LAUSR

Thrombotic occlusion of all the hepatic veins is commonly referred to as Budd-Chiari syndrome (BCS). It presents as a manifestation of a systemic procoagulant condition which may be covert but is characterizable in most cases using modern diagnostic techniques. Janus kinase 2 (JAK2) mutations are particularly important and may or may not be associated with some form of myeloproliferative disease. Between 20% and 30% of patients with BCS are JAK2 positive alone, and an additional cohort have myeloproliferative diseases including polycythemia rubra vera and thrombocythemia. Antithrombin III deficiency, protein C or S deficiency, Factor V Leiden mutations, antiphospholipid syndrome, and paroxysmal nocturnal hemoglobinuria are other typical underlying conditions. Historically, estrogen-based oral contraception was considered a cause of Budd-Chiari syndrome but is more likely to be merely the trigger in patients with an underlying procoagulant condition rather than a primary cause. A caval web causing impaired venous flow is a recognized cause of BCS and is mainly recognized in Asia, but thrombosis associated with impingement by cysts or solid malignancies is not conventionally included in the definition of this condition. The combination of ascites and hepatomegaly is the most frequently encountered manifestation of BCS. Subclinical evolution of the disease results in significant collateralization, and this protects the liver parenchyma from the impact of sudden venous congestion. Segment 1 of the liver (caudate lobe) usually has venous drainage independent of the 3 major hepatic veins that is maintained resulting in compensatory hypertrophy of this segment. Various patterns of remodeling of the parenchyma, fibrotic response, and focal lesions (benign and malignant) are evident at presentation. The 3 key objectives in the assessment of a new patient are to identify the underlying procoagulant condition, determine if advanced fibrosis or cirrhosis is present, and characterize any focal lesions present as malignant or benign. The outcomes of these investigations determine the management plan for individual patients. Anticoagulation is standard early management and may be more intense in patients with JAK2 mutations. Anticoagulation may also be the only initial therapeutic response if the presenting symptoms, particularly ascites, resolve spontaneously. Hepatic decompression is the next consideration, either by percutaneous transhepatic venous balloon angioplasty or insertion of a transhepatic portosystemic shunt or the 2 techniques in sequence. The latter technique has largely replaced surgically fashioned shunts. Decompression of the liver relieves portal hypertension and may improve liver function by reducing congestion, particularly in patients who do not have cirrhosis. Liver replacement may be the treatment of choice in patients with cirrhosis and severe impairment of liver function, as well as selected patients with hepatocellular carcinoma. Occasionally, the presentation of BCS is acute and catastrophic to the extent that the patient fulfils the definition of acute liver failure, ie, no preexisting history of liver disease together with the development of coagulopathy and encephalopathy. This topic is addressed in an article in this edition of Liver Transplantation from the US Acute Liver Failure Group combining its own data together with cases identified through a review of the literature. The combined experience was 38 cases, 19 from each source, and the rarity of the condition was confirmed by the fact that BCS accounted for <1% of cases of acute liver failure. Abbreviations: BCS, Budd-Chiari syndrome; INR, international normalized ratio; JAK2, Janus kinase 2.