An AV fistula or an arteriovenous fistula is, what experts like Vascular Surgeon in Karachi call an abnormal connection between a vein and artery. When this happens, parts of the tissue receive less blood. In case of a large AV fistula, there can be serious complications. Read on to know more about AV fistulas:

What is AV fistula?

Arteriovenous fistulas are an abnormal connection between the veins and arteries, completely bypassing the capillary bed. If this happens, the capillaries and the tissues around those capillaries receive less blood. AV fistulas are more common in the legs, though they can occur anywhere in the body. In people with chronic kidney disease, needing dialysis, AV fistulas are surgically created. Others can have AV fistulas due to congenital abnormalities, skin piercing injuries and genetic conditions.

What are the symptoms of AV fistulas?

The symptoms of AV fistulas include:

• Decreased blood pressure
• Swelling in the legs and arms
• Bulging veins through the skin like varicosities
• Fatigue
• Heart failure

Who is at risk of developing AV fistula?

The risk of AV fistula is higher in:

• Cardiac catheterization in groin
• Older individuals
• Female gender
• Individuals with higher body mass index (BMI)
• Hypertensive patients
• Patients taking medications like anticoagulants and antifibrinolytics

How are AV fistulas diagnosed?

AV fistulas are diagnosed through:

• Duplex ultrasound: one of the most effective investigations for AV fistulas is the duplex ultrasound. This ultrasound uses sound waves to evaluate the speed of blood flow and thus diagnose AV fistulas.
• MRA: magnetic resonance angiography is done for deeper fistulas under the skin. Similar to typical MRIs, whereby magnetic field is used to create picture of the soft tissues of the body, MRA also involves use of magnetic field and contrast dyes to create image of the blood vessels. This helps to visualize AV fistulas.
• CT angiogram: this imaging test can show if the blood flow is bypassing the capillary network. A contrast dye is used to create better image of the blood vessels.

What are the treatment options for AV fistulas?

AV fistulas can be treated by:

• Catheter embolization: in this procedure, a catheter is inserted into an artery near the AV fistula and a small stent or coil is then placed there. This helps to reroute the blood flow away from the AV fistula. This is a day procedure, and people who are treated with catheter embolization can be discharged on the same day. In fact, they can return to activities of daily living within the same week.
• Ultrasound guided compression: this procedure is a treatment option for AV fistulas in the legs. An ultrasound probe is used to locate the fistula and this probe is then pushed down on the fistula for about ten minutes. The compression force from the probe helps to destroy the blood flow to the damaged blood vessel.
• Surgery: for AV fistulas that cannot be treated with embolization or ultrasound guided compression, surgery remains the only option. Most often, it is the large fistulas that need surgical management, depending on their location and size.

What are the complications of AV fistula?

Without treatment from Best Vascular Surgeon in Lahore AV fistulas can have several complications, including:

• Blood clots: if there is untreated AV fistula especially in the legs, the blood flow is slowed down. This can lead to formation of blood clots and can predispose to a condition called deep vein thrombosis (DVT). If these blood clots travel to the lungs, it can result in a life-threatening condition called pulmonary embolism, and if these clots travel to the brain it can result in stroke.
• Claudication: lack of blood flow due to AV fistulas can result in blocked blood flow to the leg muscles, resulting in leg pain. This pain of the leg muscles is called claudication.  
• Heart failure: is the most serious complication of AV fistulas. This occurs because the blood flows faster in AV fistulas than in normal blood vessels. Consequently, this increased blood flow makes the heart strain as it pumps faster. In the long run, this leads to heart failure.
• Internal bleeding: the arteriovenous fistula predisposes one to internal bleeding in the stomach and intestines.