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Portal hypertension is a condition in which the blood pressure of the portal venous system is too high. It is often the result of cirrhosis of the liver. Liver cirrhosis can lead to increased intrahepatic vascular resistance and vasodilation of portal system arteries, both of which increase pressure in the portal vein. [ 4 ]
Approximately 75% of total liver blood flow is through the portal vein, with the remainder coming from the hepatic artery proper. The blood leaves the liver to the heart in the hepatic veins . The portal vein is not a true vein , because it conducts blood to capillary beds in the liver and not directly to the heart.
The human hepatic portal system delivers about three-fourths of the blood going to the liver.The final common pathway for transport of venous blood from spleen, pancreas, gallbladder and the abdominal portion of the gastrointestinal tract [2] (with the exception of the inferior part of the anal canal and sigmoid colon) is through the hepatic portal vein.
A dilated portal vein (diameter of greater than 13 or 15 mm) is a sign of portal hypertension, with a sensitivity estimated at 12.5% or 40%. [18] On Doppler ultrasonography, a slow velocity of <16 cm/s in addition to dilatation in the main portal vein are diagnostic of portal hypertension. [19]
In histology (microscopic anatomy), the lobules of liver, or hepatic lobules, are small divisions of the liver defined at the microscopic scale. The hepatic lobule is a building block of the liver tissue, consisting of a portal triad, hepatocytes arranged in linear cords between a capillary network, and a central vein.
Portal venous pressure is the blood pressure in the hepatic portal vein, and is normally between 5-10 mmHg. [1] Raised portal venous pressure is termed portal hypertension , [ 2 ] and has numerous sequelae such as ascites and hepatic encephalopathy .
The left atrial volume is commonly measured by echocardiography or magnetic resonance tomography.It is calculated from biplane recordings with the equation: = where A4c and A2c denote LA areas in 4- and 2-chamber views respectively, and L corresponds to the shortest long-axis length measured in either views.
For example, in portal hypertension, there is an abnormal portal venous flow where it flows away from the liver (hepatofugal flow) instead of the normal flow towards liver (hepatopetal flow). In jugular venous pressure waveform of the internal jugular vein, the retrograde "a" waveform is a normal flow due to right atrium contraction. Both ...