Arteriovenous Fistula – Symptoms and Causes

Understanding Blood Vessel Connections

An AV fistula happens when an artery connects directly to a vein, bypassing the tiny blood vessels called capillaries. This abnormal connection changes how blood flows through the body.

Normally, blood travels from arteries to capillaries, where oxygen and nutrients are delivered to tissues, and then to veins.

When an AV fistula forms, blood takes a shortcut from the artery straight to the vein. This means tissues that would normally receive blood from the bypassed capillaries get less blood supply.

Most commonly, these connections appear in the legs, but they can form anywhere in the body. In some cases, doctors intentionally create AV fistulas for patients with severe kidney disease who need dialysis treatment.

The symptoms of an AV fistula vary depending on its location in the body.

Without proper treatment, large fistulas can cause serious health problems. Doctors typically manage these conditions through regular monitoring, compression techniques, minimally invasive catheter procedures, or surgery when necessary.

Symptoms

People with small arteriovenous fistulas in their legs, arms, lungs, kidneys, or brain typically don’t have any noticeable signs. These smaller fistulas usually only need regular monitoring by a doctor.

Larger arteriovenous fistulas may cause several visible symptoms including:

• Bulging, purple veins that look similar to varicose veins
• Swelling in arms or legs
• Lower blood pressure than normal
• Feeling tired often
• Heart problems

When arteriovenous fistulas occur in the lungs, they can cause more serious symptoms:

• Gray or bluish coloring in lips or fingernails
• Rounded, spread-out fingertips (clubbing)
• Coughing up blood

If the fistula develops in the digestive system, bleeding in the gastrointestinal tract may occur. These symptoms help doctors determine the location and severity of the fistula, which guides treatment decisions.

When to see a doctor

If you notice any signs of an arteriovenous fistula, schedule an appointment with your healthcare provider right away.

Seeking medical care promptly helps reduce your risk of developing serious complications, such as:

• Blood clots
• Heart failure

Don’t delay getting checked if you have symptoms, as early intervention is key for better outcomes.

Causes

Arteriovenous fistulas come from two main sources: they can be present at birth (congenital) or develop later in life (acquired). Several factors can lead to these abnormal connections between arteries and veins.

Penetrating injuries are a common cause. When a gunshot or stab wound damages an area where an artery and vein lie close together, an abnormal connection may form between them.

Some people are born with arteriovenous fistulas due to improper blood vessel development during pregnancy. Medical experts haven’t fully determined why this happens in fetal development.

Certain genetic disorders can also cause these abnormal connections. For example, hereditary hemorrhagic telangiectasia (also called Osler-Weber-Rendu disease) creates irregular blood vessels throughout the body, particularly in the lungs.

In some cases, arteriovenous fistulas are created on purpose. People with advanced kidney failure often have a surgical procedure to connect an artery and vein in their forearm.

This planned fistula makes dialysis treatments more effective by providing better access to the bloodstream.

Risk Factors

Several factors may increase a person’s chance of developing arteriovenous fistulas:

• Age – older individuals face a higher risk
• Gender – women are more susceptible
• Medical procedures – cardiac catheterization, particularly involving groin blood vessels
• Medications – certain blood thinners and bleeding control drugs
• Health conditions – high blood pressure
• Body weight – higher body mass index (BMI)

Some genetic or congenital conditions also raise the risk of developing these abnormal connections between arteries and veins.

Complications

Without treatment, an arteriovenous fistula can lead to several serious health problems.

Heart Failure

When blood moves too quickly through an arteriovenous fistula, it forces the heart to pump harder than normal. This extra strain can eventually wear out the heart, leading to heart failure.

Blood Clots

Fistulas in the legs may cause blood clots to form. These clots can develop into deep vein thrombosis (DVT), which becomes dangerous if a clot breaks loose and travels to the lungs.

Some fistulas may also increase stroke risk, depending on their location.

Pain from Poor Circulation

When a fistula blocks normal blood flow to muscles, it can cause leg pain during activity. This is a condition known as claudication.

Internal Bleeding

Some arteriovenous fistulas may cause bleeding in the digestive system, affecting both the stomach and intestines.