title: Decreased portal flow volume increases the area of necrosis caused by radio frequency ablation in pigs.
abstract: OBJECTIVE
  Although radio frequency ablation (RFA) has been widely accepted as an effective treatment for hepatocellular carcinoma (HCC), severe complications are not uncommon. Major complications seem to occur as a result of over-ablation beyond the intended area. As most patients with HCC have underlying cirrhosis, we speculated that decreased portal flow might cause the necrosis associated with RFA. To confirm this hypothesis, we examined the area of necrosis resulting from RFA under varying conditions of portal flow in a porcine model.
  
  
  METHODS
  RFA was performed using ultrasonographic guidance in anesthetized pigs. During the RFA procedure, portal flow was regulated by a balloon catheter, which was set in a portal trunk. The necrosis area was measured after sacrifice and was compared with the hyperechoic area that appeared during ablation. In another session, RFA was performed close to the hepatic vein and endothelial damage was examined.
  
  
  RESULTS
  The necrosis area caused by RFA was significantly larger when the portal flow volume was decreased by 50% or more. The hyperechoic lesion was always larger than the area of pathological necrosis regardless of portal flow volume. Under conditions of decreased portal flow, the vessel endothelium near the ablated area was more readily damaged.
  
  
  CONCLUSIONS
  Decreased portal flow volume resulted in enlargement of the area of necrosis caused by RFA. Our results indicate that over-ablation could easily occur in patients with advanced cirrhosis, and that this could lead to major complications. Ultrasonographic guidance may be helpful for avoiding over-ablation.
authors.affiliation: Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yoshimoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kotoh
authors.forename: Yuki
authors.initials: Y
authors.lastname: Horikawa
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Kohjima
authors.forename: Shusuke
authors.initials: S
authors.lastname: Morizono
authors.forename: Shinsaku
authors.initials: S
authors.lastname: Yamashita
authors.forename: Munechika
authors.initials: M
authors.lastname: Enjoji
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakamuta
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D017115:Catheter Ablation / Q000009:adverse effects; D005260:Female; D008099:Liver / Q000473:pathology / Q000601:surgery*; D009336:Necrosis; D011169:Portal Vein / Q000473:pathology / Q000502:physiology*; D012039:Regional Blood Flow; D034421:Sus scrofa