Arteriovenous Fistula

What is an arteriovenous fistula?

An arteriovenous fistula is a medical condition where an artery and vein connect directly, causing blood to flow between them. It can happen at virtually any place in your body where an artery and vein are close together, especially inside of your organs and limbs (arms and legs). Depending on where fistulas are, why they happened and their size, they can be harmless (or even helpful when there’s a medical reason to create one), or they can be a major health issue and permanently damage your heart.

Who does it affect?

Arteriovenous fistulas (pronounced “are-tee-re-oh-vee-nus fis-tew-las”) can happen to anyone at any age, especially when they happen because of injuries. Certain types of fistulas are more common in certain groups of people, usually because of their life circumstances (see the Causes and Symptoms section for more details).

There are two different terms for more than one fistula, but both are correct. You can use either “fistulas” or “fistulae” (pronounced “fis-tew-lay”).

How common is this condition?

Arteriovenous fistulas are very common overall, but some types aren’t. The most common types of arteriovenous fistulas are those that are medically created for people needing dialysis. The least common arteriovenous fistulas are those you have when you’re born.

Arteriovenous fistulas are very common for people who need dialysis. The national goal, set by a partnership between the Centers for Medicare and Medicaid Services and other groups, is for 68% or more of people on dialysis to have an arteriovenous fistula.

What happens with an arteriovenous fistula, and how does it affect my body?

Your body uses different types of blood vessels for different purposes. These include:

• Arteries: These large vessels carry blood from your heart to the rest of your body.
• Veins: These large vessels return blood from your body back to your heart.
• Capillaries: These very small vessels form networks throughout your body.

Under normal circumstances, your arteries and veins don’t connect directly. Instead, blood first goes from your arteries into a network of smaller blood vessels called capillaries. Arteries and veins are like highways through a major city, providing plenty of room for blood to move quickly. Capillaries are like the city streets, providing blood flow to all tissues, even those farthest away from major blood vessels.

A fistula between an artery and a vein means that blood can move directly between them. Your arteries have higher pressure in them because of the pumping force of your heart. That can disrupt the blood flow in the connected vein and keep it from flowing in the direction of your heart. Your arteries can handle the higher pressure, but your veins can’t. That can cause them to stretch and swell.

If a fistula is in a certain place or it’s very large, your heart will pump harder to try to force blood to flow correctly. Over time, the extra work strains your heart and causes it to fail.

Fistulas can also cause problems when they happen in vital organs, including:

• Brain: Dural and pial arteriovenous fistulas.
• Heart: Coronary arteriovenous fistula.
• Spine: Spinal dural arteriovenous fistula.
• Kidneys: Renal arteriovenous fistula.

Symptoms of arteriovenous fistulas

These can vary, depending on their location. The most common symptoms include:

• Swelling. This happens around the fistula’s location and is most likely to happen when a fistula is just underneath your skin.
• Color changes of your skin (may turn purplish or bright red).
• Bulging or stretched veins.
• The area around the fistula may feel warmer than areas of your skin farther away from it.

Symptoms of ischemia from AV fistulas (“steal syndrome”)

When a fistula on one of your limbs is very large, areas farther away from the heart than the fistula may develop symptoms of ischemia. This condition (pronounced “iss-key-me-uh”) is when parts of your body don’t have enough blood flow.

If the lack of blood flow is severe enough, it can damage those areas, or the cells in those areas may even start to die. This is also sometimes called “steal syndrome” because blood is “stolen” from the affected area because the fistula diverts blood away.

The symptoms of ischemia like this include:

• Numbness and tingling.
• Cramping or pain.
• Open sores or ulcers on your skin that are slow to heal or won’t heal at all.

Symptoms of heart failure because of AV fistulas

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

• Shortness of breath (dyspnea).
• Fatigue.
• Swelling in your lower legs and feet (edema).

Congenital arteriovenous fistulas

Congenital arteriovenous fistulas often have different symptoms because of how they happen. These form as you develop in the womb, which means they can affect a larger area if that area doesn’t develop as expected.

Congenital arteriovenous fistulas will often affect how the affected body part grows. When it’s on your arm or leg, that limb may have a greater muscle mass or longer bones because of the unusual blood flow patterns. A person may also have clubbing, a swelling in the fingertips (where the fingernails become very soft, bulge upward in the middle and curve down near their fingertip). In other cases, they may not have enough blood flow to the affected limb, which will turn blue farther down because of lack of blood flow.

What causes the condition?

The three main causes of arteriovenous fistula are:

• Injuries: Trauma is the most common unintentional cause of arteriovenous fistulas. These fistulas form because of tissue damage around them, when healing structures get stuck together as they repair themselves, or a combination of both. It can sometimes take years before these are detectable.
• Congenital: A congenital condition is a condition you have at birth, meaning these fistulas form while you’re developing in the womb. They usually involve many small fistulas rather than a single bigger one. However, some are fatal if they happen in a critical location.
• Dialysis: Arteriovenous fistulas for dialysis is the most common reason people have this condition. Creating an arteriovenous fistula helps create a wider, thicker vein, which is better able to handle dialysis needles and can carry more blood out of and into your body.

In rarer cases, arteriovenous fistulas can happen because of conditions like cancer, certain types of infections or when an artery develops an aneurysm (a weakness in your artery wall that bulges out and presses against a nearby vein).

Is it contagious?

Arteriovenous fistulas aren’t contagious, which means you can’t spread them to or catch them from other people.

How is it diagnosed?

Your healthcare provider can diagnose an arteriovenous fistula with a variety of approaches, including a physical examination and diagnostic imaging. Other tests might happen, but these are most likely related to finding the underlying cause of an arteriovenous fistula.

During a physical examination, your healthcare provider will do the following:

• Look. Providers will look at areas of your body for visible signs of a problem, especially the area in question or any area that might also show evidence of the problem.
• Listen. Providers will use a stethoscope to listen to blood flow at the suspected location of a fistula. This is because blood flow disruptions from arteriovenous fistulas cause unusual sounds. These often sound like machinery because blood moves in both directions instead of just one.
• Feel. Arteriovenous fistulas aren’t just audible. In many cases, the vibration of the disrupted blood flow is something a provider can feel with their hand near the fistula. They may also press on the area gently because doing so can trigger a reflex and slow your heart rate slightly. This is a key sign of arteriovenous fistula.

What tests will be done to diagnose this condition?

The most likely tests include at least one type of imaging. The available options include:

• Duplex ultrasound mapping. This test uses ultra-high-frequency sound waves, like a bat uses sonar to “see.” This lets providers see the inside of your body, including an arteriovenous fistula.
• Angiogram. This test involves an injectable contrast and either X-rays or computerized tomography (a computer-driven 3D X-ray). The contrast is very visible on either the CT or the X-ray, and it can highlight areas inside of your body where blood flow isn’t moving as it should.
• Magnetic resonance imaging (MRI). This test uses a powerful magnet and computer imaging to generate an extremely detailed picture of the inside of your body, including any unusual structures like an arteriovenous fistula.

How is it treated, and is there a cure?

Most arteriovenous fistulas are often curable, depending on the cause, size and where they are. While it’s much harder to cure congenital arteriovenous fistulas, it’s usually possible to treat them and manage any related issues or complications.

Many people with this condition may not need treatment as a first option. The main reasons why treatment becomes necessary include:

• Hemorrhage. This is bleeding at the site of the fistula. If the bleeding is severe or won’t stop, repair is needed.
• Expansion. When a fistula or the involved blood vessels change shape and grow, that can cause problems in the surrounding tissue.
• Disrupted blood flow. Fistulas can prevent blood from reaching a part of your body or keep too much blood or fluid in a part of your body. Either of these can lead to severe problems.
• Changes in appearance. Fistulas can cause shape changes that a person may feel are embarrassing. In many cases, repairing a fistula can help partially or completely restore a person’s appearance.

What medications or treatments are used?

The most common means of treating or curing an arteriovenous fistula include:

• Catheter-based procedures. These involve a long, tube-like device that your healthcare provider will insert into a major blood vessel (usually one near your upper thigh). They’ll then direct the catheter through your circulatory system to the site of the fistula. Inside, they’ll repair the fistula. That can happen by plugging the fistula with devices like coils or stents, or filling it with a substance called cyanoacrylate glue.
• Surgery. In instances where your provider can’t reach the fistula through blood vessels from the inside, or if the fistula is very large, a surgeon can often directly access it and repair it. They may do that by directly separating the two vessels or taking a blood vessel from somewhere else in your body and grafting it into place to repair the vessels affected by the fistula.
• Radiation therapy. In some cases, a way to repair an existing fistula is to destroy the connection. Radiation therapy targets the fistula precisely and turns it into scar tissue, so blood can't pass through it.

Treating an arteriovenous fistula often involves medication as well. In cases where a fistula creates a risk of a blood clot forming, blood-thinning medications are often helpful. These medications prevent clots from blocking blood vessels where they form or from breaking loose and traveling to another part of your body, where they can cause deadly conditions like heart attack, stroke or pulmonary embolism.

Dialysis-related fistulas

Dialysis-related fistulas aren’t usually the focus of treatment unless something goes wrong with them. In those cases, surgery is often an option to repair them.

Complications/side effects of the treatment

The complications or side effects from treatments depend on the specific treatments and the location and size of the fistula. Your healthcare provider is the best person to explain the possibilities to you and help you understand what you can do to reduce your risk of these problems.

How to take care of myself/manage symptoms?

It isn’t possible to diagnose an arteriovenous fistula on your own. Many of the symptoms of this condition also happen with other, more serious conditions like aneurysms or blood clots. Because of this, you shouldn’t try to self-diagnose and treat them on your own. If your healthcare provider diagnoses you with this condition, they’re the best person to advise you on how to care for it yourself.

How soon after treatment will I feel better, and how long does it take to recover from this treatment?

The time it takes you to feel better and fully recover depends on the treatment used, as well as the size and location of the fistula. Your healthcare provider is the best person to tell you what you should expect regarding your symptoms diminishing and when you should recover.

How can I reduce my risk of developing this condition or prevent it altogether?

Arteriovenous fistulas aren’t preventable because the most common causes are injuries (which are almost always unpredictable), or they form before you’re born. When they happen in connection with dialysis, they’re intentional, and your medical provider will create one to help make your dialysis care more effective.

What can I expect if I have this condition?

The outlook for arteriovenous fistulas depends on their size, location and cause. Smaller fistulas or those in certain places often don’t need treatment, and many people will only notice mild symptoms or have no symptoms at all. Larger fistulas or those that happen in critical places are the ones that can cause the most problems. Your healthcare provider is the best person to tell you the outlook and what you can expect with these.

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

Dialysis-related fistulas usually don’t cause any problems. When they have side effects, your healthcare provider can often treat those effects or help you find alternatives that will work better. 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.

How long do AV fistulas last?

When they aren’t serious, arteriovenous fistulas can last your entire life and cause few or no problems. When fistulas are more serious, it’s important to see your healthcare provider. Quick diagnosis and treatment are essential, especially with larger fistulas. That’s because larger fistulas can cause your heart to strain until you develop heart failure. While repairing a fistula often allows your heart to return to normal even after heart failure starts, this doesn’t always happen. For that reason, it’s best to treat arteriovenous fistulas sooner rather than later.

How do I take care of myself?

If you have an arteriovenous fistula with mild or no symptoms, the best thing you can do is watch for any changes. If you have a fistula with symptoms, your healthcare provider can guide you on what to do to care for it and problems for which to watch. Some people may benefit from wearing compression garments, which put light pressure on the entire area of your body and help push fluid out of the area within the garment.

When should I see my healthcare provider?

You should call or see your healthcare provider if you notice any changes in your symptoms, especially changes that are new, get worse or that start to affect your routine or activities.

Key symptoms to watch for include:

• New or worsening pain.
• Noticeable growth around the fistula (or if you don’t know you have a fistula, any new bulges or swelling that you can’t explain).
• Color changes to an area of the body farther away from your heart than the fistula (such as a color change on a hand when you have a fistula in the same arm).

Dialysis-related fistula

You should call your provider if you notice any changes near an arteriovenous fistula that you have for dialysis reasons. Changes that are especially important to catch early include:

• Signs of infection like swelling, warmth or redness.
• Changes in how well blood flows through the fistula during dialysis.
• Any unusual bulges or changes in shape.

When should I go to ER?

You should go to the emergency room if you have any symptoms of internal bleeding or symptoms that might mean you’re not getting enough blood flow to part of your body, especially a hand or foot.

Symptoms like these include:

• Color changes of your skin, either near the fistula or on your whole body.
• Fainting or dizziness.
• Fast heartbeat or breathing.
• Shortness of breath.
• Sudden, severe pain near the fistula.

Your healthcare provider can also tell you other signs and symptoms to look for that might mean you need emergency medical attention. They can also tailor that information to fit your specific situation, including your health history, other medical conditions you might have and the treatments you’ve received in the past.

A note from Cleveland Clinic

An arteriovenous fistula is a condition that can have little to no effect on your life, or it can cause significant problems. It’s also extremely common for people with kidney disease or kidney failure to have an arteriovenous fistula created surgically, as fistulas can be very helpful for people who need regular dialysis. However, they can cause serious complications or even death in rare cases. Fortunately, advances in modern imaging and medical care mean this condition is often treatable or even curable.