BCS denotes a heterogeneous group of diseases characterized by hepatic venous outflow obstruction at the level of hepatic veins or inferior vena cava resulting in portal hypertension. The syndrome can be fulminant, acute, chronic, or asymptomatic. It occurs in 1 out of 100,000 individuals and is more common in females.
Hepatic Venous Anatomy and Pathophysiology
Hepatic veins serve as the only conduits of blood from the liver to the IVC and right heart. The right, middle, and left hepatic veins connect the liver to the retrohepatic IVC in the bare area of liver below the diaphragm. The right hepatic vein drains directly into the IVC; left and middle hepatic veins often unite to drain (80%). Small accessory hepatic veins from the pericaval liver segments drain directly into the IVC. The caudate lobe of the liver is the only hepatic segment with direct venous drainage to the IVC. This explains the degree of hypertrophy and the perfusion changes noted in the caudate lobe on imaging studies of BCS. Hepatic vein outflow obstruction leads to increased hepatic venous pressure, resulting in collateral venous circulation. The sites of collateral veins in BCS are different from portosystemic collaterals from portal hypertension. The collateral veins of deep and central tributaries of the systemic veins, such as ascending lumbar veins, vertebral venous plexus, azygous, and hemiazygous veins, are commonly seen in BCS. In addition, the increasing hepatic venous pressure leads to increased sinusoidal pressure and finally to portal vein thrombosis or portal hypertension. This cascade of events results in hepatocyte dysfunction and leads to liver failure.
Causes of Budd-Chiari Syndrome
The etiology of BCS may be separated into primary and secondary causes. Primary BCS is due to intrinsic intraluminal thrombosis or webs. BCS maybe secondarily caused by extraluminal compression (by abscess or tumor) or intraluminal invasion by tumor or parasite. The most frequent cause of BCS in Western countries is thrombotic occlusion in a hypercoagulable state.
Primary Budd-Chiari Syndrome
HEPATIC VEIN THROMBOSIS AND HYPERCOAGULABLE STATES
Hypercoagulable states and myeloproliferative disorders cause the majority of BCS cases, ~75%. The most common hypercoagulable causes of BCS include protein C or S deficiency, essential thrombocytosis, systemic lupus erythematosus, factor V Leiden, myelofibrosis, polycythemia vera, paroxysmal nocturnal hemoglobinuria, antiphospholipid syndrome, and oral contraceptive use.
HEPATIC VEIN OR INFERIOR VENA CAVA WEBS
Studies suggest that hepatic vein webs or IVC webs are mostly due to postthrombotic sequelae. Histopathology of webs has revealed replaced intima with fibrous laminar structure, fresh and organized thrombi, recanalizations, and calcifications. This correlates well clinically with late onset of disease in these patients.
EXTRINSIC COMPRESSION OF HEPATIC VEINS OR INFERIOR VENA CAVA
Mass effect from regional malignancy or infectious processes can compress the IVC leading to BCS. Infectious processes include tuberculosis, syphilis, aspergillosis, and parasites.
STENOSIS OF THE HEPATIC VEIN OR INFERIOR VENA CAVA
BCS can also be acquired, such as hepatic venous stenosis as a complication of liver transplantation. Tumor thrombi from hepatocellular carcinoma, renal cell carcinoma, or retroperitoneal sarcoma growing into the intrahepatic IVC can also cause hepatic venous obstruction leading to BCS.
Patients with BCS typically present with abdominal swelling, abdominal pain, ascites, hepatomegaly, and absent hepatojugular venous reflex. BCS should be suspected if there is simultaneous presentation of abdominal pain, ascites, and hepatomegaly. Patients with BCS can also be separated by the chronicity and severity of symptoms. These include acute fulminant, subacute, and chronic BCS. Subacute or chronic presentations are more common than acute fulminant course. The chronic presentations include those of chronic venous congestion of the liver leading to sequelae of portal hypertension and cirrhosis. Patients with subacute or chronic BCS may rarely be asymptomatic. Patients with acute hepatic venous obstruction leading to acute fulminant liver failure typically present with nausea, vomiting, and jaundice, with markedly abnormal liver function tests such as aspartate transaminase, alanine transaminase, and bilirubin levels.
Budd-Chiari Syndrome Diagnosis
The physiological flow patterns in hepatic veins reflect pressure variations in the right atrium. Hepatic venous flow is triphasic on Doppler ultrasound. The triphasic flow pattern is altered in BCS and right heart failure. Liver cirrhosis leads to decreased hepatic compliance, altering the hepatic venous waveform from a triphasic to a monophasic form. In addition, severe portal hypertension or portal vein thrombosis may cause hepatofugal flow. Specific diagnostic signs of hepatic vein involvement in BCS include nonvisualization with flow void signal, fibrous cord in place of hepatic vein, and thrombus appearing as echogenic material in the hepatic veins. Evidence of intrahepatic collateral vessels is highly suggestive of BCS. These small spiderweb early collaterals, collateral subcapsular vessels, and intrahepatic venous collaterals appear as “bicolored hepatic veins.” These veins appear bicolored due to opposing flow directions seen in adjacent veins on color Doppler imaging. Other features include collateral vessels to the IVC, hepatic and portal vein collateral vessels, and prominent caudate vein measuring ≥
3 mm in the absence of heart failure. Hepatic veins may also appear tortuous, curvilinear, fragmented, stenotic, or as a fibrous cord with slow, turbulent, or reversed flow. A combination of these ultrasound findings may be seen in other conditions such as regenerative nodules, caudate lobe hypertrophy, heterogeneous hepatic parenchyma, or portal vein thrombosis. Direct sonographic analysis of the IVC can also reveal enlargement, stenosis, or obstruction of the IVC by a thrombus or web.
COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE EXAMINATIONS
CT and MR angiography provide noninvasive anatomical definition of the hepatic artery that may be important for operative or interventional planning. CT and MR examinations may also reveal secondary causes of BCS. CT and MR portography provide important information regarding portal venous system patency or thrombosis that will dictate treatment options for portocaval shunt or transjugular intrahepatic portosystemic shunt (TIPS). CT and MR examinations can also reveal information regarding intra- and extrahepatic collateral vessels, as well as IVC morphology and patency. When performing hepatic imaging in the setting of BCS, the sluggish venous flow should be accounted for when acquiring delayed venous phase imaging.
SELECTIVE HEPATIC VENOGRAPHY
Cannulation of hepatic veins in BCS can be a challenging task. Moderate sedation with local anesthesia for adults and general anesthesia for children is preferred to facilitate the procedure. Transjugular or percutaneous transhepatic injection of contrast using fine needle access is performed with iodinated contrast or CO2 injection of liver parenchyma. The latter may be better to evaluate collateral vessels and may be used in patients with a history of adverse contrast reaction or renal insufficiency. Hepatic vein access allows for pressure measurements, analysis of hepatic venous flow dynamics, localization of the site of obstruction, catheter-directed thrombolysis, and hepatic venous stent placement. Venacavography is often performed with a jugular or femoral vein approach often combined with hepatic venography.
Treatment of Budd-Chiari Syndrome
Despite proposed guidelines for the management of BCS by an expert hepatic vascular disorder panel in 2003, the treatment of BCS remains somewhat controversial. The traditional approach to treatment involves systemic thrombolysis in all BCS patients without a specific contraindication. Patients undergoing systemic or catheter-directed thrombolysis should be closely monitored for clot propagation using a combination of Doppler sonography, CT, and MR examinations. Surgical portosystemic shunt or TIPS is performed in progressive cases of BCS or as a bridge to transplantation. Patients with acute or fulminant BCS are best served with liver transplantation. Recently, there have been an increasing number of successful reports involving endovascular techniques including angioplasty and stent placement. These techniques are especially effective in cases of hepatic or IVC webs, as demonstrated in our case.