Arteriovenous fistula is an abnormal connection between an artery and vein. Generally, blood flows from arteries to veins through the capillaries. But when an AV fistula is formed, blood flows directly from arteries into veins with high pressure bypassing capillaries.
An AV fistula can be congenital, surgically created for hemodialysis treatment (in cases of chronic kidney failure), or acquired due to trauma or arterial aneurysm.
Surgery to remove or create AV fistula is a minimally invasive procedure or short stay surgery and you can go back home the same day if your condition is stable.
Surgery to treat AV fistula
An abnormally formed or acquired AV fistula causes increase of pressure in the venous blood vessels leading to complications. Common symptoms of AV fistula are pain, swelling, and bulging of the skin at the site of formation of fistula.
A physical examination and imaging tests such as Doppler ultrasound and magnetic resonance imaging (MRI) can be performed for diagnosis. Catheter angiography is performed to confirm diagnosis in coronary and lung AV fistulas.
An AV fistula can be treated by the following procedure:
Endovascular embolization: A small, microscopic device called ‘coil’ is inserted into the affected site, thus blocking the AV fistula. It can be followed by further embolization using coils, muscle pieces or glue to remove any traces of fistula present after the surgery.
Larger fistulas are removed with the help of surgery, which can be complex, requiring plastic & vascular surgeon teams. Lung fistulas may need removal of lung lobe or segments.
Surgery to create AV fistula for chronic kidney failure
AV fistula is created surgically to gain vascular access for hemodialysis treatment. This surgery is performed usually one to six months before the first session of dialysis.
Benefits of AV fistula in kidney disease:
- lasts longest as compared to other types of access
- low risk of infections and clot formation
- reduced implantation, maintenance, and hospitalization costs
The surgeons usually place an AV fistula in the large vein of the proximal or distal forearm. Placing of fistula creates arterial flow through the vein, which can now be used for dialysis.
Before this surgery, the surgeon may perform a vessel mapping test. It is an ultrasound examination performed to identify a large vein for placing the AV fistula, and a disease free artery for the AV fistula in flow.
Av fistula may take 2 to 3 months to completely develop and be functional for hemodialysis. If the fistula doesn’t develop after the given period, repeat surgery may be performed at a different site, usually more proximal site, using the non-thrombosed part of the arterialised vein.
An AV fistula being an abnormal connection can fail and must be maintained properly. A blood thinner like aspirin ensures longer patency of the fistula. Regular isometric exercises like squeezing a ball helps development & maintenance of a hand based AV fistula. If a fistula fails it can be restituted if detected within first few hours of its closure, by giving anticoagulant injections or opening it in the Cath lab.