Venous mapping using venography and the risk of radiocontrast-induced nephropathy.

Venous mapping using venography has been considered to be the gold standard for identifying veins suitable for arteriovenous fistula (AVF) creation. By utilizing a radiocontrast medium, however, venography introduces the risk of radiocontrast-induced nephropathy. The risk of this complication in the chronic kidney disease (CKD) population has not been previously studied. Twenty-five consecutive patients (CKD stage 4 and 5) undergoing venography were enrolled in this study. Patients were advised not to fast for the procedure and were encouraged to take oral fluids. Radiocontrast-induced nephropathy was defined as a 20% decrease in the estimated glomerular filtration rate (GFR) from the baseline value at 48 hours after contrast administration. Weekly telephone calls were made for a total of 4 weeks to assess the need for dialysis. Venography was performed by interventional nephrology using 10-20 cc of low osmolarity contrast medium. Data were collected prospectively. Median age was 48.9 +/- 7.8 years and 52% of the patients had diabetes. Complete sets of pre- and postprocedure GFRs were available in 21 patients. At 48 hours, there were no differences between the pre- and postprocedure GFRs. At the third week, one patient developed flu-like symptoms with severe gastroenteritis and was hospitalized for volume depletion. This patient initiated dialysis during the hospital stay. We conclude that at 48 hours, our cohort did not develop radiocontrast-induced nephropathy. During the 4-week phone call follow-up, only one patient needed dialysis. Large-scale studies with a longer follow-up using GFR estimation are needed to confirm these preliminary findings.

Conversion of tunneled hemodialysis catheter-consigned patients to arteriovenous fistula.

OBJECTIVE: Despite their high incidence of complications, costs, morbidity, and mortality, nearly 27% of the chronic hemodialysis (HD) patients are receiving treatment via a tunneled hemodialysis catheter (TDC). METHODS: In this prospective analysis, an interventional nephrology team employed an organized program consisting of vascular access (VA) education and vascular mapping (VM) to TDC-consigned patients. A full range of surgical approaches for arteriovenous fistula (AVF) creation, including vein transpositions, was exercised. Physical examination was performed every 1 to 2 weeks after surgery to assess the development of the AVF. Fistulas that failed to develop adequately to support HD (early failure) underwent salvage [percutaneous transluminal angioplasty (PTA), accessory vein obliteration (AVL)] procedures. RESULTS: One hundred twenty-one TDC-consigned patients received VA education. Eighty-six (71%) agreed to undergo VM. Two groups were identified. Group I (N= 66; using TDC for 7.2 +/- 1.8 SD months) had never had an arteriovenous access; group II (N= 20; using TDC for 12.3 +/- 4.0 months) had a history of one or more previously failed arteriovenous accesses. Upon VM, 64/66 (97%) in group I and 18/20 (90%) in group II were found to have adequate veins for AVF creation. Seven patients (11%) in group I and 3 (17%) in group II refused surgery. In group I, 57 (89%) received an arteriovenous access (radiocephalic AVF = 15, brachiocephalic AVF = 35, transposed brachiobasilic AVF = 3, brachiobasilic AVG = 4). In group II, 15 (83%) received a transposed AVF (radiobasilic = 2, brachiobasilic = 13). Sixteen fistulas (30%) in group I and 8 (53%) in group II had early failure. All except for one fistula in each group were salvaged using PTA and/or AVL. All 70 accesses (AVF = 66, AVG = 4) remain functional, with a mean follow-up of 8.5 +/- 3.6 months. CONCLUSION: These results demonstrate that an organized approach based upon a comprehensive program utilizing VA counseling, VM, application of full range of surgical techniques, and salvage procedures can be very successful in providing optimum vascular access to the catheter-dependent patient.

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.