Hemodialysis access failure: a call to action

Economic burden of repeat renal surgery on solitary kidney--do the ends justify the means? A cost analysis

PURPOSE

Despite the high morbidity of repeat renal surgery in patients with multifocal recurrent renal carcinoma, in most patients adequate renal function is preserved to obviate the need for dialysis. To our knowledge the economic burden of repeat renal surgery has not been evaluated. We provide a cost analysis for patients requiring repeat renal surgery on a solitary kidney.

MATERIALS AND METHODS

We reviewed the charts of patients treated at the National Cancer Institute who required repeat renal surgery from 1989 to 2010. Functional, oncological and surgical outcomes were evaluated and the costs of repeat renal surgery were calculated. We then compared costs in a cohort of 33 patients who underwent repeat renal surgery on a solitary kidney and in a hypothetical patient cohort treated with uncomplicated nephrectomy, fistula placement and dialysis. All costs were calculated based on Medicare reimbursement rates derived from CPT codes. Cost analysis was performed.

RESULTS

Despite a high 45% complication rate, 87% of patients maintained renal function that was adequate to avoid dialysis and 96% remained metastasis free at an average followup of 3.12 years (range 0.3 to 16.4). Compared to the hypothetical dialysis cohort, the financial benefit of repeat renal surgery was reached at 0.68 years.

CONCLUSIONS

Repeat renal surgery is a viable alternative for patients with multifocal renal cell carcinoma requiring multiple surgical interventions, especially when left with a solitary kidney. Despite the high complication rate, renal function is preserved in most patients and they have an excellent oncological outcome. The financial benefit of repeat renal surgery is reached at less than 1 year.

Vascular access in patients receiving hemodialysis in Libya

PURPOSE

A native arteriovenous fistula (AVF) represents the optimal form of Vascular Access (VA) for patients receiving hemodialysis (HD). In Libya there are several barriers to AVF creation including lack of adequate preparation for dialysis and surgical services. We aimed to conduct the first comprehensive study of VA utilisation in HD patients in Libya.

METHODS

A prospective observational study included all adult patients receiving HD treatment in 25 HD facilities in Libya from May 2009 to Nov 2011. Researchers gathered data regarding VA through interviews with staff and patients as well as medical records. Patients with definitive VA were re-interviewed after 1 year.

RESULTS

At baseline the majority of patients (91.9%; n=1573) were using permanent VA in the form of AVF or arteriovenous graft. Patients with permanent VA were more likely to be male and less likely to be diabetic than those with CVCs. Most patients had commenced HD using a temporary CVC (91.8%). VA-related complications were: thrombosis (46.7%), aneurysm (22.6%), infection (11.5%) and haemorrhage (10.2%). Incident VA thrombosis was reported by 14.7% in 1 year. Independent risk factors for incident thrombosis were female gender and diabetes. Hospitalisation for VA related complications was reported by 31.4%.

CONCLUSIONS

Few patients in Libya initiate HD with definitive VA, but most achieve it thereafter. Improved dialysis preparation and increased provision of surgical services are required to increase the proportion of patients initiating HD with definitive VA and should be a priority in rebuilding health services in Libya after the recent conflict.

The effect of new clinical pathways on the outcome of vascular access surgery

PURPOSE

Prior to 2007, the waiting time for vascular access surgery at our center was approximately 107 days compared to a UK average of 45 days. Two new pathways were developed; the rapid and super-rapid pathways incorporating an access liaison nurse who organized vessel mapping and referred patients for surgery. This audit was to determine whether the pathways were effective in reducing the waiting times and improving vascular accesses outcomes.

METHODS

All 210 patients with established renal failure undergoing 232 vascular access procedures between January 2008 and March 2011 were studied. Detailed patient information including type of procedure and cause of access failure were stored in an Excel spreadsheet and analyzed using SPSS for Windows.

RESULTS

One hundred and twenty patients had a brachiocephalic fistula, 61 a radiocephalic fistula, 39 an access using the basilic vein ± transposition, and 11 a transposition of the long saphenous vein and one a brachio-axillary graft. Overall median waiting time from referral to access surgery was 23 days. Patients were followed up for a median of 248 days after surgery. The overall primary failure rate was 9.1% and 25 of 27 accesses failed because of thrombosis. The overall cumulative survival probability of accesses at one year was 61.4% with a mean survival of 621.2 days (SEM = 34.8).

CONCLUSION

The clinical pathways have improved VA service to patients with a drastic reduction in waiting times, elimination of synthetic access, and maintenance of satisfactory results.

Efficient transgene expression from naked DNA delivered into an arterio-venous fistula model for kidney dialysis

BACKGROUND

Patients with kidney failure frequently require the formation of an arterio-venous fistula (AVF) in which a vein is connected to an artery resulting in arterialization of the vein to allow adequate blood flow into an external 'artificial kidney'. In most patients, neo-intimal hyperplasia (NIH) ensues, causing narrowing and subsequent occlusion of the vein, leading to significant morbidity. The cellular events causing venous NIH may serve as ideal targets for molecular-based therapies. However, therapeutic gene delivery into the vascular system is seriously impeded by problems related to the low efficacy and toxicity of targeted viral vector delivery.

MATERIALS AND METHODS

To explore the feasibility of a plasmid-based vascular gene delivery system, we established a rat AVF model that develops NIH. Plasmids encoding for reporter or therapeutic genes were delivered into the blood vessels at the time or after AVF formation.

RESULTS

Intra-luminal injection of plasmid into the AVF resulted in extensive and long-term reporter gene expression at the venous limb mainly at the site of NIH formation. Transgene expression was confined to endothelial cells and myofibroblasts that migrate inwards from the adventitia and form the NIH lesion. There was no detrimental tissue reaction to plasmid delivery, contrasting with the severe inflammatory response observed after adenovirus infection. Intra-vascular delivery of a plasmid carrying the endothelial nitric oxide synthase gene resulted in sustained production of nitric oxide, previously shown to mitigate NIH formation.

CONCLUSIONS

These findings open the possibility of vascular transduction with naked DNA bearing therapeutic genes in areas prone to NIH to ameliorate vein graft pathologies using simple and clinically applicable vector delivery methods.

Aneurysm of the tibial-saphenous fistula in hemodialysis patient: the results of surgical treatment

Arteriovenous fistulas are widely used for hemodialysis patients with end-stage renal failure. Due to the lack of suitable veins because of the arteriovenous fistulas previously opened in the upper extremity, alternative access routes are being tested. Few complications of long-term alternative arteriovenous fistulas have been reported in the literature. We report the results of surgical repairs of aneurysms that occurred on anterior tibial-saphenous arteriovenous fistulas (along the vein) in patients with end-stage renal disease after 5 years on hemodialysis.

Time to move away from damage control strategy in hemodialysis vascular access management: a view from Saudi Arabia

For the last 40 years, most of the research and publications on hemodialysis access, has focused on the management of its complications e.g. thrombosis, infection, aneurysms. In other words, a damage control strategy. While this is undoubtedly an important part of access management, it is a deficient reactive strategy that does not enhance a better quality of life for patients or help reduce the burden on health care resources. To achieve these objectives, efforts should be directed at ways which provide a longer access life with fewer complications. Such an approach would save costs and reduce the suffering of the patient. In this paper we will focus on hemodialysis management in Saudi Arabia, describe the reasons for the current unsatisfactory situation, and highlight possible remedies.

Outcomes of endovascular intervention for salvage of failing hemodialysis access

OBJECTIVE

To investigate the effectiveness of endovascular balloon angioplasty to preserve the patency of failing hemodialysis arteriovenous fistulas (AVF) and prosthetic arteriovenous grafts (AVG).

METHODS

Patients on hemodialysis who received endovascular intervention for access problems were retrospectively analyzed. Fistulography was performed on patients who were suspected to have access stenosis and balloon angioplasty performed in the same setting if a stenosis of ≥50% is detected. Patients were followed up for post-operative complications and access restenosis or failure.

RESULTS

42 hemodialysis patients with 44 access sites (29 AVFs, 15 AVGs) required endovascular balloon angioplasty. There were no perioperative complications. Technical success rate was 100%. Median time from initial access creation to first balloon angioplasty was 13 months (2-146 months) for AVFs and 8 months (2-71 months) for AVGs. 19 of 44 patients subsequently developed restenosis. Median time for restenosis or access failure was 11 months (1-18 months) for AVFs and 5 months (1-10 months) for AVGs. Kaplan-Meier analysis for access patency after endovascular intervention showed 72% patency at 6 months and 32% at 12 months.

CONCLUSIONS

Endovascular balloon angioplasty is effective in restoring patency of failing hemodialysis accesses. Recurrence is common, and repeat interventions are required.

ß-Catenin is markedly induced in a murine model of an arteriovenous fistula: the effect of metalloproteinase inhibition

Neointimal hyperplasia contributes to failure of hemodialysis arteriovenous fistulas (AVFs). Increased expression of matrix metalloproteinase (MMP)-9 occurs in AVFs, and MMP-9 is implicated in neointimal hyperplasia and vascular injury. Recent studies demonstrate that MMP-9, by degrading N-cadherin, leads to increased expression of β-catenin and β-catenin-dependent proliferation of smooth muscle cells. The present study examined this pathway in the venous limb of a murine AVF model. Western analyses demonstrate that, in this model, there is diminished expression of N-cadherin accompanied by increased expression of β-catenin, c-Myc, and proliferating cell nuclear antigen (PCNA). By immunohistochemistry, β-catenin and c-Myc localized to proliferating smooth muscle cells in the venous limb of the AVF. Increased expression of β-catenin was accompanied by augmented expression of phosphorylated (p)-glycogen synthase kinase (GSK)-3β, GSK-3β, and integrin-linked kinase. The administration of doxycycline suppressed MMP-9 expression but did not reduce venous histological injury in the AVF, or increase AVF patency assessed 6 wk after its creation. Doxycycline did not influence expression of β-catenin, c-Myc, GSK-3β, or integrin-linked kinase. Thus, in this vascular injury model, the upregulation of β-catenin cannot be readily attributed to MMP-9 upregulation; increased β-catenin expression may reflect either the upregulation of p-GSK-3β, GSK-3β, or integrin-linked kinase. This study provides the first exploration of β-catenin in an AVF, demonstrating substantial upregulation of this mitogenic signaling molecule and uncovering possible mechanisms that may account for such upregulation.

Pathology of explanted polytetrafluoroethylene vascular grafts

INTRODUCTION

Graft occlusion is a well-documented etiology for arteriovenous fistulae failure. However, there is little morphologic information elucidating why synthetic vascular grafts fail. The purpose of this study was to examine the tissue responses occurring within and adjacent to explanted polytetrafluoroethylene grafts that were utilized during cardiovascular procedures and subsequently removed.

METHODS

Forty explanted polytetrafluoroethylene grafts (including 32 failed vascular grafts) originating from 18 females and 22 males who ranged in age from 6 to 82 years (mean age, 36 years) were evaluated. Duration of engraftment varied from 1 to 255 months (mean engraftment period, 64 months).

RESULTS

In addition to neointimal hyperplasia, foreign body reaction, and thrombosis, an unexpected finding was calcification involving the graft material, as well as luminal thrombus and adjacent soft tissues. Twenty-seven of forty cases (68%) showed evidence of calcification, either within or adjacent to polytetrafluoroethylene grafts. Histologic examination revealed variable degrees and patterns of calcification within and adjacent to explanted polytetrafluoroethylene membranes and conduits (arterial, arteriovenous, or cardiac grafts). A significantly longer duration of engraftment (P=.015) was identified in calcified versus noncalcified polytetrafluoroethylene materials. Patient age, serum calcium, creatinine level, and blood urea nitrogen level showed no statistically significant differences between patients with calcified grafts and patients without calcified grafts.

CONCLUSIONS

Interstitial calcification is frequently found within explanted polytetrafluoroethylene grafts and is associated with graft disruption. These findings suggest that calcification of polytetrafluoroethylene biomaterials may play a role in eventual graft failure. A better understanding of the process of polytetrafluoroethylene graft calcification may lead to novel therapies that aid in the prevention of polytetrafluoroethylene vascular graft failure.

Hemodialysis access failure: a call to action--revisited

Eighty-two percent (82%) of patients initiating hemodialysis in the United States in 2006 did so with a catheter as the functioning access. Even in patients who have been followed by nephrologists for 6 months or more, 74% of patients initiated dialysis with a catheter. This is a multifactoral problem that requires attention and solutions from all stakeholders, including the nephrologist, the vascular surgeon, the hospital, and the insurance industry, as well as the patient and family. We propose a series of specific proposals that include a process for the timely referral and timely placement of a permanent access based on the patient's estimated or measured glomerular filtration rate (GFR), and a 'pay-for-performance' measure for vascular surgeons and nephrologists who admit patients with functional permanent accesses; such pay for performance would place a higher value for patients who are admitted with a functional arteriovenous (AV) fistula than for patients who are admitted with an AV graft. We also propose that hospitals develop a less permissive process for placement of PICC (peripherally inserted central catheters) lines in patients with GFR <60 ml/min and to consider surgery for access placement as 'urgent'. Finally, a more proactive educational process for patients and their families, including an 'informed non-consent' for patients who defer placement of a permanent access needs to be considered. The morbidity, mortality, and health-care costs associated with prolonged catheter use mandate urgent attention to this problem.

The significance of the timing of referral for renal care

Research has shown that referral of patients in the stages of renal disease, to a Nephrologist has significant impact on the patients overall health and well-being. This article is a review of the literature discussing the key impact that late referral has on the patient. This will include looking at the preparation of the patient for dialysis-education and vascular access as well as discussing the modality choice for the patient. It will also address the longer-term impact such as patient survival on dialysis.

A method for monitoring vascular access function during hemodialysis

We tested a new bedside method to determine the function of native arteriovenous fistula in 16 patients performed during hemodialysis without stopping the treatment. We initially measured vascular access flow (Q(a)) in each patient using the Transonic HD01(plus) device. We then measured the pressure in arterial and venous drip chambers at different blood pump flow rates (Q(bset)=0, 50, 100, 250, 300, 350 ml/min). The intravascular blood pressure gradient (P(f)) between arterial and venous puncture sites was estimated by a mathematical model. P(f) was positive for low Q(bset), but became negative when Q(bset) overcame the threshold value (Q(Inv)). Such critical flow showed a high correlation with Q(a), even if it was systemically lower. Computer analysis of fluid dynamics showed that when the blood pump flow overcame the Q(Inv) threshold, a critical transition from laminar flow to vortex circulation took place downstream of the venous needle, causing a dangerous shearstress on the vessel wall. Our results show that Q(Inv) provides an indication of the maximal blood pump flow rate needed to be reached to maximize blood flow supply in order to limit hemodynamic stress on the vascular access.

Current practice perspectives on the management of thrombosis in children with renal insufficiency: the results of a survey of pediatric hematologists in North America

BACKGROUND

No guidelines exist for the management of venous thromboembolic events (VTE) in children with renal insufficiency (RI).

OBJECTIVE

To define current practice patterns of VTE management in children with RI.

METHODS

An online multiple choice survey encompassing general questions/clinical scenarios related to thrombosis in RI.

STUDY PARTICIPANTS

Pediatric hematologists who were members of Hemophilia and Thrombosis Research Society (HTRS) of North America.

RESULTS

Response rate was 54% (39/75). VTE was perceived as the major hemostatic problem in children with RI by half (20/39) of respondents. All respondents used anticoagulation for treatment of VTE while 56% used it for prophylaxis of VTE in this population. Management practices varied with respect to choice of anticoagulants employed, consideration of prophylactic anticoagulation, and evaluation for hereditary thrombophilia. Low molecular weight heparin was perceived as a safe anticoagulation for VTE treatment by 77% of respondents given that anti-factor Xa monitoring was performed to assess bioaccumulation in RI. Thromboprophylaxis was considered for preventing thrombosis at central venous catheter, renal allo-graft and arterio-venous fistula in the context of previous history of thrombosis and congenital/acquired thrombophilia. The majority (>70%) would treat life-threatening emergencies such as superior vena cava syndrome with fibrinolytics despite RI.

CONCLUSIONS

This pediatric study documents that substantial variability existed among pediatric hemologists with respect to VTE management in children with RI. Larger studies are required to better define the epidemiology and management of VTE in children with RI including the value of screening for underlying hereditary thrombophilia.

Catheter-related mortality among ESRD patients

Hemodialysis access-related complications remain one of the most important sources of morbidity and cost among persons with end-stage renal disease, with total annual costs exceeding $1 billion annually. In this context, the creation and maintenance of an effective hemodialysis vascular access is essential for safe and adequate hemodialysis therapy. Multiple reports have documented the type of vascular access used for dialysis and associated risk of infection and mortality. Undoubtedly, the central venous catheter (CVC) is associated with the greatest risk of infection-related and all-cause mortality compared with the autogenous arteriovenous fistula (AVF) or synthetic graft (AVG). The AVF has the lowest risk of infection, longer patency rates, greater quality of life, and lower all-cause mortality compared with the AVG or CVC. It is for these reasons that the National Kidney Foundation's Kidney Disease Outcome Quality Initiative Clinical Practice Guidelines for Vascular Access recommend the early placement and use of the AVF among at least 50% of incident hemodialysis patients. This report presents catheter-related mortality and calls for heightened awareness of catheter-related complications.

Consistent aspirin use associated with improved arteriovenous fistula survival among incident hemodialysis patients in the dialysis outcomes and practice patterns study

BACKGROUND AND OBJECTIVES

The relationship between aspirin use and arteriovenous fistula (AVF) survival has been lacking. The aim of this study was to evaluate the association between AVF survival and aspirin use.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data on 2815 incident hemodialysis patients (on dialysis <or= 30 d) using an AVF at enrollment into the Dialysis Outcomes and Practice Patterns Study between 1996 and 2004 were analyzed. Cox regression was used to examine the association between aspirin use and the risk of final AVF failure, first AVF failure, and a gastrointestinal bleeding event. Aspirin use was determined at baseline and one year later. Patients using aspirin at baseline and one year later were considered consistent aspirin users. All models accounted for facility clustering effects and were adjusted for age, race, gender, body mass index, prior permanent access failure, prior placement of a catheter, 10 comorbid conditions, laboratory data, and other medications, and stratified by regions.

RESULTS

Consistent aspirin use was significantly related to a lower risk of final AVF failure. Facility-level analysis, which may reduce confounding by indication, also showed a nearly significant trend of reduced risk of final AVF failure with greater prevalence of consistent aspirin use within dialysis facilities (P for trend = 0.07). The occurrence of a new gastrointestinal bleeding event during the study period was not associated with aspirin use.

CONCLUSIONS

These results suggest that consistent aspirin use may be beneficial for AVF survival among incident hemodialysis patients.

Vascular access infection among hemodialysis patients in Northern Jordan: incidence and risk factors

OBJECTIVES

Vascular access infection (VAI) causes significant mortality and morbidity in hemodialysis patients. The aim of this prospective, descriptive, exploratory survey of end-stage renal disease patients was to explore the incidence and risk factors of VAI.

METHODS

A total of 188 patients were included in the study from five different hospital/dialysis units in northern Jordan. All patients answered a questionnaire related to their vascular access (VA) and infection. Demographic information, etiology of renal failure, and infection history related to the access were also collected and analyzed.

RESULTS

Diabetes mellitus was the most common etiology of renal failure, followed by hypertension, urinary tract infection, and congenital malformation. The infection rate was variable according to the hospital and the type of VA; of 188 patients, 65 patients had a VAI during the year of study. Of these, 36 of 64 were because of catheters, 24 of 105 were because of arteriovenous fistulas (AVFs), and 5 of 19 were because of arteriovenous graft. Of the 65 with a VAI, 58 patients had a low level of education.

CONCLUSIONS

VAI was common in hemodialysis patients, and the risk varied substantially among different VA types and different dialysis units. The infection rate from catheters and AVFs was similar to that reported in many studies, but the infection rate in the arteriovenous graft group was lower than that for AVFs. These results can be improved by strictly following the National Kidney Foundation Disease Output Quality Initiative clinical practice guidelines for dialysis access.

Genetic deficiency of heme oxygenase-1 impairs functionality and form of an arteriovenous fistula in the mouse

Vascular access dysfunction contributes to patient morbidity during maintenance hemodialysis. In this study we determined if knockout of heme oxygenase-1 predisposed to malfunction of arteriovenous fistulas. After three weeks, all fistulas in wild type mice were patent whereas a third of the fistulas in knockout mice were occluded and these exhibited increased neointimal hyperplasia and venous wall thickening. Heme oxygenase-1 mRNA and protein were robustly induced in the fistulas of the wild type mice. In the knockout mice there was increased PAI-1 and MCP-1 expression, marked induction of MMP-2 and MMP-9, but similar expression of PDGF alpha, IGF-1, TGF-beta1, VEGF, and osteopontin compared to wild type mice. We conclude that heme oxygenase-1 deficiency promotes vasculopathic gene expression, accelerates neointimal hyperplasia and impairs the function of arteriovenous fistulas.

Long-term engraftment of bone marrow-derived cells in the intimal hyperplasia lesion of autologous vein grafts

Intimal hyperplasia of autologous vein grafts is a critical problem affecting the long-term patency of many types of vascular reconstruction. Within intimal hyperplasia lesions, smooth muscle cells are a major component, playing an essential role in the pathological process. Given that bone marrow-derived cells may differentiate into smooth muscle cells in the neointima of injured arteries, we hypothesized that the bone marrow may serve as a source for some of the smooth muscle cells within intimal hyperplasia lesions of vein grafts. To test this hypothesis, we used an established mouse model for intimal hyperplasia in wild-type mice that had been transplanted with bone marrow from a green fluorescent protein (GFP+/+) transgenic mouse. High-resolution confocal microscopy analysis performed 2 and 8 weeks after grafting demonstrated expression of GFP in 5.4 +/- 0.8% and 11.9 +/- 2.3%, respectively, of smooth muscle cells within intimal hyperplasia lesions. By 16 weeks, GFP expression in smooth muscle cells was not detected by immunohistochemistry; however, real-time PCR revealed that 20.2 +/- 1.7% of the smooth muscle cells captured from the neointima lesion by laser capture microdissection at 16 weeks contained GFP DNA. Our results suggest that bone marrow-derived cells differentiated into smooth muscle cells within the intimal lesion and may provide a novel clinical approach for decreasing intimal hyperplasia in vein grafts.

Accuracy of physical examination and intra-access pressure in the detection of stenosis in hemodialysis arteriovenous fistula

Both physical examination (PE) and intra-access pressure (IAP) measurements have been used in the identification of stenosis in an arteriovenous access. The aim of this study was to evaluate the accuracy of PE and IAP in the diagnosis of arteriovenous fistula (AVF) stenosis. A total of 84 patients were enrolled in the study (54% men, mean age of 50.7 +/- 12.7 years and mean AVF patency of 24.9 +/- 7.8 months, 52% radiocephalic). Abnormalities of pulse and thrill were used as the diagnostic tools for the detection of stenosis using the physical examination. For IAP, stenosis was suspected when the ratio between IAP at the arterial puncture site and the mean blood pressure was <0.13 or >0.43. The diagnosis of stenosis was confirmed by Doppler ultrasound (DU). Sensitivity (S), specificity (SP), positive predictive value (PPV), negative predictive value (PNV), and accuracy were calculated for the two early detection tests. According to DU, 50 (59%) AVF were considered positive for the presence of stenosis. Fifty-six (66%) AVF were considered positive for the presence of stenosis by PE and 34 (40%) by IAP. S, SP, PPV, and NPV for PE and IAP were 96%, 76%, 86%, and 93% and 60%, 88%, 88%, and 60%, respectively. The accuracy for PE and IAP was 88% and 71%, respectively. PE proved to be an accurate method for the diagnosis of stenosis and should be part of all surveillance protocols of stenosis detection in AVF.

Predictors of early dialysis vascular-access failure after thrombolysis

BACKGROUND

Vascular-access patency is critical for effective and uninterrupted haemodialysis. Limited literature exists evaluating if a surgical or repeated radiological approach is superior for reocclusion following failure of radiological recanalization. Few consistent early predictors of failure have been identified after radiological intervention for thrombosed vascular access.

METHODS

138 patients with thrombosed arteriovenous fistulas or prosthetic grafts treated by radiological intervention, over 10 years, were retrospectively investigated. Reocclusion was treated by either repeated thrombolysis or surgery. Radiological patency rates, after first and second episodes of access thrombosis at 12 months after intervention were analysed. Surgical and radiological patency rates for second access thrombosis were compared. The Cox and logistic regression models were used to identify potential factors associated with reocclusion.

RESULTS

In patients who experienced reocclusion within 1 month after radiological intervention, the 3-month repeated radiological patency rate (n = 13) was 38.5%, compared to a 60% surgical patency rate (n = 10), but this did not reach statistical significance. Radiological patency rates after first access thrombosis at 3 and 12 months were 56.6 and 39.5%, respectively. In contrast, radiological patency rates after a second access thrombosis were 51.1 and 24.4%, respectively; a statistical difference in success was not achieved. Native arteriovenous fistulas were 3.23 times as likely to remain patent over 12 months following a first radiological intervention (p < 0.02) and less likely to experience a second reocclusion event (p < 0.01). Anticoagulation was associated with a lower risk of second reocclusion, whilst a history of venous thrombosis was associated with a greater risk (p < 0.02).

CONCLUSION

Surgery achieves superior patency rates compared to repeated radiological interventions and should be considered if reocclusion occurs within a month following radiological thrombolysis.

Ultrasonographic maturation of native arteriovenous fistulae: a follow-up study

BACKGROUND/AIMS

Ideal time needed for arteriovenous fistula (AVF) maturation is still controversial. In this study, we aimed to investigate the natural course of AVF maturation and also investigated the factors affecting AVF maturation.

METHODS

We studied 31 (21M/10F, mean age 55.8 +/- 16.2) chronic renal failure patients. We evaluated the patients with color Doppler ultrasound examination before the fistula operation, at the first day, and at the first, second, third, and sixth months. Radial artery (RA) diameter, flow velocity, flow, resistance index, fistula vein diameter, flow velocity, and flow were measured.

RESULTS

Patency rates at the first post-operative day and the sixth month were 87.1% and 67.1%, respectively. Cephalic vein flow was 451.2 +/- 248.6 mL/min at the first month and 528.6 +/- 316.5 mL/min at the sixth month. Baseline RA diameter was lower in failing fistulas than that of patent fistulas. Failing fistulas were more common in women.

CONCLUSION

Blood flow was enough for hemodialysis at the end of the first month. However, fistula maturation had continued until the end of the study; women and patients with low RA diameter are particularly prone to fistula failure. Therefore, especially in these patients, AVF must be created at least three or four months before the predicted hemodialysis initiation time.

Catheter malfunction due to spontaneous permcath displacement into medium suprahepatic vein

One of the last options, when the other possibilities of vascular access present malfunction, is the insertion of a permanent catheter in a central vein, preferentially internal jugular vein. This option is considered when arteriovenous access is impossible. We report a case of malfunction due to a permanent catheter dis-placement solved by vascular interventional radiology.

Efficiency and Outcomes of Emergent Vascular Access Procedures Performed at a Dedicated Outpatient Vascular Access Center

The outpatient vascular access center (VAC) may have an important impact in improving the outcomes of emergent procedures on nonfunctioning hemodialysis access. An emergent procedure is defined as the absence of a functioning access for hemodialysis, including thrombosed graft or fistula, nonfunctioning dialysis catheters, and the need for access to initiate emergent hemodialysis. The aim of this study was to prospectively evaluate the efficiency and outcomes of all consecutive emergent hemodialysis access procedures during a 3-month period at a single high volume VAC. Data collection for each procedure included anatomic outcome, clinical outcome, the amount of time from referral to procedure and to successful dialysis, 2-week-follow-up to screen for postprocedure complications and fluoroscopy time. A total of 157 emergent procedures were performed in 136 patients with the majority of interventions on nonfunctioning grafts and tunneled catheters. The overall clinical success (defined as successful postprocedure completion of at least one dialysis treatment at the prescribed blood flow) was achieved in 149 out of 157 (95%) cases. 90% of subjects completed their procedure within 24 hours of the initial referral to the VAC. The study also demonstrated a rapid turn around time, with successful dialysis being performed within 24 hours of referral in 61% and within 48 hours in 90% of referrals. This is the first study to demonstrate both the efficiency and successful outcomes of an outpatient vascular access center in treating emergent vascular access problems.

Local Activation of Interleukin 6 Signaling Is Associated With Arteriovenous Fistula Stenosis in Hemodialysis Patients

BACKGROUND

Vascular access failure is the main cause of morbidity in hemodialysis patients. Stenosis of the arteriovenous fistula (AVF) is similar histologically to atherosclerosis. Recent studies showed that interleukin 6 (IL-6) has a key role in the pathogenesis of atherosclerosis by binding 2 specific receptors, gp80 and gp130. When activated, gp130 interacts with a tyrosine kinase, Janus kinase (JAK2), which then activates a transcription factor, signal transducers and activators of transcription (STAT3), directly turning on several proinflammatory genes. The aim of this study is to evaluate gp130 expression and JAK2/STAT3 activation within stenotic AVFs.

METHODS

44 patients undergoing surgery for AVF creation were enrolled; 10 of them had AVF failure with histologically proven AVF stenosis (wall-lumen ratio > 1). A venous fragment of the AVFs was collected during creation and revision of the vascular access. gp130 and gp80 expression, as well as JAK/STAT activation, were evaluated by means of confocal microscopy. Peripheral-blood mononuclear cells were isolated at the time of AVF creation and revision.

RESULTS

gp130 protein expression, barely detectable in native AVFs, was strikingly increased within the venous branch of stenotic AVFs. The signaling subunit of the IL-6 receptor broadly colocalized with gp80, the IL-6-binding subunit. gp130-expressing cells were mainly CD34(+), suggesting that this receptor is expressed primarily by neovasculature endothelial cells. At the same time, a significant increase in phosphorylation of JAK2/STAT3 was observed in endothelial cells of stenotic AVFs. Interestingly, peripheral-blood mononuclear cells isolated at the time of AVF failure presented strikingly greater IL-6 expression compared with dialysis age-matched controls.

CONCLUSION

IL-6 receptor activation may have a role in the pathogenesis of AVF failure in hemodialysis patients and may represent a potential therapeutic target in this setting.

Predictors of delayed transition from central venous catheter use to permanent vascular access among ESRD patients

BACKGROUND

Early arteriovenous fistula (AVF) creation is necessary to curb the use of central venous catheters (CVCs) and reduce their complications. We sought to examine patient characteristics that may influence persistent CVC use 90 days after dialysis therapy initiation among patients using a CVC.

METHODS

Data from the 1999 to 2003 Clinical Performance Measures Project was linked to the Centers for Medicare & Medicaid Services Medical Evidence (2728) form.

RESULTS

Most patients (59.4%) starting dialysis with a CVC failed to transition to permanent access within 90 days, whereas 25.4% received a graft and only 15.2% received an AVF. Older patients (>75 years) were more than 2-fold more likely to remain CVC dependent at 90 days (P = 0.0.001) compared with those younger than 50 years. In addition, race and sex were highly predictive of CVC dependence at 90 days; black females, white females, and black males were 75% (P < 0.001), 61% (P < 0.001), and 35% (P = 0.023) more likely than white males to maintain CVC use, whereas patients with ischemic heart disease and peripheral vascular disease were 35% (P = 0.023) and 39% (P = 0.007) more likely to remain CVC dependent at 90 days, respectively.

CONCLUSION

Prolonged CVC dependence is more likely to occur among patients of older age, females, blacks, and those with cardiovascular comorbidity, suggesting inadequate or late access referral or greater primary access failure. Our findings suggest possible missed opportunities for early conversion of patients to permanent vascular access that may vary by race and sex.

Tunnelled Catheters for the Haemodialysis Patient

Haemodialysis depends upon the establishment of a durable means of vascular access. Although the creation of a successful arterio-venous Fistulae (AVF) is the ideal, this is not always possible or practical. Tunnelled catheters play an important role as an interim/bridge technique for emergency access or while an AVF matures, but may be associated with significant morbidity. The aim of this review is to highlight recent evidence based developments in tunnelled catheters, including methods of placement, complications and possible management strategies.

Effects of venous needle turbulence during ex vivo hemodialysis on endothelial morphology and nitric oxide formation

Arteriovenous grafts used for hemodialysis frequently develop intimal hyperplasia (IH), which ultimately leads to graft failure. Although the turbulent jet from the dialysis needle may contribute to vessel wall injury, its role in the pathogenesis of IH is relatively unexplored. In the current study, using bovine aortic endothelial cells (BAEC) cultured on the inner surface of a compliant tube, we evaluated the effects of simulated hemodialysis conditions on morphology and nitric oxide (NO) production. The flows via the graft and needle were 500 ml/min (Reynolds number=819) and 100ml/min (Reynolds number=954), respectively. In the presence of the needle jet for 6h, 19.3% (+/-1.53%) of BAEC were sheared off, whereas no loss of BAEC was observed in the presence of graft flow alone (P<0.05). In the presence of graft flow alone, assessment of cell orientation by the Saltykov method revealed that BAEC were oriented along the flow direction. This alignment, however, was lost in the presence of needle flow. Finally, NO production was also significantly decreased in the presence of the needle flow compared to the presence of graft flow alone (16+/-3.1 vs 34.7+/-1.9 nmol/10(6)cells/h, P<0.05). NO is a key player in vascular homeostasis mechanisms modulating vasomotor tone, inhibiting inflammation and smooth muscle cell proliferation. Thus, the loss of NO signaling and the loss of endothelial integrity caused by needle jet turbulence may contribute to the cascade of events leading to IH formation during hemodialysis.

Vascular Access Outcomes and Medication Use: A USRDS Study

Several medications have been proposed to improve hemodialysis (HD) vascular access outcomes based on potentially favorable anticoagulant, antiplatelet, or pleiotropic properties. The purpose of this study was to evaluate the relationship between medication use and vascular access patency in a group of HD patients. We conducted a historical cohort study of the US Renal Data System Dialysis Mortality and Morbidity Wave II study to identify patients with an arteriovenous fistula (AVF), polytetrafluoroethylene (PTFE) graft, or a permanent catheter for vascular access. Cox regression analysis, adjusted for age, gender, race, history of coronary artery disease, peripheral vascular disease, or coronary artery bypass graft, was used to model the hazard ratio (HR) of permanent vascular access failure. Of the 2001 HD patients in the Wave II study, 901 (45%) were included in the analysis. PTFE graft patency was greater for males (HR, 0.73; 95% CI 0.53-1.00, p = 0.05) and for older individuals (HR, 0.99; 95% CI 0.98-1.00, p = 0.02). Treatment with antiplatelet medications, ticlopidine and dipyridamole (HR, 3.54; 95% CI 1.07-11.76; p = 0.04), or aspirin (HR, 2.49; 95% CI 1.31-4.73; p = 0.005) was associated with significantly worse AVF patency. Antiplatelet agents had a significant negative association with access patency in this cohort. In contrast to other published data, it was difficult to identify any beneficial effect of specific medications on access patency.

Tratamento cirúrgico da "síndrome do roubo" em acesso vascular para hemodiálise com revascularização distal e ligadura arterial

OBJETIVO: O propósito do trabalho é apresentar o resultado do tratamento da "síndrome do roubo", sintomática em acesso vascular para hemodiálise, utilizando a técnica da revascularização distal com ligadura arterial. PACIENTES E MÉTODOS: No período de dezembro de 2003 a novembro de 2004, quatro pacientes que apresentaram síndrome do roubo sintomática em acesso vascular para hemodiálise foram submetidos à revascularização distal com ligadura arterial e acompanhados até dezembro de 2005. Os quatro pacientes apresentavam dor de repouso, e dois casos evoluíram para lesão trófica. RESULTADOS: Todos os casos apresentaram regressão dos sintomas, com cicatrização das lesões tróficas e manutenção do acesso vascular, que continuou sendo utilizado para realização de sessões de hemodiálise. CONCLUSÕES: Concluímos que, atualmente, o tratamento de escolha da síndrome do roubo sintomática é a revascularização distal com ligadura arterial, pois, além de tratar a isquemia do membro, mantém o acesso vascular funcionante.

Advantages and disadvantages of surgical placement of PD catheters with regard to other methods

Peritoneal dialysis is underused for various reasons. One reason may be problems with insertion of catheters for access. Another reason is the delayed start (break-in period) of about 2 weeks after operation. This review describes various approaches to the insertion of a peritoneal dialysis catheter. The optimal conditions to strive for are given as is an overview of various techniques. This article favours surgical placement while others might prefer other techniques. Described is the use a 3-purse string suture technique that allows immediate start of dialysis after catheter insertion both for acute dialysis indications as well as for acute start in chronic dialysis patients. A key to lesser complications is to establish a team devoted to the insertions rather than to allow various physicians to perform insertions as a training procedure. An optimal access is one of the important life lines for these patients.

Time-Resolved 3D MR Angiography with Parallel Imaging for Evaluation of Hemodialysis Fistulas and Grafts: Initial Experience

OBJECTIVE

We optimized a time-resolved 3D contrast-enhanced MR angiography sequence with integrated parallel imaging technique that can provide a large field of view with high temporal and spatial resolution, by which the hemodialysis access and the entire course of the inflow and outflow vessels can be imaged at a single anatomic station. Our objective was to evaluate the feasibility and usefulness of this method in the evaluation of patients referred for possible abnormalities in hemodialysis access.

CONCLUSION

Time-resolved contrast-enhanced 3D MR angiography with parallel imaging has the potential to provide a rapid and comprehensive evaluation for the surveillance and diagnosis of hemodialysis access malfunctions. This technique may function as an important complement to conventional digital subtraction angiography and may be able to help guide medical management. The MR angiography protocol we present is a noninvasive, versatile, and time-efficient technique, without the need of direct graft puncture or flow interruption, and can be performed using a single injection of contrast material at a single station.

Associations between demographic factors and provider structures on cost and length of stay for hemodialysis patients with vascular access failure

Vascular access failure (VAF) is a major determinant of morbidity and cost for hemodialysis patients, but little is known about the care patterns and cost implications that are associated with VAF. A total of 952 episodes of VAF in 348 patients were identified using specific procedure codes. Demographic and care pattern characteristics were available as were detailed costs for each episode. The determinants of several important performance measures were evaluated: Cost per episode, inpatient versus outpatient treatment, and length of stay (LOS). Over 5 yr of study, the proportion of VAF episodes that were treated on an outpatient basis increased from 31 to 63%. Average costs of outpatient versus inpatient episodes were $1491 and $8265, respectively. Men were more likely to be treated as outpatients (odds ratio [OR] 1.56; 95% confidence interval [CI] 1.17 to 2.08), but once admitted, their LOS was longer (difference LOS +1.3; 95% CI +0.32 to +2.28) and more costly (delta$ +2603; 95% CI +632 to +4573). Nonblack, nonwhite patients were more likely to be treated as outpatients than were white patients (OR 2.07; 95% CI 1.27 to 3.36) and had shorter LOS once admitted (deltaLOS -2.37; 95% CI -4.23 to -0.49). Compared with Medicare, non-Medicare case-managed insurance was associated with a higher likelihood of outpatient treatment (OR 1.40; 95% CI 1.01 to 1.94) for VAF and shorter LOS (deltaLOS -1.36; 95% CI -2.48 to -0.24) and lower costs (delta$ -2742; 95% CI -5012 to -472) for inpatient treatment. It is concluded that gender and racial factors may influence VAF care. Over time, more VAF episodes are being treated in outpatient settings. Case management may lead to more outpatient treatment and shorter inpatient treatment of VAF.

Design of the Dialysis Access Consortium (DAC) Clopidogrel Prevention of Early AV Fistula Thrombosis Trial

BACKGROUND

The Dialysis Access Consortium (DAC) was developed to investigate interventions to improve hemodialysis vascular access outcomes. The autogenous arteriovenous fistula created by direct connection of native artery to vein is the recommended vascular access for hemodialysis. However, it fails frequently due to clotting after surgery.

PURPOSE

The DAC Early AV Fistula Thrombosis Trial tests the hypothesis that clopidogrel can prevent early fistula failure and increase the number of fistulas that ultimately become usable for hemodialysis access. This is one of two initial and concurrent trials being performed by the DAC. The companion trial investigates pharmacologic approaches to prevent venous stenosis leading to AV graft failure.

METHODS

This is a multicenter, randomized, double-blind, placebo-controlled trial that will enroll 1,284 patients over four years. Patients undergoing creation of a new native arteriovenous (AV) fistula are randomized to treatment with clopidogrel or placebo for six weeks following fistula creation surgery. The primary outcome is fistula patency at six weeks. The major secondary outcome is fistula suitability for dialysis.

RESULTS

This paper examines key aspects of this study that have broad relevance to trial design including: 1) the selection of an intermediate event as the primary outcome, 2) timing of the intervention to balance efficacy and safety concerns, 3) ethical considerations arising from required modifications of concomitant drug therapy, and 4) choosing an efficacy or effectiveness evaluation of the intervention.

CONCLUSIONS

This is the first, large, multicenter trial evaluating a pharmacologic approach to prevent early AV fistula failure and promote more usable fistulas for hemodialysis. The methodologic challenges identified and addressed during the development of this trial should help to inform the design of future vascular access trials, and are relevant to clinical trials addressing a wide range of questions.

American Society of Diagnostic and Interventional Nephrology Section Editor: Stephen Ash: Stenosis Surveillance of Hemodialysis Grafts by Duplex Ultrasound Reduces Hospitalizations and Cost of Care

Most recent randomized controlled trials (RCTs) have found that hemodialysis graft surveillance combined with preemptive correction of stenosis does not prolong graft survival. Nevertheless, such programs may be justified if they reduce other adverse outcomes or decrease the cost of care. This study tested this hypothesis by applying a secondary analysis to our original RCT. This study of 101 patients evaluated correction of stenosis based upon blood flow (Q) and stenosis surveillance. Patients were randomly assigned to control, flow, or stenosis groups, and were followed for up to 28 months. Q was measured monthly by ultrasound dilution; stenosis was measured quarterly by duplex ultrasound. Stenosis of 50% was corrected by percutaneous transluminal angioplasty (PTA) after referral for angiography. Referral criteria were: control group, clinical criteria; flow group, Q < 600 ml/min or clinical criteria; stenosis group, stenosis > 50% or clinical criteria. We compared access-related hospitalizations and cost of care, and use of central venous dialysis catheters (CVCs), among the three groups. Hospitalization rates were higher in the control and flow groups than in the stenosis group (0.50, 0.57, 0.18/patient-year, respectively [p < 0.01]), and hospitalization costs were lowest in the stenosis group (p = 0.026). The stenosis group had a trend toward lowest CVC rates (0.44, 0.32, 0.20/patient-year, respectively [p = 0.20]). The costs of care were higher in the control and flow groups than in the stenosis group (dollar 3727, dollar 4839, dollar 3306/patient-year, respectively [p = 0.015]). The costs of stenosis (dollar 142/patient-year) and Q (dollar 279/patient-year) measurements were minimal compared to the total cost of access-related care. In conclusion, stenosis surveillance by duplex ultrasound combined with preemptive correction yielded reduced hospitalization rates and costs, reduced total cost of access-related care, and a trend of reduced CVC rates. In contrast, flow surveillance did not yield a significant benefit. Stenosis surveillance provides important benefits that may justify application of such programs.