Less-known anatomical structure of the Liver - An anatomical substrate for intrahepatic portacaval shunting

Abstract

There are little known anatomical details within human liver formed through the confluence of fibrous sheathes of the portal canals and those of the hepatic veins in some areas where these structures come into contact and interdigitate.

The perivascular fibrous capsule, a layer of connective tissue enveloping the intrahepatic portion of the portal triad, extends from the portal tracts to the hepatic vein walls, ensheathing this latter vessel as the fourth element in addition to the portal triad. We have suggested the term “porta-caval fibrous con­nec­tions” (PCFC) for the ana­tomical structures for­med through the confluence of fibrous envelopes of the intrahepatic bile ducts and those of the hepatic veins. In order to reveal the  porta-caval fibrous con¬nec¬tions, 101 normal livers taken at autopsy from adult patients were studied. The following forms of the intrahepatic porta-caval fibrous connections  can be distinguished based on the area of fusion of fibrous sheathes of the portal tracts and the hepatic veins:

Complete fusion - This type of connections can principally be seen within the segments II and III.  

Tangential connection. The partial fusion, or tangential intrahepatic porta-caval fibrous connections, are mostly found within the hepatic segments II, III, VI, and VII.

The fan-shaped This peculiar type of IHPCFC is permanently present within the hepatic segment I.

Laminar forms of intrahepatic porta-caval fibrous connections  are found in 9.3% of cases and are formed through a fibrous lamina between the perivascular fibrous capsule and the hepatic vein sheath.

Thread-like intrahepatic porta-caval fibrous connections  are found in 4.7% of cases.The thread-like IHPCFC are found in the he¬patic segments II, III, VI, and VII.

The relationship of the individual elements of portal triad – with the hepatic veins within the intrahepatic porta-caval fibrous connections  is less variable. The hepatic vein is most frequently bordered by a bile duct (78.2%).  Moreover, it is frequently the only structure to have contact with the hepatic vein (49.4%) The direct relationship of the hepatic veins with the bile ducts and their mucous glands within the IHPCFC can help inflammation to spread from the bile ducts to the hepatic veins. The close anatomical relationship between the portal and the hepatic veins within the intrahepatic porta-caval fibrous connections is of great practical importance for surgical intrahepatic portacaval shunting for which it provides a favorable condition. Thus, the fibrous sheathes of the portal tracts and those of the hepatic veins, at some of points of their crossing, form a fibrous connection as a distinct anatomical detail through which the hepatic vein is in direct interaction with the portal complex and can be viewed as its part. This anatomical relationship between the portal tracts and hepatic veins is a normal occurrence in human liver. We deem that the hepatic porta-caval fibrous connections deserve an appropriate place in anatomical nomenclature.