This study was a retrospective analysis of pediatric LT using a HRLLS graft. We searched the institutional database of LT from January 2013 to December 2014, and found three cases of HRLLS graft implantation that could provide intraoperatively taken photographs showing the detailed surgical procedures. The purpose of this study was to present the detailed techniques for harvesting and implanting HRLLS grafts. The study protocol was approved by the institutional review board of the Asan Medical Center, which waived the requirement for informed consent because of the retrospective nature of this study (IRB No. 2020-0836).

The shape of the donor LLS is important for deciding whether to perform non-anatomical size reduction. If the LLS appears to be like a flat fish, it is easy and effective to perform non-anatomical resection. In contrast, it appears similar to a puffy fish, it is not indicated for non- anatomical resection because we cannot effectively reduce the graft thickness (Fig. 1).

The target of graft size reduction is to make the estimated graft-recipient weight ratio (GRWR) less than 4%. Considering that the size reduction rate following non- anatomical resection is usually less than 50%, the donors with LLS volume comparable to 4-8% of GRWR on computed tomography (CT) volumetry are theoretically indicated for size reduction. The graft thickness-to-anteroposterior diameter in the recipient’s abdominal cavity ratio should be taken into account.¹⁰ If this ratio of thickness is less than 1.0, the donors are also indicated for size reduction. If the GRWR is less than 4% and thickness ratio is less than 1.0, such LLS grafts may not require size reduction (Fig. 2).

The surface marking is made along the falciform ligament to split a usual LLS graft, and then additional markings are made transversely at the ventral part of the segment III and vertically at the lateral part of the segment II. First, the liver is transected to make a LLS graft. Thereafter, the parenchymal transection continues along the additional marking lines. The transection plane should be perpendicular to the intrahepatic glissonian branches in order to prevent unnecessary ischemia (Fig. 3). In LDLT, the HRLLS is recovered along the pace of recipient operation. In split LT, the HRLLS graft can be recovered in advance before the harvesting of other organs as in LDLT. This method is usually adopted if the pediatric and adult recipients are cared for in different hospitals. If the two recipients of the split liver grafts are cared for in the same hospital, whole liver harvesting after in situ splitting is preferred, because complete separation of two split liver grafts at the back table is more convenient and safe.

The left hepatic vein orifice of the HRLLS graft is often small, thus patch venoplasty is often used to enlarge the orifice. The three hepatic vein orifices at the recipient’s inferior vena cava (IVC) was opened to make a large orifice, which should be much larger than the diameter of the recipient’s IVC. If the recipient’s native portal vein appears normal, a branch patch can be used for portal vein reconstruction. If the portal vein appears hypoplastic, we preferentially use interposition of an external iliac vein homograft.¹¹ Since the diameter of the left hepatic artery in a HRLLS graft is often very small, we always perform arterial reconstruction under surgical microscopy. The native bile duct of the infants is very small, so hepaticojejunostomy should be used.

The mean recipient age was 4.0±1.7 months (range: 3-6) and body weight was 5.3±1.4 kg (range: 4.1-6.9). Primary diagnoses of the recipients were progressive familial intrahepatic cholestasis (PFIC) in 2 and biliary atresia in 1. The types of LT were LDLT in 1 and split deceased donor LT in 2. The mean weight of the HRLLS grafts was 191.7±62.1 g (range: 120-230) and graft-recipient weight ratio (GRWR) was 3.75±1.57% (range: 2.45-5.49). Types of the abdominal wound closure were one case of primary repair, one of two-staged closure with a mesh, and one of three-staged repair with a silo and a mesh. All three patients recovered uneventfully from the LT operation and are doing well to date for more than 6 years after transplantation.

Case No. 1: The patient was a 3-month-old 4.9 kg- weighing female infant with suspected PFIC type 2. She was born at 36 weeks through urgent cesarean section because of oligohydramnios. Jaundice developed soon after birth and progressed gradually with hepatomegaly (Fig. 4A). The general condition of this patient deteriorated rapidly, so LDLT was planned. The living donor was her mother’s sister, who was 29 years old. The whole LLS volume was measured to be 250 ml. The graft thickness ratio was 0.89 (Fig. 4B).

Recipient hepatectomy was performed according to the standard procedure of pediatric LDLT, and the size of the native liver was measured (Fig. 5). Donor surgery was performed through an upper midline incision. The left hepatic artery and portal vein were isolated and hepatic parenchyma was transected according to the standard procedure of LLS harvest. Thereafter, the size of the LLS graft was measured with a paper ruler. Considering the size of the recipient’s native liver, the lines for size reduction were drawn on the liver surface. The peripheral parts of the segment II and III were resected with a Cavitron ultrasonic aspirator (CUSA). The resected liver fragments from the segment II and III weighed 70 g and 25 g, respectively (Fig. 6).

The HRLLS graft was harvested and its weight was 120 g, making a GRWR of 2.45%. Graft implantation was performed according to the standard procedure of LDLT using a LLS graft. Reconstruction was done in the order of hepatic vein, portal vein, hepatic artery and Roux-en-Y hepaticojejunostomy. The posttransplant recovery was uneventful except for production of ascites for a prolonged period (Fig. 7). This patient was discharged at 47 days after transplantation. Currently, she has been doing well for more than 7 years after transplantation.

Case No. 2: The patient was a 3-month-old 4.1 kg- weighing female infant clinically diagnosed with PFIC. She was born in full-term spontaneous delivery. Soon after birth, jaundice developed and then hepatomegaly and splenomegaly progressed (Fig. 8). Her general condition and liver function deteriorated progressively, so she was enrolled to the waiting list with the Korean Network for Organ Sharing (KONOS) status 1. The deceased donor was a 20-year-old female with body weight of 64 kg. After laparotomy, the size of the LLS graft was evaluated by manual palpation. The surface marking was made along the falciform ligament to split a usual LLS graft, and then additional markings were made for size reduction. The liver was split into a right trisegment graft and a LLS graft, and then hepatic resection for size reduction was performed. The weight of the HRLLS graft was 225 g, making a GRWR of 5.49%. The orifice of the graft left hepatic vein appeared similar to a figure of 8, so unification venoplasty was performed after septotomy and excision of the intervening hepatic parenchyma (Fig. 9).

Recipient hepatectomy was performed according to the standard procedure for pediatric LDLT. Graft implantation was performed according to the standard procedure of LLS implantation. Reconstruction was done in the order of hepatic vein, portal vein, hepatic artery and Roux-en-Y hepaticojejunostomy. The graft was too large to allow primary abdominal wound closure, thus a staged closure was done by means of a temporary coverage with a silo using a prosthetic sheet, a temporary abdominal wall closure with Permacol patch (porcine dermal collagen implant, Medtronic, USA), and a final primary closure at 13 days after transplantation. She recovered slowly (Fig. 10) and was discharged at 68 days after transplantation. Currently, she has been doing well for 6 years after transplantation.

Case No. 3: The patient was a 6-month-old 6.9 kg- weighing female infant with biliary atresia. She was born in full-term delivery through a cesarean section. She underwent Kasai portoenterostomy at 1 month of age. Her general condition and liver function deteriorated progressively, so she was enrolled on the KONOS waiting list for split LT (Fig. 11).

The deceased donor was a 32-year-old 78 kg-weight male. In situ splitting and size reduction was performed according to the abovementioned methods. The HRLLS graft weighed 230 gm, thus making a GRWR of 3.33%. Graft implantation was performed according to the standard procedures of LLS implantation. Since there was portal vein hypoplasia, the donor’s external iliac vein segment was used for interposition graft. Graft reconstruction was done in the order of hepatic vein, portal vein, hepatic artery and Roux-en-Y hepaticojejunostomy. The abdominal wound was temporarily closed with a Permacol patch because the graft was too large to be accommodated within the abdomen (Fig. 12). At 7 days, the abdomen wound was primarily closed. The posttransplant recovery was uneventful (Fig. 13) and this patient was discharged at 40 days after transplantation. Currently, she has been doing well for more than 7 years after transplantation.