Portal flow modulation in living donor liver transplantation: review with a focus on splenectomy

Abstract

Small-for-size graft (SFSG) syndrome after living donor liver transplantation (LDLT) is the dysfunction of a small graft, characterized by coagulopathy, cholestasis, ascites, and encephalopathy. It is a serious complication of LDLT and usually triggered by excessive portal flow transmitted to the allograft in the postperfusion setting, resulting in sinusoidal congestion and hemorrhage. Portal overflow injures the liver directly through nutrient excess, endothelial activation, and sinusoidal shear stress, and indirectly through arterial vasoconstriction. These conditions may be attenuated with portal flow modulation. Attempts have been made to control excessive portal flow to the SFSG, including simultaneous splenectomy, splenic artery ligation, hemi-portocaval shunt, and pharmacological manipulation, with positive outcomes. Currently, a donor liver is considered a SFSG when the graft-to-recipient weight ratio is less than 0.8 or the ratio of the graft volume to the standard liver volume is less than 40%. A strategy for transplanting SFSG safely into recipients and avoiding extensive surgery in the living donor could effectively address the donor shortage. We review the literature and assess our current knowledge of and strategies for portal flow modulation in LDLT.

Keywords: Living donor liver transplantation; Modulation; Portal flow.

Fig. 1

Representative case of portal vein thrombosis (PVT). a The PVT (arrow) extended from the splenic vein (arrowhead) stump 3 days after living donor liver transplantation (LDLT) with simultaneous splenectomy. b Enhanced computed tomography (CT) shows a patent portal vein (arrow) 1 year after LDLT

Fig. 2

Incidence of portal vein thrombosis (PVT). The incidence of PVT after LDLT was 3.5% with simultaneous splenectomy and 4.0% with splenectomy before LDLT. In contrast, no PVT was detected in patients without portal flow modulation or in those who underwent SAL. The difference among the groups was not significant

Fig. 3

Representative case of a patient with a huge portosystemic shunt. a, b Pre-LDLT: enhanced CT shows huge splenorenal (arrow head) and mesocaval (arrowhead) shunts. The portal vein was atrophic (arrow). c, d 3 months after LDLT with splenectomy. Enhanced CT reveals a patent mesocaval shunt (arrowhead). The portal vein (arrow) was thrombosed. The splenorenal shunt was closed with simultaneous splenectomy