Answer: A replaced left hepatic artery or an accessory left hepatic artery.
Comment: The images show a contrast enhanced vessel extending the entire length of the fissure for the
ligamentum venosum. The image on the right shows the vessel extends into the lesser omentum where the left gastric
artery resides. Normally, there
should be no identifiable structures in the fissure for the ligamentum venosum. The ligamentum venosum is the
obliterated ductus venosus which in the fetus is the continuation of the left umbilical vein through the liver
to the inferior vena cava. Aside from the ligamentum
venosum which usually cannot be identified, the fissure for the ligamentum venosum contains only fat or
occasionally an extension of the peritoneal cavity. One common normal variant is to see an artery arising
from the left gastric artery that extends into this fissure and supplies the left lobe of the liver. If no left hepatic
artery is seen arising from the proper hepatic artery in the porta hepatis, this variant would be a replaced
hepatic artery which would supply the entire left lobe of the liver. If a left hepatic artery is seen arising from
the proper hepatic artery in the porta hepatis, this variant would be an accessory left hepatic artery. In this latter
case, different parts of the left lobe of the liver would be supplied by each artery. Since the porta hepatis is
not shown in the images above, it cannot be determined from these images whether this is a replaced or an accessory
left hepatic artery. The main point of this question is that any artery seen extending the full length of the
fissure for the ligamentum venosum represents variant anatomy, and the porta hepatis, the lesser omentum, and
adjacent vessels should be examined to determine the configuration of the variant anatomy.
