Improved detection of hepatitis C virus infection by transcription-mediated amplification technology in dialysis population.

BACKGROUND: Hepatitis C virus (HCV) infection remains common among patients undergoing maintenance dialysis and plays an adverse effect on survival in this population. Accurate detection of HCV viremia (HCV RNA) in dialysis patients requires a sensitive and specific diagnostic test. METHODS: The Versant HCV RNA Qualitative Assay, based on transcription-mediated amplification (TMA) technique, was prospectively evaluated in 112 dialysis patients. Performance characteristics of the Versant HCV TMA Assay were evaluated in comparison to the Amplicor((R)) 2.0 HCV test based on polymerase chain reaction (PCR) technique. In addition, anti-HCV serologic tests including third-generation enzyme immunoassay and Recombinant Immunoblot Assay were performed. RESULTS: Of the 112 specimens tested, 29 were reactive by Versant HCV TMA Assay, yielding an overall prevalence of HCV viremia of 25.9%. The concordance between TMA and PCR techniques was excellent [91% (101/112)]. Eleven specimens (10%) were invalid or equivocal by PCR due to interference phenomena; all 11 specimens had valid TMA results (2 patients being TMA reactive and 9 nonreactive). Four specimens [3.6% (4/112)] that tested PCR-negative and HCV TMA nonreactive were anti-HCV seropositive, consistent with resolved HCV infection. In the group of seronegative samples, one was reactive by TMA Assay [1.25% (1/80)]. CONCLUSIONS: The HCV TMA technology seems a highly sensitive tool for detecting HCV RNA in the dialysis population, with no evidence of specimen interference. One EIA-negative but HCV-RNA-positive patient by Versant HCV TMA Assay was identified. Prospective clinical trials are under way to assess the clinical impact related to the use of HCV TMA technology in dialysis population.

Optimal timing for secondary arteriovenous fistula creation: devastating effects of delaying conversion.

A chronic hemodialysis patient was referred to interventional nephrology for evaluation of arteriovenous access dysfunction. The patient had been receiving hemodialysis using a left forearm brachiobasilic loop graft for the past 3 years. Physical examination revealed a hyperpulsatile graft. Angiography documented a critical stenosis at the vein-graft anastomosis and a well-developed basilic vein from the elbow to the axillary region. Central veins were patent all the way to the right atrium. All attempts to navigate the wire across the stenosis failed. The patient was educated and counseled regarding the possibility of surgical creation of a secondary arteriovenous fistula (AVF). The images obtained were shared and discussed with the surgeon. A plan to create a secondary AVF using the basilic vein in the arm was made. A few months later the patient was referred to interventional nephrology, this time for thrombectomy of the same left arm loop graft. Thrombectomy could not be performed and a right internal jugular tunneled catheter was inserted. The patient again was referred to the surgeon for AVF creation. Six weeks later the patient was seen in the interventional laboratory for removal of the right internal jugular tunneled catheter. It was noted that instead of a fistula, the patient had received a right forearm brachiocephalic loop graft. Devastating consequences, such as the lost opportunity to create a fistula, insertion of a tunneled dialysis catheter, arteriovenous graft placement, exhaustion of available sites for fistula creation, and exposure to increased morbidity and mortality associated with grafts and catheters, can result if the opportunity to create a secondary AVF is not availed in a timely manner. This concept must be understood by every member of the vascular access team.

Salvage of problematic peritoneal dialysis catheters.

Peritoneal dialysis (PD) is a markedly underutilized modality for permanent renal replacement therapy in the United States owing to a low rate of patient referral and high rate of patient dropout or transfer to hemodialysis. One cause for patient loss from PD is problematic PD catheters that often are removed rather than being subjected to simple surgical salvage procedures. We report three patients with problematic catheters and our approach to their management. The first patient developed erosion of the skin overlying the portion of the catheter between the deep and superficial cuffs after 6 months of PD. The second patient developed extrusion of the superficial cuff after 4 years of PD. The third patient demonstrated a localized abscess at the incision site for catheter insertion after 3 years of PD. Other than a mild superficial exit site infection and localized abscess in the second and third patient, respectively, there were no associated infections of the catheter tunnel and cuff or of the peritoneal cavity as determined by either clinical examination, ultrasound evidence of fluid collection, or cultures and white blood cell counts. All three cases were managed successfully by interventional nephrology on an outpatient basis and under local anesthesia without either catheter removal or placement of a new PD catheter. It was possible to continue uninterrupted PD in the first and third patients, while the second patient had temporary hemodialysis to allow for complete healing of the surgical wound. We conclude that in selected cases simple interventions can salvage problematic PD catheters and maintain patients on PD.

Strategies to minimize tunneled hemodialysis catheter use.

While the use of arteriovenous grafts has recently declined, there has been an astronomical increase in hemodialysis patients dialyzing with tunneled dialysis catheters (TDCs). Recent data have indicated that over 70% of the patients with end-stage renal disease initiate dialysis with a catheter. Additionally, up to 27% of the end-stage renal disease patients in the US are using TDCs as their permanent access, with placement rates having doubled since 1996. Although most modern catheters claim to provide adequate blood flow for dialysis, they are associated with the highest incidence of complications, morbidity and mortality when compared with other types of vascular access. It is for these reasons that the National Kidney Foundation Dialysis Outcomes Quality Initiative guideline 30 as well as the Fistula First Change Concept 7 emphasize limiting the use of catheters and fostering the creation of arteriovenous fistulae. Early referral has clearly been shown to minimize the use of TDCs and maximize fistulae. This report focuses on the role of additional measures that minimize TDC use, such as dialysis modality presentation and peritoneal dialysis, vascular access education, preoperative vascular mapping and salvage of early failure and thrombosed fistulae.

Creation of secondary arteriovenous fistulas: maximizing fistulas in prevalent hemodialysis patients.

National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) guideline 29 suggests that a patient should be evaluated for a secondary arteriovenous fistula (AVF) following each episode of dialysis access failure. Regretfully, it does not appear that this approach is used, even though recent data have emphasized that veins suitable for the creation of a secondary AVF can be identified in dialysis patients who are receiving dialysis via a synthetic arteriovenous graft (AVG) or other type of potentially dysfunctional vascular access. In this study nine patients (five with an AVG and four with an AVF) with vascular access dysfunction undergoing percutaneous interventions were evaluated for secondary AVF creation. All were found to have suitable vascular anatomy and had the AVF created. The secondary fistula was successful in all nine patients with a mean follow-up of 4.8 +/- 1.4 months in post-AVG cases and 5.6 +/- 1.7 months in the post-AVF patients. In addition, it was possible to continue uninterrupted dialysis without the use of a tunneled dialysis catheter in three of the patients with AVGs. This experience demonstrates the validity and success of this approach to the management of dialysis access dysfunction. In the ongoing effort to optimize vascular health status, we suggest that during percutaneous interventions, patients should routinely have identification of vessels suitable for creation of a secondary AVF.

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.

Vascular access education, planning and percutaneous interventions by nephrologists.

To optimize vascular access care of patients with end stage renal disease, nephrologists themselves are taking a keen interest in the management of vascular access-related issues. Because of their unique clinical perspective on dialysis access and better understanding of the intricacies of renal replacement therapy, nephrologists are ideally suited for this activity. Two areas are the main focus of attention by these specialists: vascular access education and access-related percutaneous interventions. Vascular access-related procedures commonly performed by nephrologists include percutaneous balloon angioplasty for vascular access stenosis, thrombectomy procedure for a thrombosed arteriovenous access, tunneled hemodialysis catheter-related procedures and vascular mapping to determine the patient's optimal vascular access. While the performance of these procedures by nephrologists offers many advantages, appropriate training in order to develop the necessary procedural skills is critical. Recent data have emphasized that a nephrologist can be successfully trained to become a competent interventionalist. In addition to documenting excellent outcome data, multiple reports have demonstrated safety and success when these procedures are performed by nephrologists. This chapter focuses on vascular access education and hemodialysis access-related procedures performed by nephrologist and calls for a proactive approach in optimizing this aspect of patients care.