Hepatic Veno-Occlusive Disease

Hepatic veno-occlusive disease (hepatic VOD) is a condition resulting from toxic injury to the hepatic sinusoidal capillaries that leads to obstruction of the small hepatic veins.

Epidemiology

Prevalence is unknown but hepatic VOD is a rare disease. Endemic zones have been identified in which the disease is associated with the consumption of herbal tea containing pyrrolizidine alkaloids. Epidemics affecting several hundred individuals may occur after contamination of the harvest with these plants.

Clinical description

It affects children and adults. The clinical picture is characterized by painful hepatomegaly, jaundice, and fluid retention that manifests by weight gain, edemas, and ascites. Hepatic insufficiency manifesting as coagulopathy and hepatic encephalopathy may occur. Functional renal insufficiency is common. In severe cases, multiple organ failure or severe bacterial infections may occur.In developed countries, hepatic veno-occlusive disease is mainly associated with the conditioning regimen for hematopoietic stem cell transplantation, with 10 to 60% of transplant patients (depending on the conditioning regimen protocol used) developing hepatic VOD. Hepatic VOD may also occur after chemotherapy or radiation therapy.

Etiology

Hepatic sinusoidal endothelial cell lesions appear to be the primary cause of the disease, leading to non-thrombotic occlusion of hepatic veins with concentric subendothelial thickening associated with edema and eventually fibrosis.

Diagnostic methods

Diagnosis is based on recognition of the clinical manifestations (hepatomegaly, jaundice, and weight gain) and their association with a potential cause of hepatic VOD (hematopoietic stem cell transplantation or chemotherapy, exposure to pyrrolizidine alkaloids), together with exclusion of other causes of liver disease. Liver biopsy is often indicated. Imaging studies, particularly hepatic Doppler-ultrasonography, may help to confirm the diagnosis.

Differential diagnosis

Differential diagnoses include other causes of acute or chronic liver disease, and, in the case of hematopoietic stem cell transplantation, graft-versus-host disease and severe infections.

Management and treatment

No specific treatment is available. Defibrotide is frequently used, mainly on the basis of limited studies (historic comparisons) and because side effects are uncommon. Preventive treatment with heparin is often indicated, but its efficacy has not been proven. In case of hematopoietic stem cell transplantation, the main prophylactic treatment is the use of less hepatotoxic conditioning regimens.

Prognosis

Severity and course of the disease vary between patients. In severe cases, the prognosis is poor with a high mortality rate (up to 90%) due to multiple organ failure.