About Arteriovenous Fistulas

With an arteriovenous fistula (AVF), an abnormal connection has formed between an artery and a vein. Because of this, blood can move freely between these two blood vessels, bypassing the capillaries and impacting healthy circulation.

AVFs can be found in any area of the body. However, some locations may be more common, depending on the type of AVF.

There are two general types of AVF:

• Congenital: Congenital AVFs are present from birth.
• Acquired: Acquired AVFs are those that develop over the course of your lifetime.

There are several potential causes of AVFs depending on the type.

Congenital

Congenital AVFs are present from birth. They’re rare but can occur due to irregularities that happen while a fetus is developing in the womb.

It’s also possible for congenital AVFs to develop due to a genetic condition. Some genetic conditions that can cause AVF formation include hereditary hemorrhagic telangiectasia (spider veins) and capillary malformation-arteriovenous malformation syndrome.

Some general areas where congenital AVFs may be found include, but aren’t limited to, the:

• heart
• lungs
• brain
• liver

Congenital AVFs usually aren’t treated unless they become symptomatic, often later in adulthood.

Acquired

Acquired AVFs develop during your lifetime. This can occur due to trauma from surgery or an injury. These types of AVFs develop at or near the site of the trauma.

There are certain types of procedures that are more likely to be associated with AVF formation. Some examples include cardiac catheterization and needle biopsy.

AVFs due to injury typically happen due to a penetrating wound. Examples include gunshot wounds and stab wounds. They can also occur due to bone fractures or serious head injuries.

In some cases, an AVF may be surgically made for hemodialysis. This helps to make the hemodialysis process more efficient. AVFs for this purpose are typically created in the arm.

Not all AVFs cause symptoms. When symptoms are present, they can depend on the location of the AVF. Let’s take a look at some potential symptoms based on location.

• Limbs: An AVF in an extremity, such as an arm or leg, may lead to symptoms like pain and swelling of the affected area. In some cases, the affected limb can appear larger and have varicose veins.
• Heart: AVFs can cause your heart to work harder to pump blood to the rest of your body. As such, people with AVFs near the heart and in other areas of the body may show signs consistent with heart failure, such as:
  • fatigue
  • shortness of breath
  • exercise intolerance
  • fluid buildup in the body (edema)
• Lung: If an AVF affects the lung, it may lead to symptoms like:
  • shortness of breath
  • coughing up blood
  • lips and fingernails that are pale, blue, or grey in color, depending on your skin tone
• Brain: AVFs in or around the brain can lead to:
  • severe headache
  • nausea or vomiting
  • tinnitus
  • bulging of the eyes
  • vision problems
  • seizures
  • issues with language and speech
  • coordination difficulties
• Liver: An AVF in the liver can cause symptoms like:
  • abdominal pain
  • blood in the stool
  • ascites
• Kidney: When an AVF is around the kidneys, it can lead to flank pain and blood in the urine.

If you have symptoms consistent with an AVF, see your doctor for an evaluation. While your symptoms may not be due to an AVF, they could be due to another medical condition.

The diagnostic process will start with a physical exam and medical history. During this exam, your doctor will take your vital signs and evaluate your symptoms. They’ll also ask about things like:

• when your symptoms started
• how severe your symptoms are and if anything makes them better or worse
• if you have a personal or family history of any medical conditions
• whether you’ve had a significant surgery or injury in the past
• which types of medications and supplements you use

Afterward, your doctor may order the following tests to see if you have an AVF.

Duplex ultrasound

A duplex ultrasound uses two types of ultrasound technology. It allows your doctor to look at how blood flows through your blood vessels.

Angiography

Angiography creates images of your blood vessels that your doctor can use to look at the structure of your blood vessels and how blood flows through them. It often involves the injection of a special dye to help with contrast.

More traditional angiography involves the use of X-rays and the insertion of a catheter. There are also less invasive options available, such as those that use CT scan and MRI scan.

If you have an AVF that’s not causing symptoms, you may not need treatment right away. Instead, your doctor may choose to monitor it periodically. This is called conservative management.

The treatment of an AVF typically involves a procedure to repair the abnormal connection. This is often done using an endovascular method.

Endovascular repair involves the insertion of a catheter into the affected blood vessel. This is then used to aid in the placement of a stent, coil, or foam that closes the AVF and helps to direct blood flow.

An open surgery can also be used to repair AVFs. This involves opening the affected blood vessel with an incision. This type of procedure is less common, as it’s associated with more risks and a longer recovery time.

AVFs can lead to a variety of complications. However, early treatment can help prevent these.

• Venous hypertension: Venous hypertension is when the blood pressure in the veins is higher than normal. Eventually, this can result in venous insufficiency. This is where the veins have trouble returning blood back to your heart.
• Bleeding: Veins have very thin walls. In some cases, the wall of a vein in an AVF may rupture, leading to potentially serious bleeding in the body.
• Steal syndrome: This is when oxygen levels are reduced in the affected area, due to large amounts of blood passing through the AVF. It can lead to tissue death and damage.
• Heart failure: An AVF can cause the heart to work harder to pump blood throughout the body. This can lead to heart failure in rare cases.

An AVF is when an abnormal connection develops between an artery and a vein. It can either be congenital or acquired.

AVFs can happen anywhere in the body. The symptoms of an AVF can vary based on where in the body it’s located.

While some AVFs don’t cause any symptoms, others can lead to severe or life threatening complications. However, with early diagnosis and treatment, the outlook for many AVFs is generally good.