hepatic and biliary disorders
Overview of Vascular Disorders of the Liver
Introduction
The liver has a dual blood supply. The portal vein (which is rich in nutrients and relatively high in oxygen) provides two thirds of blood flow to the liver. The hepatic artery (which is oxygen-rich) supplies the rest. The hepatic veins drain the liver into the inferior vena cava. When portal vein blood flow increases, hepatic artery flow decreases and vice versa (the hepatic arterial buffer response). This dual, reciprocally compensatory blood supply provides some protection from hepatic ischemia in healthy people. Despite its dual blood supply, the liver, a metabolically active organ, can be injured by Ischemia Insufficient venous drainage Specific vascular lesions results from reduced blood flow, reduced oxygen delivery, increased metabolic activity, or all 3. Diffuse ischemia can cause Ischemic Hepatitis ; focal ischemia can cause hepatic infarction or may result from focal or diffuse obstruction or from right-sided heart failure, as in Congestive Hepatopathy . Obstruction can occur in the intrahepatic or extrahepatic veins ( may occur in the hepatic artery, hepatic vein, or portal vein. The Hepatic Artery Occlusion . Uncommonly, Hepatic vein disorders can result in focal or diffuse venous obstruction. Nearly all portal vein disorders obstruct portal vein blood flow and cause Portal Hypertension . Obstruction can be Extrahepatic— Portal Vein Thrombosis due to a hypercoagulable state, a vessel wall lesion (eg, pylephlebitis, omphalitis), an adjacent lesion (eg, Intrahepatic—eg, microvascular portal vein obstruction as occurs in Schistosomiasis , 