Portal vein embolization does not result in microvascular flow differences between the embolized and non-embolized liver lobes

Abstract

Background: Preoperative portal vein embolization (PVE) is used to increase future remnant liver volume enabling extended resections. The microvascular effects occurring after unilateral portal venous occlusion are however, poorly understood. The aim of this study is to assess the microvascular changes in the liver lobes after right PVE. Methods: Videos of the hepatic microcirculation in patients undergoing right hemihepatectomy following PVE were recorded using a handheld intravital microscope, the CytoCam. Hepatic microcirculation was measured in the embolized and the non-embolized lobe after laparotomy. AVA software v. 3.2 was used to obtain the microcirculatory parameters: total vessel density (TVD), microcirculatory flow index (MFI), proportion of perfused vessel (PPV), perfused vessel density (PVD). Results: Five patients were included after PVE (3 males, 2 females, age 66±5 years). TVD and PVD in the non-embolized lobe were significantly increased compared to TVD and PVD in the embolized lobe (i.e. 31.47±2.7 19.7±5.9 mm/mm2P:0.0159). PPV and MFI were not significantly different between the lobes indicating similar microvascular flow despite the difference in vessel density. Conclusion: The non-embolized lobe has a significantly higher microvascular density (TVD and PVD), however without differences in microvascular flow (PPV and MFI). The overall microvascular flow is not affected by PVE which casts doubts on the portal flow differential in inducing the hypertrophy response in the non-embolized lobes.