Use of the Vectra polyetherurethaneurea graft for dialysis access in HIV-positive patients with end-stage renal disease.

The primary objective of this study was to establish the safety, efficacy, infection rate, and patency of the Vectra graft (polyetherurethaneurea) for dialysis access in patients diagnosed with human immunodeficiency virus (HIV) and end-stage renal disease. The Vectra graft has a unique self-sealing property; therefore we hypothesize that these patients will have fewer infections. A Vectra graft was implanted in 30 consecutive HIV-positive patients without sufficient veins for an autologous fistula. These surgeries were carried out over a 2.5-year period. Primary graft patency was 42% at 12 months and 3 (10%) of the grafts developed infection. This rate of graft infection was less (10% vs 45%) than both our prior experience and published reports using polytetrafluorothene bridge grafts. The unique self-sealing property of the Vectra graft minimizes the development of perigraft hematoma with repetitive needle cannulation and in the immunosuppressed HIV-positive patient, may account for the observed decrease in dialysis access infection.

Multicenter evaluation of the bovine mesenteric vein bioprostheses for hemodialysis access in patients with an earlier failed prosthetic graft.

BACKGROUND: The number of patients requiring hemodialysis increases each year, with a large cohort of patients still requiring prosthetic grafts for hemodialysis. All available prosthetic vascular access grafts have predictable failure rates, leading to a large group of patients with multiple failed access grafts. This report evaluates use of mesenteric vein bioprosthesis (MVB) as a conduit for patients who have failed at least one earlier synthetic vascular access graft. STUDY DESIGN: Two-hundred seventy-six access grafts were implanted in patients who had at least one earlier failed synthetic graft. Of these grafts, 183 were MVB and 93 were synthetic. Graft histories were obtained from 128 of the 183 patients who received the MVB, representing a nonrandomized historic data set of previously failed grafts as an internal control group (INT). Patency was determined by Kaplan-Meier analysis, and the Cox proportional hazards model was used for multivariate analysis of factors predictive of effect. RESULTS: Primary patency at 12 months was 35.6% MVB versus 28.4% synthetic grafts. At 24 months, secondary patency was 60.3% MVB, 42.9% synthetic, and 18.0% INT (p < 0.0001, log- rank). Complication rates, including dilation, seroma, infection, and thrombosis, were all notably lower for the MVB compared with synthetic grafts by Cox regression (p < 0.001). Intervention rate per patient year was lower in the MVB group (0.97 versus 1.37) compared with synthetic grafts (p = 0.003). CONCLUSIONS: MVB provided superior secondary graft patency compared with both historic graft data or newly implanted nonrandomized synthetic implants. A considerable reduction in thrombosis, infection, and interventions was observed with the MVB graft. These results suggest that MVB offers a safe alternative to patients who have a history of failing synthetic access grafts and may represent an option for extending vascular access to this patient population.

Single-center review of infections associated with 1,574 consecutive vascular access procedures.

The objective of this study was to establish accurate infection rates and causes for vascular access procedures and provide information helpful in identifying means of reducing infections. Between January 1, 1996, and December 31, 2001 (60 months), a single surgeon (AFS) performed 1,574 consecutive vascular access procedures (850 patients) in 1 academic medical center. Recently, a retrospective review of these records revealed that 87 patients (10.2% of this population) underwent removal of access grafts or fistula for infection. In these 87 patients, 131 grafts and 1 fistula were removed. Thus, 8.4% (132/1,574) of the total surgeries were for infection. This review included evaluation of repeat infection, causative organism, and HIV status. Cause of infection fell into 5 major categories. Of the 87 patients, 26 had multiple graft infections. Diabetes and hypertension lead to increased end-stage renal disease, requiring more vascular access procedures. Following thrombosis, infection is the most common complication in vascular access. Therefore, mechanisms to reduce infection would be well received. These data suggest that operative infection accounted for only 6% of infective procedures, and when the entire population is considered, the operative infection rate was 0.51%. However, infections secondary to routine dialysis make up more than 50% of this infective operative population. The authors note that 17% of the infective operations were in previously infected grafts that were not initially completely removed and 23% developed in nonfunctional grafts. Multiple graft infections played a significant role in the investigation and warrant further evaluation.

Maturation and failure rates in a large series of arteriovenous dialysis access fistulas.

The objective of this study was to document maturation and failure rates in a large homogeneous series of arteriovenous fistulas (AVFs). Between January 1, 1996, and December 31, 2001 (60 months), a single surgeon (AFS) in 1 academic medical center, constructed 374 AVFs. In this series, all AVFs were developed in vessels that had not undergone previous vascular access surgery. Recently, a retrospective review of these records revealed that 291 subjects had had complete follow-up for at least 3 months, and they constitute the material for this study. AVFs were considered a failure if an early occlusion/thrombosis occurred, if in 3 months the AVF had not matured on clinical examination, or if cannulation in the dialysis center was not feasible. A total of 91 AVFs did not mature, for an overall failure rate of 31%. An evaluation of failure rates indicated rates in females were higher than in males (41% versus 27%). Other risk factors, including HIV+ status, hypertension, and diabetes, demonstrated minimal failure differences (33%, 31%, and 36%, respectively).

Early cannulation prosthetic graft (Flixene™) for arteriovenous access.

PURPOSE: Preferred hemodialysis (HD) access is an autologous fistula. Vascular grafts are used in patients with vessels unsuitable to accomplish an arteriovenous fistula (AVF). It is recommended that most current grafts mature in situ for 2-3 weeks before being accessed. Graft complications occur because the structure was not designed for the trauma of repeated cannulation. This study graft has a different structure that enables early use. Its design minimizes weeping through the graft walls and is meant to endure repeated access, thus minimizing the use of HD catheters. The purpose of this study was to show that the Flixene™ graft can be safely placed in patients where fistulas have failed and can be cannulated in 24-72 hr, while maintaining patency rates similar to other polytetrafluoroethylene (PTFE) grafts on the market. Flixene™ configuration should also reduce the incidence of pseudoaneurysms and seromas. METHODS: A prospective two-center study placed 33 grafts in 33 patients; graft efficacy, post-operative complications, and patency were evaluated. Ease of cannulation and dialysis center complications related to early cannulation were documented. Six month follow-up data was analyzed. RESULTS: Successful access was achieved in all 33 patients within 72 hr (29 patients within 24 hr). Overall primary patency at 6 months was 49%; primary-assisted patency at 6 months was 80%. No pseudoaneurysms or seromas were documented at 6 months. Complications were typical of graft access. CONCLUSION: Early cannulation was successful in all patients. Primary and secondary patency rates at 6-months were equivalent to other data reported on PTFE grafts. Flixene™ successfully prevented pseudoaneurysm and seroma formation at 6 months of prospective follow-up. This graft is a better last-resort option for patients who cannot receive a fistula, compared to double-lumen cuffed catheters.

Maintaining vascular access: the management of hemodialysis arteriovenous grafts.

For the nephrologist and surgeon, maintaining vascular access is a significant challenge in hemodialysis (HD), because the portal is vulnerable to infection, stenosis, and thrombus. Vascular access options for HD include the placement of arteriovenous (AV) fistulas, AV grafts, and double-lumen, cuffed central vein catheters. Catheter use is generally associated with higher rates of infection and could compromise the adequacy of HD. Primary AV fistulas, which are generally recommended and provide excellent HD access, are not always the ideal choice for certain patients, such as the elderly or patients with diabetes mellitus. AV grafts allow for a large surface area available for cannulation, and thrombosed grafts have longer patency rates after revision than do revised fistulas. Although both AV fistulas and AV grafts are vulnerable to thrombosis and/or stenosis, surveillance and techniques such as Doppler ultrasound and intravascular ultrasound can minimize such complications. In addition, pharmacotherapeutic options are being studied to determine whether these complications can be prevented. Studies using a variety of pharmacologic agents have been conducted to determine whether stenosis and graft thrombosis can be prevented and have produced varying results. The use of warfarin can result in significant bleeding, but agents such as fish oil and angiotensin-converting enzyme inhibitors have shown some effect in increasing the patency in AV grafts and fistulas. Additional randomized trials with at least 1 or 2 yrs of follow-up are necessary to assess the long-term use of these pharmacotherapies.

A multicenter study of permanent hemodialysis access patency: beneficial effect of clipped vascular anastomotic technique.

OBJECTIVE: There is an urgent and compelling need to reduce the morbidity and expense of maintaining hemodialysis vascular access patency. This large, long-term, retrospective, multicenter study, which compared access patency of autogenous arteriovenous fistulas (AVF) and synthetic bridge grafts (AVG) created with conventional sutures or nonpenetrating clips, was undertaken to resolve conflicting results from previous smaller studies. DESIGN: Patency data for 1385 vascular access anastomoses (clipped or sutured) was obtained from 17 hospitals and dialysis centers (Appendix). Five hundred eighteen AVF (242 clip, 276 suture) and 827 AVG (440 clip, 384 suture) were analyzed. Statistical comparisons were made with Kaplan-Meier survival analysis, log-rank test, two-sample t test, and X(2) test. The Cox proportional hazards model was used to confirm Kaplan-Meier analysis. RESULTS: Access patency (primary, secondary, overall, and intention to treat) was significantly improved in access anastomoses constructed with clips. In the intention-to-treat group, primary patency at 24 months was 0.54 for clipped AVF and 0.34 for sutured AVF, and was 0.36 for clipped AVG and 0.17 for sutured AVG. At 24 months, primary patency rate for AVF successfully used for dialysis was 0.67 for clips and 0.48 for sutures, and for AVG was 0.39 for clips and 0.19 for sutured constructs. Interventions necessary to maintain patency were significantly fewer in clipped anastomoses. CONCLUSION: Replacing conventional suture with clips significantly reduces morbidity associated with maintaining permanent hemodialysis vascular access. This beneficial effect may be due to the biologic superiority of interrupted, nonpenetrating vascular anastomoses.