Purpose
Although reducing hepatic blood flow with continuous hepatic vein balloon occlusion during RF ablation has been shown to increase the quality of ablation, a consensus has yet to be reached as to the best way to achieve this effect. Intermittent hepatic vein balloon occlusion was performed to study its effects on coagulation necrosis and its potential efficacy on maintaining vessel patency.
Purpose
Although reducing hepatic blood flow with continuous hepatic vein balloon occlusion during RF ablation has been shown to increase the quality of ablation, a consensus has yet to be reached as to the best way to achieve this effect. Intermittent hepatic vein balloon occlusion was performed to study its effects on coagulation necrosis, local tumor recurrence, and its potential efficacy on maintaining vessel patency.
Material and methods
Eight non-anticoagulated patients with primary (n=2) and metastatic (n=6) liver tumors having a mean diameter of 4.2 cm (range 2.4-6.5 cm) were treated. The mean distance of the peritumoral vessels from the lesion was 1.56 mm (range 0-6.50 mm). The mean diameter of balloon occluded vessels was 7.1 mm (range 4.1-9.0 mm). Intermittent balloon occlusion was performed for a period of 12 minutes per needle location. During this time, the balloon was inflated for an arbitrarily selected time of three minutes to impede hepatic venous flow and then deflated for 1 minute to maintain patency of the hepatic vein and perfusion to normal liver tissue, in cycles throughout the RF ablation.
Material and methods
Eight non-anticoagulated patients with primary (n=2) and metastatic (n=6) liver tumors having a mean diameter of 4.2 cm (range 2.4-6.5 cm) were treated. The mean distance of the peritumoral vessels from the lesion was 1.56 mm (range 0-6.50 mm). The mean diameter of balloon occluded vessels was 7.1 mm (range 4.1-9.0 mm). Intermittent balloon occlusion was performed for a period of 12 minutes per needle location. During this time, the balloon was inflated for an arbitrarily selected time of three minutes to impede hepatic venous flow and then deflated for 1 minute to maintain patency of the hepatic vein and perfusion to normal liver tissue, in cycles throughout the RF ablation. One patient had the balloon inflated for the full 12 minute ablation due to tumor invasion of vein and the desire to thrombose and coagulate the vein. Examples are also shown of RF ablation combined with chemoembolization, portal vein coil embolization, and the Pringle maneuver.
Results
Six of ten (60%) of the balloon-occluded hepatic veins were patent. No clinical sequelae of hepatic vein thrombosis were noted. All thromboses were evident at first imaging follow-up. Balloon occlusion resulted in ablations with a mean diameter of 6.3 cm (range 4.3-9.3 cm). The mean length of follow-up with CT and/or MRI was 12 months (range 3-38 months). Local tumor control was achieved in 5 of 8 patients, despite large vessel proximity. Two of three patients without local control had tumors touching the portal vein.
Results
Six of ten (60%) of the balloon-occluded hepatic veins were patent. No clinical sequelae of hepatic vein thrombosis were noted. All thromboses were evident at first imaging follow-up. Balloon occlusion resulted in ablations with a mean diameter of 6.3 cm (range 4.3-9.3 cm). The mean length of follow-up with CT and/or MRI was 12 months (range 3-38 months). Local tumor control was achieved in 5 of 8 patients, despite large vessel proximity. Two of the three patients without local control had tumors touching both the portal and hepatic veins while the third patient had a tumor touching an accessory hepatic vein.
Conclusion
Exactly how the technique of intermittent occlusion compares to continuous balloon occlusion (in terms of treatment volumes and occlusion rates) is unknown. The rationale for intermittent balloon occlusion was an attempt to balance the risk for thrombosis with the benefit of obtaining complete tumor necrosis. An alternative approach may be to study various intermittent occlusion periods (i.e. 3, 5, and 10 minutes) and its effects on ablation diameter. The optimal methodology of achieving large ablation diameters is yet to be proven, and the pathophysiology of balloon occlusion requires further investigation.