Impaired volume regeneration of split livers with partial venous disruption: A latent problem in partial liver transplantation

Background. In living-donor and split-liver transplantations using a hemi-liver graft, it is practically impossible to maintain complete venous drainage in both the right and left livers, because the middle hepatic vein can be preserved only on the unilateral side. However, it is not clear whether partial venous disturbances affect postoperative liver volume regeneration. Methods. Living donors who underwent left-sided hepatectomy preserving the middle hepatic vein (group A, n=40) or left hepatectomy with middle hepatic vein resection (group B, n=37) were reviewed. Volume regeneration of the remnant right paramedian (segments V + VIII) and lateral (segments VI + VII) sectors and overall liver volume was assessed at 3 postoperative months by computed tomography. Results. In group A, both sectors showed a proportional increase by 21.7% (P=0.991), whereas in group B the rate of increase of the right paramedian sector was less than that of the right lateral sector (13.3% vs. 36.5%, P<0.001). Comparisons of rate of increase for each sector between the groups indicated that interruption of the middle hepatic venous drainage impaired enlargement of the right paramedian sector and induced a compensatory hypertrophy of the right lateral sector. Overall liver mass restoration rate in group B was inferior to that in group A (78.9% vs. 85.0%, P=0.001). Conclusions. Split livers with partial outflow disturbances are associated with latent disadvantages in postoperative liver volume regeneration even if venous congestion is not evident. These results suggest a problem of regenerative capacity of right liver grafts.