Relationship Between Venous Drainage Patterns and Regeneration of Segments 5 and 8 in Right Lobe Grafts in Adult Living-Donor Liver Transplant Recipients

OBJECTIVES: Hepatic venous congestion is associated with impaired graft regeneration in living-donor liver transplant, and the management of middle hepatic vein tributaries in the right lobe graft represents an unresolved issue. In this study, we aimed to investigate the precise outflow pattern of segments 5 and 8 between the right hepatic vein and middle hepatic vein and the respective regeneration rates after living-donor liver transplant with right lobe graft, as available data on these relevant topics are scarce. MATERIALS AND METHODS: We conducted a retrospective analysis of computed tomography scans with 3-dimensional simulation, vessel reconstruction, and volume measurement of 38 right lobe grafts without middle hepatic vein. Follow-up time was 3 months after living-donor liver transplant. RESULTS: In donors, segments 5 and 8 measured 141.9 ± 48.8 mL (21.0% of graft volume) and 230.4 ± 52.5 mL (34.3% of graft volume), respectively, with significant difference between volumes (P < .01). Percentage of segmental venous drainage in segment 5 was 55.5 ± 17.2% for the middle hepatic vein and 41.0 ± 20.9% for the right hepatic vein; drainage in segment 8 was 46.4 ± 13.2% for the middle hepatic vein and 52.9 ± 13.2% for the right hepatic vein. The outflow pattern was significantly different between segments for both veins (P = .01 for middle hepatic vein and P < .01 for right hepatic vein), showing that segment 5 was statistically more dependent on the middle hepatic vein and segment 8 was more dependent on the right hepatic vein. For living-donor liver transplant recipients, the prevalence of middle hepatic vein tributary reconstruction was 39.5%. At 3-month follow-up, the regeneration rate for the posterior sector was 85.8 ± 39.9%, whereas rates for segments 5 and 8 were 33.4 ± 39.7% and 68.4 ± 41.0%, respectively (P < .01). CONCLUSIONS: In living-donor liver transplant with right lobe graft and without middle hepatic vein, segment 5 is the most vulnerable graft area for impaired regeneration. Segments 5 and 8 should be evaluated independently on the basis of their respective outflow patterns to more precisely plan the outflow management and patient outcomes.