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Encyclopedia > Arteriovenous malformation

Arteriovenous malformation or AVM is a congenital disorder of the veins and arteries that make up the vascular system . The cause of this disorder is unknown, but is not generally thought to be hereditary, unless in the context of a specific hereditary syndrome. A congenital disorder is a medical condition that is present at birth. ... The arterial system The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... Heredity (the adjective is hereditary) is the transfer of characteristics from parent to offspring, either through their genes or through the social institution called inheritance (for example, a title of nobility is passed from individual to individual according to relevant customs and/or laws). ...

Arteries and veins are part of the human cardiovascular system. Normally, the arteries in the vascular system carry oxygen-rich blood at a relatively high pressure. Structurally, arteries divide and sub-divide repeatedly, eventually forming a sponge-like capillary bed. Blood moves through the capillaries, giving up oxygen and taking up waste products from the surrounding cells. Capillaries successively join together, one upon the other, to form the veins that carry blood away at a relatively low pressure. The heart acts to pump blood from the low pressure veins to the high pressure arteries. Human circulatory system. ...

If the capillary bed is thought of as a sponge, then an AVM is the rough equivalent of jamming a tangle of flexible soda straws from artery to vein through that sponge. On arteriorgram films AVM formation often resemble a tangle of spaghetti noodles. This tangle of blood vessels forms a relatively direct connection between high pressure arteries and low pressure veins.

The result is a collection of blood vessels with abnormal connections and without capillaries. This collection, often called a nidus, can be extremely fragile and prone to bleeding. AVMs can occur in various parts of the body including the brain (see cerebral arteriovenous malformation), spleen, lung, kidney, spinal column, and liver. AVMs may occur in isolation or as a part of another disease (e.g. Von Hippel-Lindau disease or hereditary hemorrhagic telangiectasia). The word capillary is used to describe any very narrow tube or channel through which a fluid can pass. ... A sketch of the human brain by artist Priyan Weerappuli, imposed upon the profile of Michaelangelos David. ... A cerebral arteriovenous malformation (AVM) is a congenital disorder of blood vessels within the brain, characterized by tangle(s) of veins and arteries. ... The spleen is a ductless, vertebrate gland that is closely associated with the circulatory system, where it functions in the destruction of old red blood cells in holding a reservoir of blood. ... The lungs flank the heart and great vessels in the chest cavity. ... The kidneys are bean-shaped excretory organs in vertebrates. ... The spinal cord is a part of the vertebrate nervous system that is enclosed in and protected by the vertebral column (it passes through the spinal canal). ... The liver is an organ in living beings, including humans. ... Von Hippel-Lindau disease (VHL) is a rare inherited genetic condition involving the abnormal growth of tumors in parts of the body which are particularly rich in blood supply. ... In medicine, hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is a genetic disorder that leads to vascular malformations. ...

This bleeding can be devastating, particularly in the brain. They can cause severe and often fatal strokes. If detected before the stroke occurs, usually the arteries feeding blood into the nidus can be closed off, ensuring the safety of the patient. A stroke, also known as cerebrovascular accident (CVA),[1] is an acute neurologic injury in which the blood supply to a part of the brain is interrupted. ...

External links

  • Information about arteriovenous malformations from the Children's Hospital, Seattle.
  • UK Support Group for AVM conditions

  Results from FactBites:
Arteriovenous Malformation - Cerebral - Health Encyclopedia News Story - WNBC | New York (700 words)
A cerebral arteriovenous malformation is a birth defect in which there is an abnormal connection between the arteries and veins in the brain.
The cause of cerebral arteriovenous malformation (AVM) is unknown.
Arteriovenous malformations vary in their size and location within the brain.
Arteriovenous Malformations and Other Vascular Lesions of the Central Nervous System Fact Sheet: National Institute of ... (4298 words)
In contrast, cavernous malformations, telangiectases, and venous malformations are all low-flow lesions.
A few types of vascular malformations are known to be hereditary and thus are known to have a genetic basis.
Venous malformations and capillary telangiectases rarely require surgery; moreover, their structures are diffuse and usually not suitable for surgical correction and they usually do not require treatment anyway.
  More results at FactBites »



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