GUIDELINES [ back to index ]
5. Placement of upper arm A/V fistula
Fistulas can also be created in the upper arm or at the elbow. These fistulas are a good alternative, when wrist fistulas cannot be created. Whilst proximal fistulas are recommended by some authors as the first access in patients with diabetes 1 2, others feel peripheral access can be successfully created. In 2000, Rodriguez reported much better long-term secondary patency rates for forearm fistulas compared with upper arm fistulas (50 % secondary patency at 7 years for forearm fistulas versus 3.6 years for brachiocephalic fistulas and 5 years for brachiobasilic fistulas) 3.
In an article published in 1977, Kinnaert reported 2 years secondary patency rates ranging from 78.5 % to 100 % for end to side radiocephalic fistulas, and 61 % for ulnar-basilic fistulas. In another article published in 1994, he reported secondary patency rates for upper arm fistulas ranging from 69 % to 80 % at 1 year and from 49 % to 68 % at 4 years 3-5. Data by Dixon et al.. 6 favour upper arm A/V fistulas. The group found higher 1-, 3- and 5-year patency rates in upper arm fistulas (71 %, 57 % and 57 %) compared to forearm A/V fistulas (54 %, 46 % and 36 %) and grafts (54 %, 28 %, 0 %), but upper arm A/V fistulas required more interventions than forearm A/V fistulas (1.0 versus 0.6 per access, respectively).
*1 Evaluation of brachial artery
Inspection may occasionally reveal a meandering brachial artery, in some cases appearing like a true arterial aneurysm. This is found in patients with other signs of severe atherosclerotic disease, particularly in patients with diabetes mellitus and nephrosclerosis.
Palpation of the brachial artery along the upper arm should be performed bilaterally to compare the quality of the pulses. A high brachial artery bifurcation occurs in 19 % of patients. In diabetics, however, the artery may be difficult to palpate due to calcification.
Auscultation revealing a high-frequency bruit along the subclavian / axillary artery in combination with a blood pressure difference exceeding 20 mm Hg may be a sign of impaired arterial supply of the extremity.
*2 Evaluation of cephalic vein
The cephalic vein lies on the outer side of the upper arm on the medial border of the deltoid muscle. It passes subcutaneously from the elbow upwards and turns subfascially in the upper arm before it joins the subclavian vein. The vein may be visible, but usually can only be palpated. A tourniquet is applied as high as possible in the axilla and the vein is then examined by palpation along its course. Size, compressibility and patency are judged. If the vein cannot be felt because of its deep position, additional imaging techniques like colour Doppler ultrasound may be necessary 7.
*3 Brachiocephalic fistula
The brachiocephalic A/V fistula is only one of a great variety of possible A/V anastomoses in the elbow region. The individual topography of veins and arteries determines the type of fistula chosen. Depending on the individual situation, the proximal radial artery, the distal brachial artery just above its bifurcation or even the proximal ulnar artery can be used to create the A/V anastomosis. The final determinant for the choice of artery is its diameter and the quality of its wall. The arterial wall should ideally be without calcification. As for forearm fistulas, the brachiocephalic fistula should provide an optimal position for cannulation.
Brachiocephalic fistulas can be created by an end-cephalic vein to side-brachial artery anastomosis at the elbow. A second possibility is to form an anastomosis between the perforating vein of the median cubital vein and the brachial artery, called the Gracz A/V fistula (for details: see appendix).
The complication rate is less than in grafts 8, but such fistulas may cause high-output cardiac failure in the long-term 9 or steal phenomena in the short-term10. Patency and complication rates of standard brachiocephalic and the Gracz type A/V fistulas are similar 5 11.
*4 Assessment of brachial artery by duplex ultrasound
A standardised duplex ultrasound (see appendix) examination of the brachial artery in the supine patient should be performed. Brachial artery diameter, Doppler waveform, flow measurement and vessel wall characteristics are evaluated. Normal diameters of brachial arteries range from 2.5 to 4 mm. With adequate arterial inflow a typical tri-phasic Doppler waveform with a rapid systolic upslope, reversed flow and low diastolic flow is anticipated. Stenosis in the artery results in flattening of the systolic peak with absence of reversed flow. Vessel wall calcification may be noticed by echolucent shadows. An arterial inflow of > 40 ml/min is associated with better outcome of the A/V fistula 12.
*5 Assessment of cephalic and basilic veins
A standardised duplex ultrasound (see appendix) examination of the cephalic vein from the elbow up to its junction with the subclavian vein and also of the basilic vein at the medial side of the elbow up to its junction with the deep axillary veins should be performed if the clinical examination does not completely clarify the anatomical situation. Vein diameters, compressibility and continuity are checked with a tourniquet placed as high as possible in the axilla. In particular, the location of the junction of the basilic and deep veins is recorded. Because of its deep location duplex investigation of the basilic vein is recommended , although the anatomic position does protect it from cannulation. A diameter of 3-4 mm is desirable for the creation of a brachiocephalic or brachiobasilic A/V fistula 13, however, the continuity and the absence of stenosis are more important than the absolute diameter of the vein.
(For comments on CO2 venography and MRA see *2 Placement of Forearm A/V Fistula.)
*6 Brachiocephalic fistula with transposed cephalic vein
Normally, the cephalic vein is in an ideal subcutaneous position and cannulation can usually be performed successfully. The subcutaneous transposition of the cephalic vein may be necessary only in very obese patients. The fatty tissue layer can often simply be resected resulting in a subcutaneous position of the cephalic vein thus allowing for easy cannulation. Transposition of the vein into a new subcutaneous tunnel apart from the incision needed for mobilisation of the vein, however, is preferred by some groups, because the vein then does not lie beneath scar tissue.
*7 Brachiobasilic transposed fistula
First described by Dagher et al.. in 1976 14 the brachiobasilic anastomosis with consecutive mobilisation of the arterialised vein into a subcutaneous position 5 is still superior to the insertion of a graft.
Rivers et al.. investigated the patency rate in brachiobasilic transposed A/V fistulas. After 30 months, 49 % of fistulas were patent 15. In a pilot study, Hibberd described a patency rate of 70 % after one year in brachiobasilic fistula, while Burkhard and Cikrit found a patency rate of 90 % after one year 16 17 . Infection and thrombosis occur less often than in grafts, and though they are more likely to mature than brachiocephalic fistulas, they are more susceptible to late thrombosis 18 19 . On the other hand, Rodrigues et al.. found better secondary patency rates in brachiobasilic fistulas when compared to brachiocephalic fistulas 3. In summary, there is no doubt that the technique of subcutaneous placement of an arterialised basilic vein is superior to graft insertion. However, there has been no clinical trial comparing these two types of upper arm A/V fistulas, so no definitive advice can be given. Selection of the appropriate A/V fistula will depend on quality and topography of the vessels involved.
*8 Jump graft fistula
It is also possible to create a jump graft fistula, using a short interposition graft with a diameter of 6 mm between the brachial artery and the cephalic vein when the latter is diseased or occluded at the elbow level 20. However, this operation actually changes the autogenous fistula partially into a graft, with all the well-known potential drawbacks of grafts at the venous anastomosis. The alternative is to fully mobilise the cephalic vein and anastomose to a more proximal site on the brachial artery.