Portal hypertension overview: Difference between revisions
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==Pathophysiology== | ==Pathophysiology== | ||
Portal venous pressure is determined by portal blood flow and portal vascular resistance. Increased portal vascular resistance is often the main factor responsible for it. The consequences of portal hypertension are due to blood being forced down alternate channels by the increased resistance to flow through the portal system. Due to formation of alternate channels initially some of the portal blood and later most of it is shunted directly to the systemic circulation bypassing the [[liver]]. | Portal venous pressure is determined by portal blood flow and portal vascular resistance. Increased portal vascular resistance is often the main factor responsible for it. The consequences of portal hypertension are due to blood being forced down alternate channels by the increased resistance to flow through the portal system. Due to formation of alternate channels initially some of the portal blood and later most of it is shunted directly to the systemic circulation bypassing the [[liver]]. | ||
==Causes== | |||
Many conditions can result in portal hypertension. In North America and Europe, it is usually the result of an intrahepatic block due to [[cirrhosis]] of the [[liver]]. However, in less industrialized parts of the world, climate permitting, the major cause is [[schistosomiasis]]. | |||
==Diagnosis== | ==Diagnosis== | ||
===Laboratory Findings=== | ===Laboratory Findings=== | ||
Revision as of 15:33, 16 April 2013
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Portal hypertension is hypertension in the portal stem which causes an obstruction in the portal vein and its branches. It is often defined as a portal pressure gradient (the difference in pressure between the portal vein and the hepatic veins) of 12 mm Hg or greater.
Pathophysiology
Portal venous pressure is determined by portal blood flow and portal vascular resistance. Increased portal vascular resistance is often the main factor responsible for it. The consequences of portal hypertension are due to blood being forced down alternate channels by the increased resistance to flow through the portal system. Due to formation of alternate channels initially some of the portal blood and later most of it is shunted directly to the systemic circulation bypassing the liver.
Causes
Many conditions can result in portal hypertension. In North America and Europe, it is usually the result of an intrahepatic block due to cirrhosis of the liver. However, in less industrialized parts of the world, climate permitting, the major cause is schistosomiasis.
Diagnosis
Laboratory Findings
Liver function tests for assessment of severity of the disease.
X Ray
Barium swallow is done in presence of varices where it is seen as filling defects (bag of worms appearance). Barium enema is useful in cases of colonic varices.
Endoscopy
Upper gastrointestinal endoscopy is very reliable. It shows the presence of cherry red spots. Proctoscopy is useful in cases of rectal varices.
Echocardiography or Ultrasound
Ultrasonography is useful to note the size of liver, spleen, portal vein, splenic vein and to look for the presence of collaterals.
Other Imaging Findings
Portal venography is useful in evaluating the patency and the calibre of portal vein and splenic vein.
Other Diagnostic Studies
Hepatic venous pressure drainage measurement is a gold standard for measuring portal hypertension. If more than 5 mm of Hg it is considered as significant.
Treatment
Medical Therapy
Treatment with a non-selective beta blocker is often commenced once portal hypertension has been diagnosed, and almost always if there has already been bleeding from esophageal varices. Typically, this is done with either propranolol or nadolol. The addition of a nitrate, such as isosorbide mononitrate, to the beta blocker is more effective than using beta blockers alone and may be the preferred regimen in those people with portal hypertension who have already experienced variceal bleeding. In acute or severe complications of the hypertension, such as bleeding varices, intravenous octreotide (a somatostatin analogue) or intravenous terlipressin (an antidiuretic hormone analogue) is commenced to decrease the portal pressure.