Causes of increased resistance to flow are described as follows:

Prehepatic

• Portal vein or splenic vein thrombosis

• Congenital atresia or stenosis of portal vein

• Extrinsic compression (tumors)

• Splanchnic arteriovenous fistula

• Schistosomiasis (early stage)

• Primary biliary cirrhosis (early stage)

• Idiopathic portal hypertension (early stage)

• Nodular regenerative hyperplasia: Pathogenesis probably is obliterative venopathy. The presence of nodules that press on the portal system also has been postulated to play a role, although nodularity is present in most cases without clinical evidence of portal hypertension.

• Myeloproliferative diseases: These act by direct infiltration by malignant cells.

• Polycystic disease

• Hepatic metastasis

• Granulomatous diseases (sarcoidosis, tuberculosis): Clinical liver dysfunction is rare in sarcoidosis. Portal hypertension is an unusual, although well-recognized manifestation of hepatic sarcoidosis. Sarcoid granulomas frequently localize in the portal areas, resulting in injury to the portal veins.

Intrahepatic, predominantly sinusoidal and/or postsinusoidal

• Hepatic cirrhosis

• Acute alcoholic hepatitis

• Schistosomiasis (advanced stage)

• Primary biliary cirrhosis (advanced stage)

• Idiopathic portal hypertension (advanced stage)

• Acute and fulminant hepatitis

• Congenital hepatic fibrosis

• Vitamin A toxicity.

• Venoocclusive disease

Posthepatic

• Inferior vena cava (IVC) obstruction

• Right heart failure, Constrictive pericarditis, Tricuspid regurgitation

• Budd-Chiari syndrome

• Arterial-portal venous fistula

• Increased portal or splenic flow

Pharmacological therapy

• Somatostatin (not available in the United States) is an endogenous hormone that decreases portal blood flow by splanchnic vasoconstriction at pharmacological doses, without significant systemic adverse effects.

• Octreotide is a synthetic analogue of somatostatin that usually is administered at a constant infusion of 50 mcg/h. Octreotide has been shown to be effective in reducing the complications of variceal bleeding after emergency sclerotherapy. Its efficacy as first-line treatment for variceal bleeding has not been established.

• Vasopressin is the most potent splanchnic vasoconstrictor. It reduces blood flow to all splanchnic organs, decreasing portal venous inflow and decreasing portal pressure. Use of vasopressin is limited by adverse effects related to splanchnic vasoconstriction (eg, bowel ischemia) and systemic vasoconstriction (eg, hypertension, myocardial ischemia). Continuous infusion of 0.2-0.4 IU/min (not to exceed 0.8 IU/min) is recommended. Vasopressin always should be accompanied by intravenous nitroglycerin at a dose of 40 mcg/min (not to exceed 400 mcg/min) to maintain systolic blood pressure greater than 90 mm Hg. Adding nitrates to vasopressin therapy significantly improves efficacy, although adverse effects of combination therapy are higher than those associated with terlipressin or somatostatin.

• Terlipressin = REMESTYP is a synthetic analogue of vasopressin that has longer biological activity and significantly fewer adverse effects than vasopressin.

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