About - An arteriovenous (AV) fistula is an abnormal connection between an artery and a vein. Normally, blood flows from arteries into smaller blood vessels called capillaries before reaching the veins. An AV fistula allows blood to flow directly from an artery into a vein, bypassing the capillaries. Some AV fistulas are present from birth (congenital), while others develop later because of an injury, certain medical procedures, or disease. AV fistulas can occur in different parts of the body, including the arms, legs, lungs, brain, and other organs. An AV fistula may sometimes cause no symptoms and may be discovered during an examination or imaging test performed for another reason. However, larger or high-flow fistulas can place extra strain on the heart and may cause circulation problems or other complications. A special type of AV fistula is surgically created for hemodialysis. In this procedure, an artery and vein are intentionally connected, usually in the arm, to provide reliable access for dialysis. Unlike an abnormal AV fistula, a surgically created dialysis fistula is planned and monitored as part of treatment for kidney failure.
The symptoms of an AV fistula depend on its size, location, and the amount of blood flowing through it. Small AV fistulas may not cause noticeable symptoms. Possible symptoms include:
Fatigue or weakness
Low blood pressure (hypotension)
Rapid heartbeat or palpitations
Shortness of breath
Swelling of the arms or legs
Purplish or bluish skin
Bulging or enlarged veins
Warmth over the affected area
A throbbing sensation in the affected area
A continuous buzzing or humming sound over the fistula, sometimes called a bruit
Pain or discomfort in the affected limb
Reduced circulation to tissues beyond the fistula
When an AV fistula occurs in the brain or its surrounding blood vessels, symptoms may be different and can include severe headaches, seizures, vision problems, neurological changes, or bleeding. A large AV fistula can increase the amount of blood returning to the heart. Over time, this may place additional stress on the heart and, in severe cases, contribute to heart failure.
Some AV fistulas develop before birth because of abnormal development of blood vessels. These may be associated with certain genetic or vascular conditions.
An AV fistula can occasionally develop after procedures that involve blood vessels, including catheter-based procedures. This is more likely when an artery and vein located close to each other are injured.
Doctors intentionally create an AV fistula in some people with advanced kidney disease who require hemodialysis. The connection provides durable access to the bloodstream for dialysis.
A fistula can develop between arteries and veins around the brain or its protective coverings. These fistulas may cause neurological symptoms and, depending on their location and blood-flow pattern, can carry a risk of bleeding.
A pulmonary AV fistula, also called a pulmonary arteriovenous malformation (PAVM), is an abnormal connection between blood vessels in the lungs. It can allow blood to bypass normal oxygen exchange in the lungs.
A surgically created AV fistula is commonly used for long-term hemodialysis. It is usually created by connecting an artery and a vein in the arm. With time, the vein becomes stronger and larger, allowing repeated access during dialysis.
A doctor may suspect an AV fistula after taking a medical history and performing a physical examination. During examination, the doctor may listen over the affected area with a stethoscope. A continuous abnormal sound, known as a bruit, may indicate increased blood flow. Depending on the location and suspected cause, tests may include:
Doppler ultrasound uses sound waves to examine blood flow through arteries and veins. It can help identify an abnormal connection and determine the direction and speed of blood flow.
CT angiography uses computed tomography and contrast material to produce detailed images of blood vessels. It may be used to evaluate AV fistulas in different parts of the body.
MRA uses magnetic resonance imaging to visualize blood vessels without conventional catheter angiography. It may be particularly useful for evaluating vascular abnormalities in the brain and other areas.
During angiography, a catheter is inserted into a blood vessel and contrast material is used to visualize the vascular system. It can provide detailed information about the location and blood-flow pattern of an AV fistula and may also allow treatment during the same procedure in selected cases.
Some AV fistulas can be treated using minimally invasive techniques. A doctor may insert a catheter into a blood vessel and use devices such as coils, plugs, or other materials to reduce or block abnormal blood flow.
Surgical repair may be recommended when an AV fistula is large, symptomatic, difficult to treat with an endovascular procedure, or associated with complications.
A surgically created dialysis AV fistula is not usually treated as an abnormal fistula because it is intentionally created for medical treatment. However, it requires regular monitoring for problems such as narrowing, clotting, infection, or inadequate blood flow.
A continuous buzzing or whooshing sound over a blood vessel
Unexplained shortness of breath or fatigue
Persistent low blood pressure
Symptoms that develop after a vascular procedure or significant injury
Seek urgent medical attention for sudden severe headache, seizures, loss of consciousness, sudden weakness or numbness, difficulty speaking, severe shortness of breath, chest pain, or significant bleeding.
Congenital AV fistulas generally cannot be prevented. However, some acquired fistulas may be avoided by taking appropriate precautions during medical procedures and by promptly treating significant vascular injuries. People with a surgically created dialysis AV fistula should follow their healthcare team’s instructions to protect the access site and attend regular examinations.
An arteriovenous fistula is an abnormal connection between an artery and a vein that allows blood to flow directly from the artery into the vein without passing through the normal capillary network.
An AV fistula may be harmless when it is small and causes no symptoms, but some fistulas can lead to complications. Large or high-flow fistulas may affect circulation and put extra strain on the heart.
An AV fistula may be present from birth or develop after trauma, vascular procedures, catheterization, surgery, or certain blood-vessel abnormalities. AV fistulas are also intentionally created for hemodialysis.
Yes. A large or high-flow AV fistula can increase the amount of blood returning to the heart. In some people, this increased workload may contribute to heart failure.
Depending on its location, an AV fistula may cause a throbbing or pulsating sensation, warmth, swelling, or prominent veins. A healthcare professional may be able to detect a continuous buzzing sound over the fistula.
Diagnosis may involve a physical examination and tests such as Doppler ultrasound, CT angiography, magnetic resonance angiography, or conventional angiography.
No. A dialysis AV fistula is intentionally created by a healthcare professional to provide vascular access for hemodialysis. An abnormal AV fistula develops unintentionally or as a result of a vascular condition or injury.
A vascular surgeon or interventional radiologist may treat many AV fistulas. Cerebral or dural fistulas may require evaluation by specialists such as a neurosurgeon or interventional neuroradiology team. A nephrologist may manage dialysis-related AV fistulas.
Some small acquired AV fistulas may close spontaneously, particularly after certain procedures or injuries. However, this cannot be assumed. Medical evaluation and appropriate follow-up are important.
This information is provided for general educational purposes only and should not be considered a substitute for professional medical advice, diagnosis, or treatment. Symptoms and treatment requirements can vary from person to person. Always consult a qualified healthcare professional for an accurate diagnosis and appropriate treatment. If you experience severe or sudden symptoms, seek immediate medical attention.
