**3.4.2 Adult-to-adult LDLT**

The expansion of LDLT to the adult population began in the countries where the availability of deceased donors was scarce, and in some cases, totally unavailable.[105-107] The law for deceased organ retrieval was instituted in Japan in 1998, however, the lack of societal acceptance of organ retrieval from brain dead donors resulted in live donation being the main source of grafts for patients awaiting transplantation in Japan and other countries in Asia.[108]

On November 2, 1993, the Shinshu group performed the first successful adult-to-adult LDLT.[28] By June 2002, there were 433 adult LDLT cases recorded in European Liver Transplantation Regestery,[109] with 3 years graft and patient survival rate of 65% and 68% respectively. According to the United Network for Organ Sharing (UNOS), 731 adult LDLT cases have been performed in the United States by October 2001. The 3 years graft survival was 47% between 1998 and 1999 (n=156) but it improved significantly to 61% between July 1999 and June 2001 (n=285).[110] According to the Japanese Liver Transplantation Society, 1063 adult LDLT procedures were performed in Japan by the end of 2002. The 5 years survival rates were 83% in children and 69% in adults.[111] The lesser outcome in adults compared to that in children indicates that problems remain in adult LDLT.

In LDLT, donor safety must be assured. This may be achieved by optimizing graft size to ensure safety of both donor and recipient, technical expertise in liver procurement from the donor as well as ethical problems of using non-related live donors. As regarding the optimum size of the graft, it was found that, a graft volume of >40% of the recipient standard liver volume is necessary,[112] while for the living donor the remnant liver mass must be more than 30% of the whole liver.[113] The term "standard liver volume" has become a key concept in LDLT and it has been estimated using the following formula:[114]

Standard liver volume (SV) in ml = 706.2 x (body surface area [m2]) + 2.4.

successful series of LDLT with an overall graft survival of 75% and patient survival of 85%.[97] Furthermore, he was the first to report a prospective ethical analysis of this radical

LDLT in children involves the removal of an adult donor left lateral segment (segment 2 and 3). Monosegment transplantation (segment 3) was introduced in Japan to solve the problem of "Large for size" grafts in small children.[99] The donor operation has been associated with a low and acceptable risk for complications. The donors being related to the recipients (parents), the risk for the donor is balanced by the great benefit to be received by the

LDLT was initially restricted to children with chronic disease, in relatively stable condition, in order to avoid a major psychological pressure on the potential donor.[98] With larger experience, it was extended to emergency cases such as fulminant hepatic failure. Auxiliary transplantation, initially developed in this indication,[78] and in metabolic disorders,[100]

The continued shortage of cadaver livers in the face of growing list of recipients plus the

The expansion of LDLT to the adult population began in the countries where the availability of deceased donors was scarce, and in some cases, totally unavailable.[105-107] The law for deceased organ retrieval was instituted in Japan in 1998, however, the lack of societal acceptance of organ retrieval from brain dead donors resulted in live donation being the main source of grafts for patients awaiting transplantation in Japan and other countries in

On November 2, 1993, the Shinshu group performed the first successful adult-to-adult LDLT.[28] By June 2002, there were 433 adult LDLT cases recorded in European Liver Transplantation Regestery,[109] with 3 years graft and patient survival rate of 65% and 68% respectively. According to the United Network for Organ Sharing (UNOS), 731 adult LDLT cases have been performed in the United States by October 2001. The 3 years graft survival was 47% between 1998 and 1999 (n=156) but it improved significantly to 61% between July 1999 and June 2001 (n=285).[110] According to the Japanese Liver Transplantation Society, 1063 adult LDLT procedures were performed in Japan by the end of 2002. The 5 years survival rates were 83% in children and 69% in adults.[111] The lesser outcome in adults

In LDLT, donor safety must be assured. This may be achieved by optimizing graft size to ensure safety of both donor and recipient, technical expertise in liver procurement from the donor as well as ethical problems of using non-related live donors. As regarding the optimum size of the graft, it was found that, a graft volume of >40% of the recipient standard liver volume is necessary,[112] while for the living donor the remnant liver mass must be more than 30% of the whole liver.[113] The term "standard liver volume" has become a key concept in LDLT and it has been estimated using the following

Standard liver volume (SV) in ml = 706.2 x (body surface area [m2]) + 2.4.

compared to that in children indicates that problems remain in adult LDLT.

surgical innovation prior to performing their first LDLT.[98]

transplant recipient, as well as the donor's psychological benefit.

could also be performed with a living donor liver.[101-104]

**3.4.2 Adult-to-adult LDLT** 

Asia.[108]

formula:[114]

advantages of LDLT have led to the introduction of LDLT in adults.

In order to obtain the optimum graft size in adult-to-adult living donor transplantation, many graft types has been introduced. The strategy of selection of left or right liver graft is influenced by the patient's preoperative condition as patient with advanced liver disease require a larger liver mass.[115] The model for end-stage liver disease (MELD) score could become a satisfactory criterion for differentiating between high and low-risk patients and therefore determine the type of graft to use.[116] In the initial adult LDLT procedures only a left liver graft was used. In 1998, the Shinshu group reported satisfactory results using a left liver graft in 13 patients.[107] To cover wide range of recipient body weight, the right lobe graft was introduced in 1998 in Kyoto university.[117] In the same year, the University of Colorado group also introduced the right liver graft in adult LDLT,[118] the group performed 80 adult LDLT. In the first 10 cases, the right lobe graft was procured without the middle hepatic vein (MHV), 3 grafts were lost. As a result, the group included the MHV in the right lobe graft in the subsequent 70 cases. No graft loss was experienced.[119] The reason may be due to the prevention of congestion of the anterior segment of the right lobe which is drained by the MHV. However, the right lobe graft including the MHV was first introduced by the Hong Kong group in 1996.[106] In this situation, the volume of the remnant liver should be at least greater than 30% and the anatomy of vein 4 must be precisely evaluated before this procedure is accepted. However, the outcome of initial 8 donors and recipients were not without complications, one recipient died and the recipients as well as the donors experienced high morbidity.[106] The next 92 patients subsequently received extended right liver grafts (right lobe graft including the MHV) with the following innovations: elimination of venovenous bypass from the routine protocol, preservation of segment 4 venous drainage for donors, venoplasty of MHV and right hepatic vein (RHV) into a single orifice for better venous return and easy vein reconstruction in recipients and preservation of the blood supply to the right hepatic ducts. Over time the mortality rate of recipient decrease from 16% in the initial 50 cases to 0% in more recent patients.[120]

Lee, aggressively reconstructed the MHV tributaries in right liver grafts without the MHV trunk and named this type of graft a modified right lobe graft.[121] Ghobrial, also recommended reconstruction of the MHV tributary veins when the RHV in the graft was <1.5 cm in diameter.[90] All MHV tributaries with a size >5 mm should be preserved during donor hepatectomy and reconstructed with autogenous interposition vein grafts.[122]

Right hepatectomy imposes an increased surgical risk on the donor due to the reduced residual liver volume. A recent report indicated that in 25% of potential donors, the right liver had an estimated volume of >70% of the whole.[123] Since safe donation was possible only when estimated residual liver volume was >30%, right hepatectomy is not possible for some potential donors. The University of Tokyo group was the first to design the right lateral sector graft consisting of segment 6 and 7 in those donors with right livers over 70% of liver volume and the estimated volume of the right lateral segments is greater than that of the left liver and at the same time >40% of the recipient's standard liver volume.[124] Between January 2000 and April 2001, 6 of 32 adult-to-adult LDLT with a right lateral sector graft were performed. The postoperative course was uneventful in all donors and all recipients survived the operation.[125]

Lee et al, were the first to devise dual grafts from 2 living donors.[126] Most commonly, both donors donate the left liver or left lateral segment. The first left liver graft is orthotopically implanted in the original left position, the second left liver graft is rotated 180 degrees and positioned heterotopically in the right upper quadrant fossa. Because the bile duct is now located behind the portal vein and hepatic artery, bile duct reconstruction is necessary before reconstruction of vessels. An interposition vein graft might be necessary for the reconstruction of the hepatic or portal vein. By the end of 2003, this technique was used in 93 patients with satisfactory results. However the procedure has limited appeal due to the high requirements of economic and medical resources including 3 operating rooms and 3 surgical teams working simultaneously.[127]
