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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 ]
The portal vein and hepatic arteries form the liver's dual blood supply. Approximately 75% of hepatic blood flow is derived from the portal vein, while the remainder is from the hepatic arteries. [4] Unlike most veins, the portal vein does not drain into 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.
Portal hypertension is defined as increased portal venous pressure, with a hepatic venous pressure gradient greater than 5 mmHg. [3] [4] Normal portal pressure is 1–4 mmHg; clinically insignificant portal hypertension is present at portal pressures 5–9 mmHg; clinically significant portal hypertension is present at portal pressures greater than 10 mmHg. [5]
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.
Blood flow through the left coronary artery is at a maximum during diastole (in contrast to the rest of systemic circulation, which has a maximum blood flow during systole.) splanchnic circulation: 15%: low: Flow increases during digestion. hepatic circulation: 15%: Part of portal venous system, so oncotic pressure is very low renal circulation ...
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 .
In a normal circulatory system, the volume of blood returning to the heart each minute is approximately equal to the volume that is pumped out each minute (the cardiac output). [12] Because of this, the velocity of blood flow across each level of the circulatory system is primarily determined by the total cross-sectional area of that level.