Portal hypertension indicates a serious condition where there is elevated blood pressure in the portal vein. The portal vein is very important, it is located in the abdominal cavity and it is formed by a confluence of veins that drain blood form the intestines and spleen. The blood from the portal vein flows into the liver tissue, where the portal vein divides into small branches. These small branches of the portal vein are in a close contact with liver cells that destroy toxic compounds and absorb and utilize nutrients. The little blood vessels then connect into larger hepatic veins that join the inferior vena cava.
There are numerous reasons of portal hypertension. The most common is liver cirrhosis; usually due to chronic alcoholism (other causes can be found in the text dedicated to liver cirrhosis). Cirrhotic tissue poses a greater resistance to the blood flow and increases the local blood pressure. Other possible cause of portal hypertension is a right-side heart failure when the blood accumulates in the liver and in major veins including the portal vein. The pressure in the portal vein may be also elevated due to a local compression of the vein by a close tumor (liver tumor, tumor of the gallbladder or biliary tract tumors), or by narrowing of the venous lumen by a blood clot (portal vein thrombosis).
Very rare cause of portal hypertension is a so-called Budd-Chiari syndrome. It is a closure of the hepatic veins that drain blood from the liver into the inferior vena cava.
The accumulation of blood in the portal vein may be initially asymptomatic. However, the overpressure may be transmitted into the veins draining the intestines, which can cause a variety of non-specific digestive problems including loss of appetite, feelings of filled stomach, occasional vomiting, etc. However, more serious problems can develop. The accumulated blood can filter in the abdominal cavity resulting in formation of ascites. In addition, the blood tries to find other paths into the inferior vena cava than through the liver tissue. Such paths are the interconnecting veins in the esophageal wall and superficial skin veins of the abdomen. These veins are unable to handle the increased blood flow and expand. This leads to occurrence of esophageal varices and dilated abdominal veins looking like bluish streaks. As it may resemble snakes, the physicians refer it to as the Caput Medusae (head of Medusa) in reminiscence to this mythical creature.
We can find presence of the complications of portal hypertension (ascites by the naked eye or by ultrasound, esophageal varices using the upper GI endoscopy, etc.), but these are only indirect evidences. The confirmation can be done by abdominal ultrasound where we can measure the width of portal vein and the local blood flow – two important values for evaluation of portal hypertension. Even more accurate is the measurement of pressure gradient in hepatic veins. However, this test is invasive as it is necessary to insert a special probe into the hepatic veins.
The treatment is difficult. If possible, it is necessary to remove the causative factors. In alcohol-related portal hypertension, total abstinence is needed. Furthermore, we can use different drugs lowering the pressure in the portal vein (nitrates, certain antihypertensive agents). In severe complications of portal hypertension non-responding to conservative therapy, it is possible to use the so-called TIPS. It is a special tube that is inserted into the hepatic veins and through the liver tissue into the portal vein. The connection of portal and hepatic veins allows the blood to easily flow through the liver tissue and significantly decreases the portal pressure (however, it has many side-effects – see the related article). The ultimate solution in cirrhosis-related portal hypertension is the liver transplantation.