Ex Situ Machine Perfusion of Human Donor Livers via the Surgically Reopened Umbilical Vein: A Proof of Concept

Abstract

Background: Machine perfusion of donor livers is typically performed via the portal vein main stem. Instead, cannulation of a reopened umbilical vein could allow machine perfusion during organ procurement and subsequent implantation in the recipient without interruption of the portal venous circulation. We aimed to assess the feasibility of portal venous machine perfusion via the umbilical vein.

Methods: During back table inspection of 5 human livers declined for transplantation, the umbilical vein was surgically reopened, dilated, and cannulated. Hypothermic and normothermic oxygenated machine perfusion (NMP) were performed using the umbilical vein for portal inflow. Three livers were perfused with hypothermic machine perfusion, 1 full liver graft underwent NMP for 4 hours, and 1 left lateral split procedure was performed under continuous NMP with portal perfusion via the umbilical vein.

Results: In all livers, access to the portal venous system via the umbilical vein was successfully achieved with good portal flows and macroscopically homogeneous perfusion. The full liver graft that underwent NMP via the umbilical vein for 4 hours showed good lactate clearance, normalized pH, and achieved good bile production with pH >7.55. During the split procedure under continuous NMP via the umbilical vein, the left lateral segment and extended right lobe remained equally perfused, as demonstrated by Doppler ultrasound.

Conclusions: Machine perfusion with portal perfusion via the umbilical vein is feasible. Portal venous flows were similar to those obtained after cannulation of the portal vein main stem. This technique enables continuous oxygenated perfusion of liver grafts during procurement, splitting, and implantation.

FIGURE 1.

Step-by-step approach for cannulation of the umbilical vein for ex situ machine perfusion. A, Schematic drawing of human portal venous anatomy with usual machine perfusion via the PV main stem. B, Schematic drawing of machine perfusion through the UV with alternative flow pattern. C, The UL of a human donor liver before dissection of the UV. D, Introduction of the FBC to pneumatically dilate the obliterated UV. E, Adequately dilated insertion of the UV into the left intrahepatic PV branch (denoted by the *). F, Connection between UV and PV main stem ensured (demonstrated by a probe). G, Cannulation of the UV with a 24F cannula. H, Normothermic machine perfusion via the UV and the SA. The proximal stump of the PV main stem was closed with a nontraumatic vascular clamp. FBC, Fogarty balloon catheter; PV, portal vein; SA, supratruncal aorta; UL, umbilical ligament; UV, umbilical vein.

FIGURE 2.

Ex situ evaluation of the liver that underwent NMP via the umbilical vein. A, Macroscopic appearance of the liver during NMP via the umbilical vein. B, Lactate clearance of the full liver graft during NMP. C, Normalization of perfusate pH of the full liver graft during NMP. No sodium bicarbonate was administered. D, Ultrasound image with Doppler acknowledging the position of the 24F perfusion cannula (denoted by the *) in the UV. E, Ultrasound image with Doppler demonstrating the patency of peripheral PV branches in the right liver lobe. F, Ultrasound image with Doppler visualizing adequate venous outflow from the RHV. LPV, left portal vein; NMP, normothermic machine perfusion; PV, portal vein; RHV, right hepatic vein; SA, supratruncal aorta; S7 PV, segment 7 portal vein branch; UV, umbilical vein.

FIGURE 3.

Step-by-step approach to perform an ex situ continuous oxygenated liver split procedure using the umbilical vein. A, Experimental setting for the splitting of liver 5. The PV was clamped and the whole liver graft was perfused normothermically via the UV. B, The LLS was perfused with NMP via the UV and SA after the splitting. The ERL was removed from the perfusion device and preserved on ice. The LLS was perfused with NMP via the UV and SA after the splitting. The ERL was removed from the perfusion device and preserved on ice. C, LLS procedure during continuous NMP. D, NMP of LLS after splitting under NMP via the UV and SA. E, Conceptual clinical ex situ splitting procedure: until PV dissection, continuous oxygenated machine perfusion via the PV main stem is performed. The UV is cannulated but clamped to prevent blackflow. F, Conceptual ex situ split procedure: after PV dissection, hypothermic machine perfusion via both the PV main stem and UV allows continuous oxygenation of both partial liver grafts during and after splitting. ERL, extended right lobe; LHV, left hepatic vein; LLS, left lateral segment; NMP, normothermic machine perfusion; PV, portal vein; SA, supratruncal aorta; UV, umbilical vein.