Portal hypertension. It is defined as abnormally high blood pressure in the portal vein, a large-caliber vein that carries blood from the intestine to the liver. The portal vein receives blood that comes from the entire intestine, spleen , pancreas, and gallbladder . After entering the liver, blood is divided into small channels that run through it. When blood leaves the liver, it flows into the general circulation through the hepatic vein .
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- 1 Factors
- 2 Symptoms and diagnosis
- 3 Treatment
- 4 Sources
There are two factors that can increase the pressure in the blood vessels of the portal system: the volume of blood flowing through them and the increase in resistance to the passage of blood through the liver. In western countries, the most common cause of portal hypertension is increased resistance to blood circulation caused by cirrhosis.
Portal hypertension leads to the development of veins (called collateral vessels) that connect the portal system to the general circulation, bypassing the liver. Because of this diversion, substances in the blood that are normally filtered by the liver enter directly into the general blood circulation.
Collateral vessels develop at specific points, the most important of which is the lower end of the esophagus. There the vessels become congested and tortuous, that is, they become varicose veins (called esophageal varices). These congested vessels are fragile and prone to bleeding, sometimes severe. Other collateral vessels can develop around the navel and rectum.
Symptoms and diagnosis
Portal hypertension frequently causes an increase in spleen volume. A certain amount of fluid can leave the liver and accumulate in the abdominal cavity, causing its distention, a process called ascites . Varicose veins located at the lower end of the esophagus and stomach , bleed easily and sometimes massively.
Varicose veins of the rectum can also bleed, although this case is less frequent. The doctor can usually feel an enlarged spleen through the abdominal wall. The fluid retained in the abdomen can be detected due to the increase in volume of the abdomen and also by the dull sound that is perceived when giving light blows (percussion).
Ultrasonography and radiographs provide considerable information about portal hypertension. Ultrasound can be used to examine blood circulation in the vessels of the portal system and to detect the presence of fluid in the abdomen. Computed tomography (CT) can also be used to examine the dilation of the veins. The pressure of the portal system can be measured directly by inserting a needle into the liver or spleen through the abdominal wall.
To minimize the risk of bleeding from esophageal varices , the doctor may try to reduce the pressure in the portal vein. One way to do this is by administering propranolol , a drug used to treat high blood pressure .
The bleeding from ruptured esophageal varices is considered a medical emergency. To contract the bleeding veins, some drugs can be administered intravenously, such as vasopressin or octreotide, and blood transfusions to counteract their loss. An endoscopy is usually performed to confirm that the bleeding is caused by varicose veins. The veins can then be blocked with elastic bandages or with injections of chemicals administered through the same endoscope. If the bleeding continues, a catheter with a balloon tip can be passed through the nose and slid down the esophagus. By inflating the balloon, the varicose veins are compressed , and the bleeding is usually stopped.
If this continues or is repeated, a bypass procedure can be performed to connect the venous system of the portal vein with the general (systemic) venous system. This decreases the pressure in the portal vein because the pressure in the general venous system is lower. There are several types of derivative interventions, among which it is worth mentioning the one carried out using X-ray guidance in the radiology department, and using special instruments. Bypass interventions are generally effective in stopping bleeding, but they do pose some risk. In addition, they can increase the likelihood of brain dysfunction caused by liver failure ( hepatic encephalopathy ).