Under normal circumstances, your blood flows from your arteries into your capillaries and then into your veins. The blood that flows through those capillaries delivers nutrients and oxygen to the various tissues below in the process.
An arteriovenous fistula (AVF) indicates a miscommunication in that progression, whereby the capillaries are bypassed and blood flows directly from the arteries to the veins.
By skipping the capillaries, the tissues below those capillaries don’t get the nutrients and oxygen they need.
Typically, arteriovenous fistulas develop in the legs. But they can occur anywhere in the body, including the brain and spine, and can vary in size, length and number.
Arteriovenous fistulas can either be congenital (present at birth) or acquired (occurring because of some event after birth). Acquired arteriovenous fistulas are most common, and can be the result of:
- A penetrating injury (such as from a knife or bullet) to a side-by-side artery and vein
- A symptom of Osler-Weber-Rendu disease, which is a genetic condition leading to the abnormal development of blood vessels throughout the body, especially in the lungs
Smaller neurovascular arteriovenous fistulas may go unnoticed, resulting in no symptoms and presenting no need for treatment. Symptoms that may appear with most other arteriovenous fistulas include:
- Reduced blood pressure
- Swelling in the arms and legs
- Progressive weakness in the extremities
In rare cases, an arteriovenous fistula may become large enough to cause intracranial bleeding, or spinal cord ischemia.
A large enough arteriovenous fistula can lead to serious complications, to include bleeding into the brain or lack of oxygen to the spinal cord.
When a doctor suspects arteriovenous fistula involving the brain or spine, imaging tests will be ordered to confirm diagnosis. Potential tests include:
- Magnetic resonance imaging (MRI): A magnetic field is used to create images of your body’s tissues
- Magnetic resonance angiography (MRA): A special dye is injected prior to your MRI to create clearer images of your blood vessels
- Computed tomography angiography (CTA): A special dye is injected and a series of X-ray images are taken to show blood flow through your arteries
- Cerebral angiography or Spinal angiography: A catheter (thin plastic tube) is inserted into your artery through a small invision. Using X-ray guidance, your physician navigates the catheter to the area being examined, injects a special dye and takes a series of X-ray images.
In some cases, particularly with smaller arteriovenous fistulas , your doctor may simply want to monitor the situation.
For most neurovascular arteriovenous fistulas, and those with possible complications, the Neurointerventional team at MedStar Georgetown University Hospital offers a wide range of treatment options, including:
- Catheter embolization: A minimally invasive procedure that uses X-ray and other imaging techniques to insert a catheter in an artery near your arteriovenous fistula. A small coil or embolizing material (e.g. polymer glue) is then placed at the arteriovenous fistula site to redirect the blood flow. The majority of arteriovenous fistulas can be treated with this method.
Surgery: For larger arteriovenous fistulas that can’t be treated with catheter embolization