Hepatic Infarction

Hepatic infarction is ischaemic necrosis of liver parenchyma following interruption of blood supply. It is rare in native livers because of the dual supply from the hepatic artery and portal vein.

It occurs when both supplies fail, or when the hepatic artery is occluded in a setting of poor portal flow, anatomical variants or disease.

Causes are hepatic artery thrombosis after liver transplantation (the commonest), shock and prolonged hypotension, pre-eclampsia, eclampsia and HELLP syndrome, sickle cell crisis, vasculitis (polyarteritis nodosa), antiphospholipid syndrome, disseminated intravascular coagulation, chemoembolisation, hepatic artery ligation or injury at surgery, trauma and cocaine use.

Pathophysiology.

Occlusion of an arterial branch and reduced portal flow cause segmental necrosis. In pregnancy related disease, fibrin deposition in the sinusoids and microvascular obstruction cause periportal necrosis and subcapsular haematoma.

Bile ducts are injured early because they depend on arterial flow.

Sudden right upper quadrant pain, fever, nausea and vomiting, jaundice, and tender hepatomegaly. Complications are abscess, biloma, haemorrhage, rupture and acute liver failure.

Red flags.

• Shock or sepsis.
• Acute liver failure (INR over 1.5 with encephalopathy).
• Sudden severe abdominal pain with hypotension (rupture).

Aspartate and alanine aminotransferase rise sharply (often over 1,000 units/L) with raised lactate dehydrogenase and bilirubin, then fall quickly over days. CT with contrast shows wedge shaped, peripheral, non-enhancing hypodense areas, which may contain gas if infected. Doppler ultrasound and CT angiography show vascular occlusion. Check for pregnancy, platelet count, haemolysis markers, clotting, thrombophilia and vasculitis markers.

Differential diagnosis.

• Liver abscess.
• Ischaemic hepatitis.
• Hepatic tumour or metastasis.
• Acute viral hepatitis.
• Budd-Chiari syndrome.
• Hepatic trauma.

Treat the cause and support the patient. Resuscitate shock, maintain mean arterial pressure at 65 mmHg or more and correct anaemia, with transfusion at haemoglobin 70 g/L.

• Unfractionated heparin (thrombosis, once haemorrhage is excluded): 80 units/kg IV bolus (maximum 5,000 units), then 18 units/kg/h; adjust to anti-Xa 0.3 to 0.7 units/mL; monitor platelets, anti-Xa and bleeding; use lower doses with coagulopathy or bleeding.
• Piperacillin-tazobactam (abscess, infected necrosis or biloma): 4.5 g IV every 6 hours for 5 to 7 days after drainage; maximum 18 g daily; monitor renal function and blood counts; reduce for creatinine clearance under 40 mL/min.
• Magnesium sulphate (pre-eclampsia or HELLP with seizure risk): 4 g IV over 5 to 15 minutes, then 1 g/h by infusion for 24 hours after delivery; maximum infusion 2 g/h; monitor reflexes, respiratory rate and urine output; reduce the infusion in renal impairment.

Obstetric causes need delivery and haematology support. Revascularise a thrombosed transplant artery within hours by surgery or endovascular therapy. Drain collections percutaneously. Resect or retransplant for liver failure or extensive necrosis.

Monitoring. Liver enzymes, INR, lactate, glucose and renal function every 6 to 12 hours initially; repeat imaging at 1 to 2 weeks.

Referral and escalation. Hepatology, transplant centre, interventional radiology and critical care; obstetrics for pregnancy related disease.