Directing portal flow is essential for graft survival in auxiliary partialheterotopic liver transplantation in the dog

Background/Purpose: Auxiliary liver transplantation is an attractive altern ative for orthotopic liver transplantation in patients with certain inborn errors of metabolism of the liver in which complete resection of the liver is unnecessary or even contraindicated. Because in these diseases portal hy pertension is mostly absent, finding a balance in portal blood distribution between native liver and graft is complicated. The objective of this study was to investigate requirements for long-term (180 days) graft survival in auxiliary partial heterotopic liver transplantation (APHLT) in a dog model . Methods: A metabolic defect was corrected in 26 dalmation dogs with a 60% b eagle heterotopic auxiliary liver graft. Four groups of different portal in flow were studied. In the ligation group the portal vein to the host liver was ligated. In the split-flow group graft and host liver received separate portal inflow. In the banding group the distribution of the portal flow wa s regulated with an adjustable strapband and in the free-flow group the por tal blood was allowed to flow randomly to host or graft liver. Results: Metabolic correction increased in all groups after transplantation from 0.19 +/- 0.02 to 0.70 +/- 0.05 (P < .0001) but remained significantly better in the ligation and split-flow groups (graft survival, 135 +/- 27 a nd 144 +/- 31 days). In the banding group metabolic correction decreased si gnificantly after 70 days, and although the grafts kept some function for 1 55 +/- 14 days, in 4 of 6 dogs portal thrombosis was found. In the free-flo w group, competition for the portal blood led to reduced correction within 12 days and total loss of function in 96 +/- 14 days. Graft function also w as assessed with technetium (Tc) 99m dimethyl-iminodiacetic acid uptake. A good linear association between HIDA uptake and metabolic correction was ob served (r = 0.74; P < .0005). Grafts that contributed more than 15% to the total uptake of HIDA showed biochemical correction. This indicates a critic al graft mass of about 15% to 20% of the hepatocyte volume to correct this metabolic defect. Conclusion: Auxiliary partial heterotopic liver transplantation can be a va luable alternative treatment for inborn errors of hepatic metabolism if the native liver and the graft receive separate portal blood inflow. Copyright (C) 1999 by W.B. Saunders Company.