Arteriovenous Fistula : Causes, Symptoms and Risk Factors

An arteriovenous (AV) fistula is an unequal connection between an artery and a vein. Normally, blood flows from the arteries into the capillaries which are tiny blood vessels, and then into the veins. The blood carries nutrients and oxygen from the capillaries to the body's tissues.

An arteriovenous fistula allows blood to flow directly from an artery into a vein, avoiding some capillaries in the process. When this happens, there is reduced blood flow to the tissues beneath the avoided capillaries.

Arteriovenous fistulas usually develop in the legs, though they can occur anywhere in the body. Severe kidney disease patients may have surgery to create an arteriovenous fistula for dialysis purposes.

The symptoms of arteriovenous fistulas vary depending on where they are located in the body. An untreated large arteriovenous fistula may have serious consequences. Treatment options for arteriovenous fistulas include compression, monitoring, catheter-based procedures, and occasionally surgery.

Causes Of Arteriovenous Fistula 

Arteriovenous fistulas can be congenital (existing from birth) or develop later in life (acquired). The following are a few causes of arteriovenous fistulas:

• Puncture wounds on the skin: An arteriovenous fistula can develop from a gunshot or stabbing trauma to a part of the body where a vein and artery are close together.
• Congenital arteriovenous fistulas: Some children develop their arteries and veins abnormally while still in the womb
• Genetic conditions: Pulmonary arteriovenous fistulas, or arteriovenous fistulas in the lungs, can be caused by a genetic disorder that causes aberrant blood vessels throughout the body, but especially in the lungs. One such illness is inherited hemorrhagic telangiectasia, often known as Osler-Weber-Rendu disease.
• Surgery related to dialysis: Patients with advanced renal failure may have surgery to create an arteriovenous fistula in the forearm, which will simplify the administration of dialysis.

Symptoms Of Arteriovenous Fistula 

The majority of the time, small arteriovenous fistulas in the arms, legs, brain, kidneys, or lungs show no symptoms at all. Medical professionals may typically keep an eye on minor arteriovenous fistulas without offering therapy. Large arteriovenous fistulas may be the cause of the symptoms.

Symptoms of an arteriovenous fistula could include the following:

• These protruding purple veins are visible through the skin, much like varicose veins.
• Enlargement of the arms or legs reduction in blood pressure
• Heart attack tiredness
• Serious consequences may result from pneumonia brought on by a large arteriovenous fistula in the lung.
• Lips or fingernails that are pale, gray, or blue from cyanosis, a disorder in which blood flow is impeded
• The tips of the fingers expand and show clubbing
• Coughing blood
• In the digestive tract, an arteriovenous vein can result in gastrointestinal (GI)

Risk factors Of Arteriovenous Fistula 

People with particular genetic or congenital abnormalities are more likely to develop arteriovenous fistulas. Other potential risk factors for arteriovenous fistulas include the following:

• Older age
• Females are  affected more than men
• Heart catheterization, especially if the groin blood arteries are affected; several treatments, including blood thinners and anticoagulant-controlled therapies (anticoagulant lyrics)
• Increased BP
• Higher body mass index (BMI)

Diagnosis Of Arteriovenous Fistula 

An arteriovenous fistula may be identified by a medical expert using a stethoscope to listen to the blood flow in the arms and legs. Blood passing through an arteriovenous fistula makes a buzzing sound.

If your doctor suspects you have a fistula, more testing is typically done to confirm the diagnosis. The following tests are performed to determine whether an arteriovenous fistula exists:

• Duplex ultrasonography: Duplex ultrasonography is the most common and effective way to find an arteriovenous fistula in the arms or legs. Duplex ultrasonography uses sound waves to evaluate blood flow velocity.
• Computerized tomography, or CT angiography: This imaging examination can detect blood flow evasion from the capillaries. An intravenous dye (contrast) is given for this test. The dye makes blood vessels in the photos more visible.
• Magnetic resonance imaging: This test may be carried out if you exhibit signs of a deep-seated arteriovenous fistula beneath your skin. Radio waves and a magnetic field are used in magnetic resonance imaging (MRI-like) and magnetic resonance angiography (MRA) to create images of the body's soft tissues. The administration of dye (contrast) via an IV is used to enhance the visibility of blood arteries in images.

Treatment Of Arteriovenous Fistula 

If an arteriovenous fistula is small and does not cause any further health problems, treatment may involve close supervision by a medical practitioner. A small percentage of arteriovenous fistulas heal on their own if left untreated.

If medical intervention is necessary for an arteriovenous fistula, your physician may recommend:

• Ultrasound-guided compression: This could be a good substitute for a leg arteriovenous fistula that shows up well on ultrasonography. During this procedure, an ultrasonic probe is applied to the fistula for around 10 minutes. The compression stops blood flow to the damaged blood vessels.
• Catheter embolization: During this procedure, an artery near the arteriovenous fistula is punctured with a thin, flexible tube known as a catheter. The fistula site is then treated with a small coil or stent to reroute blood flow. Following a catheter embolization, many patients are discharged from the hospital in less than a day and can resume their normal lives within a week or so.
• Surgery: Large arteriovenous fistulas that do not respond to catheter embolization may require surgery. Surgery is needed depending on the location and size of the arteriovenous fistula.

Complications Of Arteriovenous Fistula 

If an arteriovenous fistula is not treated, complications could occur. There might be some serious problems. They include:

• Cardiac failure: This is the most hazardous adverse effect of large arteriovenous fistulas. Blood flows through an arteriovenous fistula faster than it does through typical blood veins. The increased blood flow causes the heart to pump harder. The strain that the heart experiences over time may lead to heart failure.
• Blood clots: An arteriovenous fistula can lead to blood clots in the legs. Blood clots in the legs can cause a condition called deep vein thrombosis (DVT). A pulmonary embolism, or potentially fatal deep vein thrombosis (DVT) clot, may result. A stroke might happen as a result of the fistula, depending on where it is.
• Leg pain due to reduced blood flow (claudication): An arteriovenous fistula preventing blood supply to the muscles may be the cause of leg pain.
• Internal bleeding: Arteriovenous fistulas can cause bleeding in the stomach and intestines.

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