Arteriovenous Fistula

Excerpt

Arteriovenous fistulas (AVFs) are abnormal connections between an artery and a vein (see Image. Diagram of Arteriovenous Fistula). In certain contexts, these may also be referred to as arteriovenous malformations. AVFs can exist almost anywhere in the body, depending on the etiology. These can be divided into 2 groups: acquired or congenital. Acquired fistulas can be further subdivided into surgically created, as in for hemodialysis, or secondary to trauma, whether accidental or procedure-related.

The anatomy of the fistula depends on its location in the body. AVFs for hemodialysis are typically created in the extremities, and vascular surgeons generally prefer the upper extremities over the lower extremities. The cephalic and basilic veins are often used for the surgical creation of an AVF. The radial artery at the volar wrist and the brachial artery at the antecubital fossa and medial upper arm are typical anatomical locations for fistula creation. However, the radio-cephalic AVF is the preferred initial access for hemodialysis.

The literature has described 2 types of lower extremity surgical AVFs for hemodialysis. The superficial femoral or popliteal vein can be mobilized from the knee to anastomose with the superficial femoral artery, called an SFV transposition. The saphenous vein can create a loop AVF on the anterior thigh, anastomosed with the common femoral artery.

Although no type of congenital AV fistula is common, reported locations for congenital AVFs include pulmonary, aortocaval, dural, carotid-cavernous, coronary, and hepatic. While the majority of neck fistulas do occur secondary to trauma, congenital vertebrovertebral fistulas and carotid-jugular fistulas have been described in children.

AVFs as a result of iatrogenic injury are typically a result of surgical procedures, invasive line placement, or needle biopsy. The literature demonstrates multiple reports of iatrogenic injury resulting years after surgical procedures. Traumatic AVF can essentially occur wherever there is trauma, and these can also have a late presentation. Greater than 50% of traumatic AVFs happen in the lower extremities, and about one-third occur in the femoral vessels, while 15% take place in the popliteal vessels.