Anatomy of the Hepatic Veins

The hepatic veins drain deoxygenated blood from the liver to the inferior vena cava (IVC), which, in turn, brings it back to the right chamber of the heart. Relatively larger in size, there are three major hepatic veins—the left, middle, and right—corresponding to the left, middle, and right portions of the liver. These structures originate in the liver’s lobule and also serve to transport blood from the colon, pancreas, small intestine, and stomach. Anatomically, they’re often used as landmarks indicating portions of the liver, though there can be a great deal of variation in their structure.

When a blockage occurs of these veins and blood is unable to drain from the liver, a rare disease, Budd-Chiari syndrome can result. These veins can also develop hypertension—high blood pressure in these veins—can also arise in cases of chronic liver disease. Notably, this is often a feature of liver cirrhosis.

Anatomy

Structure & Location

The hepatic veins arise from the core vein central liver lobule—a subsection of the liver—and drain blood to the IVC. These veins vary in size between 6 and 15 millimeters (mm) in diameter, and they’re named after the corresponding part of the liver that they cover. These include:

• Right hepatic vein: The longest of the hepatic veins, the right hepatic vein and lies in the right portal fissure, which divides the liver into an anterior (front-facing) and posterior (rear-facing) sections.
• Middle hepatic vein: This vein runs at the middle portal fissure, dividing the liver into right and left lobes. It runs just behind the IVC.
• Left hepatic vein: This vein is found in the left portal fissure, splitting up the left lobe of the liver into a more medial and lateral sections. 
• Caudate lobe veins: These terminal veins perform the function of draining blood directly to the IVC. They run from the caudate lobe, which is connected to the right lobe of the liver via a narrow structure called the caudate process.  

Anatomical Variations

Variations to the anatomy of the hepatic veins are not uncommon and occur in approximately 30% of the population. In most cases, the right hepatic vein will be what’s affected. Doctors have observed early bifurcation (splitting into two) or trifurcation (splitting into three) of this vein—with some people even having two of them—as these drain into the IVC. Occasionally, the middle and left hepatic veins do not form a singular vein but rather run separately. In addition, there may be one singular, rather than multiple, caudate lobe veins.

Function

The primary function of the hepatic veins is to serve as an important cog of the circulatory system. They deliver deoxygenated blood from the liver and other lower digestive organs like the colon, small intestine, stomach, and pancreas, back to the heart; this is done via the IVC. Since the liver serves the important function of filtering blood as it moves from the digestive tract, these veins are particularly important for overall health.

Clinical Significance

As noted above, problems of the liver can impact the hepatic veins and vice-versa. Most commonly, these veins can be impacted in cases of cirrhosis, in which there is scarring of the liver tissue due to a range of diseases, including hepatitis B, alcohol use disorder, and genetic disorders, among other issues. In these cases, blood flow is slowed down and these veins can develop high blood pressure (hypertension), which is potentially very dangerous.

Clots of the hepatic veins lead to a rare disorder called Budd-Chiari syndrome. This disease is characterized by swelling in the liver, and spleen, caused by the interrupted blood flow as a result of these blockages. It also increases pressure on these veins, and fluid may build up in the abdomen. In turn, this can lead to varicose veins in that part of the body—swollen and misshapen large veins at the body’s surface—and, this condition is among those that lead to liver cirrhosis. Other symptoms include fatigue, abdominal pain, jaundice (a yellowing of the skin), nausea, and bleeding in the esophagus of the throat.

If you suspect you have any of these issues, be sure to seek out medical attention as soon as possible.