Dual Grafts for Transplantation

Indication

Selection criteria for dual LL or LLS transplantation requires two concurrent situations. First, the volume disproportion between RL and LL (RL > 70% of TLV) in the donor liver exists, and the right hepatectomy endangers donor safety ( Fig. 57-2 ). Second, the donor’s LL is too small to meet the metabolic demands of the recipient. Under these circumstances, dual-graft LDLT using two LLs can provide an adequate graft volume to the recipient while leaving a safe remnant liver volume in the donor ( Fig. 57-3 ). Besides the graft-to-recipient size mismatching and the unacceptable right-to-left-lobe volume discrepancy, severely steatotic (>60% steatosis) LLS or LL grafts have been successfully transplanted to low (<20) Model for End-Stage Liver Disease (MELD) patients in nonurgent dual-graft LDLT.

Operative Procedure

This new procedure needs a few technical modifications during implanting the heterotopic right-positioned LL graft. The rotation of the heterotopic liver graft through 180 degrees of sagittal orientation brings hilar structures into reversed position. The bile duct lies behind the portal vein (PV) and hepatic artery. If the PV anastomosis is performed before the bile duct anastomosis, biliary reconstruction of the heterotopic liver graft will be difficult or impossible in such a limited and hidden area. Thus the first technical modification is that the bile duct is reconstructed by duct-to-duct anastomosis before the PV anastomosis lying ventrally. Therefore the liver graft with a single duct opening is the first choice for the heterotopic right-sided graft to facilitate an easy and fast duct-to-duct anastomosis and to decrease the graft ischemic time. In addition, a longer length of hepatic artery is needed for tension-free anastomosis compared to the orthotopic left-sided graft because the recipient’s right hepatic artery arises from the most dorsal position. As the orthotopic left-sided graft, the bigger-size and better-quality graft is commonly preferred because it has less possibility of vascular complications as a result of its natural position. In addition, it has no strict limitation on the number of bile duct openings because biliary reconstruction with hepaticojejunostomy after hepatic artery (HA) anastomosis does not need to be hurriedly performed ( Fig. 57-4 ).

The thickness of the LL or LLS graft is too thin compared to that of the RL of the recipient’s resected liver. Therefore the second technical modification is that tissue expander filled with saline solution (from 200 to 450 mL) is inserted underneath the graft. This relieves undue tension on the hilar anastomoses of the heterotopic liver graft because the LL graft is usually too small to replace the right upper quadrant space after total hepatectomy in the recipient. The tissue expander is gradually deflated after the fifth postoperative day and removed after 2 weeks, when the undue tension on the hepatic hilum is relieved by sufficient regeneration of the right-sided liver graft.

In the recipient operation both the right and left branches of the PV and hepatic artery are dissected free from the surrounding tissue as peripherally as possible to obtain enough length for future bilateral vascular anastomoses. The bile duct is similarly dissected to the level of the hilum without disturbing the course of the right hepatic artery behind the common hepatic duct. The proximal part of the recipient’s vena cava should be mobilized from its retroperitoneal attachment because venoplasty of the recipient’s hepatic veins and graft implantation are performed under clamping of the suprahepatic and infrahepatic vena cava. Venovenous bypass (Bio-Pump, Bio-Medicus, Inc) is necessary when the recipient hemodynamics is unstable during the test clamping of the vena cava. It is also helpful to reduce bowel edema for future hepaticojejunostomy to the left-sided graft when more than 2 hours of anhepatic phase is expected.

Which graft will be positioned heterotopically is determined by consideration of the number of bile duct openings, the length and number of hepatic arteries, the degree of steatosis, and the expected graft volume of each liver graft (see Fig. 57-4 ). Harvest of liver grafts and the recipient’s hepatectomy are usually performed simultaneously. Before implantation of the liver grafts, venoplasty of the hepatic veins in the recipient and/or the liver grafts at the bench should be performed to make wide outflow orifices of approximately 35 to 40 mm in diameter for prevention of the occasional outflow obstruction during liver graft regeneration. At the back table the hepatic vein of the liver graft is enlarged by augmentation venoplasty if its diameter is less than the target diameter of 35 to 40 mm. The venoplasty is performed using a rectangular vein patch after slit incision at one or both corners of the graft hepatic vein ( Fig. 57-5 ). In the recipient the right hepatic vein (RHV) is enlarged and elongated by longitudinal incision at the inferior corner with or without augmentation venoplasty. The left and middle hepatic veins (LMHV) are converted to a single common opening by division of the septum between the MHV and the LHV. The common hepatic vein opening is then enlarged and elongated by an additional transverse incision at the right corner and circumferentially fenced with a vein patch to facilitate hepatic vein anastomosis under redundancy to prevent the tearing of the posterior wall anastomosis. Venoplasty corresponding to the size of the hepatic vein between the liver graft and the recipient is an essential step so that the surgeon can perform engraftment without difficulty during hepatic vein anastomosis and can also avoid postoperative outflow disturbance. An autologous bisected great saphenous vein segment is the preferred augmentation and fencing material at our department because it has a thicker and stronger wall than other homologous vascular grafts.

Engraftment procedures using two LL grafts are as follows. First, a 180-degree rotated LL graft is heterotopically placed into the right upper quadrant space, and its hepatic vein anastomosis to the recipient RHV is performed. Second, the hepatic vein of the orthotopically positioned LL graft is anastomosed to the common opening of the LMHV. Third, the PV anastomosis of the orthotopic graft is performed to the recipient’s left PV. Fourth, the orthotopic left-sided graft is reperfused earlier to avoid bowel congestion and reduce the graft ischemic time. Before reperfusion of the orthotopic liver graft proceeds, a vascular clamp is applied to the recipient’s RHV to prevent regurgitation of caval flow into the heterotopic right-sided graft after release of the caval clamps. Vascular clamps to the vena cava and the PV trunk are then removed together under new clamping of the recipient’s right PV. Fifth, bile duct anastomosis of the right-sided (heterotopic) graft to the recipient’s bile duct is performed in duct-to-duct fashion earlier than PV anastomosis because of the reversed hilar structures of the graft. Sixth, the PV of the right-sided heterotopic liver graft is anastomosed to the recipient’s right PV and is reperfused after removal of the vascular clamps on the recipient’s RHV and right PV. Seventh, hepatic artery anastomoses are performed, and finally a Roux-en-Y hepaticojejunostomy to the left-sided (orthotopic) liver graft is performed. As an additional procedure, a tissue expander filled with saline solution should be inserted underneath the right-sided (heterotopic) graft to relieve undue tension on the hilar anastomoses ( Fig. 57-6 ).