Arteriovenous malformation (AVM)

Normally, arteries carry blood with oxygen under high pressure from the heart to the brain and body.

• A huge number of capillaries distribute the blood to the tissues
• Veins carry blood with less oxygen at low pressure back to the heart
• Capillaries connect high pressure arteries to low pressure veins

When an arteriovenous malformation (AVM) occurs, the capillaries are missing. The arteries connect directly to the veins. This causes the blood to flow very fast through these large vessels and raises the blood pressure in the veins. Over time, this reduces the blood supply to the skin and tissue around the AVM.

What does an AVM look like?

There are some common outward signs of AVM. For example:

• At birth, the skin on top of the AVM may be pink or red. Over time, the skin will look dark red or purple.
• An AVM can affect a small area, such as a lip, or it may take up an entire arm or leg.
• The skin over the malformation usually feels warmer than other skin.
• A pulse from the heartbeat may be felt under the affected area.

AVMs are most common in the head, but they may appear anywhere on the body or on internal organs.

What causes AVM?

AVM is caused by abnormal blood vessel development. Some AVMs are caused by genetic mutations and can be hereditary. Most AVMs are present at birth (congenital), but less than half are diagnosed at birth. It may take years to be diagnosed.

How do doctors diagnose AVM?

The diagnosis is usually confirmed by an imaging test such as an ultrasound, MRI, CT, or angiography. Scans must be done to see how big the malformation is and which tissues are involved. Angiography is used to precisely show which arteries are connected to which veins.

What are the complications and symptoms of AVM?

The complications and symptoms of AVM can vary from child to child, but there are some common symptoms and complications, including:

• Swelling and pain
• Crusting and bleeding on skin
• Severe bleeding (hemorrhage)
• Headaches and other neurological symptoms if the AVM is in the head
• Heart failure may develop due to the large amount of blood that flows through the AVM

How do you treat AVM?

Treatment will vary depending on the size and location of your child's AVM and the symptoms and complications your child is experiencing.

Treatment options may include:

• Embolization can be used to treat the AVM or to prepare it for surgery. A tiny catheter inserted into the patient's artery is used to inject material into the abnormal blood vessels to close them.
• Sclerotherapy is a chemical is injected into a blood vessel. This will damage the inside of the vessel so blood cannot flow through it. The vessel will then collapse and form scar tissue.
• Surgery will remove as much of the AVM as possible. Several surgeries may be needed to remove the entire AVM.

Are there other problems that are linked to AVMs?

Some AVMs may be linked to a group of problems called a syndrome. Your doctor will ask you questions about the family health history. Some of the syndromes linked to AVMs are Hereditary Hemorrhagic Telangiectasia, Capillary Malformation-AVM, Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome and Parkes-Weber syndrome.

Are there other websites or references that may be helpful?

• Mulliken JB, Burrows PE and Fishman SF. Mulliken and Young's Vascular Anomalies. Hemangiomas and Malformations second edition. Oxford University press 2013
• Blei F, Anglin C. 100 Questions and Answers about Vascular Anomalies. Jones and Bartlett publishers 2011

Alert

Call your child's doctor, nurse, or clinic if you have any concerns or if your child has:

• Sudden swelling
• An infection that will not heal
• Bleeding that will not stop
• Special health care needs not covered by this information