The Study Of Mechanism Of Graft Injury In Small-for-Size Liver Transplantation And The Graft Protection Of Affiliating Portosystemic Shunt In Bama Miniature Pigs

BackgroundThe success associated with liver transplantation has resulted in an explosive increase in the number of patients being added to active waiting lists worldwide. Unfortunately, cadaveric liver donor rates have remained stagnant, despite earnest efforts to improve them. The divergence between supply and demand has been increasingly extended. Living donor liver transplantation (LDLT) was developed to alleviate organ shortage, especially in Asian countries, where the cadaveric graft supply is markedly limited. With the experience accumulated in pediatric cases, the practice of LDLT has recently been extended to adult patients. Graft size is not a critical problem in the adult-to-child transplant, as a relatively small volume of liver is transplanted into a small recipient. However, the liver mass necessary to sustain life has become an issue with the adult to-adult procedure. Small size is a dominant factor contributing to impaired postoperative graft function. The greater magnitude of a right or extended right lobectomy carries a corresponding increase in the risk to the donor. Theoretically, the ideal situation should be resection of the minimum graft volume that will be necessary to maintain the metabolic demands of the recipient. The distinct characteristic of LDLT in adults is that the graft, which is less than the recipient's original liver, must accept the whole portal blood flow. It was postulated that the excessive portal blood flow relative to the small-for-size graft would induce portal hypertension after reperfusion, which in turn leads to injury of the graft. Therefore, a detailed systemic elucidation of the portal hemodynamic changes and the mechanism of injury of partial (even small-for-size) liver grafts is necessary and will provide helpful information for improve the results of LDLT in adults.ObjectiveReckoning with that small-for-size liver transplantation plays an important role in LDLT development, the aims of present study are to elucidate the mechanism of graft injury in small-for-size liver transplantation and observe the protective effects of affiliating distal splenorenal or mesocaval H-shunt on small-for-size grafts in miniature pigs.Methods and results1. To get a detailed knowledge of the miniature porcine liver, we anatomized 10 porcine liver in vivo and in vitro. The results showed that the miniature porcine liver weight and volume positively correlated to its body weight. The linear regression equations are Y=211.3093+0.0094X (R2=0.99) and Y=213.84+8.73X (R2=0.95) respectively. The pig liver has three main lobes: the right lateral lobe(12.78±1.43%), the median lobe, which is further subdivided into separate left (20.94±1.08%) and right (28.81±2.05%) median lobes, and the left lateral (33.67±2.48%) lobe. The caudate lobe adjoins to the right lateral lobe, accounting for 3.98±1.04% of the whole liver. The left lateral lobe is the largest one of all the lobes. The vascular and biliary architecture of miniature porcine liver has numerous similarities with human and is a useful organ model for studying hepatic surgery and liver transplantation.2. The imitated orthotopic partial liver transplantation models with whole (Group A), right half (Group B) or right median combined with caudate lobe liver graft (Group C) were established by skeletonized and denervated anatomic dissection around the liver, hepatectomy and perfusion in situ. The graft recipient weight ratio (GRWR) in Group C was 0.61% and this group could be considered as small-for-size liver transplantation (SFSLT). The animal survival in Group C was only 20% by postoperative day (POD) 7.3. We dynamically measured portal hemodynamics with a multifunctional physiological monitor and Color Doppler Flow Imaging (CDFI). The portal venous pressure (PVP) rose immediately after reperfusion. PVP in SFSLT group, the peak of which reached to 28.6±2.07mmHg, displayed significantly higher than that in the groups with whole or right half liver graft transplantation at all time points except the data of the only...