Ischemic Cholangiopathy, Ischemic Hepatitis

Ischemic Cholangiopathy

Ischemic cholangiopathy is damage to one or more bile ducts caused by inadequate blood flow.

Bile ducts (such as the hepatic ducts and the common bile duct), unlike the liver, are supplied with blood from only one major blood vessel, the hepatic artery. Thus, disruption of blood flow through the hepatic artery can prevent the bile ducts from obtaining enough oxygen. Consequently, the cells lining the ducts are damaged or die—a disorder called ischemic cholangiopathy. Blood flow can be disrupted by the following:

• Surgical trauma during liver transplantation or removal of the gallbladder by laparoscopy
• Injury from radiation therapy
• A disorder that makes blood more likely to clot (blood clotting disorder)
• A procedure to block a bleeding blood vessel that causes clot formation (embolization)

Ischemic cholangiopathy is mostly commonly seen in those who have had a liver transplant.

Symptoms and Diagnosis

The damaged bile duct narrows (causing a stricture) so that the flow of bile slows or is blocked. As a result, bile pigment (bilirubin) is retained, the skin and the whites of the eyes turn yellow (called jaundice) and the urine becomes dark. As bile (containing pigment such as bilirubin) does not enter the small intestine, the stools become pale. Itching (termed pruritus) is common, often beginning in the hands and feet but usually affecting the whole body. Itching is especially worse at night. Bile duct infection (cholangitis) may also occur, producing abdominal pain, chills and fever.

The diagnosis comes from the symptoms and abnormal blood test results, especially in people who have conditions that make ischemic cholangiopathy more likely (eg, liver transplant recipients). Ultrasonography helps doctors visualize the ducts, but the results may be inconclusive. Better definition often requires magnetic resonance imaging of the bile ducts (a procedure called magnetic resonance cholangiopancreatography or MRCP) or endoscopic retrograde cholangiopancreatography (ERCP). ERCP involves inserting a flexible viewing tube (endoscope) through the mouth and into the small intestine and injecting dye into the bile duct system.

Treatment

In addition to detecting the narrowing of the bile ducts, ERCP can be used in treatment. A wire with a deflated balloon at its end is introduced through the endoscope; doctors inflate the balloon to widen (dilate) the narrowing. A mesh tube (stent) then keeps the duct open.

People who have had a liver transplant on occasion may require another transplant.

Ischemic Hepatitis

Ischemic hepatitis is damage throughout the liver caused by an inadequate blood or oxygen supply.

• Heart or respiratory failure may reduce the blood flow or oxygen supply to the liver.
• People feel nauseated and vomit; the liver may be tender and enlarged.

In ischemic hepatitis, liver cells are damaged or die because the liver does not receive enough blood or oxygen.

Ischemic hepatitis differs from other types of hepatitis. Usually, “hepatitis” implies inflammation of the liver, which can have many causes, most commonly a virus (as in hepatitis A or B). In ischemic hepatitis, however, the liver is not inflamed; rather liver cell death (necrosis) occurs. It is termed hepatitis because, as in viral and other types of hepatitis, liver enzymes called aminotransferases leak from damaged liver cells into the blood.

Causes

For ischemic hepatitis to develop, the liver's requirements for blood, oxygen or both are not being met. The most common cause for such unmet needs is when blood flow throughout the body decreases. Causes include the following:

• Heart failure
• Respiratory failure
• Shock
• Massive bleeding
• Severe dehydration

A severe infection that affects all or most of the body, such as sepsis, can increase the liver's need for oxygen and thus contribute to ischemic hepatitis.

Because the liver receives blood from the hepatic artery and portal vein, narrowing or blockage of one of these vessels does not usually cause ischemic hepatitis. This disorder results when blood flow in both vessels is reduced or blocked. The most common cause of blocked blood vessels is a blood clot. (Blockage by a blood clot is termed thrombosis.) Blood clots in the hepatic artery can have many causes, such as the following:

• Injury of blood vessels (as occurs during liver transplantation surgery)
• Aneurysms of the hepatic artery
• Inflammation of the artery (vasculitis)
• Use of cocaine (causing spasm of the artery)
• Tumors, certain medical procedures, or heart infections (endocarditis) that cause emboli—clumps of material, such as a piece of fatty material or blood clot on the wall of an artery—to break off and travel through the bloodstream and become lodged in a blood vessel

Disorders that make blood more likely to clot (blood clotting disorders) can cause blockages in arteries or veins. These disorders may be inherited or acquired.

Symptoms and Diagnosis

Symptoms include nausea and vomiting. The liver may be tender and enlarged.

Doctors suspect ischemic hepatitis when results of liver biochemical and blood clotting tests are abnormal, especially in people who have a condition that can cause the disorder. Blockage of the hepatic artery can be detected using ultrasonography, magnetic resonance angiography, or x-rays taken after a radiopaque dye (which is visible on x-rays) is injected into an artery (arteriography).

Treatment

Doctors focus on treating the condition that is reducing blood flow to the liver. If blood flow can be restored, ischemic hepatitis commonly resolves. Liver failure can occur if people already have severe scarring of the liver (cirrhosis).

Adapted from: Merck & Co., Inc.