Hepatic ischemia

Hepatic ischemia is a condition in which the liver does not receive enough blood or oxygen. It results in damage to the liver cells.

The term “ischemic hepatitis” is not fully appropriate because it is not a liver inflammation (the main feature of hepatitis). However, the increase in the level of transaminases is very similar to that seen in other types of hepatitis (toxic hepatitis or acute viral hepatitis).

The main cause of hepatic ischemia is cardiac disease:

• Heart attack (myocardial infarction)
• Arrhythmias
• Cardiac tamponade
• Cardiogenic shock

There are other causes for hepatic ischemia:

• Severe respiratory failure (second most common cause)
• Sepsis (third most common cause)
• Low blood pressure (acute hypotension)
• Hypovolemic shock from hemorrhage, dehydration, and heat stroke
• Sickle cell crisis
• Hepatic artery thrombosis in transplant patients or who have a preexisting portal vein thrombosis
• Obstructive sleep apnea
• Acute lower limb ischemia

Hepatic ischemia is seen in 1 to 2.5 % of patients admitted to an intensive care unit.

The symptoms can be very similar to hepatitis:

• Nausea and vomiting
• Anorexia
• Malaise
• Right upper quadrant pain
• Jaundice
• Altered mental status

The diagnosis is defined according to the following criteria:

1. Cardiac, circulatory or pulmonary failure.
2. Marked increase in blood transaminases (AST and ALT). Levels are generally greater than 20 times the normal upper limit.
3. Exclusion of other causes of acute liver injury (such as toxic hepatitis and acute viral hepatitis).

AST, ALT and lactic dehydrogenase (LDH) levels are markedly elevated. The ALT/LDH ratio is generally less than 1.5 which helps distinguish ischemic hepatitis from other forms of hepatitis.

ALT, AST and LDH generally peak 1–3 days after the precipitating event and return to normal values in 7–10 days after the blood supply to the liver is restored.

An increase in the level of bilirubin in the blood may be seen a few days after transaminases reach their peak (generally not above 4 times the normal upper limit).

There is no specific therapy for ischemic hepatitis.

The treatment must be focused on the underlying cause that is causing the inadequate blood flow to the liver.

If the disease causing the liver ischemia can be reversed quickly the prognosis is usually good with a complete recovery.

However, the overall prognosis is poor with mortality rates of at least 25% because hepatic ischemia is usually seen along with serious disorders such as sepsis, acute renal failure or coagulopathies. Hepatic ischemia can sometimes lead to liver failure.