Resolution of hepatic venous congestion following gradual occlusion of middle hepatic vein interposition graft in living donor liver transplantation

Background: The middle hepatic vein (MHV) interposition vessel graft (IVG) is often occluded within a few months after living-donor liver transplantation (LDLT). We aimed to assess the mechanisms of resolving the hepatic venous congestion (HVC) that develops after gradual occlusion of the MHV-IVG. Material/Methods: This study comprised two parts. Part I involved an assessment of the process of HVC resolution in the remnant right liver after donation of an extended left liver graft (n=100). Part II involved an evaluation of the timing and patterns of gradual MHV-IVG occlusion and HVC resolution in LDLT recipients (n=100). Results: In Part I, the analysis of 1-week dynamic computed tomography (CT) showed pre-existing collaterals in 8, appropriate compensation in 44, and HVC in 48 patients. In Part II, reconstruction of a segment V vein (V5) and a segment VIII vein (V8) was the most common reconstruction type (n=65). The patency rates of MHV-IVG were 90% at 3 months, 65% at 6 months, 37% at 12 months, and 18% at 24 months. The patency rate of V5 was inferior to that of V8. CT imaging analysis indicated that extrinsic compression of IVG, development of intrahepatic collaterals, and IVG shrinkage were the main mechanisms underlying late MHV-IVG occlusion. Moreover, the timing of MHV-IVG occlusion was well correlated with that of neo-collateralization. Conclusions: MHV-IVG reconstruction effectively prevents HVC in LDLT. Although gradual MHV-IVG occlusion is well compensated by neo-collateralization, we believe that the patency of the IVG should be maintained for at least 6 months after LDLT.