Assessment of hepatic microvascular flow and density in patients undergoing preoperative portal vein embolization

The microvascular effects occurring after unilateral preoperative portal vein embolization (PVE) are poorly understood. The aim of this study was to assess the microvascular changes in the embolized and the non-embolized lobes after right PVE.

Videos of the hepatic microcirculation in patients undergoing right hemihepatectomy following PVE were recorded using a handheld vital microscope (Cytocam) based on incident dark field imaging. Hepatic microcirculation was measured in the embolized and the non-embolized lobes at laparotomy, 3-6 weeks after PVE. The following microcirculatory parameters were assessed: total vessel density (TVD), microcirculatory flow index (MFI), proportion of perfused vessel (PPV), perfused vessel density (PVD), sinusoidal diameter (SinD) and the absolute red blood cell velocity (RBCv).

16 patients after major liver resection were included, 8 with and 8 without preoperative PVE. Microvascular density parameters were higher in the non-embolized lobes when compared to the embolized lobes (TVD: 40.3 ± 8.9 vs. 26.8 ± 4.6 mm/mm² (p < 0.003), PVD: 40.3 ± 8.8 vs. 26.7 ± 4.7 mm/mm² (p < 0.002), SinD: 9.2 ± 1.7 vs. 6.3 ± 0.8 μm (p < 0.040)). RBCv, PPV and the MFI were not significantly different.

The non-embolized lobe has a significantly higher microvascular density, however without differences in microvascular flow. These findings indicate increased angiogenesis in the hypertrophic lobe.