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Thrombosis in arteriovenous (AV) fistula occurs when blood does not flow smoothly through the fistula, artery, or vein due to narrowing of the blood vessel
Thrombosis in arteriovenous (AV) fistula occurs when blood does not flow smoothly through the fistula, artery, or vein due to narrowing of the blood vessel. This narrowing is called stenosis, and it can cause the blood in the fistula to coagulate and form a blood clot.
Thrombosis that develops in the AV fistula of the leg can lead to a painful condition called deep vein thrombosis. If the thrombus travels from the leg to the lungs, it can result in pulmonary embolism, which is a life-threatening complication. If the blood clot travels to the brain, it can lead to a stroke.
How is thrombosis in AV fistula managed?
Thrombosis in AV fistula can be treated with a procedure called a thrombectomy.
Thrombectomy involves inserting a catheter into the artery using imaging guidance. The catheter is used to dissolve and remove the clot.
What causes AV fistula?
Normally, blood flows from arteries into capillaries and then into veins. When an AV fistula develops, blood flows directly from an artery into a vein, bypassing the capillaries. AV fistulas are of two types:
- Congenital (present at birth): Congenital arteriovenous (AV) fistulas are rare. These can develop when there is abnormal development of arteries or veins when the baby is in the mother’s womb.
- Acquired (developed after birth): Acquired AV fistulas can be caused by an injury that involves piercing into an artery and a vein that lies side by side. This can be caused by a knife or bullet that penetrates the skin and reaches the artery or vein.
In some cases, doctors may deliberately create an AV fistula for medical interventions such as dialysis to widen the blood vessel for easier penetration of the needle. These are usually done between an adjoining vein and artery in the arm.
How is AV fistula diagnosed?
Doctors can diagnose AV fistula by listening to the sounds of blood flow using a stethoscope. Because the sound resembles the sound of machinery, it is referred to as a machinery murmur. Other diagnostic methods include:
- Doppler ultrasound: Doppler ultrasonography uses sound waves to produce colored images that depict the blood flow through the arteries and veins. This test is used to confirm a diagnosis and determine the extent of AV fistula.
- Magnetic resonance imaging (MRI): MRI uses a combination of radio and magnetic waves to detect fistulas that are located in deeper blood vessels.
- Angiography: Angiography is a surgical diagnostic procedure in which doctors inject a liquid contrast agent into a blood vessel. The contrast agent highlights problematic areas, which show up on imaging studies (such as computed tomography or magnetic resonance angiography).
How is AV fistula treated?
Treatment of AV fistula depends on its size and whether it is congenital or acquired.
Treatment of congenital AV fistula
Treatment is usually not necessary for congenital AV fistulas, especially for smaller fistulas, which may close on their own. Treatment may be planned only if the AV fistula causes problems and involves an endovascular procedure called catheter embolization, which blocks the fistula and reroutes blood flow. This procedure involves using a small flexible tube (catheter) to inject coils or plugs into the fistula.
Treatment of acquired AV fistula
Treatment of acquired AV fistulas involves a surgical procedure in which the connection is cut and the holes in the artery and vein are closed. The doctor will decide on the type of surgery needed depending on the size and location of the AV fistula.