Chapter 90D Hepatic resection for living donor transplantation
Overview
Donor hepatectomy is a major surgical operation performed on a healthy subject only for the benefit of a recipient, who requires liver transplantation (see Chapter 97A). In 1989, Strong (1999) performed donor left hepatectomy and removed segment IV of the liver on the back table prior to implantation of segments II and III into a pediatric recipient. In 1990, Tanaka and coworkers (Yamaoka et al, 1994) used a right liver graft to transplant a pediatric recipient. Living donor left liver transplantation (LDLT) for adults was first performed by Makuuchi in 1993 (Hashikura et al, 1994). The first case of right liver adult LDLT was performed by Fan in 1996 (Lo et al, 1997a). A priori, the right liver graft included the middle hepatic vein (MHV) to address the problems of small-for-size syndrome by providing good venous outflow of the right anterior sector. The first seven recipients who underwent right LDLT all had acute liver failure before the transplantation; one died from candidiasis and the other six survived (Lo et al, 1997b). Subsequently, semiurgent and elective cases were accepted.
Donor Workup
Donor workup is started after indication for LDLT for the potential recipient is ascertained. The workup is to evaluate whether the donor will be psychologically and physically healthy in the long-term after recovery from the organ donation. In a stepwise fashion, expedience is achieved without omission (Chan et al, 2007a). Only healthy individuals who have reached the age of consent are accepted (Abecassis et al, 2000).
Step 1
A detailed medical history is taken to identify any comorbidities. A body mass index of 30 kg/m2 or more (27 kg/m2 for Asians; World Health Organization, 2004) raises the concern for fatty liver– and obesity-related comorbidites. Blood group compatibility is verified. Hepatitis B and C virus and HIV carrier status preclude liver donation, although hepatitis B core antibody positivity by itself does not preclude liver donation, it mandates lifelong prophylaxis with lamivudine in the recipient (Lo et al, 2003).
Step 2b
Chest radiographs are taken, and an electrocardiogram is performed. Computed tomography (CT) of the liver under sodium bicarbonate cover (Merten et al, 2004) is also performed, and maximum-intensity projections of the portal veins and hepatic veins are produced. Volumetry of the donor liver by the Heymsfield method (Heymsfield et al, 1979) measures the volumes of the right liver and left liver (for pediatric recipients, segments II and III), using the MHV as a demarcation line on the plane between the right and left livers (Fig. 90D.1). Attenuation of the liver parenchyma in comparison with the spleen on the plain film is appraised for detection of fatty change. Hepatic vein anatomy is determined by the axial cuts in the venous phase and by maximum-intensity projections for easier appreciation. The presence of any inferior hepatic veins allows anticipation at the operation of either preservation or division. Attention to the presence of the segment IVb hepatic vein or segment III hepatic vein draining into the MHV calls for a more caudal division of the MHV to preserve adequate drainage of segment IV of the remnant left liver (Chan et al, 2004a). The right, left, and segment IV hepatic arteries are also illustrated by the three-dimensional (3D) reconstructions for the images obtained during the arterial phase.
Side and Size of Graft
The graft to standard liver volume ratio (Urata et al, 1995) is crucial in LDLT. A ratio of more than 35% is required for a predictable recipient success (Fan et al, 2003a). However, a 20% overestimation of the right liver graft size based on CT volumetry is commonly given a conversion factor of 1.19 g/mL (Chan et al, 2006a). Because the left liver is usually one third the size of the total liver, for a donor with a body size no larger than the recipient, the left liver is usually less than 35% of the recipient standard liver volume. For an individual with a larger left liver/right liver ratio, the left liver may be large enough. It is worth noting that in left LDLT, a gram-to-gram equivalence of graft is not applicable, and a left liver graft of the same size as the right is less efficacious (Chan et al, 2007b).
Donor Right Hepatectomy (See Chapter 98B)
Exposure
The donor is placed supine on the operating table with care to avoid pressure sores over the occiput, heels, and sacrum. The position of the donor must be optimal for the surgeon and his first assistant to face the operative field directly, unhindered by the metal bars of the upper hand retractor or those used to set up a fence between the surgeon and anesthetist (Fan, 2007). Access is gained through a right subcostal incision with upper midline extension. The ligamentum teres is ligated and divided, and the falciform ligament is taken down. The two curved blades of the Bookwalter retractor (Codman and Shurtleff, Raynham, MA) pull the rib cage laterally and anteriorly to open up the aperture made by the costal margins. Excising the xiphoid process may improve access to the suprahepatic inferior vena cava (IVC) and the roots of the hepatic veins. Following careful laparotomy, intraoperative ultrasonography (IOUS) is performed to study the junction of the middle and left hepatic veins with the IVC. The relation of the segment IVb hepatic vein to the MHV, already known from CT, is ascertained by IOUS. This also registers the flow characteristics of the hepatic arteries, portal veins, and hepatic veins for reference throughout the operation.
Isolation of Major Vessels and Parenchymal Transection
The triangle of Calot is dissected, and the cystic artery is divided between ligatures. The gallbladder is dissected from its fossa, and the cystic duct is cannulated with a 3.5-Fr Argyle catheter (Tyco Healthcare, Mansfield, MA). The cystic duct is then severed at the site of insertion of the catheter for delivery of the gallbladder. Next, the peritoneum overlying the right hepatic duct (RHD) is divided for identification. A large metal LigaClip (Ethicon Endo-Surgery, Cincinnati, OH) is put on the liver capsule at the planned line of division of the RHD, 3 to 4 mm away from the duct confluence. The biliary anatomy is then demonstrated by operative cholangiogram with undiluted contrast under fluoroscopy with a C-arm. The image quality of the cholangiogram can be improved by temporary and gentle occlusion of the distal common bile duct with an atraumatic vascular clamp (Featherlight Bulldog Clamp; Geister, Tuttlingen, Germany) (Fig. 90D.2). To avoid devascularization of the donor distal common bile duct, care must be taken not to dissect more tissue than necessary for application of the clamp; the clamp must be removed once the cholangiogram is finished. The supine donor will have the right posterior sectoral duct demonstrated first, followed by the right anterior sectoral duct and then the left ducts (Fan et al, 2002). The parallax technique executed by rotation of the C-arm to the right clarifies the anteroposterior position of the right anterior and posterior sectoral ducts. This also provides the true anteroposterior view of the biliary system. A marking is made with reference to the LigaClip on the liver capsule with diathermy for the line of division of the RHD.
FIGURE 90D.2 Operative cholangiogram with metal clip marking the planned line of division of the right hepatic ducts.
Hilar dissection is continued to isolate the right hepatic artery and right portal vein. The space between the right hepatic artery and right hepatic duct should not be disrupted in order to preserve the blood supply to the latter. To gain an entire length of the right portal vein, branches to the caudate lobe are ligated and then divided. It is important to note that a sizeable branch from the right portal vein may represent vessels supplying segment VI, which should be preserved (Fig. 90D.3). Temporary right liver inflow control is performed (Fig. 90D.4A) to mark the line of transection along Cantlie’s line (Fig. 90D.4B) with electrocautery. The line on the inferior surface is just to the left of the gallbladder fossa, joining the planned line of division of the right hepatic duct marked earlier.
The right triangular ligament is then taken down, leaving the Gerota fascia intact. In a normal donor liver, the right adrenal gland can often be freed from the liver with careful dissection using electrocautery. Minor bleeding from the right adrenal gland is controlled by the argon beam coagulator, and more severe bleeding is addressed by plication with sutures. Short hepatic veins on the right side of the midline of the IVC are divided between ligatures and plicated as required. Inferior right hepatic veins (RHVs) larger than 5 mm are preserved for anastomosis with the IVC in the recipient (Fig. 90D.5).
In contrast to hepatectomy for neoplasm (see Chapter 90A, Chapter 90B, Chapter 90C, Chapter 90E, Chapter 90F ), continuous inflow control during liver transection is not practiced. Although the Pringle maneuver with intermittent reperfusion of the liver, which is adopted by some centers, has been shown to result in less blood loss in the donors, the difference did not reach statistical significance (Imamura et al, 2002). Possible explanations to this are that bleeding from the hepatic vein tributaries is not controlled by inflow control, and there is bleeding during the 5-minute reperfusion interval. Another potential advantage of the Pringle maneuver is downregulation of the apoptosis pathway by ischemic preconditioning for grafts with a long cold ischemic time (Clavien et al, 2000); however, this has been associated with poorer initial graft function by a prospective trial in deceased donor liver procurement (Azoulay et al, 2005). For adult LDLT, prolonged cold ischemia should not be an issue, because graft delivery matches the explantation of the native liver. In addition, a low central venous pressure (CVP) can be attained through good rapport with the anesthetist, and this lowered pressure has been proven effective in reducing blood loss (Jones et al, 1998). Elevating the head and the trunk by 10 to 15 degrees and complete muscle relaxation of the donor are also helpful.
