Arteriovenous Fistula

An arteriovenous fistula (AV fistula) is an abnormal link between an artery and a vein. Blood flows from one to the other instead of going through the capillaries between them. You can be born with it or get it through an injury or surgery for dialysis.

An AV fistula can form anywhere in your body where an artery and a vein are close together. Depending on their location, cause and size, they can be harmless. They can even be helpful when there’s a medical reason to create one. But some can be a major health issue and damage your heart.

Arteriovenous fistulas are rare overall, except those that surgeons create to make dialysis easier. Those are the most common types. The least common AV fistulas are those you have at birth.

Arteriovenous fistulas can happen to anyone at any age, especially when an injury causes them.

Types of AV fistulas

Arteriovenous fistulas can be congenital (present at birth) or acquired. You can acquire an AV fistula from an injury (even years later) or from a procedure to prepare for dialysis. Types by location may include:

• Coronary (heart)
• Dural and pial (brain)
• Peripheral (arms and legs)
• Renal (kidneys)
• Spinal dura (spine)

Symptoms of AV fistulas

Symptoms can vary based on where the arteriovenous fistula is. The most common symptoms include:

• Swelling around the fistula
• Skin color changes (like purple or bright red)
• Bulging or stretched veins
• Warmth in the area around the fistula

Congenital arteriovenous fistulas often change how the affected body part grows. An AV fistula on your arm or leg may give that limb greater muscle mass or longer bones. You may also have swelling in your fingertips (clubbing). In other cases, you may not have enough blood flow to the affected limb. This makes it turn blue.

AV fistula causes

The three main causes of arteriovenous fistulas are:

• Dialysis: Creating an arteriovenous fistula helps make a wider, thicker vein. This is better able to handle dialysis needles and can carry more blood out of and into your body.
• Injuries: Arteriovenous fistulas form from trauma because of tissue damage around them. Healing structures can get stuck together. It can sometimes take years to detect these.
• Congenital: These fistulas form during fetal development and are present at birth. They usually involve many small fistulas rather than a single bigger one. Some are fatal if they happen in a critical place.

In rarer cases, AV fistulas can happen because of conditions like cancer, infections or when a weak artery wall bulges out (aneurysm) and presses against a nearby vein.

Complications of this condition

When blood moves between an artery and a vein, it can disrupt the blood flow in the vein and keep it from flowing toward your heart. The higher pressure of blood coming from arteries into veins can make veins stretch and swell.

When an AV fistula on one of your limbs is very large, areas farther away from the heart than the fistula may not get enough blood flow. If the lack of blood flow is severe enough, it can damage those areas.

Large arteriovenous fistulas can also cause problems for your heart. Because blood isn’t flowing correctly around the fistula, your heart tries to make up for this by pumping harder. Over time, that damages your heart and causes heart failure.

How doctors diagnose this condition

A healthcare provider can diagnose an arteriovenous fistula with a physical exam and imaging. Other tests may help them find the cause.

During a physical exam, your provider will:

• Look at areas of your body for signs of a problem.
• Use a stethoscope to listen for blood flowing back and forth.
• Feel the vibration of the disrupted blood flow with their hand near the fistula.

The most likely tests for AV fistulas include at least one type of imaging, like:

• Duplex ultrasound mapping using sound waves
• Angiogram using a contrast injection to show areas of unusual blood flow on X-rays or CT
• MRA using a powerful magnet and computer imaging

How is it treated?

Treating an AV fistula often involves a procedure and medication. Common treatments include:

• Catheter-based procedures: A healthcare provider inserts a tube (catheter) into a major blood vessel. They move the tube to the fistula and repair or plug it with a device or substance.
• Surgery: A surgeon can separate the two vessels or take a blood vessel from elsewhere in your body and graft it into place to make a repair.
• Radiation therapy: In some cases, a provider uses radiation therapy to turn the fistula into scar tissue. This keeps blood from passing through it.
• Medication: Blood-thinning medications keep clots from blocking blood vessels or breaking loose and moving to another part of your body.

Treatment depends on the cause, size and location of the AV fistula. Healthcare providers can usually treat them and manage any related issues. Most arteriovenous fistulas are curable. But it’s harder to cure the kind you’re born with.

Many people with an AV fistula may not need treatment unless they have:

• Something go wrong with a dialysis-related fistula
• Severe or nonstop bleeding
• Problems in nearby tissue from growth or a change in shape in the fistula
• An issue with too little blood reaching a body part or too much staying there
• Heart failure symptoms due to the fistula

When should I see my healthcare provider?

Call or see your provider if you notice any changes in your symptoms. These include symptoms that are new, get worse or that start to affect your routine. Key symptoms to watch for include new or worse pain, growth around the fistula or skin color changes to an area of your body. For a dialysis fistula, watch for signs of infection or changes in shape or in how well blood flows through the fistula.

You should go to the emergency room if you have any symptoms of internal bleeding or poor blood flow. These include:

• Fainting or dizziness
• Fast heartbeat or breathing
• Shortness of breath
• Sudden, severe pain near the fistula

You may want to ask your provider:

• How did this AV fistula happen?
• Do I need treatment?
• What’s the best treatment for me?
• How often do I need follow-up visits with you?

What can I expect if I have an AV fistula?

The outlook for arteriovenous fistulas depends on their size, location and cause. Smaller fistulas or those in certain places often don’t need treatment. Many people will only notice mild symptoms or have no symptoms at all. Larger fistulas or those in critical places can cause the most problems.

Congenital fistulas often have a good prognosis if they aren’t in a critical place. When they’re in a dangerous spot or very severe, they can cause serious issues or even death.

Dialysis-related fistulas usually don’t cause any problems. When they cause side effects, your healthcare provider can often treat them. They may do a follow-up surgery to repair the fistula or return the affected blood vessels to their original shape and location in more severe cases.

Is an AV fistula permanent or temporary?

Arteriovenous fistulas don’t go away unless you fix them. AV fistulas that aren’t serious can last your whole life and cause few or no problems. Larger fistulas can make your heart strain until you develop heart failure. Repairing a fistula often allows your heart to return to normal even after heart failure starts. It’s best to treat arteriovenous fistulas sooner rather than later.

Is there anything I can do to feel better?

If you have an AV fistula with symptoms, you may benefit from wearing compression garments. These put light pressure on an entire area of your body and help push fluid out of that area. Your provider can let you know if you should wear them.