A V fistula

 Arteriovenous Fistula (AVF)  

AVF is a communication between an artery and a vein that may be either congenital or acquired (trauma or surgical).  

Structurally, they are arterialised (become dilated, tortuous and thick-walled).  

Physiologically, there is an increase in venous return (as blood starts flowing from arteries to veins, which causes an increase in cardiac output, which in turn results in an increase in systolic BP, leading to cardiac failure.  

On examination, there is a presence of pulsatile swelling, a thrill and auscultation reveals machinery murmur (buzzing continuous murmur).  

Nicoladoni's / Branham's sign is observed in AVF: On pressing the artery proximal to the fistula, there is a decrease in the size of the pulsatile mass, disappearance of palpable thrill and decrease in heart rate.

Surgically created Arterio-Venous fistula: It is commonly used for patients with end-stage renal disease who require hemodialysis. 

Aspect	Details
Purpose-	• Used for hemodialysis• Provides high blood flow for effective dialysis
Site Selection-	• Prefer distal placement• Non-dominant arm is typically used
Arterial Quality-	Requires a strong arterial pulse for success
Vein Preservation-	Avoid placing venous lines in the arm intended for fistula

Examples of Surgically created fistulas are:  

Brescia-Cimino fistula: It is created between the Radial artery and the Cephalic vein.  

Snuff Box fistula: It is created between the Posterior branch of the radial artery and Cephalic vein.  

Feinberg fistula: It is created between the Radial artery and the Basilic vein.