Vascular Diseases of Liver
The blood supply of the liver is unique compared to other organs in that it has a dual blood supply from the:
- Portal vein, which provides about 75% of the blood, brought to the liver and is rich in nutrients and oxygen, is brought to the liver from the intestines
- Hepatic artery, which provides the remaining blood is rich in oxygen, comes from the heart, and is the main provider of oxygen supply
This dual supply can compensate in situations when there is insufficient blood supply from either of the blood vessels offering some degree of protection to the liver.
Blood leaves the liver through the hepatic veins. The hepatic veins carry blood to the inferior vena cava (IVC), which is the largest vein in the body. The IVC also carries blood from the abdomen and lower parts of the body to the right side of the heart.
Vascular disorders of the liver result from insufficient or inadequate blood flowing into (inflow block) or being drained out of the liver (venous outflow obstruction). In both situations, the liver cells do not receive enough oxygen or nutrients. The liver damage thus caused can be limited to a specific region of the liver (focal type) causing effects based on the location of the liver damage. At other times the blood supply is compromised such that liver damage is spread out across the entire liver (diffuse type), which is more serious as it leads to cirrhosis and liver failure.
Inadequate blood flow (inflow block) can result from heart failure, blood clotting disorders and infections. Such blockages may be complete or partial.
- Heart failure, when severe, causes blood to back up from the heart into the IVC. This congestion increases pressure within the IVC itself as well as the other veins that carry blood to it, including the hepatic veins, which drain blood from the liver. If this pressure is high enough, the liver becomes engorged (congested) with blood causing liver damage and stop it from functioning normally
- Portal vein thrombosis is narrowing or blockage by a blood clot of the portal vein bringing blood to the liver from the intestines. Very small blood vessels within the liver tissue can also get blocked
- Mainly is seen in disease states leading to significant fall in blood pressure such as heart attack or septic shock due to some severe bacterial infection or after a road traffic accident with lot of blood loss and so.
- Treatment is mainly support blood pressure with fluids, blood products and treat the primary cause
- Sometimes, too late intervention can present with ‘shock liver’ wherein there is irreversible damage to liver cells, hence progressed into liver failure
Budd-Chiari syndrome (BCS) is also referred to as hepatic venous outflow tract obstruction (HVOTO). As the name suggests, BCS is caused by an obstruction by blood clots blocking the blood flow out of the liver. This can occur at any level of the veins when blood clots block blood flow from the liver right up the right sided chamber (called the atrium) in the heart
- Is relatively rare
- Mostly seen in adults and rare in children
- Follows a long-term course
Mainly of two types:
- Primary type is found at birth and is relatively common in Asia
- Secondary type is due to obstruction, more commonly by a blood clot in patients with some systemic diseases, or by a tumor. It has also been reported in patients who have long-term infections, pregnancy, and oral contraceptive use. In India, poor nutrition and low economic status have also been observed
- Fatigue, upper abdominal pain, nausea and vomiting can occur early on. Soon typical symptoms of obstruction in the blood flow out of the liver appear:
- Liver enlargement
- Spleen may also be enlarged
- Back up of blood also causes increase of pressure in the portal vein causing portal hypertension. This causes:
- Enlarged blood vessels of the upper gut that can rupture and bleed by a recurrent cough and by vomiting
- Fluid buildup in the abdominal cavity, called ascites, which is difficult to control
- Legs swell up as salt and water get retained unable to be flushed out by the kidneys
- Distended veins appear over the distended abdomen
- Swelling in the scrotum of males can occur
- Jaundice, yellowish discoloration of the skin and eyes
- Mild elevations in the liver enzymes serum aminotransferase and alkaline phosphatase are seen in 25-50% of patients.
- Ultrasonogram is the first imaging test ordered
- Magnetic resonance imaging (MRI) and computed tomography (CT) scanning are then requested for diagnostic confirmation
- Oral medications in the form of clot dissolving medications are advised when the obvious cause for obstruction is a blood clot
- A low-sodium diet along with diuretics to control ascites and leg swelling
- Balloon angioplasty [percutaneous transluminal angioplasty (PTA)], by which a tiny balloon is placed at the site of obstruction to widen the affected blood vessel
- A stent, similar to the stenting procedure done for heart blockages, can be carried out in the liver. Stenting helps to keep widen the vein
- Transjugular intrahepatic portacaval shunt (TIPS) or Direct intrahepatic portacaval shunt (DIPS) connects a branch of the hepatic vein and the portal vein which can decompress the liver
- Liver transplant is necessary in the presence of cirrhosis and when all other treatments fail.
- Because of the liver’s dual blood supply, may not cause symptoms unless the block is severe
- Can present with pain in the right side of the upper abdomen, fever, nausea, vomiting, and jaundice
- Increase in the white blood cell counts and the liver enzyme aminotransferase level are common
- Imaging studies will confirm the diagnosis, followed by an angiography, which can pinpoint the site and extent of the block. Angiography is a technique by which details of the blood vessels can be visualized. Sometimes the type of treatment is also done via angiography.
- Treatment is directed at the cause of the blockage
Sometimes BCS is detected on imaging done for some other indication as none of the symptoms listed above may be present.
Ascites fluid tap
Ascites is commonly seen in patients with cirrhosis. Analysis of the fluid content provides vital clues of any other co-existing infections or causes contributing to formation of ascites.
The main goal of treatment is to provide relief from the symptoms and the selection of treatment depends on the cause of the BCS
Sometimes the following procedures may be required:
Hepatic artery occlusions are caused by blood clots, tumors, severe inflammation or other abnormalities in the artery supplying the liver
Consultation with a liver specialist can help to establish treatment options. Interventional approach requires an inter-disciplinary team of interventional radiologists, hematologists, oncologists, gastroenterologists, and liver surgeons depending on each case.