Temporary liver blood-outflow occlusion increases effectiveness of radiofrequency ablation: an experimental study on pigs.

Aim: To evaluate the feasibility of liver blood outflow (LBOF) occlusion and its impact on the effectiveness of radiofrequency ablation (RFA).

Methods: The experiment was performed on 10 pigs. The animals were divided into groups A and B according to RFA protocol. In group A (n=5) the RFA time was that taken to reach the target temperature of 105 degrees C, whereas group B (n=5) had a constant RFA temperature of 105 degrees C and constant time of 8min. The liver blood flow (LBF) was quantified using Doppler ultrasonography before LBOF occlusion and after that. RFA were performed using an expandable 3cm RF needle. Two liver ablations created in different liver lobes were compared; the first ablation was created before balloon inflation and the second one was created under LBOF occlusion. The time required for RFA procedure, liver ablation volumes, shape and microscopic changes of the thermoablated zones were recorded.

Results: The LBF dropped significantly in all liver vessels after balloon inflation. The volume of the ablated area was 8.2+/-2.2cm(3) and increased significantly after LBOF occlusion to 17.4+/-3.8cm(3) (p<0.001), in group A. A significant enlargement of the ablated area with occluded LBF was registered in group B, it was 6.7+/-2.8cm(3) versus 19.4+/-1.8cm(3) respectively (p<0.01).

Conclusions: Temporary LBOF occlusion led to a significant reduction in liver blood flow, enlargement of the thermoablated area volume and homogeneity of the coagulated zones.