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.
Centre for the Study of Liver Disease and Departments of Surgery and Pathology, University of Hong Kong, Pokfulam, Hong Kong. kcng66@yahoo.com
Kelvin K
KK
Ng
Chi Ming
CM
Lam
Ronnie T
RT
Poon
Tony W
TW
Shek
David W
DW
Ho
Sheung Tat
ST
Fan
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