablation (EA) is a technique of liver ablation that produces extreme pH changes in the local microenvironment. An ex-vivo perfused liver model compared EA vs. radiofrequency ablation (RFA) and analysed biochemical, immunological and histologic parameters. Methods: Seventeen pigs were perfused extracorporeally with normothermic autologous blood, five of which underwent RFA and five EA after one hour from reperfusion. Arterial, venous blood samples and histologic specimen were collected hourly and analysed for 1) arterial blood gases content, 2) biochemical parameters, 3) cytokines, 4) and tissue modifications. Results: No significant differences were registered among techniques for biochemical and immunologic parameters investigated. EA created a smaller transitional zone of ablation compared to RFA and histologically a particular pattern of changes in which the coagulative necrosis and hemorrhages affected mainly the peripheral area of the lobule, while the sinusoidal dilatations the centrilobular area. No significant changes were found for the apoptosis and the regeneration activity. Conclusions: Although results of the histological changes are interesting, the technical complexity of the ex-vivo model increased the number of parameters to monitor, especially concerning the liver viability and the administration of external substances to maintain a physiologic environment. Furthermore, the high portal vein pressures used and long warm ischemia times registered could have biased results. For the purpose of this study an in-vivo model would have been more appropriate.