EXPERIMENTAL AND CLINICAL TRANSPLANTATION

This case report describes the first ex situ full-right/full-left splitting of a liver from a pediatric deceased donor in the Middle East with an excellent outcome for both recipients. The left lateral split-liver transplant requires division of the deceased donor liver into a left lateral lobe for a pediatric recipient and an extended right lobe for an adult recipient, thus producing only 1 graft for a pediatric recipient. Full-right/full-left liver transplant, which splits the liver along the line of Cantlie, is a much more complex and challenging surgery, even though the technique is fully developed, and is theoretically able to produce 2 sizeable grafts for 2 pediatric recipients. However, the full-right/full-left liver transplant remains limited because of the small vascular structures and therefore was not recommended and was not previously described in the literature.

Key words : Deceased donor liver transplant, Pediatric liver transplant

Split-liver transplant was first introduced in the late 1980s to overcome the persistent problem of organ shortages, especially in pediatric patients.^1,2

Left lateral split requires division of the deceased donor liver into a left lateral lobe (segments 2 and 3) for a pediatric recipient and an extended right lobe (segments 1, 4, and 5-8) for an adult recipient, thus producing only 1 graft for a pediatric recipient. Several studies have shown that the outcome of transplant of the left lateral lobe derived from a split liver is similar to outcomes with whole liver transplant.1-3 Full-right/full-left liver transplant splits the liver along the line of Cantlie and is a much more complex and challenging surgery, even though the technique is fully developed and is theoretically able to produce 2 sizeable grafts for 2 adult recipients. A full-right/full-left split-liver transplant from a pediatric deceased donor is limited because of the small vascular structures and therefore was not recommended and was not previously described in the literature. Here, we are presenting a case of full-right and full-left lobes split from a pediatric deceased donor liver that were subsequently transplanted to 2 pediatric recipients, and we report the long-term outcomes of both grafts.

Donor characteristics
The deceased donor was an 8-year-old female, blood group A, who died from a massive spontaneous intracranial hemorrhage with tonsillar herniation. Donor height was 130 cm, and donor weight was 30 kg. The laboratory results at the time of procurement were as follows: 138 μmol/L Na, 29 IU/L aspartic transaminase, 28 IU/L alanine aminotransferase, 31 IU/L γ-glutamyl transferase, and 10 μmol/L bilirubin. The donor was on dopamine at 10 μg/kg, and intensive care unit (ICU) stay was 3 days. Multiorgan retrieval was performed, which included liver, kidneys, heart, and lungs. For logistical reasons, the split-liver procedure was performed ex situ.

Recipient characteristics and criteria for selection
Recipient 1 was a 7-month-old female diagnosed with biliary atresia. Her blood group was O Rh+. Her body weight was 5.4 kg. The intraoperative findings included the following congenital anomalies: a preduodenal portal vein; a hepatic artery originating directly from the aorta, and a caval aplasia.

Recipient 2 was a female aged 3 years and 2 months who was diagnosed with neonatal sclerosing cholangitis. Her blood group was A Rh+. Her weight was 12.7 kg.

Both recipients were at the top of the wait list, and their weights were appropriate for the expected weight of both hemi-livers.

Ex situ splitting technique
After standard bench treatment of the whole liver (450 g) in cold preservation solution, the detailed anatomy of the liver vasculature confirmed standard anatomy of the hepatic artery and portal vein. The segment 4 artery originated from the left hepatic artery. Exploration of the venous anatomy revealed a middle hepatic vein that mainly drained the right hepatic lobe. Exploration of the biliary anatomy revealed no significant anomalies. Because of the small left lateral lobe of this small pediatric whole liver, the index patient with biliary atresia and body weight of 5.4 kg was designated to receive the whole left lobe. Consequently, the decision was to perform a full-right/full-left ex situ split because the quality of the liver, the anatomy of the vessels, and the lobar volume distribution were all in favor of this procedure.

The ex situ split began with dissection of the main arterial trunk, and the right hepatic artery was cut from the proper hepatic artery to retain the main arterial trunk as part of the left graft. The main portal vein was completely dissected free up to the main portal vein bifurcation, and the right portal vein was cut from the main portal vein to retain the main portal vein as part of the left graft. The left main hepatic duct was cut beside the main bile duct bifurcation to retain the main bile duct as part of the right graft. The vena cava was split into 2 halves (split-cava technique).⁴ The liver parenchyma was transected with the sharp knife technique along the line of Cantlie on the left side of the middle hepatic vein to retain the middle hepatic vein as part of the right graft. Because segment 1 of the bile duct was separately draining into the main bile duct, the decision was made to remove segment 1 from the left lobe. After careful closure of all vessel openings on the resection plane, both grafts were stored in ice until implant.

Implant surgical technique in recipient 1: full left lobe
Recipient 1 underwent transplant of the full left lobe (segments 2, 3, and 4) of the graft (212 g). The donor’s caval patch included the left hepatic vein and was anastomosed to the recipient’s common venous opening, which drained directly to the right atrium. The main portal vein of the donor was anastomosed with the preduodenal confluence venosum of the recipient. After an uneventful portovenous reperfusion, the common hepatic artery of the graft was anastomosed to the common hepatic artery of the recipient. The left main bile duct stump was anastomosed to a jejunal loop (Roux-en-Y).

Implant surgical technique in recipient 2: full-right lobe
The implant began with the caval patch of the right lobe (which includes the right hepatic vein, the middle hepatic vein, and the inferior hepatic veins), which was anastomosed side-to-side to the recipient’s vena cava. The right portal vein stump of the graft was anastomosed to the recipient’s main portal vein. After portovenous reperfusion, the right hepatic artery of the graft was anastomosed to the right hepatic artery of the recipient. The main hepatic bile duct was anastomosed to the jejunal loop (Roux-en-Y).

Results in recipient 1 with full-left lobe
The postoperative course was uneventful without complications with 7-day ICU stay. She was discharged home 26 days after liver transplant. At that time, liver function tests had normalized, and the immunosuppression regimen included tacrolimus, prednisolone, and mycophenolate.

One year after transplant at the age of 19 months old, the patient is at home and clinically well.

Results in recipient 2 with full-right lobe
Recipient 2 spent 5 days in the ICU, and the postoperative course was without complications.

She was discharged home 18 days after the liver transplant. At that time, liver function testshad normalized, and the immunosuppression regimen included tacrolimus and prednisolone. One year after transplant, she is at home and clinically well.

The left lateral splitting technique, which results in a left lateral hemi-graft and an extended right hemi-graft, is feasible especially for 1 pediatric and 1 adult recipient from an adult deceased donor liver. This technique might not be applicable in a pediatric donor because the functional liver volume can only be distributed between 2 other children. In this case, a full-right/full-left split-liver procedure is the solution to realize 2 usable hemi-grafts. We could not have performed the usual split-liver technique, which creates an extended right lobe and a left lateral segment because the likely result would be a left lateral lobe insufficient for a pediatric recipient of less than 10 kg body weight and an extended right lobe insufficient for an adult recipient.

For our recipients, the deceased donor liver was of good quality and was anatomically appropriate for full-right/full-left liver split for recipients with graft-to-recipient weight ratio greater than 1 with no previous surgery, which allowed a short cold ischemia time.

Full-right/full-left split-liver transplant is technically challenging, but it is safe when performed by an experienced surgical team. In situ liver split has advantages compared with the ex situ approach on the back table. These advantages include the control of bleeding and bile leakages from the cut surface, the ease of detection of anatomic variations, and the assessment of the graft quality under physiological conditions.^4,5 However, logistical requirements may lead to the application of the ex situ split technique as shown in our case.

An optimal venous outflow of both hemi-grafts is a critical factor for success. The best technique to realize this outcome is the split-cava technique. In contrast to the conventional split-liver procedure in which the vena cava remains with the right lobe and consecutive caudate lobe resection may be required, the split-cava technique maintains the venous drainage of segment 1 and the dorsal parts of the right lobe.6 In this case, we did not perform a split of the middle hepatic vein because (1) segments 4 and 8 of the right lobe were mainly drained via the middle hepatic vein and (2) the graft/recipient weight ratio of the left lobe recipient was 4%, which indicates a low risk for a small-for-size situation.

This case report describes the first ex situ full-right/full-left splitting of a pediatric deceased donor liver with an excellent outcome for both pediatric recipients. Full-right/full-left split allows the expansion of the organ donor pool for pediatric and adult liver transplants. The technique is theoretically feasible yet is still underutilized when considered in the context that 15% of deceased donor livers can be split into full-right and full-left grafts. However, this procedure requires a team with extensive surgical experience with split-liver techniques and advanced expertise in pediatric and adult segmental liver transplant techniques. The logistical requirements for the full-right/full-left split-liver transplant are extensive because 2 complex liver transplant surgeries are in progress simultaneously.

Selection of suitable pediatric deceased donor livers and assignment to appropriate recipients are key factors for success of a full-right/full-left split-liver transplant. Although the surgical techniques have evolved to an established level and are well described, there has not been sufficient practice to consider the procedure as a standard surgical procedure.

Volume: 19 Issue: 3 March 2021

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