Last Modified: August 16, 2010
The portal vein is a major vein in the portal venous system, which drains blood from the gastrointestinal tract into the liver. The entire system of veins is very important as it allows the liver to filter out harmful substances absorbed by the gastrointestinal tract.
When the liver is damaged, the blood in the portal venous system may back up, causing an increase in blood pressure. This increased blood pressure in the portal venous system is called portal hypertension.
Since blood is unable to flow easily through the liver, it bypasses the liver by using other blood vessels. Complications arise as these other blood vessels have thin walls and are not capable of handling the increased blood flow. Varices (enlarged blood vessels) develop and hemorrhaging may occur.
Since the blood bypasses the liver, toxic substances remain in the blood. These poisons and waste materials build up and complications eventually occur.
Causes of Portal Hypertension
Portal hypertension is most often caused by cirrhosis or scarring of the liver. Excess scar tissue in the liver reduces the flow of blood, which causes blood to back up in the portal vein.
Cirrhosis is normally a result of liver damage, which may be caused by a variety of conditions including hepatitis and excessive alcohol consumption.
Blood clots in the liver or the portal vein may cause portal hypertension, though this condition is less common. Increased blood flow may also cause portal hypertension.
Symptoms of Portal Hypertension
Most people with portal hypertension show no initial symptoms of the condition. As the condition develops, though, certain symptoms become evident, including:
- gastrointestinal bleeding
- tarry or bloody stools
- vomiting blood
- ascites, or fluid build-up in the abdomen
- encephalopathy, or altered brain functioning.
Symptoms of Cirrhosis
When diagnosing portal hypertension, doctors often look for symptoms of cirrhosis first because people with cirrhosis are at a very high risk of developing portal hypertension. Some symptoms of cirrhosis are:
- vomiting blood
- abdominal swelling
- weight loss
- lack of appetite
- edema (excess fluid build up) in the legs.
Complications of Portal Hypertension
The backed up blood in the portal venous system must find an alternate route back to the heart and lungs if it cannot easily pass through the liver. The three main alternate routes are through the veins:
- in the esophagus, resulting in esophageal varices
- in the skin of the abdomen
- in the rectum and anus, resulting in hemorrhoids.
Complications arise because none of these veins are able to handle the increased blood flow. The veins enlarge and weaken, increasing the risk of hemorrhage. Hemorrhaging of the veins in people suffering from portal hypertension is dangerous and may prove fatal.
If levels of blood toxins build up when the blood bypasses the liver, cognitive functions may be impaired and encephalopathy — confusion and forgetfulness — occurs.
Treating Portal Hypertension
No cure exists for cirrhosis of the liver; the damage is permanent and irreversible. Treatments do exist for portal hypertension, though, and they range from reducing blood pressure in the portal vein to stopping or preventing hemorrhages.
Endoscopic Therapy: Endoscopic therapy is often the first treatment used for varicose veins and hemorrhoids. Endoscopic therapy consists of either sclerotherapy — a procedure where a solution is injected into the enlarged vessel, causing it to shrink and close — or banding, a procedure in which a band is used to close off the enlarged vessel. Endoscopic therapy is used to reduce blood pressure by rerouting blood from the over-stressed, closed-off veins to stronger, more capable veins.
Medications: Nitrates and beta blockers may be prescribed to lower the blood pressure in the portal vein while medications such as propranolol and isosorbide may be used to reduce the risk of hemorrhages.
Diet: Changes to the patient's diet may be made to prevent further damage and scarring of the liver. For example, patients may be asked to avoid all alcohol in order to avoid further damage to the liver.
Transjugular Intrahepatic Portosystemic Shunt (TIPS): TIPS is a procedure in which a stent is placed in the liver, rerouting blood flow and allowing for easier flow through the liver.
Distal Splenoral Shunt (DSRS): DSRS is a surgical procedure that connects the splenic vein — the vein from the spleen — to the left kidney vein. The splenic vein originally drains into the portal vein, but this surgical procedure allows the blood to bypass the liver, thus reducing blood pressure in the portal venous system.
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