Overview of Arteriovenous Fistula

Arteriovenous Fistula (AVF)

An AVF is the result of a direct surgical anastomosis between an artery and a vein. This direct communication allows the vein to increase in size and “arterialize” due to the increased pressure transmitted from the artery¹. Some authors refer to arterialization as venous remodeling because the entire vascular bed must undergo dramatic remodeling to accommodate blood-flow rates that have increased by a factor of 10-50 times over baseline values². Though several forms of AVF are possible, the classic AVF construction involves the radial artery and cephalic vein at the wrist (radiocephalic, wrist, or Cimino fistula), the brachial artery and cephalic vein in the anticubital fossa (brachiocephalic or upper arm fistula) or brachial artery and basilic vein (transposed brachiobasilic fistula) in the upper arm. Both American and Canadian guidelines recommend beginning with the most distal native vessel fistula possible (preferably the radiocephalic)^3,4,5. The brachiocephalic and brachiobasilic fistulae are the second and third choices, respectively^3,5. This order of AVF placement allows the later creation of a more proximal AVF if the distal AVF becomes unusable. Selection of the non-dominant arm is preferable in order to facilitate activities of daily living.

When classic AVF construction is not possible, alternative upper extremity fistulae may be created through connection of the ulnar artery and vein. These ulnar-ulnar fistula often need to be transposed to the front of the arm to facilitate cannulation. Fistula in the lower extremity, such as the superficial femoral-common femoral with thigh transpositions, are rare because of their inconvenient location and concerns about the possible development of distal ischemia. However, adequate outcomes (particularly decreased postoperative ischemia) have been reported with appropriate patient selection and selective intraoperative femoral vein tapering^{3, 6}.

Access decisions have a significant impact on patient outcome¹. United States Renal Data System (USRDS) data confirm that AVF have the lowest complication rates of any available vascular access (0.64 procedures per patient year versus 1.61 for arteriovenous grafts (AVG)^7,8. Both diabetic and non diabetic patients with AVF have a significantly lower relative risk of death than those with AVG and catheter^9,10. For these reasons, the National Kidney Foundation-Dialysis Outcomes Quality Initiative (KDOQI) Clinical Practice Guidelines for Vascular Access recommend placement of an AVF access in preference to AVG or dialysis catheters. AVF placement is recommended at least 6 months prior to the initiation of chronic HD to allow sufficient time for AVF maturation and for possible revision⁵.

A functioning AVF may be difficult to achieve in some patient populations. Choosing a suitable “healthy” artery and vein, together with expert surgical technique is critical for adequate maturation and long term AVF success².
Timely referral to a nephrologist and preoperative imaging to assess the presence of an adequate inflow artery and outflow vein is a prerequisite for appropriate AVF placement⁷. The Dialysis Outcomes and Practice Patterns (DOPPS) III reports that patients were less likely to use an AVF if they were female, of older age, had a greater body mass index or had diabetes, peripheral vascular disease or recurrent cellulitis/gangrene¹¹. These patient characteristics are associated with a high (approximately 40%) AVF primary failure rate¹².

References:

1. Sands JJ. Vascular access 2007. Minerva Urol Nefrol 59:237-249, 2007
2. Konner K. The anastomosis of the arteriovenous fistula—common errors and their avoidance. Nephrol Dial Transplant 17: 376-379, 2002
3. Oliver MJ. Chronic hemodialysis vascular access: Types and placement. Retrieved from www.uptodate.com on January 14, 2008
4. Jindal K, Chan CT, Deziel C, Hirsch D, Soroka SD, Tonelli M, Culleton BF. Hemodialysis Clinical Practice Guidelines for the Canadian Society of Nephrology. J Am Soc Nephrol 17 (Suppl 1):S16-S23, 2006
5. KDOQI Clinical Practice Guidelines for Vascular Access. Am J Kidney Dis 48(Suppl 1):S176-S273, 2006
6. Gradman WS, Laub J, Cohen W. Femoral vein trasposition for arteriovenous hemodialysis access: Improved patient selection and intraoperative measures reduce postoperative ischemia. J Vasc Surg 41:279-284, 2005
7. Sands, JJ. Vascular access: The past, present and future. Blood Purif 27, 2009 (in print)
8. U.S. Renal Data System, USRDS 2007 Annual Data Report: Atlas of Chronic Kidney Disease and End-Stage Renal Disease in the United States, National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 2007
9. Dhingra RK, Young EW, Hulbert-Shearon TE, Leavey S, Port FK. Type of vascular access and mortality in US hemodialysis patients. Kidney Int 60:1443-1451, 2001
10. Pastan S, Soucie JM, McClellan WM. Vascular access and increased risk of death among hemodialysis patients. Kidney Int 62: 620-626, 2002
11. Ethier J, Mendelssohn DC, Elder SJ, Hasegawa T, Akizawa T, Akiba T, Canaud BJ, Pisoni RL. Vascular access use and outcomes: An international perspective from the dialysis outcomes and practice patterns study. Nephrol Dial Transplant 23:3219-3226, 2008
12. Maya ID and Allon M. Core curriculum in nephrology vascular access: Core curriculum 2008. Am J Kidney Dis 51:702-708, 2008

P/N 101032-01 03/2009