"Anatomical" versus "territorial" belonging of the middle hepatic vein: virtual imaging and clinical repercussions.

Background: Venous drainage patterns are of vital importance in live donor liver transplantation. The purpose of this study was to delineate "anatomical-topographical" and "territorial-physiologic" patterns of the middle hepatic vein (MHV) in a 3-D liver model as determined by the Pringle line and its drainage volume of the right and left hemilivers.

Methods: One hundred thirty-seven consecutive live donor candidates were evaluated by 3-D CT reconstructions and virtual hepatectomies. Based on right (R) and left (L), anatomical (A) and territorial (T) belonging patterns of the MHV, each individual was assigned to one of four possible types: type I:A(R)-T(R); type II:A(L)-T(L); type III:A(R)-T(L); type IV:A(L)-T(R). Couinaud's anatomical MHV variants A-C were subsequently included in our combined anatomical/territorial MHV belonging classification.

Results: The MHV showed a significant predominance of right "anatomical" (59.1%) and left "territorial" belonging patterns (65.7%). The paradoxical combinations A(R)-T(L) (type III) and A(L)-T(R) (type IV) were encountered in 36.5% and 11.7% of cases, respectively. The constellations Couinaud's A-belonging type IV and Couinaud's C-belonging type IV were predictive of right hemiliver venous congestion.

Conclusions: (1) Almost half of all livers in our series had paradoxical "anatomical"/"territorial" MHV belonging patterns that placed them at risk for right and left hepatectomies. (2) The proposed combined "anatomical"/"territorial" MHV belonging types (I-IV) provide useful preoperative information. (3) Combined types III and IV as well as Couinaud's A-IV, and Couinaud's C-IV should be considered particularly risky for venous congestion in right hemiliver grafts and in extended left hepatectomies.