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===Description===
== Introduction<br> ==
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; Increased blood return to the right heart raises cardiac output, there is decreased blood perfusion at the affected site and venous hypertension will arise.<br>
Some causes of an arteriovenous fistula include trauma, surgery and neoplasia amongst others.
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== Clinical Signs<br> ==
Signs depend on where the AV fistula has formed. Some signs include subcutaneous oedema, presence of a warm swelling, inflammation, pain, palpable vibration (thrill) over fistula, increased pulse & heart rate, an auudible continuous murmur over the fistula site and the Branham sign (decreased heart rate with surgical occlusion of blood flow to fistula). <br>
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== Diagnosis<br> ==
Clinical signs and history are quite indicative of the condition. <br>
Angiography can be performed and an abnormal direct connection between an artery and a vein will be found. Ultrasonography can also be used to demonstrate the presence of abnormal flow.
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====History & Clinical Signs====
== Treatment and Control<br> ==
Treatment is to surgically ligate the abnormal vessels to and from the fistula area. Another possible procedure would be amputation of the limb in severe cases.<br>
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== Prognosis<br> ==
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.
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== References<br> ==
Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company<br>Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2)W.B. Saunders Company<br>Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier <br>
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[[Category:Vascular_Diseases_-_Dog]] [[Category:Vascular_Diseases_-_Cat]] [[Category:Arterial_Pathology]] [[Category:To_Do_-_Review]]
[[Category:Vascular Diseases - Dog]][[Category:Vascular Diseases - Cat]][[Category:Arterial_Pathology]][[Category:To_Do_-_Cardiovascular]]