GUIDELINES [ back to index ]
15. Management of graft stenosis
*1 More than 50 % reduction of graft diameter
A reduction of > 50 % of the lumen diameter in association with haemodynamic change is recommended as the triggering point for treatment of stenosis 1.
The impact of the stenosis is more obvious in prescribed blood flows as high as 500 ml/min than in 200 ml/min. The stenosis can lead to a reduction in the adequacy of the dialysis therapy 2. The progression of the narrowing is quite different in individual patients and, therefore, repeated measurements are necessary to decide whether and how the stenosis should be treated. Multiple stenoses and longer stenoses are probably better treated surgically.
*2 Stenosis at the arterial anastomosis
Like in A/V fistulas, most arterial inflow stenoses can successfully be treated by angioplasty.
Stenosis of the arterial anastomosis itself can be dilated, if only the afferent artery and the graft at the anastomosis is affected but the efferent artery is not stenosed.
If there is an additional stenosis of the efferent artery, angioplasty of the anastomosis alone will enhance graft flow with the risk of peripheral ischaemia due to reduced peripheral arterial perfusion. In these patients, either dilatation of the efferent artery by interventional radiology or through surgical revision of the anastomosis, may resolve the problem.
*3 Intra-graft stenosis
Intra-graft (or mid-graft) stenoses are found in the cannulation segment of access grafts which have been in use for at least some months. They result from excessive in-growth of fibrous tissue through puncture holes. These stenoses can be treated by percutaneous transluminal angioplasty (PTA) 3, graft curettage 4, and segmental graft replacement.
Replacing the damaged graft segment is not only the most straight-forward but also the most durable means to restore or maintain graft patency 5. When only part of the cannulation segment is replaced (the remaining can be treated by curettage or intraoperative PTA if necessary), the access can be used for further haemodialysis without the need of a central venous catheter.
When re-stenosis occurs in a non-exchanged part of the graft, this can be replaced after healing of the new segment (i.e. after two weeks), again without the need for central venous access.
*4 Stenosis at the venous anastomosis
The most frequent cause for access graft dysfunction and thrombosis is venous anastomotic stenosis 3 6 7. As access grafts should be implanted only in patients with exhausted peripheral veins, vein saving procedures like PTA or patch angioplasty should be preferred to graft extensions to more central vein segments, although the latter may provide superior patency rates 8 9.
When PTA repeatedly fails, additional stent implantation can be considered 10 11. When stent or a patch fail, graft extension is still possible. This staged application of different therapeutic options is very likely to enhance cumulative graft function to a greater extent than primary use of the best option.
When the interval between the recurrence of stenosis becomes shorter, surgery should be considered.
Frequent graft occlusion can occur in severely hypotensive patients, in certain types of thrombophilia, and in subclinical graft infections. These conditions have to be excluded if no or mild stenosis (< 50 %) is found at graft thrombectomy.
*5 Flow at least plus > 50 % of baseline
After successful percutaneous transluminal angioplasty (PTA) the access blood flow (Qa) usually increases almost twofold, but in half of the grafts the blood flow decreases to baseline within three months 12. There is no correlation between the change in blood flow and the residual stenosis 13 14. In 20 30 % of the grafts, PTA does not increase blood flow to more than 600 ml/min, indicating insufficient dilatation with an undersized balloon, immediate recurrence of stenosis, or the existence of unidentified and not corrected stenosis either more centrally or at the arterial inflow.
Long-term outcomes did not correlate with angiographic results, but with Qa values before PTA and the increase in Qa due to the procedure 14. However, it may be argued, that the dilatation has not been sufficient in these grafts.