GUIDELINES [ back to index ]
20. Management of high flow in A/V fistula and graft
*1 Suspected high flow
• Cases of long-term high flow have been published as complications of both distal and proximal A/V fistulas but it is more important and occurs earlier in upper arm fistulas1-6. While Murphy et al. reported one case of cardiac failure in 74 brachiobasilic A/V fistulas 7, Ono et al. reported one case of congestive heart failure out of four axillary artery to contralateral axillary vein bridge grafts 8.
• As the aetiology of cardiac failure in dialysis patients is complex (including anaemia, fluid overload, uncontrolled hypertension, intrinsic cardiac disease) the diagnosis of high-output cardiac failure may be overlooked for some time 5.
• The creation of an A/V fistula, however, does not necessarily lead to a significant increase in cardiac load after fistula maturation 1 9.
*2 Conservative treatment
• Conservative treatment should include control of body weight, modest exercise, diet and medical treatment (ACE inhibitors, AT1-receptor antagonists, b -blockers, diuretics, digitalis etc.), as recommended by current guidelines.
*3 High fistula flow
• For many years, there was no consensus among physicians about the upper limit of normal access flow 2. When access flow is greater than 1000-1500 ml/min1 or flow/cardiac output ratio > 20% 10, then cardiac failure may result.
• Depending on the condition of the patient, cardiac failure may occur at different access flow rates. Extreme flow rates of up to 19.4 l/min have been described in a 27-year old male patient in superb physical condition 6. Most patients will show cardiac failure with lower access flows.
*4 Flow reduction
• Flow reduction by banding or interposition grafting may be an option to limit blood-
flow through the A/V fistula. The results of these procedures, however, are usually disappointing due to insufficient flow reduction or uncontrolled flow increase after the operation.• More appropriate measures are the following:
• In the case of a distal radio-cephalic A/V fistula, ligation of the radial artery proximally to the anastomosis results in significant flow reduction, because afterwards the A/V fistula is fed only by the ulnar artery via the palmar arch 11.
• In the case of an elbow A/V fistula (brachiocephalic or brachiobasilic), moving the arterial anastomosis distally will cause a flow reduction of about 50 % 12. The anastomosis of vein or graft to the brachial artery is ligated, and a vein or graft is inserted connecting the proximal or distal radial or ulnar artery with the old access.
• Radial artery transposition is an alternative method to reduce excessive high flow in proximal fistulas. Following ligation of the brachiocephalic or brachiobasilic access anastomosis, the radial artery is transected and dissected in the forearm, and then anastomosed to the access vein at the elbow. Mean flow reduction is 65 % 12.
• It is obvious that preoperative and postoperative access flow measurements are mandatory in patients with flow reducing operations.