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− | ==Arteriovenous Fistula== | + | ==[[Arteriovenous Fistula]]== |
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− | ===Description===
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− | *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.
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− | '''The consequences of an arteriovenous fistula are the following:'''
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− | 1. Increased blood return to the right heart raises cardiac output
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− | 2. Decreased blood perfusion at the affected site
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− | 3. Venous hypertension
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− | *Predisposing causes of arteriovenous fistula formations are: trauma, surgery, neoplasia, etc.
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− | ===Diagnosis===
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− | ====History & Clinical Signs====
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− | *Signs depend on where the AV fistula has formed.
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− | -Subcutaneous edema
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− | -Warm Swelling
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− | -Inflammation
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− | -Pain +/-
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− | -Palpable vibration (thrill) over fistula
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− | -Increased pulse & heart rate
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− | -Audible continuous murmur over the fistula site
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− | -Branham sign (decreased heart rate with surgical occlusion of blood flow to fistula)
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− | ====Angiography====
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− | -Abnormal direct connection between an artery and a vein
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− | ====Ultrasonography====
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− | -Abnormal flow visualized
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− | ===Treatment===
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− | -Surgical ligation of abnormal vessels to and from the fistula area
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− | -(+/-) Amputation
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− | ===Prognosis===
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− | -Good with complete ligation and cessation of blood flow through the fistula
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− | -Poor if surgical ligation is unsuccessful at stopping blood flow through the fistula
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