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===Description===
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== Introduction<br> ==
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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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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>
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Some causes of an arteriovenous fistula include trauma, surgery and neoplasia amongst others.
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'''The consequences of an arteriovenous fistula are the following:'''
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<br>
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1. Increased blood return to the right heart raises cardiac output
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== Clinical Signs<br> ==
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2. Decreased blood perfusion at the affected site
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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 &amp; 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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3. Venous hypertension
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<br>
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== Diagnosis<br> ==
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*Predisposing causes of arteriovenous fistula formations are: trauma, surgery, neoplasia, etc.
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Clinical signs and history are quite indicative of the condition. <br>
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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.&nbsp;
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===Diagnosis===
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<br>
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====History & Clinical Signs====
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== Treatment and Control<br> ==
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*Signs depend on where the AV fistula has formed.
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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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-Subcutaneous edema
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<br>
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-Warm Swelling
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== Prognosis<br> ==
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-Inflammation
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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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-Pain +/-
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<br>
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-Palpable vibration (thrill) over fistula
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== References<br> ==
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-Increased pulse & heart rate
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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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-Audible continuous murmur over the fistula site
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<br>
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-Branham sign (decreased heart rate with surgical occlusion of blood flow to fistula)
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<br>
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<br>
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====Angiography====
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[[Category:Vascular_Diseases_-_Dog]] [[Category:Vascular_Diseases_-_Cat]] [[Category:Arterial_Pathology]] [[Category:To_Do_-_Review]]
 
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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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[[Category:Vascular Diseases - Dog]][[Category:Vascular Diseases - Cat]][[Category:Arterial_Pathology]][[Category:To_Do_-_Cardiovascular]]
 
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