gms | German Medical Science

Introduction: The need for precise experimental-surgical procedures parallels the development of clinical hepatobiliary-surgery rising. Currently intra-hepatic size regulation became a clinical relevant topic since it was observed that Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy (ALPPS) in contrast to simples portal vein occlusion leads to a faster increase in the portally occluded lobe.

The intra-hepatic vascular anatomy in rodents, its variations and corresponding supplying and draining territories in respect to the lobar structure of the liver has not yet been described. We performed a detailed anatomical imaging study in rats and mice to allow for further refinement of experimental surgical approaches.

Material and methods: 15 LEWIS-rats and 10 C57Bl/6N-mice were subjected to imaging using CT-or MRI-technology. 2D scan-data were used for segmentation of intra-hepatic vascular tree as prerequisite for 3D-visualization. 3D-reconstruction was needed for an analysis of the vascular anatomy and for determination of shape and volume of the dependent portal vein (PV) and hepatic vein (HV) territories.

Results: Variations in hepatic vascular anatomy were observed in terms of branching pattern and of distance of branches to each other in rats, but not in mice.

PV: In the majority of the cases the right inferior lobe was not only supplied by a single right inferior portal vein (4/15 cases) as expected, but received additional blood supply through a branch of the right superior portal vein (11/15 cases). This is of surgical relevance when ligate the right-superior PV prior to resection of the right-superior lobe. The right inferior lobe can lead to atrophy and in case of simultaneous ligation of the corresponding branch of the hepatic artery to necrosis of the right inferior lobe.

The portal vein stem divided into right-median PV and left portal stem, which divided into left-median and left-lateral PV. The length of the left portal stem before the division into left-median and left PV was highly variable. In case of a short left portal stem with a wide space between left-median PV and left-lateral PV resection of the left lateral lobe requires a simple ligation of the narrow base of the lobe. In case of a long left portal stem with little space between left-median PV and left-lateral PV, resection of the left lateral lobe can be easily complication by accidental ligation of the left median PV.

HV: The distance between the right-superior- and right-median-HV was also highly variable. In case of a small distance, the piercing suture placed for resection of the right median lobe can damage the right-superior-HV and compromise its outflow.

The drainage of left median and left lateral lobe varied in terms of confluent HVs. This is potentially of importance when planning a transection of the median lobe.

Conclusion: Refinement of experimental hepatobiliary procedures in terms of resection of single lobes or part of liver lobes or ligation of portal and/or hepatic vein branches requires sound knowledge of the intra-hepatic vascular anatomy.

In the rat, lobar borders are not necessarily also borders of vascular territories as one might assume. This is of importance for the development of surgical planning based on vasculature territories and volume calculation prior to experimental surgery like portal vein ligation, right median hepatic vein ligation, partial hepatectomy or ALPPS.