Portal Hypertension

Overview

As a rule, most organs and tissues in the body receive blood through the arteries which bring oxygenated blood from the heart. The deoxygenated blood is then collected and carried back to the heart by veins. However, the liver is unique in that three-fourths of the blood it receives actually arrives through the venous system. The hepatic portal vein, or the portal vein for short, collects blood from the gastrointestinal tract and other organs such as the spleen and pancreas and carries this blood into the liver rather than back to the heart.

This blood is infused with nutrients obtained through digestion and these nutrients need to be processed in the liver. The liver also receives oxygen-rich blood through the hepatic artery. Blood from both sources converges in specialized structures called hepatic sinusoids, a mesh of microscopic blood vessels where this blood is then processed. Blood from the liver then returns to the heart through the hepatic veins which drain into the inferior vena cava.

What Is Portal Hypertension?

Sometimes, there is increased blood pressure within the portal vein or the minor vessels that drain into it. This is known as portal hypertension. Usually, this condition arises as a consequence of liver disease such as liver cirrhosis. There can be a variety of other causes as well. Portal hypertension can lead to the formation of additional blood vessels in an attempt to bypass the affection section of the vasculature.

When the venous pressure within the portal vein exceeds that of the inferior vena cava by more than 5mm Hg, the condition can be identified as an instance of portal hypertension. Generally, the pressures may need to be even higher for the condition to be detected.  

What Causes Portal Hypertension?

Someties, the condition is idiopathic.

In other words, there is no identifiable cause. Generally, however, the pressure within the portal system is dependent on two major factors, namely, the influx of blood and any conditions that offer obstruction to the smooth outflow of blood from the liver.

There may be abnormalities or obstructions in the vessels leading into or out of the liver as a result of blood clots or scarring, for instance.

Thus, the underlying problem responsible for portal hypertension may originate either outside of the liver or within it, as we shall see in the list below:

• Liver infections such as Hepatitis B and C and certain parasitic infections.
• Liver cirrhosis which often occurs as result of chronic alcoholism.
• A tumor compressing the portal vein.
• Arsenic poisoning.
• Blood clots in the portal vein.
• Blood clots in the hepatic veins.
• Blood clots in the inferior vena cava.
• Congenital absence of the portal vein.
• Alpha1-antitrypsin deficiency.
• Problems with the bile ducts.
• Cardiac problems such as restrictive pericarditis.
• Myeloproliferative conditions.
• Enlargement of the spleen.
• Problems with blood vessels in the spleen.
• Hemochromatosis.
• Wilson’s disease.
• Cystic fibrosis.
• Fatty liver.
• Liver peliosis.
• Focal nodular hyperplasia.

What Are Some Symptoms And Indications Of Portal Hypertension?

A patient may develop portal hypertension due to a variety of causes, as we have seen above, although the condition may not always be clinically significant. In other words, it may or may not produce any noticeable symptoms. When symptoms do arise, this is usually due to complications associated with hypertension. The patient may notice a few or more of the following indications:

• Swelling of the abdomen.
• Abdominal pain.
• Fever.
• Weight gain.
• Blood in the stools. Stools may be black or tarry in appearance.
• Vomiting blood.
• Mental confusion.
• Lethargy.
• Forgetfulness.
• Swelling of the legs.

What Are Some Potential Complications?

There can be a range of critical consequences when portal hypertension reaches a severe stage.

• Ascites: This is the build-up of fluid in the peritoneal cavity. As a result, the abdomen swells visibly. The pressure that this puts on the diaphragm can make it difficult to breathe normally.
• Varices: Abnormally high pressure within the portal vein causes the formation of distended or swollen veins called varices in areas such as the stomach, rectum, and esophagus.
• Upper gastrointestinal hemorrhage: Oesophageal varices can rupture and start bleeding and this should be treated as a medical emergency.
• Hepatic encephalopathy: The patient may be lethargic or irritable and there may be changes in mental state. This condition can also disrupt normal sleep patterns.

What Do Diagnosis And Treatment Involve?

Diagnosing subclinical portal hypertension is challenging and the condition is usually noticed in the context of symptomatic liver disease such as advanced liver cirrhosis. Presence of tell-tale signs such as ascites and oesophageal varices could point to portal hypertension. The process of diagnosis could involve the following steps:

• Physical examination.
• Medical history.
• Blood tests.
• Fecal occult blood tests.
• Ultrasound imaging.
• Computerised tomography (CT) and magnetic resonance imaging (MRI) scans.
• Gastrointestinal endoscopy.
• Hepatic venography.
• Liver biopsy.

The treatment mainly addresses hypertension and the associated symptoms. Some of the treatment methods are:

• Lifestyle modifications– In order to treat portal hypertension, an individual should make certain changes in his/her lifestyle such as intake of a balanced diet, regular physical activity, and stress management, avoiding excessive alcohol consumption, and quitting smoking.
• Medications- Certain medications can help in controlling the blood pressure and relaxing the blood vessels. They reduce the pressure in the portal vein and lessen the risk of internal bleeding. Drugs such as propranolol and isosorbide are usually prescribed by the doctors.
• Water pills or diuretics– In case of ascites (accumulation of fluid in the abdominal cavity), diuretics are prescribed in order to reduce the fluid levels in the body. Salt intake is also restricted in the diet in order to prevent fluid retention in the body.
• Sclerotherapy or variceal ligation- This procedure is executed with the aim of controlling bleeding in the hepatic blood vessels. Sclerotherapy involves the injection of the varicose veins (gnarled, enlarged vein) with a solution that causes scarring. The blood is thereby re-routed to the normal direction. Variceal ligation (banding) is a procedure of blocking the small veins that feed the varices. The unhealthy blood flow is blocked by means of rubber bands.
• Nonsurgical Transjugular Intrahepatic Portal-Systemic Shunt (TIPSS)-this procedure is performed to control acute bleeding. This procedure diverts the regular blood flow from the portal vein to the other blood vessels by creating new pathways.

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