Arteriovenous Malformations

Arteriovenous malformations (AVMs) are structural abnormalities of the abnormal blood vessels that affect both arteries and veins. They can occur anywhere in the body, but the majority are found in the brain and spine.

AVMs are congenital, but may not cause symptoms until later in life, if ever. AVMs can cause damage to surrounding tissue in the following three ways:

Reduce the amount of oxygen and nutrients reaching brain or spinal tissues

Hemorrhaging can result in a stroke or spinal damage. While the risk of rupture is low, it increases over time (the average risk is 2-4% per year). Consequently, treatment of AVMs in otherwise healthy people is recommended.

This page contains the following information about arteriovenous malformations:

Facts About Arteriovenous Malformations

Arteries carry oxygen and nutrient rich blood from the heart to the brain and spinal cord. The blood within arteries is high-pressure due to the pumping action of the heart. Typically, these arteries feed into smaller arteries and eventually into capillaries. As the blood enters the smaller vessels, pressure is reduced. In the capillaries, oxygen and nutrients are taken from the blood and waste is deposited into the blood. The low-pressure blood within the veins returns to the heart and lungs. Arteries are strong, thick-walled vessels, whereas veins are thinner and weaker.

AVMs develop when one or more relatively large arteries connect directly to one or more veins through a network of vessels called a “nidus”. The nidus does not reduce the pressure of the blood from the larger arteries as small arteries and capillaries do. Since the walls of the veins are not capable of withstanding the pressure of blood from larger arteries, the veins expand and push against surrounding tissue.

The pressure of these enlarged veins and insufficient oxygen can cause tissue damage. Additionally, there may be a rupture in a supplying artery, vein or the nidus, which causes hemorrhaging. Hemorrhaging in the brain may result in a stroke.

Risk Factors

There are no risk factors that predispose a person to have an arteriovenous malformation. They are usually congenital, but may or may not be hereditary.

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Reducing the Risk

There is nothing you can do to prevent an arteriovenous malformation. However, by recognizing symptoms and getting prompt medical attention, you may reduce the risk of having a stroke or spinal damage.

Symptoms of Arteriovenous Malformations

Most people with an AVM experience few or no symptoms. Symptoms that may occur include:

Arteriovenous malformations are a serious condition. They can cause a stroke or severe damage to the spinal tissue. If you experience any of the listed symptoms, see your doctor immediately. If you experience any symptoms of stroke, call 911.

Imaging Exams for Detecting Arteriovenous Malformations

Your doctor may order a CT angiography or MR angiography to detect an arteriovenous malformation. These exams produce detailed images of the blood vessels in the brain and spine and allow a radiologist to accurately identify abnormalities.

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Radiology Procedures for Treating Arteriovenous Malformations

Arteriovenous malformation embolization is a minimally invasive procedure for treating arteriovenous malformations. This procedure uses various substances to block the blood vessels in the nidus, thus reducing the likelihood of a rupture. It may be successful on its own, or may be combined with surgery.

Additional Information

The information on this page was taken in part from the following sources. Visit the listed web sites for additional information on arteriovenous malformations.

Sources

Risk of an AVM rupturing is low but increases over time; consequently, treatment of AVMs is recommended. AVMs are congenital, but may not cause symptoms until later in life, if ever.