Key words : Auxiliary partial orthotopic liver transplantation, Low graft-to-recipient weight ratio, Small-for-size syndrome

Introduction

Acute liver failure (ALF) is a life-threatening condition that can result in multiorgan failure and death if not treated promptly. A timely liver transplant is lifesaving.¹ However, the shortage of deceased donor livers has led to the development of alternative transplant techniques such as auxiliary partial orthotopic liver transplant (APOLT).^2,3 Auxiliary liver transplants have also been described as rescue procedures using small grafts in patients with ALF until recovery of native liver function.⁴ This allows the native liver to regenerate and eventually eliminates the need for lifelong immunosup-pression.³ With refinements in surgical techniques and better understanding of the pathophysiology of ALF, the results of APOLT have improved.⁴ Due to technical difficulty, this procedure is not commonly performed.⁴ Although numerous studies have been published, there are limited data from India on APOLT as a rescue procedure. Here, we report 2 cases of ALF patients who successfully underwent auxiliary liver transplant as a rescue procedure using an extra-small-for-size graft.

Case Report

Case 1
A 12-year-old female patient presented with a history of jaundice and malaise of 7-day duration. At admission, her bilirubin was 11.5 mg/dL, serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase were 617 IU/mL and 1730 IU/mL, respectively, and the international normalized ratio (INR) was 12.5. She had grade 2 encephalopathy. She gave a history of ingestion of herbal medicines for acne. Etiological workup results, including viral markers, autoimmune markers, and evaluation for Wilson disease, were negative. At 24 hours after admission, the patient’s encephalopathy progressed to grade 4, and intuba-tion was required. Her INR became unrecordable, and she developed metabolic acidosis.

A plan for an urgent liver transplant was made according to King’s College Criteria. Her father was of a compatible blood group and was evaluated as a living donor. Liver volumetry showed a total liver volume of 1053 mL, a right lobe volume of 805 mL (graft-to-recipient weight ratio [GRWR] 1.6), and a left lobe volume of 248 mL (GRWR 0.45). Right lobe graft was not feasible as the remnant liver volume was 23.5% of the total liver volume, which is well below our cutoff value of 30% in the donor. Given the low GRWR of the left lobe, paucity of other suitable donors, and worsening recipient liver function, a left lobe auxiliary liver transplant was planned after discussion of the risks with the patient’s family.

The left lobe was retrieved from the donor. The recipient’s left lobe was removed, and the left lobe graft was implanted in an orthotopic manner (Figure 1). The operative details are shown in Table 1. Portal pressure after reperfusion was 10 mm Hg and increased to 14 mm Hg after clamping the portal vein to the native liver. Postoperatively, the donor had an uneventful recovery and was discharged on day 5. The recipient was extubated on postoperative day 1. The bilirubin and INR results showed a downward trend. She recovered well and was discharged on postoperative day 12.

A computed tomography (CT) scan at 3 months after transplant showed hypertrophy of the native and graft liver (Figure 2). Technetium Tc 99m mebrofenin scan showed good and homogenous tracer uptake and excretion from the native and graft liver. The patient was started on tacrolimus, mycophenolate mofetil, and steroids immediately after transplant. The steroids were stopped 3 months after surgery. The mycophenolate mofetil was stopped 1 year after surgery. The tacrolimus trough levels were maintained between 6 and 8 ng/mL for the first 6 months and between 4 and 6 ng/mL after 6 months. As of this report, she had completed 2 years of follow-up, and the tacrolimus trough levels remained between 2 and 4 ng/mL, with the tacrolimus dose tapered further with close monitoring of the liver function tests.

^{Case 2}
A 23-year-old male patient with no preexisting comorbidities and no history of drug use presented with a 2-week history of jaundice. At presentation, his bilirubin was 12.2 mg/dL, serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transa-minase were 598 IU/mL and 708 IU/mL, respectively, and INR was 3.17. Etiological workup results, including viral markers, autoimmune markers, and evaluation for Wilson disease, were negative. The CT abdomen scan showed a shrunken liver. A transjugular liver biopsy showed submassive necrosis with regenerative nodules. The bilirubin rose to 18 mg/dL and INR increased 7.1 on day 5 of admission, followed by development of encepha-lopathy and metabolic acidosis.

As King’s College Criteria were met, a living donor liver transplant (LDLT) was planned, and donor evaluation was started. The suitable donor was the recipient’s 18-year-old sister, who had no medical comorbidities. According to the institutional protocol, for LDLT we consider donors from the age of 18 years to 55 years. On evaluation, her liver function tests were normal. Volumetry showed a right lobe volume of 330 mL (GRWR 0.5). Because the GRWR was low and the sister was the only available donor, a right lobe APOLT was planned.

A right lobe graft without the middle hepatic vein was retrieved from the donor, and a neo-middle hepatic vein was reconstructed by anastomosing segment 5 and segment 8 veins to a polytetraf-luoroethylene graft. In the recipient, the right lobe was removed, and the right lobe graft was implanted in an orthotopic manner (Figure 3). The operative details are listed in Table 1. Portal pressure after reperfusion was 12 mm Hg and increased to 16 mm Hg after clamping the portal vein to the native liver.

Postoperatively, the donor recovered well and was discharged on day 6. The recipient was extubated after 48 hours. The bilirubin and INR trended downward. The patient developed a fever on postoperative day 10. A CT scan of the abdomen showed a collection at the cut surface of the liver. The collection was drained percutaneously. However, in view of persistent fever, the patient was reexplored on postoperative day 12. At the time of surgery, graft hypertrophy was evident, along with atrophy of the native liver. There was necrosis at the cut surface of the native liver. In view of the above findings, the native liver was explanted. Postoperatively, the fever subsided, and the patient was discharged. At the 10-month follow-up, the patient and the donor were healthy and remained well.

Discussion

For patients with ALF that is unresponsive to medical management, liver transplant is lifesaving, with graft weight being an important determinant of outcome in LDLT.^1,5 A procedure with portal flow modulation using splenic artery ligation, portocaval shunt, and splenectomy has been described for small grafts.⁶ Kusakabe and colleagues⁷ and Uemura and colleagues8 have shown that LDLT with good outcomes can be achieved with GRWR of 0.6 with portal flow modulation; however, a higher GRWR is preferred in patients undergoing transplant for ALF. Auxiliary liver transplant technique has also been used by Kobayashi and colleagues as a rescue procedure in ALF using small grafts.⁴ The smallest graft in their series had a GRWR of 0.42, which was performed as a heterotopic auxiliary liver transplant (HALT).

In our 2 cases, we encountered a situation in which the GRWR was very low, which rendered LDLT with conventional grafts unfeasible. In the first patient, the GRWR was 0.45 using the left lobe graft; because of inadequate remnant in the donor, the right lobe graft could not be used. The scenario was similar in the second case, with a right lobe GRWR of 0.5. There were no other prospective suitable donors for either patient. One option in such cases is to use an extra-small graft for LDLT, but this carries a higher risk of complications such as graft failure, small-for-size syndrome, and biliary and vascular complications. Auxiliary partial orthotopic liver transplant is another option in such cases, in which an auxiliary liver graft is implanted alongside the native liver to supplement its function. The portal flow to the graft is modulated, and the functional liver mass in the recipient’s remnant liver adds to the liver function.

Auxiliary partial orthotopic liver transplant is technically demanding, and complication rates are higher versus the conventional deceased donor or living donor transplants.⁹ In the series by Kobayashi and colleagues, 2 of the 5 patients died from sepsis and from cytomegalovirus pneumonia, and complications were seen in all 5 patients.⁴ In patients with ALF with coagulopathy and hemodynamic instability, APOLT should be selected wisely. In our 2 cases, although the patients had severe coagulopathy, we felt that the risk of using an extra-small-for-size graft for conventional LDLT outweighed the risk of an APOLT. We also considered the option of a HALT. However, there is lack of evidence, except for few case reports, related to success of HALT in ALF.3 In addition, because of technical issues such as high incidence of abdominal compartment syndrome, portal flow, and hepatic venous outflow problems, HALT is not widely practiced.^3,10

Postoperatively, both patients recovered well. With refinements in surgical techniques and improved results of transplant over time, APOLT should be reconsidered as a rescue procedure in extra-small-for-size grafts when no other suitable option is available. Withdrawal of immunosup-pression with APOLT should be viewed as a secondary advantage.

Conclusions

Auxiliary partial orthotopic liver transplant using extra-small-for-size grafts was successfully perfor-med in the 2 cases we presented here, and both patients had good postoperative recovery. Hence, APOLT should be considered as a rescue procedure in selected cases where no other suitable option is available.

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