Endovascular treatment of arteriovenous malformations

What is an arteriovenous malformation (AVM)?

Arteriovenous malformation (AVM) are a tangle of blood vessels with abnormal communications between arteries and veins.

Normally, high pressure arteries are connected to low pressure veins via a network of tiny blood vessels called capillaries. Normal tissues obtain its nutrients and oxygen supply from this capillary network.

In AVMs, abnormal connections are formed between arteries and veins. These connections often skip the normal capillary bed and result in direct communication between arteries and veins. This means that normal tissues in that part of the body would be starved of oxygen and nutrients. With time, this may lead to pain and fragility in that part of the body. In addition, AVMs may grow in size over time due to rapid blood flow. This can cause reduced function of the involved organ or body part. Finally, the rapid blood flow through an AVM means that the heart needs to work extra hard to pump more blood around the body.

AVMs can occur in any part of the body, from head to toe. Different organ functions may be affected depending on its location. However, most AVMs are small, may not cause any problems and are often discovered by chance.

What might I experience if I have an AVM?

If the skin is involved by the AVM, it may show reddish, bluish or purplish colour. If the limb is involved, it can be swollen. On touching, the involved part is often warm. You may also feel a pulse or buzz. In serious cases, the skin surface may break down and form painful ulcers.

How are AVMs treated?

You may be advised to undergo treatment for the AVM if you experience bleeding, pain, or skin ulcers. Other reasons for treatment include deteriorating heart function and normal functioning of the involved organ or body part.

Treatment of AVMs requires a team approach with input from medical professionals specialised in different aspect of its management.

Embolization is one of the means to treat AVMs. It is a minimally invasive procedure often performed by an interventional radiologist. The aim is to cut off or slow down blood flow in the AVM by closing off the abnormal connections, while preserving blood supply to normal tissue. Various substances, including alcohol, medial glue, metallic coils, can be injected into the blood vessels to achieve this goal.

Embolization of AVM is a complex procedure. Depending on the site and type of your AVM, the interventional radiologist will discuss the treatment options and risks with you. In some occasions, “staged” (i.e. more than one) embolization has to be performed. In some large AVMs, embolization may provide relief of symptoms but not completely cure the AVM.

Common risks of AVM embolization include skin injury and ulceration. The substances used may block off vessels supplying normal part of the body, which can lead to reduced blood supply to normal tissue and organs. Some of the substances used may lead to reduced function of the lungs.