Inflow stenosis in arteriovenous fistulas and grafts: a multicenter, prospective study

BACKGROUND: Traditionally, arteriovenous hemodialysis access inflow stenosis has been reported to occur infrequently (0% to 4%). In contrast, recent reports have suggested a significantly higher incidence (14% to 42%). Interpretation of these studies has been complicated by the presence of one or more confounding factors such as retrospective study design, small sample size, arteriovenous fistulas grouped with grafts to determine the incidence of inflow stenosis, inclusion of fistulas that had failed primarily, failure to provide adequate definition of inflow stenosis, and the technique of retrograde angiography. This is a report of a prospective, multicenter study to examine the incidence of inflow stenosis separately in arteriovenous fistulas and grafts. METHODS: Patients were referred to interventional nephrology either for percutaneous balloon angioplasty or thrombectomy procedures. Angiography to evaluate access inflow (arterial anastomosis and adjacent vascular structures) was performed in all cases. This was accomplished by retrograde angiography using either manual occlusion of the venous side and/or advancing a diagnostic catheter across the arterial anastomosis. Multiple images using digital subtraction angiography were recorded in multiple planes. An inflow stenosis was defined as stenosis within the arterial system, artery-graft anastomosis (graft cases), artery-vein anastomosis (fistula cases) and juxta-anastomotic region (the first 2 cm downstream from the arterial anastomosis). Vascular stenosis was defined as >/=50% reduction in luminal diameter judged by comparison with either the adjacent vessel or graft. A standardized definition for anastomotic stenosis was applied. RESULTS: Two hundred and twenty three consecutive procedures (grafts, 122; fistulas, 101) were performed in 158 patients. Inflow stenosis occurred in 36/122 (29%) in graft cases. All had a coexisting stenosis on the venous side. In fistula cases, 41/101 (40%) had inflow stenosis. Of these, 22 (54%) had a coexisting lesion on the venous side. Overall, inflow stenosis occurred in 77/223 procedures (35%). CONCLUSION: This prospective, multicenter study demonstrates that access inflow stenosis occurs in one third of the cases referred to interventional facilities with clinical evidence of venous stenosis or thrombosis. This is much higher than has been traditionally reported.