C.  Short lag time from construction to maturation D.  Easy to correct surgically when thrombosed

Immediately after surgery, the patient complained of numbness of the left hand with slight pain of the fingers. On examination the left radial pulse, which had existed previously, was absent, and the fingers were cold and cyanotic. Evaluation of the patient in the vascular laboratory with forearm Doppler pressure measurement revealed an index of 0.3. Interestingly the left forearm segmental pressure index was normalized after manual compression of the graft, while the left radial pulse reappeared with this maneuver. The evaluation confirmed an obvious hemodynamic “steal.” The patient’s condition deteriorated within a few hours; she developed severe, acute, painful weakness of the hand, wrist-drop, and minimal ability to flex the wrist.

Question 3

Which of the following statements regarding the incidence of steal after proximal access construction is correct?

A.  The incidence of asymptomatic steal after proximal access construction, detected in the vascular laboratory, is rare.

B.  Clinically obvious mild ischaemia after the construction of a proximal AV fistula occurs in about 10% of cases.

C.  Severe ischaemia necessitating surgical correction complicates 2–4% of patients ­following a proximal AV fistula.

Question 4

Whichofthefollowingareindicationsforsurgicalcorrectionofstealafterproximalaccess construction?

A.  Absence of ipsilateral preoperative existed radial pulse B.  Severe symptoms (rest pain, paralysis, wrist-drop)

C.  Abnormal forearm segmental pressure index measurement D.  Abnormal ipsilateral nerve conduction studies

E.  Reversal of flow in the distal artery in colour-flow duplex imaging

Urgent surgical correction was performed. Under local anaesthesia, a small segment of saphenous vein was harvested. The brachial artery was ligated just distal to the take-off of the graft. A vein bypass was constructed from the brachial artery 4–5 cm proximally to the inflow of the graft to a point distal to ligation (Fig. 42.1). Complete relief of symptoms occurred immediately postoperatively. The recovery of the patient was uneventful. She was discharged home on the third postoperative day with a palpable left radial pulse and a patent AV graft.

Fig. 42.1 (a) The operation before the creation of the corrective procedure. (b) The corrective procedure with ligation of the artery just distal to the AV graft take-off and the venous bypass from a point proximal to the inflow to a point just distal to ligation (DRIL procedure). A, brachial artery; AV, axillary vein; BV, basilic vein; G, arteriovenous PTFE graft; VG, vein graft

Question 5

Which of the following are acceptable corrective options for limb-threatening steal following proximal access construction?

A.Percutaneous transluminal angioplasty

B.Flow reduction procedures (banding, plication or tapering of the AV fistula)

C.AV fistula closure

D.The DRIL (distal revascularization interval ligation) procedure

42.1 Commentary

Construction of an AV fistula provides a sufficiently superficial arterialized vein that can be punctured with ease while its flow is high enough to permit efficient dialysis. Postdialysis compression of a matured thick-wall arterialized vein in order to stop bleeding can be obtained readily and reliably.

The classic first-choice site for an AV fistula construction is between the radial artery and the cephalic vein at the wrist, as introduced by Brescia et al.1 in 1966. If the cephalic vein at the wrist or forearm is not usable, then the next alternative is to move to the antecubital fossa. The AV fistula can be constructed at this site between the median cubital vein and the brachial artery. The superficial cephalic vein provides enough length of vein

suitable for haemodialysis venipunctures. Alternatively, if the cephalic vein is not usable, then the brachial artery can be anastomosed to the basilic vein of the upper arm. However, the latter is situated under the deep fascia in the arm, and mobilisation and transposition to a subcutaneous new position is always necessary. When an autologous AV fistula either at the wrist or the elbow cannot be created, then an AV graft using synthetic material bridging an artery and a vein in the upper extremity (either forearm or arm) is the next choice. Grafts may be placed in straight, looped or curved configurations. AV grafts and fistulas are created in the lower extremity only rarely, as they are prone to infection at this site.

The order of preference for placement of AV fistulas in patients requiring chronic haemodialysis according to dialysis outcomes quality initiative (DOQI) guidelines established by the United States Kidney Foundation is2:

1.A wrist radial-cephalic AV fistula.

2.An elbow (brachial-cephalic) AV fistula.

If it is not possible to establish either of these types of fistula, then access may be established using:

3.An AV graft of synthetic material (PTFE grafts are preferred over other synthetic material).

4.A transposed brachial-basilic vein fistula.

Cuffed, tunnelled central venous catheters should be discouraged as permanent vascular access. [Q1: B]

Recognising the superiority of the autologous AV fistulas over grafts, DOQI guidelines recommend an aggressive strategy increasing the number of native fistulas. DOQI guidelines suggest that autologous AV fistulas should be constructed in at least 50% of all new patients electing to receive haemodialysis as their initial form of renal replacement therapy.2 Bridge AV grafts should be reserved for those patients whose vein anatomy does not permit the construction of an autologous AV fistula.3,4 Autologous fistulas, especially distal ones at the wrist, present a lower complication rate compared with other access options.5 A vein must be matured before use for vascular access. The time required for maturation of an autologous fistula varies among patients. It is not correct to use a fistula within the first month after its construction. Premature cannulation may result in a higher incidence of haematoma formation, with associated compression of the still soft-wall vein, leading to thrombosis. Allowing the AV fistula to mature for 3–4 months may be ideal.2

In contrast, PTFE AV grafts need a shorter maturation time and can be used approximately14daysafterplacement.Withinthisperiod,anattempttocannulatethestilloedematous arm may lead to graft laceration from inaccurate needle insertion. An AV graft may be considered matured when swelling of the subcutaneous tunnel has reduced to the point that its course is easily palpable. Additionally, after the first 2 weeks, fibrous tissue formation round the graft is able to seal the holes caused by each needle puncture. PTFE grafts are easily thrombectomised, with a reported unassisted patency following thrombectomy at 6 months close to 50%.6 In contrast, autologous fistulas when thrombosed are difficult to salvage.2 [Q2: A, B]

The reversal of flow after creation of an AV fistula in the distal artery beyond the fistula and before the point of entry of collateral vessels has been characterised as steal. This is caused by a pronounced pressure drop in the distal artery, while pressure increases with increasing distance away from the fistula as a consequence of inflow from arterial collaterals.7 Stealoccursinmorethan90%ofproximalAVfistulas–whenthearterialanastomosis is at the brachial artery – but in most patients, the collateral vasculature is adequate to maintain distal flow, and severe ischaemia does not develop in the hand.8,9 Clinically obvious mild ischaemia from steal occurs in about 10% of patients. The presentation is coldness and numbness of the hand, and the symptoms resolve spontaneously within 1 month.8 Theterm“steal”isusedinappropriatelyforthisconditioninmanyreportsbecauseitmeans reversal of flow and not any of its potential ischaemic sequelae. A wide spectrum of symptoms and signs may occur, however, such as paraesthesias and sensory loss, weakened or absentdistalpulse,muscleweaknessandwrist-drop,restpainusuallygettingworseduring dialysis, muscle atrophy and – if left untreated – digital gangrene. The reported rate of steal-induced severe ischaemia necessitating immediate surgical treatment is 2.7–4.3%.8,9 In contrast to proximal AV fistulas, the incidence of symptomatic steal following distal radiocephalic AV fistulas is rare, at a rate of 0.25%.10 [Q3: B, C]

Clinical signs and symptoms of steal syndrome do not differ from those of leg ischaemia. Therefore it can be classified according to Fontaine´s classification: stage I, reduced wrist-brachial pressure index, coldness of the hand or no symptoms; stage II, intermitted pain during haemodialysis; stage III, continuous ischaemic rest pain; and stage IV, ulceration and necrosis. Stages I and II should be closely observed and treated conservatively (e.g., wearing gloves).11

In most reports, the indication for surgical correction of steal is based on clinical grounds only.8,9 Low segmental pressure, as measured by Doppler, distal to the fistula is not an indication per se for surgical correction of steal. Additionally, absence of a radial pulse is a common finding in approximately one-third of patients following proximal access creation.9 A corrective surgical procedure is indicated when proven haemodynamic steal causes severe stage III and/or stage IV ischaemic symptoms early after access construction (rest pain, paralysis, cyanosis of digits, wrist-drop). Mild ischaemic symptoms that persist beyond 1 month from access creation should be observed closely. When these “mild” symptoms are present for a long time, there is always a threat of irreversible neurological impairment, termed “ischaemic monomelic neuropathy.” This is a serious and disabling complication causingsensorimotordysfunction withouttissue necrosis.12 Abnormal deterioratednerveconductionstudiesinthepresenceofevenmildischaemiaareanindication for surgical correction of steal.9 [Q4: B, D]

Several catheter-based and surgical techniques have been used to correct steal-induced ischaemia. Arterial stenoses proximal to the AV fistula are eligible for percutaneous transluminalangioplastyandmayaugmentbloodflowtotheperipherywithreliefofsymptoms. However, such proximal inflow stenoses contribute to steal syndrome in only 20% of patients who have distal extremity ischaemia.13 In the vast majority of cases (80%) steal is caused by discordant vascular resistance and a poorly formed arterial collateral network. A variety of surgical techniques have been applied to correct limb-threatening steal including fistula closure with simple ligation, various flow reduction techniques (banding, placation or tapering) and the DRIL (distal revascularization interval ligation) procedure