Figure 59-5. Potential venous collaterals that develop with portal hypertension. The veins of Sappey drain portal blood through

the bare areas of the diaphragm and through paraumbilical vein collaterals to the umbilicus. The veins of Retzius form in the

retroperitoneum and shunt portal blood from the bowel and other organs to the vena cava.

The portal venous concentration of nitric oxide, a potent vasodilator, has been shown to be elevated

in patients with cirrhosis and portal hypertension.165 In addition to nitric oxide, many other vasodilators

are elevated in portal hypertension, including prostacyclin, endotoxin, and glucagon.166

Etiology

Many pathologic processes can cause portal hypertension (Table 59-8). These are usually classified as

prehepatic, hepatic, or posthepatic (presinusoidal, sinusoidal, or postsinusoidal) conditions. As noted

above, in prehepatic and posthepatic conditions, portal hypertension is the result of mechanical venous

obstruction at the level of the portal or hepatic veins, respectively, whereas cirrhosis is the main cause

of hepatic portal hypertension.

Budd–Chiari Syndrome and Veno-occlusive Disease

The BCS is caused by hepatic venous obstruction. The name of the syndrome is derived from two

investigators, the first of whom (Budd)167 described the classic presentation of abdominal pain, ascites,

and hepatomegaly, and the second of whom (Chiari)168 described the pathologic characteristics of the

liver. The obstruction may occur at the level of the inferior vena cava, the hepatic veins, or the central

veins within the liver itself and may be the result of congenital webs (most common in Africa and Asia),

acute or chronic thrombosis (most common in the West), and malignancy. With occlusion of the hepatic

veins, pressure increases in the central veins. As a result, centrilobular congestion, necrosis, and, with

chronic disease, fibrosis and cirrhosis with portal hypertension develop.

In the West, the most common causes of this syndrome are hypercoagulable states associated with

polycythemia vera, myeloproliferative disorders, paroxysmal nocturnal hemoglobinuria, and defects in

the coagulation cascade, as in conditions associated with high estrogen levels (e.g., pregnancy, use of

birth control pills).169,170 Neoplasms may cause hepatic venous obstruction by direct invasion and

occlusion of the vessels, or by establishment of a prothrombotic milieu secondary to the malignancy

itself. In the East, the major causes of obstruction of the vena cava and hepatic veins are membranous

webs that directly occlude the vessels. The etiology of vena cava webs is unknown. Veno-occlusive

disease is characterized by obliterative endophlebitis of the intrahepatic veins (Table 59-3). Causes of

veno-occlusive disease include medications, toxins, and pyrrolizidine alkaloids.

BCS may present with acute, subacute, or chronic symptoms and is often misdiagnosed. This is

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unfortunate, because early treatment will prevent the development of hepatic fibrosis, which can lead to

end-stage liver disease. Nearly 50% of patients have had symptoms for more than 3 months.171 Acute

symptoms include hepatomegaly, right upper quadrant abdominal pain, nausea, vomiting, and ascites.

In the chronic form of the disease, patients may present with the sequelae of cirrhosis and portal

hypertension, including variceal bleeding, ascites, spontaneous bacterial peritonitis, fatigue, and

encephalopathy. In the chronic form, the entire liver atrophies except for the caudate lobe, which may

hypertrophy because its hepatic vein(s) enters the vena cava separately, so that venous outflow is not

impeded.100 The hypertrophy of the caudate lobe creates a longitudinal narrowing of the retrohepatic

vena cava, which is surrounded by parenchyma, leading to secondary obstruction of the caval flow in

the abdomen.

ETIOLOGY

Table 59-8 Common Causes of Portal Hypertension

Although the diagnosis can be made by ultrasonographic evaluation of the liver and its vasculature

with a sensitivity of 85% to 95%,169 cross-sectional imaging is essential for staging and planning

therapy. Duplex scanning may reveal the location of the obstruction and characterize the flow within

the vena cava and hepatic, portal, mesenteric, and splenic veins. Other common ultrasonographic

findings consistent with BCS include lack of visualization of the hepatic veins, an enlarged caudate lobe

with compressed inferior vena cava, enlarged intrahepatic collaterals, splenomegaly, and ascites.101.

Thrombus within the hepatic veins or inferior vena cava may be directly visualized using contrastenhanced magnetic resonance angiography (MRA).172

Because the vascular obstruction is usually well established at the time of presentation,

anticoagulation alone is rarely sufficient therapy for BCS. Although major open surgery has been

favored in the past, including mesoatrial shunting,173,174 and even liver transplantation,175 minimally

invasive approaches are now preferred.176 The mainstay of therapy is mechanical decompression with a

side-to-side portosystemic shunt, optimally achieved with a percutaneous portacaval shunt (see below).

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After shunt placement, the pressure on the vena cava by the caudate lobe is gradually relieved, leading

to restoration of liver function.

A more direct solution, which is necessary in the face of complete caval obstruction, is the creation of

a mesoatrial shunt, which was described by Cameron and Maddrey.173 This radical procedure has been

largely supplanted by percutaneous portacaval shunting (TIPS). The rates of postprocedural

encephalopathy are usually not increased in patients with BCS, because they have anatomically healthy

livers that recover fully if decompression is achieved early prior to the establishment of cirrhosis. In

patients with end-stage liver disease, liver transplantation may be performed.175 The 5-year survival

rate for patients with good hepatic function before the shunt procedure is approximately 60%, with a

34% to 88% survival for patients after liver transplantation.177 Postoperatively, patients are treated

with long-term anticoagulation to prevent recurrent thrombosis.

As noted, minimally invasive treatment using TIPS may be first-line therapy, and it has supplanted

surgical shunting in our practice.178,179 Case reports and small series have suggested efficacy for this

technique,180 and a recent larger study has indicated 1- and 5-year survival rates of 93% and 74%,

respectively.181 Many patients develop shunt occlusion; however, further angiographic manipulation

and long-term anticoagulation are required to maintain patency.

Portal Vein Thrombosis

Portal vein thrombosis is commonly associated with advanced cirrhosis, and may be the ominous

portent of a HCC. Spontaneous portal vein thrombosis in the absence of cirrhosis is the cause of portal

hypertension in fewer than 10% of adult patients but is the most common cause in children.182,183 In

contrast to patients with cirrhosis-induced portal hypertension, these patients have normal liver function

and are not as susceptible to the development of complications such as encephalopathy. Causes of portal

vein thrombosis include umbilical vein infection (the most common cause in children), coagulopathies

(protein C and antithrombin III deficiency), hepatic malignancy, myeloproliferative disorders,

inflammatory bowel disease, pancreatitis, trauma, and previous splenorenal shunt.184 Most cases in

adults are idiopathic.

The diagnosis can be made by sonography, which reveals an echogenic lesion in the lumen of the

portal vein and an absence of portal venous flow on duplex examination.185 With time, cavernous

transformation of the portal vein may occur, in which channels develop within the clotted portal

vein.182 CT and MRI are also useful in establishing the diagnosis. Often, the initial manifestation of

portal vein thrombosis is variceal bleeding in a noncirrhotic patient with normal liver function.

Splenomegaly is another common finding.

The initial therapeutic option for the control of hemorrhage caused by portal vein thrombosis is

esophageal variceal ligation. If unsuccessful, the distal splenorenal shunt has been the traditional

surgical treatment for patients with isolated portal vein thrombosis. In patients whose intrahepatic

portal vein is patent (most commonly children), however, a shunt created by placing an internal jugular

vein graft between the superior mesenteric vein and the patent left portal vein within the parenchyma

of the liver (Rex shunt) may be the optimal therapeutic procedure for reestablishing physiologic portal

flow.186 This is the most elegant solution for portal obstruction because the portal pressure is reduced

by restoring blood flow to the liver, preventing chronic hepatic atrophy and dysfunction, which can

occur in a patient with long-standing portal decompression. In fact, in our practice, the Rex shunt is the

first-line treatment and we reserve splenorenal shunting for patients who have no remnant intrahepatic

portal system to receive the shunted blood.

CLASSIFICATION

Table 59-9 Child–Turcotte Criteria for Hepatic Functional Reserve

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