The inception of hemodialysis in 1960 using short-lived thrombosis prone Scribner type prosthetic shunts was followed in 1966 by the introduction of the Brescia-Cimino arteriovenous (AV) fistula. The AV fistula is created by anastomosing an artery, usually the radial in the forearm, or the brachial at the antecubital fossa, to the superficial venous system of the arm. The vein dilates and hypertrophies over a period of 4 to 8 weeks (maturation), at which time it can be safely cannulated for each dialysis session. The preferred sites for AV fistula in order are non-dominant forearm, non-dominant upper arm (brachium), dominant forearm, and dominant upper arm. Flow becomes significant when the diameter of the vein exceeds that of the artery by 20%. If the size of the vein exceeds the artery by 75%, maximum flow is limited by the arterial inflow. A minimal flow of 200cc/min is necessary for dialysis. Average flow rate of radial based fistulas is about 300cc, and for brachial artery based fistulas about 1000cc. The higher flow proximal fistulas have an increased risk of steal syndrome and extremity ischemia, and in a patient with cardiac compromise, may cause enough decreased peripheral resistance to push cardiac output (increased heart rate and stroke volume) to the point of cardiac failure. Decreased heart rate with temporary occlusion of an AV fistula is the Branham sign.
There is a 10-20% failure of AV fistulas in the first year, and the five year patency is 75%. At the wrist, end to side vein to artery anastomosis with ligation of the distal vein is preferred to avoid a steal syndrome in the hand. Side to side, and end artery to side vein can result in venous congestion in the hand.
When native veins are unsuitable or exhausted, a bridge graft may be placed to act as a conduit. Initially, saphenous vein was used, and now polytetrafluoroethylene (PTFE) is the material of choice. An advantage of the prosthetic conduit is that it does not require a maturation period before use, and obviates the need for temporary catheter based dialysis in acute situations.
Gelabert, HA and Freischlag, JA in Rutherford, RB, Vascular Surgery (5th ed), W.B. Saunders, Phila., pp. 1466-1477.
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