Measurement of intrahepatic pressure during radiofrequency ablation in porcine liver.
OBJECTIVE
To identify the most effective procedures to avoid increased intrahepatic pressure during radiofrequency ablation, we evaluated different ablation methods.


METHODS
Laparotomy was performed in 19 pigs. Intrahepatic pressure was monitored using an invasive blood pressure monitor. Radiofrequency ablation was performed as follows: single-step standard ablation; single-step at 30 W; single-step at 70 W; 4-step at 30 W; 8-step at 30 W; 8-step at 70 W; and cooled-tip. The array was fully deployed in single-step methods. In the multi-step methods, the array was gradually deployed in four or eight steps. With the cooled-tip, ablation was performed by increasing output by 10 W/min, starting at 40 W.


RESULTS
Intrahepatic pressure was as follows: single-step standard ablation, 154.5 +/- 30.9 mmHg; single-step at 30 W, 34.2 +/- 20.0 mmHg; single-step at 70 W, 46.7 +/- 24.3 mmHg; 4-step at 30 W, 42.3 +/- 17.9 mmHg; 8-step at 30 W, 24.1 +/- 18.2 mmHg; 8-step at 70 W, 47.5 +/- 31.5 mmHg; and cooled-tip, 114.5 +/- 16.6 mmHg. The radiofrequency ablation-induced area was spherical with single-step standard ablation, 4-step at 30 W, and 8-step at 30 W. Conversely, the ablated area was irregular with single-step at 30 W, single-step at 70 W, and 8-step at 70 W. The ablation time was significantly shorter for the multi-step method than for the single-step method.


CONCLUSIONS
Increased intrahepatic pressure could be controlled using multi-step methods. From the shapes of the ablation area, 30-W 8-step expansions appear to be most suitable for radiofrequency ablation.
Kawamoto
Chiaki
C
Department of Gastroenterology and Hepatology, Saitama Medical Center, Saitama Medical University, 1981 Tsujido-machi, Kamoda, Kawagoe, Saitama 350-8550, Japan. kawamoto.c@vesta.ocn.ne.jp
Yamauchi
Atsushi
A
Baba
Yoko
Y
Kaneko
Keiko
K
Yakabi
Koji
K
D000818:Animals; D001794:Blood Pressure; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D007813:Laparotomy / Q000379:methods; D008099:Liver / Q000098:blood supply / Q000601:surgery*; D008102:Liver Circulation; D013552:Swine