Portal vein pressure is the key for successful liver transplantation of an extremely small graft in the pig model.

In partial-liver transplantation, the use of small grafts sometimes results in graft failure, usually caused by portal hypertension after transplantation (Tx). Portal hypertension after Tx can be decreased with a porto-caval shunt (PCS). The purpose of this study is to clarify the effect of the PCS on extremely reduced-size liver Tx. In a pig model, the posterior segment of 25% of a whole liver was transplanted orthotopically. The pigs were divided two groups: group A, graft with PCS ( n=7), and group B, graft without PCS ( n=7). The PCS was made by means of side-to-side anastomosis of the portal vein and the inferior vena cava. We examined the portal vein pressure, survival rate, regeneration rate of the graft, Ki-67 as an index of cell proliferation, and histological findings, and carried out liver-function tests. In group A, five pigs survived for more than 4 days and the remaining two died of a perforated gastric ulcer on post-operative day (POD) 2. In group B, all pigs except one died of graft failure within 24 h. Portal vein pressure after reperfusion in group A and group B was of statistically significant difference ( P<0.05), 14.2+/-3.2 and 18.9+/-4.7 cmH(2)O, respectively. In group A, the regeneration rate of the graft was 94%, 4 days after Tx, and Ki-67 stained remarkably in the parenchymal hepatocytes. In TEM finding, structure of the sinusoid was also well maintained after Tx. From these results we can conclude that the key to success in liver Tx with extremely small grafts lies in the control of the portal vein pressure.