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Arteriovenous malformation or AVM is a congenital disorder of the veins and arteries that make up the vascular system. The genetic transmission patterns of AVM (if any) are unknown, and AVM is not generally thought to be an inherited disorder--unless in the context of a specific hereditary syndrome.

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.

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 arteriogram 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 no 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).

This bleeding can be devastating, particularly in the brain. It can cause severe and often fatal strokes. If detected before a stroke occurs, usually the arteries feeding blood into the nidus can be closed off, ensuring the safety of the patient.

Contents 1 Noteworthy cases 2 Cases in fiction 3 References 4 External links

• On December 13, 2006, United States Senator Tim Johnson (South Dakota) was diagnosed with AVM and treated at George Washington University Hospital.^[1]

• Stuart Sutcliffe, the Beatles' original bassist, died of a brain hemorrhage in 1962. It was originally thought to have been caused by blows to the head during various scuffles in seedy sections of Liverpool, but it is now believed to have been caused by AVM. This theory, however, though highly likely, is not, and can never be completely confirmed.

• A.J. Price, a point guard on the University of Connecticut Men's Basketball team was diagnosed with AVM in 2004 and was treated with a series of radiosurgeries

• The character Nate Fisher on the HBO television show Six Feet Under suffers from AVM.
• An episode of the television sit-com Becker used a cerebral AVM as a plot device.
• The character John Henry Giles, a fictional jazz legend from the series "House", was eventually diagnosed with AVM in the episode DNR.
  • Furthermore, House's patient in Top Secret has AVM due to HHT.
• An episode of Grey's Anatomy season 1 episode 9, the 'psychic' who is thought to have visions, actually has cerebral AVM.

1. ^ "Sen. Johnson recovering after brain surgery", AP, December 14, 2006.

• Information about arteriovenous malformations from the Children's Hospital, Seattle.
• General NIH AVM Page National Institute of Health general AVM page(USA).
• Detailed AVM Page NIH USA NIH(USA) AVM Detail page
• UK Support Group for AVM conditions
• behindthegray.net | Subarachnoid Haemorrhage support group with forums, articles, chat and general advice.
• AVM Foundation | A non-profit organization in Virginia, USA