Changes in functional capacity after portal branch ligation in rats

Preoperative portal branch embolization is performed to increase residual liver lobe volume so that posthepatectomy liver insufficiency associated with major hepatic resection can be prevented. Although it is essential to evaluate functional liver capacity after portal branch embolization. the timing of hepatectomy from this viewpoint remains unelucidated. The aim of this study was to clarify the optimal timing of hepatectomy after portal branch embolization. We evaluated the functional capacity of the liver after portal branch ligation (PBL) in rats, and studied the correlation between morphological and functional changes. Morphological changes were evaluated on the basis of the liver lobe weight ratio, and the proliferating cell nuclear antigen labeling index. Functional changes were evaluated by the indocyanine green disappearance rate and serum aminopyrine clearance as functional capacity. Although the total liver weight ratio remained unchanged after PBL, the unembolized lobe ratio increased significantly. Although functional capacity was minimal 2 days after PBL, it had recovered to the preoperative value by 8 days after PBL. The functional capacity of the liver after PBL was minimal around the cellular proliferative period but recovered thereafter. These findings suggest that major hepatectomy after portal branch embolization should be perfomed following the cellular proliferative period of the unembolized lobe.