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Original Article
March 1, 2006

Safety Limit of Large-Volume Hepatic Radiofrequency Ablation in a Rat Model

Author Affiliations

Author Affiliations: Centre for the Study of Liver Disease (Drs Ng, Lam, Poon, Shek, and Fan and Mr Ho) and Departments of Surgery (Drs Ng, Lam, and Poon and Mr Ho) and Pathology (Dr Shek), University of Hong Kong, Pokfulam, Hong Kong.

Arch Surg. 2006;141(3):252-258. doi:10.1001/archsurg.141.3.252
Abstract

Background  Large-volume hepatic radiofrequency ablation (RFA) has been used to treat large liver tumors, but its safety limit is unknown. This study aimed to investigate the possible systemic responses of large-volume hepatic RFA and to estimate its safety limit in normal and cirrhotic rats.

Hypothesis  Large-volume hepatic RFA causes a significant systemic inflammatory reaction.

Design  Experimental study.

Setting  University teaching hospital.

Intervention  Using the Cool-tip RF System (Radionics, Burlington, Mass), RFA was performed for different percentages of the liver volume by weight in normal and cirrhotic Sprague-Dawley rats.

Main Outcome Measures  Changes in concentrations of serum inflammatory markers (tumor necrosis factor α [TNF-α] and interleukin [IL] 6), functions of various end organs, and survival rates were assessed.

Results  In the normal liver groups, the concentrations of TNF-α and IL-6 were significantly elevated in the early postoperative period when 50% (mean ± SD TNF-α concentration, 130.3 ± 15.6 pg/mL; mean ± SD IL-6 concentration, 163.2 ± 12.2 pg/mL) and 60% (mean ± SD TNF-α concentration, 145.7 ± 13.0 pg/mL; mean ± SD IL-6 concentration, 180.8 ± 11.0 pg/mL) of the liver volume were ablated compared with the control group (mean ± SD TNF-α concentration, 30.4 ± 9.9 pg/mL, P<.001; mean ± SD IL-6 concentration, 28.4 ± 6.7 pg/mL, P<.001). The concentrations of TNF-α and IL-6 in other groups remained similar to those in the control group. Thrombocytopenia, prolonged clotting time, and interstitial pneumonitis occurred when 50% and 60% of the liver volume were ablated. The 4-week survival rates were 100%, 60%, and 0% when 40%, 50%, and 60%, respectively, of the liver volume were ablated. Similar systemic inflammatory responses and poor survival rates were observed among the cirrhotic liver groups when 30% and 40% of the liver volume were ablated.

Conclusions  The normal rats can tolerate RFA of 40% of the liver volume with minimal morbidity and no mortality whereas the cirrhotic rats can only tolerate 20% of the ablated liver volume. Beyond that limit, RFA would cause significant systemic inflammatory responses and poor survival.

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