The Michigan Vascular Access/MiDRE primer in Vascular Access

Chapter 11 - Wrist fistulas

The most well known location for AV fistulas is at the wrist. The so-called Brescia-Cimino fistula was the earliest described fistula and is still the gold standard for fistula creation. This fistula provides convenient and comfortable dialysis, preserves all the upper arm options, and should be the first choice where the patientís anatomy permits.

A wrist fistula
In order to have a fistula, you must have a vein that can be developed, a good enough artery to supply the blood flow necessary, and a surgeon who is able to put the two together. Deceptively simple, this fistula has the highest failure rate.
Percent matured Time to release
Wrist fistulas 78% 72 days
Forearm fistula 83% 75 days
Antecubital fistulas 85% varies
Brachiocephalic AVF 85% 62 days
Superficialized BCAVF 95% 102 days
Transposed basilic AVF—one stage 96% 50 days
Transposed basilic AVF—otwo Stage 98% 113 days

Reasons for failure:
Arterial insufficiency is probably the primary reason for failure of the wrist fistula, followed by inflow "swing zone" stenosis, poor development of the forearm cephalic vein, and insufficient outflow. At the risk of repeating myself, the radial artery is usually the smallest artery in the arm and most susceptible to diabetic small vessel disease. Inadequate inflow will lead to poor flow, resulting in inadequate dialysis, difficulty cannulating and frequent infiltration, call for repeated interventions to "fix" a situation that may not always be fixable, frustration for all, and ultimately, more time on the catheter if the patient and dialysis team are not able to cut the losses and move on to something that works.

The cephalic vein (superficial) and radial artery (deeper) at the wrist

This is a small radial artery which will never be able to drive a fistula and should not be used

The result of doing a wrist fistula with too small a radial arteryĖa beautiful fistula but essentially unusable

Here the radial artery itself is thrombosed above the fistula, and flow is retrograde from the hand via the palmar arch and the ulnar artery
Swing zone stenosis refers to stenosis in the short portion of the distal vein which is mobilized and "swung" over to meet the artery. Typically the anastom0sis itself is widely patent, but an inflow segment stenosis is present in the first several centimeters of the fistula. Unlike arterial insufficiency, swing zone stenosis is treatable with retrograde venoplasty and occasional stenting. I have a number of patients with 5, 6 or 7mm by 2.5 cm Viabahn stents in the inflow segments. These inflow stents hold up extremely well. An alternative is inflow revision, in which the toughened distal fistula is mobilized and re-anastomosed to the artery centimeters above the previous anastomosis. Either way, an otherwise acceptable wrist fistula can be rescued.

Mid-fistula stenosis is also a frequent cause for complicated dialysis or fistula failure and can also be treated with venoplasty, sometimes in conjunction with a branch ligation. In general, large branches only develop when an outflow stenosis creates the hemodynamic necessary for diversion of flow. Willy-nilly branch ligation without correction of outflow problems can be counterproductive. One exception is early diverting branches siphoning flow away from the intended zone of cannulation.

Outflow problems are also common and sometimes treatable. The forearm cephalic vein drains to the cephalic continuation in the upper arm, to the basilic system via the median antecubital, and to the brachial veins via the connecting deep branches in the antecubital fossa. Unfortunately, the patientís experiences in the hospital with antecubital IVs and PICC lines may have damaged these routes, and elevated venous pressures, poor flows and forearm swelling may be the result. Beyond wishing that all the health care team was on board with the concept of venous preservation, one must be alive to this problem when planning a forearm fistula in order to avoid an unacceptable or suboptimal result.

Snuffbox fistulas are created from the cephalic vein at the back of the thumb and the dorsal branch of the radial artery, found between the extensor tendons of the thumb in the "anatomic snuffbox". Aside from adding an inch or so of usable length to a fistula, the disadvantages outweigh the advantages: the scar and fistula visible at the wrist may be unsightly, the smaller branch of the radial artery, and the tendency of the cephalic vein to have a lot of early diverting branches all make this fistula more problematic and less useful.

Diagram of the "anatomic snuffbox"

A fresh "snuffbox" fistula
In conclusion, the wrist fistula may still be the "gold standard", especially in younger patients, where the long chess game of life dictates that all options should be jealously maintained if possible, but also avoided in elderly patients with bad arteries in the forearm. "Trying" a wrist fistula that will never develop at the cost of keeping a catheter for months and months is a foolish strategy, and should be guarded against.

When central stenosis develops you have run out of time and may ultimately lose the chess game of life

Michigan Dialysis Research and Education (MiDRE)
Saint Mary's Mercy Hospital