Technical Considerations

The hemodialysis patient population, often advanced in age, suffers from serious systemic disease and multiple comorbidities. Tissues are often fragile, arteries may be calcified or diseased, and surgical wounds may heal slowly or poorly. Therefore, meticulous technique, use of fine instruments, and gentle tissue handling are essential to avoid complications. Care must be taken to avoid cautery or retraction trauma to nearby sensorimotor nerves. Minimizing vessel manipulation can reduce vasospasm of artery or vein.

End-to-side or side-to-side AV anastomosis may be performed, depending on the ability to mobilize the vein in question and the need to preserve multiple (retrograde) venous outflow paths. Surface venous anatomy varies considerably, particularly near the antecubital fossa; adjustment in placement of the skin incision or use of draining venous side branches may be necessary. Anastomosis diameter, relative to size of inflow artery and outflow vein, may be a factor in achieving adequate arterial inflow for fistula dilation or in the development of “arterial steal” from the hand circulation. Subcutaneous tunneling of prosthetic graft material must be deep enough to allow puncture site sealing, but not so deep to be undetectable for cannulation. Attention to hemostasis and layered coverage of underlying vascular anastomosis or prosthetic graft material will protect against wound complications and graft infection.

Preoperative Vessel Mapping by Duplex Ultrasound

Standard vessel-mapping protocols provide important information regarding approach to the best AVF or AVG location. Cephalic vein diameter is shown in Figure 35-1, A. Venous fibrosis, identified by thickened vein walls or incomplete compressibility, may predict poor distensibility with arterial inflow. Thrombosis from venipuncture or IV placement is shown in gray-scale imaging (Fig. 35-1, B). The basilic vein often lies deep and medial in the arm and will need superficialization if used for AVF (Fig. 35-1, C). A small or heavily calcified radial artery at the wrist, a common finding in diabetic patients, may contraindicate use of this artery for inflow (Fig. 35-1, D).

Radiocephalic Fistula

The approach for radiocephalic AVF is through a longitudinal skin incision along the anterolateral distal forearm that allows exposure of both the cephalic vein and the radial artery proximal to the flexor retinaculum. The superficial branch of the radial nerve, a small sensory branch, is often identified in the surgical field; excessive traction or transection may cause annoying numbness along the posterior thumb or lateral dorsum of the hand (Fig. 35-2, A; see also later Fig. 35-4).

After dilation and maturation, fistula cannulation takes place on the dorsolateral forearm.

Brachiocephalic Fistula

The approach for brachiocephalic AVF is through a transverse or curvilinear skin incision at or just distal to the antecubital crease, where cephalic vein is close to the distal brachial artery (Fig. 35-2, B). The cephalic vein must be mobilized sufficiently to deliver it medially and into the deeper plane, where the brachial artery resides. Radial artery takeoff is variable and may occur anywhere between axillary artery and brachial artery terminus. A smaller-caliber artery encountered in the more superficial incision may represent radial artery variation. In this case, clamping of brachial artery will not diminish radial artery pulsation at the wrist.

Toward the brachial artery terminus, the large median nerve diverges medially but may still be encountered close to the artery at this level. This important sensorimotor nerve should be preserved. Interruption of smaller sensory nerves, such as branches of lateral or medial antebrachial cutaneous nerves, may result in annoying numbness over lateral or medial forearm, respectively (see Fig. 35-4).

Once mature, cannulation of brachiocephalic AVF takes place on the anterior arm.

Brachiobasilic Fistula

For brachiobasilic AVF, transposition of the basilic vein to a more superficial and anterior location is generally required for comfortable arm position during cannulation and to prevent inadvertent puncture of the adjacent (and pulsatile) brachial artery in thin patients. The basilic vein, often inaccessible with venipuncture, is sometimes the obvious choice in patients without suitable cephalic or median cubital veins. Skin incision for anastomosis is sited medially at, above, or below the antecubital crease, depending on basilic and antecubital surface venous anatomy. Curved extension of the incision onto the medial arm may be helpful.

During same-stage transposition, the incision is extended cephalad on the medial arm, or skip incisions are used, to mobilize and harvest the basilic vein up to its entry into the axillary vein. Side branches are divided between ligatures. Branches of the medial antebrachial cutaneous nerve are often entwined around the basilic vein, making superficialization impossible without dividing one or the other. To avoid annoying numbness over the medial forearm, the vein must be divided and then anastomosed to itself after delivering it from under the nerve branch.

For two-stage transposition, AV anastomosis is performed at the first operation through a limited skin incision, followed several weeks later by harvest and superficialization of arterialized basilic vein. Cannulation of the mature and superficialized fistula takes place on the anteromedial arm.

Forearm Looped Graft

This common configuration places a loop of prosthetic material between arterial and venous circulations. The forearm looped approach is by transverse or longitudinal skin incision in the proximal forearm, just below the antecubital crease (Fig. 35-3). This approach allows exposure of both the inflow artery, usually the brachial artery terminus or proximal radial artery, and an outflow vein, either median cubital or median cephalic/basilic, depending on anatomy. If no antecubital surface vein is suitable, a deep brachial vein may be accessible through the same exposure.

Prosthetic graft, usually expanded (porous) polytetrafluoroethylene (ePTFE), is passed through a shallow subdermal tunnel and looped over the anterior forearm. A small counterincision just distal to the apex aids graft placement. Leaving enough subcutaneous tissue for layered closure of this counterincision will minimize risk of prosthetic exposure, should the skin incision break down.

By convention, the venous (return) limb is sited laterally on the forearm. If a medial outflow vein is selected, graft limbs may be crossed over one another proximally. Maintaining the expected subcutaneous configuration will avoid misidentification of graft limbs during cannulation. Construction of the venous anastomosis over venous side branches and bifurcations helps maximize outflow and may develop arm veins for use as a future AVF.

Attention to hemostasis and careful layered closure over prosthetic material may reduce risk of graft exposure and infection. Prosthetic AVG do not require time to dilate and may be cannulated as soon as tissue incorporation occurs. Any perigraft edema or ecchymosis should be allowed to resolve. Most AVGs are usable 7 to 14 days after implantation.

Brachioaxillary Graft

The brachioaxillary approach is used when more distal options have been exhausted, or when distal arterial or venous anatomy is not adequate to support AV flow. Arterial inflow is from the distal brachial artery, exposed through a longitudinal skin incision in the medial arm, above antecubital crease.

The median nerve is closely associated with the brachial artery at this level, usually encountered first on opening the neurovascular sheath. Great care must be taken with use of cautery and retraction. Mobilization of the large, motor median nerve will allow gentle vessel loop retraction posteriorly, to expose the brachial artery fully. The axillary vein is exposed through a second skin incision, placed at the base of the hair-bearing area. A longitudinal incision allows extension if significant venous branching dictates additional exposure in either direction. The axillary vein is fairly superficial and will be encountered before reaching the axillary artery.

Prosthetic graft, usually ePTFE, is passed through a shallow subdermal tunnel created between the two incisions, arching laterally onto the anterior arm, in a C configuration. Although most of the graft must be shallow enough for cannulation, tunneling the anastomotic ends more subcutaneously allows layered closure of the incisions and reduces the risk of prosthetic exposure, should the skin incision break down. Time to AVG cannulation is as described earlier.

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