Korean J Radiol.  2004 Dec;5(4):240-249. 10.3348/kjr.2004.5.4.240.

Radiofrequency Ablation of Rabbit Liver In Vivo: Effect of the Pringle Maneuver on Pathologic Changes in Liver Surrounding the Ablation Zone

• Kim SK
• Lim HK
• Ryu JA
• Choi DG
• Lee WJ
• Lee JY
• Lee JH
• Sung YM
• Cho EY
• Hong SM
• Kim JS

• KMID: 1118831
• DOI: http://doi.org/10.3348/kjr.2004.5.4.240

Abstract

OBJECTIVE
We wished to evaluate the effect of the Pringle maneuver (occlusion of both the hepatic artery and portal vein) on the pathologic changes in the hepatic vessels, bile ducts and liver parenchyma surrounding the ablation zone in rabbit livers. MATERIALS AND METHODS: Radiofrequency (RF) ablation zones were created in the livers of 24 rabbits in vivo by using a 50-W, 480-kHz monopolar RF generator and a 15-gauge expandable electrode with four sharp prongs for 7 mins. The tips of the electrodes were placed in the liver parenchyma near the porta hepatis with the distal 1 cm of their prongs deployed. Radiofrequency ablation was performed in the groups with (n=12 rabbits) and without (n=12 rabbits) the Pringle maneuver. Three animals of each group were sacrificed immediately, three days (the acute phase), seven days (the early subacute phase) and two weeks (the late subacute phase) after RF ablation. The ablation zones were excised and serial pathologic changes in the hepatic vessels, bile ducts and liver parenchyma surrounding the ablation zone were evaluated. RESULTS: With the Pringle maneuver, portal vein thrombosis was found in three cases (in the immediate [n=2] and acute phase [n=1]), bile duct dilatation adjacent to the ablation zone was found in one case (in the late subacute phase [n=1]), infarction adjacent to the ablation zone was found in three cases (in the early subacute [n=2] and late subacute [n=1] phases). None of the above changes was found in the livers ablated without the Pringle maneuver. On the microscopic findings, centrilobular congestion, sinusoidal congestion, sinusoidal platelet and neutrophilic adhesion, and hepatocyte vacuolar and ballooning changes in liver ablated with Pringle maneuver showed more significant changes than in those livers ablated without the Pringle maneuver (p < 0.05) CONCLUSION: Radiofrequency ablation with the Pringle maneuver created more severe pathologic changes in the portal vein, bile ducts and liver parenchyma surrounding the ablation zone compared with RF ablation without the Pringle maneuver. Therefore, we suggest that RF ablation with the Pringle maneuver should be performed with great caution in order to avoid unwanted thermal injury.

Keyword

Animals; Liver, interventional procedure; Radiofrequency (RF) ablation

MeSH Terms

Animals
Bile Ducts/*pathology/surgery
*Catheter Ablation
Disease Models, Animal
Hepatic Artery/*pathology/surgery
Liver/*blood supply/pathology/*surgery
Male
Necrosis
Portal Vein/pathology
Rabbits

Figure

• 

  Fig. 1 Photographs of gross specimens of rabbit livers resected immediately after radiofrequency ablation. A. Liver ablated without the Pringle maneuver. B. Liver ablated with the Pringle maneuver. The ablation zone (arrows) created with the Pringle maneuver (B) is substantially larger than that (arrows) of the A liver ablated without the Pringle maneuver (A).

• 

  Fig. 2 Photograph of a gross specimen of a rabbit liver resected three days (in the acute phase) after radiofrequency ablation with the Pringle maneuver. The dissected liver shows portal vein thrombosis (thin arrows) adjacent to the ablation zone (arrows).

• 

  Fig. 3 Gross specimen (A) and microphotograph (B) of a rabbit liver resected two weeks (in the late subacute phase) after radiofrequency ablation with the Pringle maneuver. A. Gross specimen shows tortuous dilatation of the bile duct (thin arrows) adjacent to the ablation zone (arrows). B. Microphotograph (H & E, ×40) shows the markedly dilated bile duct (arrows).

• 

  Fig. 4 Fresh gross specimen (A) and microphotograph (B) of a rabbit liver resected seven days (in the early subacute phase) after radiofrequency ablation with the Pringle maneuver. A. Fresh gross specimen shows a wedge shape infarction (thin arrows) adjacent to the ablation zone (arrows). B. Microphotograph (H & E, ×100) of the infarction exhibits coagulative necrosis of the hepatocytes with loss of nuclei and preservation of the general tissue architecture.

• 

  Fig. 5 Microphotographs (H & E, ×100) of the resected specimens obtained immediately after radiofrequency ablation. The microphotograph of the specimen ablated with the Pringle maneuver (B) shows the distended central vein (arrows) and sinusoids (thin arrows), suggesting congestion, while the central vein (arrows) and sinusoids are normal in the liver ablated without the Pringle maneuver (A).

• 

  Fig. 6 Microphotographs (H & E, ×400) of resected specimens obtained immediately after radiofrequency ablation. The microphotograph of the liver specimen ablated with the Pringle maneuver (B) shows mild proliferation of bile duct epithelium (arrows), whereas it is normal (arrows) in the liver ablated without the Pringle maneuver (A).

• 

  Fig. 7 Microphotographs (H & E, ×100) of resected specimens obtained after radiofrequency ablation with the Pringle maneuver. The microphotograph of the resected specimen obtained immediately after ablation (A) shows the distended portal vein (arrows), suggesting congestion, while the portal vein (arrows) is normal in the specimen obtained two weeks after ablation (B).

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