Atrioventricular Fistula

Definition

Definition of Atrioventricular Fistula
An arteriovenous (AV) fistula is an abnormal connection between an artery and a vein. Normally, your blood flows from your arteries to your capillaries to your veins. Nutrients and oxygen in your blood travel from your capillaries to tissues in your body.

Symptoms

Symptoms of Atrioventricular Fistula
Small arteriovenous fistulas in your legs, arms, lungs or kidneys often won't have any symptoms and usually don't need treatment other than monitoring by your doctor. Larger arteriovenous fistulas may cause symptoms.

Arteriovenous fistula symptoms may include:

1. Swelling and reddish appearance on the skin surface
2. Purplish, bulging veins that you can see through your skin, similar to varicose veins
3. Decreased blood pressure

An arteriovenous fistula in your lungs (pulmonary arteriovenous fistula) is a serious condition and can cause:

1. Bloody sputum
2. Difficulty breathing, especially when exercising
3. Nosebleeds
4. Blueness of the skin
5. Clubbing of fingers
6. Infections in the valves of your heart

Causes

Causes of Atrioventricular Fistula
Causes of arteriovenous fistulas include:

1. Cardiac catheterization: An arteriovenous fistula may develop as a complication of a procedure called cardiac catheterization. During cardiac catheterization, a long thin tube called a catheter is inserted in an artery or vein in your groin, neck or arm and threaded through your blood vessels to your heart. If the needle used in the catheterization crosses an artery and vein during your procedure, and the artery is widened (dilated), this can create an arteriovenous fistula. Although this is the most common way an arteriovenous fistula may develop, it's still rare.
2. Injuries that pierce the skin: It's also possible to develop an arteriovenous fistula after a piercing injury, such as a gunshot or stab wound. This may happen if your wound is on a part of your body where a vein and artery are side by side.
3. Being born with an arteriovenous fistula: Having an arteriovenous fistula you're born with (congenital) is uncommon. Doctors aren't sure what causes congenital arteriovenous fistulas.
4. Genetic conditions: Arteriovenous fistulas in the lungs (pulmonary arteriovenous fistulas) are usually caused by a genetic disease (Rendu-Osler-Weber disease, or ROWD) that causes blood vessels to develop abnormally throughout your body, but especially in the lungs.
5. Surgical creation (AV fistula procedure): People who have late-stage kidney failure may also have an arteriovenous fistula surgically created to make it easier to perform dialysis. If a dialysis needle is inserted into a vein too many times, the vein may scar and be destroyed. Creating an arteriovenous fistula widens the vein by connecting it to a nearby artery, making it easier to insert a needle for dialysis and causing blood to flow faster.

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Diagnosis of Atrioventricular Fistula
To diagnose an arteriovenous fistula, your doctor will use a stethoscope to listen to the blood flow through the area where he or she thinks you may have a fistula. The blood flow through an arteriovenous fistula makes a sound similar to clicking or humming machinery (machinery murmur).

If your doctor hears a machinery murmur, you'll have other tests to confirm that the murmur is caused by an arteriovenous fistula. These can include:

1. Doppler ultrasound: Doppler ultrasound is the most effective and common way to check for an arteriovenous fistula. In Doppler ultrasound, an instrument called a transducer is pressed to your skin. The transducer produces high-frequency sound waves, which bounce off red blood cells. A Doppler ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency).
2. Computerized tomography (CT) Angiogram: A CT angiogram allows your doctor to check your arteries to see if blood flow is bypassing the capillaries. You'll receive an injection of a dye that shows up on CT images, and the doughnut-shaped CT scanner will be moved to take images of the artery your doctor believes is narrowed. The images are then sent to a computer screen for your doctor to view.
3. Magnetic resonance imaging (MRI): Your doctor may use MRI if he or she thinks you may have an arteriovenous fistula in an artery that's deep under your skin. This test allows your doctor to see the soft tissues in your body. During an MRI, you lie on a table inside a long tube-like machine that produces a magnetic field. An MRI machine uses the magnetic field and radio waves to create pictures of your body's tissues. Using the images from the test, your doctor may be able to see an arteriovenous fistula.

Treatment

Treatment of Atrioventricular Fistula
It's possible your doctor may suggest only monitoring your arteriovenous fistula, especially if it's small and doesn't cause any other health problems. Some small arteriovenous fistulas close without treatment.

If your arteriovenous fistula requires treatment, your doctor may recommend catheter embolization. In this procedure, a catheter is inserted in an artery near the site of your arteriovenous fistula. Doctors use X-ray and other imaging techniques to guide the catheter to your fistula, and a small coil or stent is placed at the site of your fistula to reroute your blood flow. Many people who have catheter embolization stay in the hospital for 24 hours or less and can resume all their daily activities within a week.

Large arteriovenous fistulas that can't be treated with catheter embolization may require surgery. The type of surgery you'll need depends on the size and location of your arteriovenous fistula.

Prognosis

Prognosis of Atrioventricular Fistula
Consult with your doctor.

Prevention

Prevention of Atrioventricular Fistula
Consult with your doctor.