*What is an AVM?

An arteriovenous malformation (AVM) is a complex tangle of abnormal arteries and veins linked by one or more direct connections called fistulas or shunts.

Over time, the high blood flow and shunting of high-pressure arterial blood through the AVM causes the feeder arteries and veins making up the AVM to dilate (or expand). This dilation weakens veins, making them susceptible to hemorrhage; feeder arteries become susceptible to aneurysms, a weakened spot in the blood vessel wall that expands and can eventually hemorrhage. A hemorrhage in the brain is a type of stroke in which a blood vessel ruptures and bleeds into the surrounding brain. For more stroke information, please visit the American Stroke Association.

*Excerpt from The Aneurysm and AVM Foundation, a site focused on the intracranial (found in the cranium or brain) aneurysm or AVM. However, aneurysms and AVMs can develop anywhere in the body's arteries.