The main hepatic anatomic variations for the purpose of split-liver transplantation

Variant hepatic anatomy must be recognized and appropriately managed during split-liver transplantation to ensure complete vascular and biliary supply to both grafts. The aim of this study is to demonstrate the importance of an assessment of the hepatic anatomical structures for the purpose of split-liver transplantation.

Human cadaveric livers (n = 60) were obtained from routine autopsies. The cadavers and the livers had to comply with the following requirements: 1) minimum age 18 years: 2) no liver pathology to be expected from medical history and 3) no liver pathology noted at the autopsy. Resections were carried out en bloc with liver, celiac trunk, left gastric artery, lesser omentum, superior mesenteric artery and head of the pancreas. The main anatomical structures of the liver as hepatic artery, portal vein, biliary tree and hepatic veins were dissected out and recorded in detail also correlating to hepatic segments for application of the liver splitting.

The right, the median and left hepatic vein is unique, respectively, in 59 (98.3%), 53 (88.3%) and 46 (76.3%) cases. The portal vein trunk has been divided into right and left branch in 59 (98.3%) cases. A median branch appeared in 9 (15.2%) cases and no bifurcation of the portal vein occurred in 1 (1.6%) case. The right and left hepatic ducts were multiple, respectively, 47 (78.3%) and 57 (95%) cases, however, the median hepatic duct, was unique in 16 (26.6%) cases. Looking at the intrahepatic distribution of the right hepatic duct we found four branches in 28 (59%) cases, towards segments V, VI, VII, VIII; two branches in 11 (23%) cases, towards segments V, VI and two branches in 8 (17%) cases, towards segments VII, VIII. Fifty-seven cadavers had multiple left hepatic ducts. The intrahepatic dissection showed that the major branches distribution were towards hepatic segments II and III. Three separate branches of the left hepatic duct were found, in 11 (19%) cases towards hepatic segments II, III and IV. Two intrahepatic ducts, coming from hepatic segments V and VI, drained separate to left intrahepatic biliary tree in 1 (2%) case. The arterial irrigation of the liver was made basically by right and left hepatic artery, only in 9 (15%) cases was there a median hepatic artery. Right hepatic artery, coming from the superior mesenteric artery, was present in 15 (25%) cases and left hepatic artery originating from left gastric artery in only 2 (3.3%) cases. Left hepatic artery had two exceptional origins, in 1 (1.6%) case coming directly from the abdominal aorta and in another from the superior mesenteric artery. The right and left hepatic artery was accessory, respectively, in 11 (18.3%) and 2 (3.3%) cases. Right hepatic artery was dominant in 4 (6.6%) cases. The median hepatic artery directed, respectively, to segment IV in 6 (10%) and to segment II and III in 3 (4.9%) cases.

The study has shown that technique of controlled liver splitting for transplantation in two recipients could be an acceptable method for increasing the number of liver allografts. The anatomical and technical details of the splitting procedure are critical to the success of this technique. Good graft function and avoidance of complications depends on each graft having an intact arterial and portal blood supply as well as biliary and venous drainage from all retained liver segments. The absence of bifurcation of the portal vein, is a rare anomaly, and would certainly contraindicate the partition of the liver.