Dual Grafts for Transplantation

CHAPTER 57

Dual Grafts for Transplantation Sung-Gyu Lee  •  Deok-Bog Moon  •  Chul-Soo Ahn

CHAPTER OUTLINE TWO LEFT LOBES DUAL-GRAFT LIVER TRANSPLANTATION

CURRENT RESULTS AND ISSUES IN DUAL-GRAFT LIVER TRANSPLANTATION

Indication Operative Procedure

SUMMARY

RIGHT AND LEFT LOBES DUAL-GRAFT LIVER TRANSPLANTATION Indication Operative Procedure

The shortage of cadaveric liver grafts has stimulated the development of innovative surgical procedures with various forms of living donor liver transplantation (LDLT), especially in adult patients, which produce satisfactory results comparable to whole-liver deceased donor liver transplantation (DDLT). For adult LDLT, insufficient graft size has been a major obstacle for an expansion of this procedure when the liver graft is confined to the left lobe (LL). To expand adult LDLT, right-lobe (RL) grafts have been used, with a rapid increase in the number of cases, but the risk to the donor increases with the extent of donor hepatectomy. It is reported that operative mortality for the RL donor is estimated to be as high as 0.5% to 1%. Regarding the recipients, the most important factor for a successful outcome after adult LDLT is the size of the liver graft. Meanwhile the safe remnant liver volume after RL donation has been reported to be greater than 30% to 35% of the total liver volume (TLV) of the donor, whereas the safe limit of the graft volume is greater than 40% to 50% of the recipient’s standard liver volume. Leelaudomlipi et al1 reported that in 25% of donors evaluated the volume ratio of RL was over 70% of TLV, or in other words, the remnant liver volume after RL donation was less than 30% of TLV. Even though the donor has a sufficiently large RL that it has adequate volume as a liver graft for an adult recipient, the remnant LL is too small to ensure donor safety in these procedures. Undoubtedly the safety of donors must have top priority when considering LDLT, and the inevitable risk to the donor should not be allowed in an LDLT procedure. The donor demonstrating RL to LL volume disproportion (RL > 70% of TLV) on preoperative volumetric computed tomography should not be allowed to donate the RL for a large-size adult recipient. As an alternative, dual LL or left lateral segment (LLS) transplantation can be an option to avoid the small-for-size graft (SFSG) problem caused by a LL 736

liver transplantation (LT) alone and the critical right lobectomy posing an independent donor risk.2-5 The ethical issue of putting two donors at risk simultaneously for one recipient can be debatable. However, because the clear relationship between donor mortality and the extent of resection has been demonstrated, the sum of potential risks from two donors’ left lobectomies will be much lower than the risk of an inappropriate right hepatectomy. To alleviate the SFSG problem by summing the suboptimal volumes of two LL grafts, dual LL grafts LT preserving the donors' safety is realistic and justified. Although LDLT with dual LL grafts is a technically complex and elaborate procedure, dualgraft LT can solve problems related to SFSG. It can also help expand the donor pool for LDLT and even for split-liver DDLT by application of two RL and one dual LL/LLS split transplantation to three recipients from two deceased donors.6 Furthermore, if a large-size recipient requires a bigger graft liver volume than the volume of a RL from a small-size donor when a RL harvest from one of two potential donors is decided to be safe, one RL and one LL graft from two independent donors can be transplanted to a large-size recipient to avoid the SFSG problem.3,6,7 This chapter introduces the technical aspects and the issues of dual-graft (two LLs or a RL and a LL) transplantation by reviewing our 300 dual-graft LTs.

TWO LEFT LOBES DUAL-GRAFT LIVER TRANSPLANTATION Not all potential living donors can donate their RL because safe donation is possible only when the estimated remnant liver volume is more than 30% of the donor’s TLV. At the Asian Medical Center the minimally accepted remnant liver volume in RL donors is

57  Dual Grafts for Transplantation

individualized by age and degree of steatosis (Fig. 57-1).8 If the remnant LL hepatic mass is fully functioning without congestion injury by middle hepatic vein (MHV) preservation, the lower limit of 30% remnant liver volume is acceptable if the donor’s age is 35 years or less and preoperative donor liver biopsy reveals no steatosis. However, when donor age increases, the degree  35 years and  no fatty change : 30% remnant liver volume: Acceptable  35 years and  15% fatty change : 30%-35% remnant liver volume: Acceptable  35 years and 15% < fatty change  30% :  35% remnant liver volume: Acceptable 35–55 years and  15% fatty change : > 35% remnant liver volume: Acceptable FIGURE 57-1 n Minimally accepted remnant liver volume in rightlobe donor should be individualized when the remnant liver is fully functioning without congestion caused by hepatic vein outflow deprivation.

737

of steatosis increases, and congestion injury of liver segment IV by extended RL hepatectomy (MHV is included in RL graft) is expected, the lower limit of the remnant liver volume in donors should be increased.

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.9

360 mL

220 mL

960 mL > 70%

527 mL > 70%

Potential donor 1

Potential donor 2

FIGURE 57-2 n Two potential donors demonstrated a large right lobe (>70% of total liver volume) and small left lobe (<30%) on preoperative volumetric computed tomography.

A

B

C

FIGURE 57-3 n Regeneration of two left-lobe grafts in dual-graft liver transplantation. A, Preoperative computed tomography (CT) scan of the recipient demonstrated large amounts of ascites and shrunken cirrhotic liver. B, CT scan on the seventh day after transplant demonstrated two well-functioning left-lobe liver grafts with no manifestation of the small-for-size graft syndrome. The right-sided left-lobe graft was not fully regenerated and needed tissue expander support from behind to relieve tension on hilar anastomoses (white arrow). C, CT scan taken 3 weeks after transplant showed that two regenerated left-lobe liver grafts looked like a triangular-shaped normal liver.

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PART VI  Split and Living Donor Transplantation Two left lobes dual-graft LDLT

• Bigger-size graft • Single bile duct opening • Longer hepatic artery

Heterotopic graft

Orthotopic graft

• Better-quality graft • Multiple bile duct openings

FIGURE 57-4 n Which graft will be located in the orthotopic left-sided position? LDLT, Living donor liver transplantation.

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 leftsided 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

57  Dual Grafts for Transplantation

1

20 mm

3

2

Slit incision

4

35-40 mm

739

Rectangular vein patch

FIGURE 57-5 n Augmentation hepatic venoplasty of left-lobe graft at the back table.

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).

RIGHT AND LEFT LOBES DUAL-GRAFT LIVER TRANSPLANTATION Two LLs dual-graft liver transplantation is a good strategy to avoid SFSG and to ensure donor safety when potential donors show a volume disproportion between right and left liver lobes. However, we often encounter large-body-size recipients requiring bigger liver volume than the sum of the two LLs or a single RL graft of the potential donors. As an alternative approach to avoid SFSG in large-size recipients, dual-graft liver transplantation using RL and LL grafts can be employed when one of the potential donors can donate his or her RL without endangering donor safety.

Indication When a large-size recipient cannot receive adequate graft volume from an acceptable RL donor, and another potential donor is available, dual right- and left-lobe transplantation has been performed since 2001 to avoid SFSG. The eligibility criteria for the RL donor are the same as those for single RL LDLT. As for the simultaneous LL or LLS donor, however, even suboptimal donors, such as those who are 50 years of age or older or those with moderate to severe steatosis, can be selectively acceptable in low-MELD (<20) patients. As additional considerations before proceeding to RL and LL dual-graft transplantation, we need to reappraise the recipient’s preoperative condition, such as the MELD score and the presence of long-standing portal hypertension, and the adequacy of the estimated liver graft volume from transplantation of a single RL or two LLs. If the recipient shows low MELD status without coexisting portal hypertension, the minimum requirement of liver graft volume

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PART VI  Split and Living Donor Transplantation

360-Degree GSV fence on MHV+LHV trunk

Anastomosis of right-sided graft HV

Anastomosis of left-sided graft HV

Anastomosis of left-sided graft PV

Reperfusion of left-sided graft

Duct-to-duct anastomosis of right-sided graft

PV anastomosis of right-sided graft

Reperfusion of right-sided graft

Anastomosis of hepatic arteries

Tissue expander applied

FIGURE 57-6 n Anastomosis of dual-graft living donor liver transplantation using two left lobes. GSV, Great saphenous vein; HV, hepatic vein; LHV, left hepatic vein; MHV, middle hepatic vein; PV, portal vein.

can be lowered to 0.7% of graft weight–to–body weight ratio (GWBWR) or 35% of graft volume/standard liver volume of the recipient. When procurement of a right posterior sector graft is feasible because LL volume is disproportionately small (<30% of total liver volume) and PV branching of the donor demonstrates type III anomaly (early separate branching of posterior PV), right posterior sector and LL/LLS dual-graft LDLT can also be applicable for

donor safety if the sum of the liver grafts meets the metabolic demands of the recipient.

Operative Procedure In the donor operation, procurement of a RL graft with or without the MHV, or right posterior sector graft as a right-sided positioning graft, and LL or LLS graft as a left-sided positioning graft is performed considering

57  Dual Grafts for Transplantation

741

Rt

Lt

FIGURE 57-7 n Dual-graft living donor liver transplantation using right (Rt) and left (Lt) lobes.

donor safety and avoidance of SFSG for the recipient. At the back table, hepatic venoplasty to create a large outflow orifice is performed in both grafts. The RHV of the RL or posterior sector graft is incised caudally, augmentation venoplasty is performed with a rectangular vein patch, and the MHV tributaries of the RL graft are reconstructed with an interposition graft such as an autologous great saphenous vein, PV, dilated umbilical vein, cryopreserved iliac vessel, or artificial polytetrafluoroethylene graft. The MHV trunk of the extended RL graft is elongated using a sizable interposition vascular graft for separate reconstruction, or it is transformed into a single common opening with the RHV using quilt venoplasty for an integrated single anastomosis. Venoplasty of the LMHV of the LL graft is the same as that for two LLs dual-graft LT. In the recipient operation the extent and method of hepatic hilar and perihepatic dissection is the same as that for two LL dual-graft LT, but retrohepatic mobilization of the vena cava should be extended down toward the infrahepatic side for reconstruction if a sizable (≥5 mm) inferior RHV is present in the RL or posterior sector graft. After total hepatectomy, venoplasty to create a wide orifice corresponding to the right- and left-side liver grafts is performed at both the RHV and LMHV under cross-clamping of supra hepatic and infrahepatic vena cava, and the method is the same as that for two LLs dual-graft LT. Both RL and LL grafts are implanted orthotopically; thus the engraftment procedures are not complex. First, the RL graft is placed into the right upper quadrant fossa, and reconstruction of the hepatic veins is performed. The interposition graft of the MHV tributaries is anastomosed to the anterior wall of the inferior vena cava below the recipient’s LMHV. Second, the LL graft is placed orthotopically, and its hepatic vein and PV are reconstructed sequentially. Third, the recipient’s right PV is anastomosed to the PV of the RL or posterior sector graft. Then the suprahepatic and infrahepatic vena caval cross-clamps are removed, and both liver grafts are simultaneously reperfused. Fourth, after completion of the hepatic artery anastomoses, biliary reconstruction to both

grafts is performed using only a Roux-en-Y hepaticojejunostomy or a combination of duct-to-duct and Roux-en-Y hepaticojejunostomy (Fig. 57-7). The sequence of reconstruction might vary from center to center concerning the prolonged ischemia of liver grafts, but the most important point of implementing these complicated procedures is correct and safe anastomosis under a good operating field to prevent postoperative inflow and outflow vascular complications. Because these reconstruction procedures are performed using ice-slush filling to protect the liver grafts against ischemic rewarming, prolongation of liver graft ischemia (up to 90 minutes) does not result in primary dysfunction of liver grafts.

CURRENT RESULTS AND ISSUES IN DUAL-GRAFT LIVER TRANSPLANTATION Donor safety and SFSG have been the critical issues in adult LDLT. LDLT using a RL graft has contributed to reducing SFSG, but more than 25% of potential donors cannot donate their RL to recipients because of the risk to donor safety, considering their RL and LL volume discrepancy, age, and steatosis. When there are two living donors willing to donate their partial liver despite inadequacy for RL donation, two LLs dual-graft LDLT is a useful strategy to expand the application of adult LDLT by meeting the minimum required GWBWR. Of 2227 adult LDLT recipients in our department, 300 adult LDLTs using dual grafts were performed from March 2000 to February 2011 (Fig. 57-8). The mean GWBWR with two LLs dual-graft LDLT (median, 0.98%; range, 0.59% to 1.39%) approaches that of a RL LDLT (median, 1.01%; range, 0.63% to 2.27%). Furthermore, in view of donor risk, the sum of two LL donors’ risk is lower than that of a RL graft donor. In our 2525 donors there was no donor mortality. Major morbidity occurred in two donors after 598 living donor hepatectomies in 300 dual-graft LDLTs. One donor needed a repeat hepatectomy for a

742

PART VI  Split and Living Donor Transplantation

Left lobe

Left lobe

Lateral segment

Lateral segment

Left lobe

154

Lateral segment

62 (2; cadaveric split graft) Left lobe

Posterior segment Lateral segment

10 Posterior segment

Left lobe

Right lobe

61

3

10

FIGURE 57-8 n Three hundred adult living donor liver transplantations using dual grafts.

persistent cut-surface bile leak from the remnant medial segment after donation of LLS, and another donor underwent percutaneous drainage for bile leakage from the cut surface. SFSG even after a RL LDLT is often encountered in a large-size recipient if the donor body size is much smaller than that of the recipient. Dual LDLT of RL and LL grafts from two acceptable living donors has been performed to avoid SFSG, and it constituted 25% (74 of 300) of our dual-graft LDLTs. The most common indication for dual-graft LDLTs was hepatitis-B virus–related cirrhosis in 239 patients (80%), and 44 patients had complications of acute-onchronic liver failure. Fulminant hepatic failure was the second-most common cause of dual-graft LDLT, and urgent transplantations for status 1 and 2A patients constituted 21% of our dual-graft LDLTs (62 of 300). The recipients were predominantly male, and fifties to sixties was the most common age-group (Fig. 57-9). The operation time averaged 17 hours (range, 13 to 26 hours), but it did not adversely affect the postoperative infection rate or the outcome of patients. The most difficult part of all the operative procedures was PV reconstruction in patients who were associated with PV thrombosis and/or stenosis.10 The incidence of biopsy-proven acute cellular rejection was similar to that in single-graft LDLT (17%), and three fourths of acute rejection developed simultaneously in both grafts. The most common complications in dual-graft recipients were biliary strictures (28%) and hepatic venous outflow obstruction of the heterotopic right-sided LL graft (15%). Hepatic vein obstruction rarely occurred in orthotopically positioned liver grafts, as in left-sided LL or rightsided RL grafts. This might be related to the progressive compression of the hepatic vein anastomosis by the regeneration of a heterotopically positioned LL graft. Two liver

grafts in dual-graft LDLT do not demonstrate competitive growth but regenerate cooperatively. Unilateral liver graft atrophy developed infrequently, and it was mostly related to the discrepancy of portal inflow to the liver grafts primarily by inappropriate anastomotic technique or secondarily because of unrecognized hepatic vein outflow obstruction by compression of the regenerating liver graft. However, it did not affect patients’ liver function or survival.

SUMMARY Because of the shortage of deceased organ donation, adult LDLT has been established as a good alternative to treat end-stage liver disease patients, but donor safety and SFSG have remained as critical issues in adult LDLT practice. Dual-graft LDLT can be the solution to overcome these obstacles, although its operative procedure is technically complex and elaborate. This procedure can not only maximize the safety of individual donors, particularly in two LL lobes dual-graft LDLT, but also alleviate SFSG related to the recipient’s metabolic demands when single-graft LDLT is not promising a good outcome because of inadequate graft size and/or increased donor risk. In addition, dual-graft LDLT is a useful strategy for increasing the living donor pool by making the donation of their livers realistic, even though the volume and the quality of the individual liver graft are suboptimal. Acknowledgment I sincerely thank my colleagues Jung Man Namgoong, MD, and Bo-Hyun Jung, MD, for their contributions to the preparation of the figures and proofreading for this chapter.

57  Dual Grafts for Transplantation

Indication

Male : Female = 261 : 39 113

120 100

PB

100

PS Bu C dd Wil -Chi son ar i C

18 FHF

2

2

3

1

2

239 HBV cirrhosis

Ot he r

42 44 Acute-on-chronic liver failure

40

100 HCC

20

7

15

lic ho sis o c Al irrho c

80 60

is

hos V-cirr

C 14 H

743

35

9 1

0 10

20

MELD 19.3 ± 10.2 (range 5-61)

30

40 50 Age distribution (from 15 to 68 years)

60

70 years

FIGURE 57-9 n Patient’s demographic data for 303 dual-graft living donor liver transplantations from March 21, 2000, to February 9, 2011. FHF, fulminant hepatic failure; HBV, hepatitis B virus; HCC, hepatocellular carcinoma; HCV, hepatitis C virus; MELD, Model for End-Stage Liver Disease; PBC, primary biliary cirrhosis; PSC, primary sclerosing cholangitis.

Pearls and Pitfalls • The shortage of cadaveric liver grafts has stimulated the development of innovative surgical procedures with various forms of living donor liver transplantation (LDLT), especially in adult patients. • For adult LDLT, insufficient graft size has been a major obstacle for an expansion of this procedure when the liver graft is confined to the left lobe (LL). • To expand adult LDLT, right-lobe (RL) grafts have been used, with a rapid increase in the number of cases, but the risk to the donor increases with the extent of donor hepatectomy. • The safety of donors must have top priority when considering LDLT. • A donor demonstrating RL to LL volume disproportion (RL > 70% of total liver volume) on preoperative volumetric computed tomography should not be allowed to donate the RL for a large-size adult recipient because of the inevitable risk to the donor. •  As an alternative, dual LL or left lateral segment transplantation can be an option to avoid the smallfor-size-graft (SFSG) problem caused by a LL liver transplantation alone when the critical right lobectomy poses an independent donor risk. •  A RL and LL dual-graft transplantation from two independent donors can be performed to a large-size recipient to avoid the SFSG problem, if a large-size recipient requires a bigger graft liver volume than the volume of a RL from a small-size donor when a RL harvest from one of two potential donors is decided to be safe.   

REFERENCES 1. Leelaudomlipi S, Sugawara Y, Kaneko J, et al. Volumetric analysis of liver segments in 155 living donors. Liver Transpl. 2002;8(7): 612-614. 2. Lee S, Hwang S, Park K, et al. An adult-to-adult living donor liver transplant using dual left lobe grafts. Surgery. 2001;129(5): 647-650. 3. Broering DC, Walter J, Rogiers X. The first two cases of living donor liver transplantation using dual grafts in Europe. Liver Transpl. 2007;13(1):149-153. 4. Yang CH, Chen CL, Wang CC, et al. Dual grafts in adult-to-adult living donor liver transplantation: a single center experience in Taiwan. Surgery. 2009;145(2):212-218. 5. Song GW, Lee SG, Hwang S, et al. Dual living donor liver transplantation with ABO-incompatible and ABO-compatible grafts to overcome small-for-size graft and ABO blood group barrier. Liver Transpl. 2010;16(4):491-498. 6. Lee SG, Hwang S, Park KM, et al. Seventeen adult-to-adult living donor liver transplantations using dual grafts. Transplant Proc. 2001;33(7-8):3461-3463. 7. Soejima Y, Taketomi A, Ikegami T, et al. Living donor liver transplantation using dual grafts from two donors: a feasible option to overcome small-for-size graft problems? Am J Transplant. 2008;8(4):887-892. 8. Hwang S, Lee SG, Lee YJ, et al. Lessons learned from 1,000 living donor liver transplantations in a single center: how to make living donations safe. Liver Transpl. 2006;12(6):920-927. 9. Moon DB, Lee SG, Hwang S, et al. Resolution of severe graft steatosis following dual-graft living donor liver transplantation. Liver Transpl. 2006;12(7):1156-1160. 10. Moon DB, Lee SG, Hwang S, et al. Umbilical portion of recipient’s left portal vein: a useful vascular conduit in dual living donor liver transplantation for the thrombosed portal vein. Liver Transpl. 2004;10(6):802-806.