Treatment of stenosis and thrombosis in haemodialysis fistulas and grafts by interventional radiology.

BACKGROUND: There are no large series reporting the long-term results after radiological treatment of both stenosis and thrombosis in native fistulas (AVFs) and prosthetic grafts. METHODS: Between 1987 and 1999, 726 dilations, 135 stent placements and 257 declotting procedures were performed in 209 consecutive forearm AVFs, 74 upper arm AVFs and 156 prosthetic grafts. The stents used were the Wallstent*, the Craggstent*, and the Passager*. Declotting was performed by manual catheter-directed thromboaspiration, with or without previous urokinase infusion. RESULTS: The initial success rates ranged from 78 to 98%. The rate of significant complications was 2%. Primary patency rates at 1 year were twice as good for forearm AVFs (50%) than for grafts (25%) (P<0.05), and were 34% for upper arm AVFs. Secondary patency rates were similar in the 3 groups at 1 year (80-86%) and at 2 years (68-80%). Reintervention was necessary every 18 months in forearm AVFs compared to every 9 months in grafts (P<0.05). Thrombosed grafts fared worse than failing grafts. Accesses of less than 1 year's duration needed more reinterventions than older accesses (every 16 months versus 30 in forearm AVFs, every 7 months versus 13 in grafts, P<0.05). CONCLUSIONS: The percutaneous treatment of stenosis and thrombosis in haemodialysis access achieves patency rates similar to those reported in the surgical literature and confirms that grafts must be avoided as much as possible given their poorer outcome, especially after the first thrombosis. Poorer outcome is also demonstrated in accesses of less than 1 year's duration.

Wallstents and Craggstents in hemodialysis grafts and fistulas: results for selective indications.

PURPOSE: To report the value of selective placement of self-expandable stents (Wallstent and Craggstent) for the treatment of limitations and, occasionally, of complications of dilation in hemodialysis access, and especially for delaying restenosis. MATERIALS AND METHODS: This is a retrospective study of a 7-year period, during which 41 Wallstents and 11 Craggstents were placed in 26 polytetrafluoroethylene (PTFE) grafts, 15 native fistulas, and nine central veins of 47 patients. The indications were stenosis recoil (n = 13), recurrent restenosis within 6 months (n = 33), restenosis after 6 months (n = 3), and acute angioplasty-induced rupture (n = 1). Restenosis after stent placement necessitated redilation and percutaneous declotting and 10 additional stent placements. RESULTS: Two initial misplacements were corrected immediately. Primary patency rates for PTFE grafts were 58% +/- 10% at 6 months and 23% +/- 10% at 1 year, respectively. Secondary patency rates were 100% at 6 months and 88% +/- 8% at 1 year, respectively. For native fistulas, primary patency rates were 47% +/- 12% at 6 months and 20% +/- 18% at 1 year. Secondary patency rates were 95% +/- 6% at 6 months and 79% +/- 14% at 1 year. It was necessary to reintervene after stent placement to maintain or to restore patency every 9 months for PTFE grafts and every 7.3 months for native fistulas. When stents were placed for treatment of early recurring restenosis, the mean interval between radiologic interventions (redilations or declottings) performed to maintain or to restore patency before stent placement was multiplied by 2.1 after stent placement for both grafts (3.2 months increased to 6.9, P < .01) and native fistulas (2.9 months increased to 6.2, P < .02). CONCLUSIONS: Wallstents and Craggstents are valuable for the treatment of failure of regular dilation and they double the intervals between reinterventions for early (< 6 months) recurring stenoses in PTFE grafts and native fistulas.

Manual thromboaspiration and dilation of thrombosed dialysis access: mid-term results of a simple concept.

PURPOSE: To report the feasibility, safety, and effectiveness of manual thromboaspiration as a single means of declotting dialysis access. MATERIALS AND METHODS: Between April 1994 and December 1996, 59 consecutive conduits (43 polytetrafluoroethylene [PTFE] grafts, 16 native fistulas) were declotted with 8-F or 7-F angulated catheters. Unmasked stenoses were dilated. Clinical and paraclinical nephrologic surveillance (poor flow, palpation, difficulties with cannulation, increased compression times, increasing venous pressures) led to redilations and stent placements. Rethromboses were treated with further declotting by aspiration. The results are presented according to the life-table method. RESULTS: The initial success of 43 of 43 PTFE grafts (mean procedure time, 119 min +/- 29 [standard deviation]) led to a primary patency rate of 85% +/- 5% (SE) at 1 month, 33% +/- 8% at 6 months, and 24% +/- 12% at 1 year. A graft was ligated 6 days after declotting for acute bleeding in one patient given high-dose warfarin. The secondary patency rates were 86% +/- 7% at 6 months and 86% +/- 9% at 1 year, with a mean duration of patency of 5.7 months between two radiologic interventions performed to maintain or to restore patency, and 19 stents were placed at a mean follow-up of 3 months. The success rate was 81% for native fistulas, with primary patency rates of 81% +/- 10% at 1 month, 74% +/- 14% at 6 months, and 60% +/- 27% at 1 year; secondary patency rates of 81% +/- 12% at 6 months and 81% +/- 18% at 1 year. CONCLUSION: Thromboaspiration is a safe and effective method for declotting dialysis access, yielding a low rethrombosis rate during the first month. Overall radiologic management with reintervention on average every 6 months results in high secondary patency rates at 1 year (81%-86%).

Urea rebound and residual renal function in the calculation of Kt/V and protein catabolic rate.

Kt/V-urea and protein catabolic rate (PCR) are used for dialysis prescription and evaluation of protein intake of patients on regular dialysis treatment. The study was undertaken to determine the implication of urea rebound and residual renal function (RRF) on the calculation of Kt/V-urea and PCR for 61 patients. Kt/V-urea and PCR were calculated, implementing or not urea rebound at one hour after the end of dialysis session. Urea and creatinine rebound rate in patients without RRF was significantly higher than in patients with RRF (P < 0.05). In patients without RRF, creatinine generation rate and Kt/V-urea calculated without rebound were significantly higher than calculated with rebound (P < 0.001). On the contrary, calculation of urea generation and PCR is not affected by these parameters. It is concluded that: (1) Rebound rate magnitude of urea and creatinine is dependent on solute molecular weight, RRF and probably on dialysis duration, whereas rebound rate magnitude of phosphorus is not affected, and (2) Rebound should be taken into account in the calculation of Kt/V-urea and creatinine generation rate in patients without RRF, otherwise, they would be overestimated.

The most suitable calculation of Kt/V-urea: Kt/V = ln(Ci/Cf).

Although various simplified calculation formulae of Kt/V-urea based on urea kinetic modeling have been reported, all the formulae include errors such as post-dialysis urea rebound and urea generation during a dialysis session. In the present study, in order to calculate the precise Kt/V-urea, a formula of Kt/V-urea, taking into account post-dialysis plasma urea rebound and urea generation during a dialysis session (Kt/V-P) was proposed, and compared to other formulae already published, in 49 dialysis patients without residual renal function (26 M and 23 F; mean age, 65 +/- 2 years; mean dialysis duration, 70 +/- 7 mos). The precise post-dialysis plasma urea concentration was significantly higher than the actually measured post-dialysis plasma urea concentration by approximately 12%, and Kt/V-P corresponded to Kt/V-urea = ln(Ci/Cf) with the best correlation in the formulae utilized in the present study, around 1 of Kt/V-urea, which is clinically the most important range. It is concluded that Kt/V-urea = ln(Ci/Cf) is the most suitable formula for the calculation of Kt/V-urea, when post-dialysis plasma urea rebound and urea generation during a dialysis session are taken into account.

[First consultations in nephrology. Comparison of 2 multicenter studies conducted at a 5-year interval]. / Primo-consultations en néphrologie. Comparaison de deux études multicentriques rélisées à cinq ans d'intervalle.

An investigation of "kidney outpatient" first consultations carried out in 1985 with the cooperation of 19 nephrological teams distributed all over France. Each team had taken part in a similar investigation in 1980. The work allowed to collect 1200 records. Analysis of the main results is presented. The comparison between the 1980th and the 1985th investigations shows a remarkable stability of the results, but suggests two new and interesting features: the progress of Dip-stick studies and serum creatinine concentration in general practice and the decreasing part taken by hypertension in "kidney disease out-patient" activity in 1985.