Arteriovenous Fistula

Description

• As the name implies, an arteriovenous fistula is an abnormal direct connection between an artery and a vein. This connection causes the capillary circulation to be completely ignored. We will concentrate on peripheral fistulas here.

The consequences of an arteriovenous fistula are the following:

1. Increased blood return to the right heart raises cardiac output

2. Decreased blood perfusion at the affected site

3. Venous hypertension

• Predisposing causes of arteriovenous fistula formations are: trauma, surgery, neoplasia, etc.

Diagnosis

History & Clinical Signs

• Signs depend on where the AV fistula has formed.

-Subcutaneous edema

-Warm Swelling

-Inflammation

-Pain +/-

-Palpable vibration (thrill) over fistula

-Increased pulse & heart rate

-Audible continuous murmur over the fistula site

-Branham sign (decreased heart rate with surgical occlusion of blood flow to fistula)

Angiography

-Abnormal direct connection between an artery and a vein

Ultrasonography

-Abnormal flow visualized

Treatment

-Surgical ligation of abnormal vessels to and from the fistula area

-(+/-) Amputation

Prognosis

-Good with complete ligation and cessation of blood flow through the fistula

-Poor if surgical ligation is unsuccessful at stopping blood flow through the fistula