Safety limit of large-volume hepatic radiofrequency ablation in a rat model.
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.


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


METHODS
Experimental study.


METHODS
University teaching hospital.


METHODS
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.


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


RESULTS
In the normal liver groups, the concentrations of TNF-alpha and IL-6 were significantly elevated in the early postoperative period when 50% (mean +/- SD TNF-alpha concentration, 130.3 +/- 15.6 pg/mL; mean +/- SD IL-6 concentration, 163.2 +/- 12.2 pg/mL) and 60% (mean +/- SD TNF-alpha 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-alpha 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-alpha 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.
Ng
Kelvin K
KK
Centre for the Study of Liver Disease and Departments of Surgery and Pathology, University of Hong Kong, Pokfulam, Hong Kong. kcng66@yahoo.com
Lam
Chi Ming
CM
Poon
Ronnie T
RT
Shek
Tony W
TW
Ho
David W
DW
Fan
Sheung Tat
ST
D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D015850:Interleukin-6 / Q000032:analysis; D008106:Liver Cirrhosis, Experimental / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D010976:Platelet Count; D011184:Postoperative Period; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D014914:Whole Blood Coagulation Time
D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha