GUIDELINES [ back to index ]
13. Management of A/V fistula thrombosis
*1 Postpone dialysis if possible
• Postponement of dialysis might be possible in patients who are not expected to develop pulmonary oedema. Increase in body weight since the last dialysis session must be checked to assess amount of excess water. Furthermore, the patients must not show symptoms of uraemia, and the potassium level must not exceed 5.6 mmol/L.
*2 Treat fistula thrombosis within 48 hours whenever possible
• The duration and site of A/V fistula thrombosis as well as the type of access are important determinants of treatment outcome. Fistula thrombosis should be treated without unnecessary delay. Early declotting allows an immediate use without need for central venous access. Thrombi become progressively fixed to the vein wall, which makes surgical extraction more difficult. Thrombosis may affect the postanastomotic vein segment as result of anastomotic stenosis or may begin at the needle site. When the clot is localised at the anastomosis in radiocephalic and brachiocephalic fistulas, the outflow vein may remain patent due to the natural sidebranches that continue to carry venous blood flow. In this type of clotting it is possible to create a new proximal anastomosis 1 2 even after some days.
• Thrombosis in A/V fistulas with transposed basilic veins usually leads to clot propagation of the entire vein.
• Although comparative studies are missing, the available literature 3-13 strongly suggests that thrombosed autogenous A/V fistulas should preferably be treated by interventional radiology. The only exception may be forearm A/V fistulas thrombosed due to anastomotic stenosis. It is likely that in such cases, creation of a proximal new anastomosis will provide excellent results although no surgical series has ever demonstrated that to date. There remains a paucity of literature on the results of surgical intervention for fistula thrombosis although there are many papers confirming the success of radiological intervention.
*3 Interventional thrombolysis
• Thrombolysis can be performed mechanically or pharmacomechanically. While the immediate success rate is higher in grafts than in A/V fistulas (99 % versus 93 % in forearm A/V fistulas), the primary patency rate of the forearm A/V fistula at one year is much higher (49 % versus 14 %). One year secondary patency rates are 80 % in forearm and 50 % in upper arm A/V fistulas, respectively 3.
• In A/V fistulas, the combination of a thrombolytic agent (urokinase or plasminogen activator tPA) with balloon angioplasty resulted in immediate success rates of 94 %.
• Liang et al. reported a success rate of 93 % and a primary patency rate at one year of 70 % in restoring flow of thrombosed forearm A/V fistulas by PTA 12.
• Haage et al. performed 81 percutaneous treatments of thrombosed A/V fistulas 5. Full flow restoration was achieved in 88.9 % of A/V fistulas, although primary one-year patency rate was only 26 %, overall one-year patency rate was 51 %.
*4 Surgical thrombectomy
• Surgical thrombectomy is performed with an embolectomy catheter. In tortuous or aneurysmal veins, manual retrograde thrombus expression can be helpful.
• On-table completion angiography of the reopened vein as well as the central venous outflow tract should be performed whenever possible to find/exclude additional stenoses or a persistent thrombus. Identification and simultaneous correction of the underlying cause(s) of thrombosis are integral parts of any surgical or interventional declotting procedure (see Algorithm “Management of A/V Fistula Stenosis“, *1).
• The best results of surgery probably will be encountered after proximal re-anastomosis for anastomotic stenosis of forearm A/V fistulas – which is indeed the most frequent location of stenosis in this type of access. Primary (secondary) patency of the new proximal anastomosis has been reported to be as high as 80% (89 % - 95 %) at one year and 67 % (87 % - 89 %) at two years 2.
*5 Provide treatment plan in patients document
• Regular multidisciplinary meetings with nephrologists, dialysis nurses, surgeons and interventional radiologists are needed to establish a treatment plan for difficult or complicated vascular accesses. Adequate documentation of the outcome of these meetings, results of investigations, description of radiological and surgical interventions are of utmost importance. Ideally, a database should be used for this purpose. Information from the surgeon to the dialysis nurse, concerning the time and location of first cannulation of new / revised accesses, is to be incorporated in the treatment plan. If access failure recurs frequently in a short time period, a new fistula may need to be created 15.
*6 Assess for other causes of thrombosis
• The vast majority of access thrombosis is due to stenosis of the A/V fistula. Other causes such as post-dialysis hypotension, excessive dehydration, hypercoagulability (deficiency of AT3, protein S, antiphospholipid antibodies), trauma, or prolonged compression of the puncture site are probably only associated risk factors or triggers to reveal an underlying stenosis. Infection can also cause or be associated with access thrombosis.
• If prolonged compression of the puncture site is necessary, the patient should be taught how to compress it without occluding the vascular access. Mechanical devices should be avoided and haemostasis should be performed with a sterile gloved finger over a small haemostatic gauze. The nurse, the assistant nurse or the patient must feel the thrill under the finger during the tamponade.