Effect of vascular occlusion on radiofrequency ablation of the liver: Results in a porcine model

OBJECTIVE. This study determined the effect of vascular occlusion on radiof requency lesion shape, volume. and temperature in a porcine liver model. SUBJECTS AND METHODS. Radiofrequency lesions (n = 33) were created in the l ivers of six domestic pigs in vivo using a multiprong radiofrequency electr ode. Lesions were randomly assigned to one of four vascular occlusion group s: portal vein, hepatic artery, Pringle maneuver (both hepatic artery and p ortal vein), or no occlusion, Radiofrequency parameters were time, 7 min: p ower. 50 W: and target temperature, 100 degreesC, Temperatures were measure d 5, 10, and 15 mm from the electrode. After the animals were sacrificed, t he lesions were excised. Lesion volume, diameter, and shape; maximum temper ature: and time exposed to lethal temperatures (42-60 degreesC) were determ ined. RESULTS. Lesion volume was greatest with the Pringle maneuver lesions (12.6 +/- 4.8 cm(3)), followed by occlusion of the portal vein (8.6 +/- 3.8 cm(3 )), occlusion of the hepatic artery (7.6 +/- 2.9 cm(3)), and no occlusion ( 4.3 +/- 1.0 cm(3)) (p < 0.05). Maximum lesion diameter was similar with the Pringle maneuver (3.3 +/- 0.3 cm), the portal vein (3.3 +/- 0.2 cm), and t he hepatic artery (3.2 +/- 0.2 cm) groups compared with no occlusion (2.6 /- 1.0 cm) (p < 0.05). Minimum lesion diameter ranged from 2.9 cm for Pring le maneuver lesions to 1.0 cm for lesions with no occlusion (p < 0.05). Vas cular occlusion increased the lime tissue was exposed to lethal temperature s (>42-60 degreesC) and created more spherical lesions than no occlusion, CONCLUSION. Vascular occlusion combined with radiofrequency ablation increa ses the volume of necrosis, creates a more spherical lesion. and increases the time tissue is exposed to lethal temperatures when compared with radiof requency alone. Most of this vascular occlusion effect could be accomplishe d with hepatic artery occlusion alone.