Microinflammation is involved in the dysfunction of arteriovenous fistula in patients with maintenance hemodialysis:

Nitric oxide releasing nanomatrix gel treatment inhibits venous intimal hyperplasia and improves vascular remodeling in a rodent arteriovenous fistula

Vascular access is the lifeline for hemodialysis patients and the single most important component of the hemodialysis procedure. Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients, but nearly 60% of AVFs created fail to successfully mature due to early intimal hyperplasia development and poor outward remodeling. There are currently no therapies available to prevent AVF maturation failure. First, we showed the important regulatory role of nitric oxide (NO) on AVF development by demonstrating that intimal hyperplasia development was reduced in an overexpressed endothelial nitric oxide synthase (NOS3) mouse AVF model. This supported the rationale for the potential application of NO to the AVF. Thus, we developed a self-assembled NO releasing nanomatrix gel and applied it perivascularly at the arteriovenous anastomosis immediately following rat AVF creation to investigate its therapeutic effect on AVF development. We demonstrated that the NO releasing nanomatrix gel inhibited intimal hyperplasia formation (more than 70% reduction), as well as improved vascular outward remodeling (increased vein diameter) and hemodynamic adaptation (lower wall shear stress approaching the preoperative level and less vorticity). Therefore, direct application of the NO releasing nanomatrix gel to the AVF anastomosis immediately following AVF creation may enhance AVF development, thereby providing long-term and durable vascular access for hemodialysis.

Is fetuin-A a biomarker of dialysis access dysfunction?

BACKGROUND

The arteriovenous (AV) access function of hemodialysis (HD) patients can be impaired by afferent artery stiffness due to preexisting microcalcification and by venous stenosis secondary to neointimal hyperplasia in whose development participates an upregulated local inflammatory process. Fetuin-A is a circulating potent inhibitor of vascular calcification and plays an important anti-inflammatory role. The aims of this prospective study were to investigate the relationship between baseline serum fetuin-A levels and: blood flow (Q_A) values at baseline, AV access failure (thrombosis or intervention for stenosis) during follow-up and primary unassisted AV access patency.

METHODS

We measured baseline serum fetuin-A levels and Q_A values of the AV access in 64 HD patients under routine Q_A surveillance for stenosis. Patients were classified into tertiles according to their baseline fetuin-A levels (g/L): <0.5 (tertile-1), 0.5-1.20 (tertile-2), and >1.20 (tertile-3).

RESULTS

Fetuin-A was positively correlated with Q_A (Spearman coefficient = 0.311, p = 0.012). Fourteen patients (21.9%) underwent AV access failure and they had lower fetuin-A (0.59 ± 0.32 g/L) and lower Q_A (739.4 ± 438.8 mL/min) values at baseline compared with the remaining patients (1.05 ± 0.65 g/L and 1273.0 ± 596.3 mL/min, respectively) (p = 0.027 and p < 0.001, respectively). The AV access failure rate was highest (34.8%) in tertile-1 (lowest fetuin-A level). Unadjusted Cox regression analysis showed a decrease in the risk of AV access patency loss by increasing fetuin-A concentration (hazard ratio 0.395 (95% confidence interval: 1.42-1.69), p = 0.044) but it was not confirmed in the adjusted model, although the hazard ratio was low (0.523). Kaplan-Meier analysis showed that patients in tertile-3 (highest fetuin-A concentration) had the highest primary unassisted AV access patency (λ² = 4.68, p = 0.030, log-rank test).

CONCLUSION

If our results are confirmed in further studies, fetuin-A could be used as a circulating biomarker to identify HD patients at greater risk for AV access dysfunction, who would benefit from much closer dialysis access surveillance.

Arteriovenous fistula maturation and the influence of fluid dynamics

Arteriovenous fistula creation is the preferred vascular access for haemodialysis therapy, but has a large failure rate in the maturation period. This period generally lasts 6 to 8 weeks after surgical creation, in which the vein and artery undergo extensive vascular remodelling. In this review, we outline proposed mechanisms for both arteriovenous fistula maturation and arteriovenous fistula failure. Clinical, animal and computational studies have not yet shown a definitive link between any metric and disease development, although a number of theories based on wall shear stress metrics have been suggested. Recent work allowing patient-based longitudinal studies may hold the key to understanding arteriovenous fistula maturation processes.

Elevated Serum Interleukin-18 Level is Correlated with Vascular Access Dysfunction in Patients on Maintenance Haemodialysis

Introduction: We evaluated the impact of serum interleukin-18 (IL-18) level on short-term vascular access (VA) function in chronic haemodialysis (HD) patients. Materials and Methods: Samples were collected from 80 clinically stable patients (58.8% were men) with a mean age of 60.9 years (standard deviation 11.7 years) who were undergoing maintenance HD and were followed up for 1 year. Multivariate logistic regression was used to analyse data on demographics, biochemical parameters and serum IL-18 level to predict VA dysfunction events. The cut-off for IL-18 was derived from the highest score obtained on Youden index. Survival data was analysed using Cox proportional hazards regression analysis and Kaplan-Meier method. Results: Patients were classified as having either low IL-18 (<199.3 pg/mL) or high IL-18 (≥199.3 pg/mL). Multivariate logistic regression showed that serum IL-18 level was independently correlated with VA dysfunction events; patients with high IL-18 had a higher risk of VA dysfunction events than those with low IL-18 (odds ratio 9.47, 95% confidence interval 1.75–51.31, P = 0.009). In patients with high IL-18, Kaplan- Meier survival analysis found that incidence of VA dysfunction was significantly higher than patients with low IL-18 (P = 0.047). After adjustment for age, gender, inflammation (C-reactive protein) and calcium-phosphorus metabolism, decreased serum albumin and increased serum IL-18 levels were found to be independent prognostic predictors of VA dysfunction. Conclusion: HD patients with high IL-18 level tend to have worse rates of VA dysfunction. In HD outpatients, IL-18 is an independent risk factor for short-term VA dysfunction. Key words: Access survival, Cytokines, Short-term

Association between dyslipidemia and CCL2 in patients undergoing hemodialysis

INTRODUCTION

Hemodialysis (HD) is associated with high risk for cardiovascular diseases including acute myocardial infarction, stroke and congestive heart failure. C-C Motif Chemokine Ligand 2 (CCL2), also known monocyte chemotactic protein-1 (MCP-1) can be produced by a variety of cells, reaching increased levels in dyslipidemic chronic kidney disease (CKD) patients undergoing HD treatment. The main of this study was to evaluate the association between of CCL2 plasma levels and dyslipidemia in CKD patients undergoing HD.

METHODS

A cross-sectional study enrolled 160 Brazilian HD patients. CCL2 plasma levels were measured by capture ELISA. The association between CCL2 levels and dyslipidemia was investigated using linear regression, adjusted for classic and non-classical CVD risk factors.

RESULTS

A significant association was observed between CCL2 levels and dyslipidemia (P = 0.029), even after adjustment for possible confounding variables, such as age, gender, body mass index, diabetes mellitus, HD time, urea pre-hemodialysis and interdialytic weight gain (P = 0.045).

CONCLUSION

Our findings show that CCL2 levels are associated with dyslipidemia, which suggests a role of this cytokine in the pathogenesis of cardiovascular disease in HD patients. A better understanding of this pathogenesis could contribute to the discovery of new therapeutic targets that would reduce cardiovascular complications in these patients.

C-reactive protein as a prognostic risk factor for loss of arteriovenous fistula patency in hemodialyzed patients

BACKGROUND

Inflammation is a cardiovascular risk factor in hemodialysis patients, but its influence on vascular access patency is still debatable. Our prospective study investigated this issue.

METHODS

A total of 258 patients receiving an arteriovenous fistula (AVF) between 2006 and 2016 at the Municipal Hospital Arad were included. Demographic, clinical, and laboratory characteristics were collected at the time of creation of the AVF. The primary study end point was AVF patency loss, defined as an event occurring at least 2 months after AVF formation and requiring surgical revision or replacement of the fistula. The patients were followed up for a median time of 26 months.

RESULTS

In our group, the mean age was 59.7 ± 13.2 years (median, 62 years), and 60.1% were male. During follow-up, 134 patients (51.9%) maintained AVF patency, whereas 124 (48.1%) lost AVF patency within a mean time of 23.3 ± 28.1 months (median, 10.5 months). We found that age (hazard ratio [HR], 1.015; P = .035) and C-reactive protein (CRP) level (HR, 1.17; P < .0001) were associated with a higher risk of loss of AVF patency. The protective factors for AVF patency were autosomal dominant polycystic kidney disease (HR, 0.336; P = .009), pre-emptive AVF (HR, 0.648; P = .031), and higher level of triglycerides (HR, 0.998; P = .035). In the multivariate adjusted Cox model, CRP level remained an independent predictor for loss of AVF patency (HR, 1.17; 95% confidence interval, 1.1-1.3; P < .0001).

CONCLUSIONS

In our study, CRP level was an independent predictor of AVF patency loss, whereas better AVF survival was independently associated with autosomal dominant polycystic kidney disease and pre-emptive AVF. As a simple noninvasive marker of chronic inflammation, CRP level may be a useful tool to predict AVF outcomes. Further research is needed to assess the protective effects of inflammation reduction on AVF survival.

Local Adipose-Associated Mediators and Adaptations Following Arteriovenous Fistula Creation

Introduction

Local inflammation is an important regulator of vascular remodeling. We hypothesized that adipose tissue adjacent to hemodialysis arteriovenous fistulae modulates maturation.

Methods

During fistula creation, perivenous adipose was collected from 111 participants in the Hemodialysis Fistula Maturation Study. Nine adipose-associated mediators were measured. Duplex ultrasound was performed at 4 time points postoperatively from 1 day to first cannulation (10–26 weeks). Associations between logarithmically transformed biomarker levels and fistula remodeling were evaluated using mixed effects regression.

Results

Elevated interleukin (IL)-6 and monocyte chemoattractant protein (MCP)-1 were associated with a reduction in the fractional vein diameter during the early time frame of 1 day to 2 weeks (diameter change of 26.6% and 20.4% at the 25th and 75th percentile for IL-6, P = 0.01; 27.8% and 21.1% at the 25th and 75th percentile for MCP-1, P = 0.02), but not in later stages of remodeling. Local leptin levels showed a significant negative correlation with fractional venous flow increase between 2 and 6 weeks (percent flow change 31.4% and 11.3% at the 25th and 75th percentile for leptin, P = 0.03).

Conclusion

Thus, impaired fistula vein dilation and reduced capacity for flow augmentation associate with specific local adipose phenotypic signatures in a time-dependent manner. In view of adipose tissue plasticity, these findings raise the possibility of novel adipose-based strategies to facilitate fistula maturation.

CorMatrix Wrapped Around the Adventitia of the Arteriovenous Fistula Outflow Vein Attenuates Venous Neointimal Hyperplasia

Venous neointimal hyperplasia (VNH) at the outflow vein of hemodialysis AVF is a major factor contributing to failure. CorMatrix is an extracellular matrix that has been used in cardiovascular procedures primarily as scaffolding during surgery. In the present study, we sought to determine whether CorMatrix wrapped around the outflow vein of arteriovenous fistula (AVF) at the time of creation could reduce VNH. In mice, the carotid artery to the ipsilateral jugular vein was connected to create an AVF, and CorMatrix scaffold was wrapped around the outflow vein compared to control mice that received no scaffolding. Immunohistochemistry, Western blot, and qRT-PCR were performed on the outflow vein at 7 and 21 days after AVF creation. In outflow veins treated with CorMatrix, there was an increase in the mean lumen vessel area with a decrease in the ratio of neointima area/media + adventitia area (P < 0.05). Furthermore, there was a significant increase in apoptosis, with a reduction in cell density and proliferation in the outflow veins treated with CorMatrix compared to controls (P < 0.05). Immunohistochemical analysis revealed a significant reduction in fibroblasts, myofibroblasts, macrophages, and leukocytes with a reduction in Tnf-α gene expression (P < 0.05). In conclusion, outflow veins treated with CorMatrix have reduced VNH.

Cytokine Signature in End-Stage Renal Disease Patients on Hemodialysis

Hemodialysis is a modality of blood filtration in which accumulated toxins and water are removed from the body. This treatment is indicated for patients at the end stage of renal disease. Vascular access complications are responsible for 20–25% of all hospitalizations in dialyzed patients. The occurrence of thrombosis in the vascular access is a serious problem that may severely compromise or even make the hemodialysis impossible, which is vital for the patient. The aim of this study was to investigate inflammatory profile in patients undergoing hemodialysis as well as the association between these alterations and vascular access thrombosis. A total of 195 patients undergoing hemodialysis have been evaluated; of which, 149 patients had not experienced vascular access thrombosis (group I) and 46 patients had previously presented this complication (group II). Plasma levels of cytokines including interleukin (IL-) 2, IL-4, IL-5, IL-10, TNF-α, and IFN-γ were measured by cytometric bead array. Our results showed that patients with previous thrombotic events (group II) had higher levels of the IL-2, IL-4, IL-5, and IFN-γ when compared to those in group I. Furthermore, a different cytokine signature was detected in dialyzed patients according to previous occurrences or not of thrombotic events, suggesting that elevated levels of T-helper 1 and T-helper 2 cytokines might, at least in part, contribute to this complication.

C-reactive protein variability is associated with vascular access outcome in hemodialysis patients

BACKGROUND

Hemodialysis (HD) vascular access failure is one of the most important causes of morbidity and contributes to the cost of dialysis care. There is paucity of data evaluating long-term monitoring of C-reactive protein (CRP) on outcome of HD vascular access.

METHODS

We conducted a retrospective study to investigate whether variability of serum CRP level was associated with vascular access failure rate over a 7-year period. A total of 318 HD patients were included. Their demographic data, co-morbidities and biochemical data were reviewed and collected. Serum high-sensitivity CRP (hs-CRP) level was measured every 6 months. Patients were divided into three groups according to their serial hs-CRP levels. Patients with their hs-CRP below 2 mg/L were defined as low group (n=65, 20.4%) and those with higher than 4 mg/L were defined as high (n=39, 12.3%). The rest were classified as fluctuated hs-CRP group (n=214, 67.3%). Treatment of vascular access failure includes angioplasty and access re-creation.

RESULTS

Their body mass index, indicators of dialysis adequacy and serum albumin and hs-CRP levels differed significantly among three groups. The annual vascular access failure rate was significantly higher in fluctuated hs-CRP group than in high hs-CRP group (0.41 vs 0.36, P=.037). Serum albumin was a significant associate of vascular access failure. Kaplan-Meier survival analysis indicated patients with high or fluctuated hs-CRP had shorter free interval of vascular access failure than low hs-CRP group.

CONCLUSIONS

HD patients with fluctuated hs-CRP levels were associated with increased vascular access failure.

CD44 Promotes Inflammation and Extracellular Matrix Production During Arteriovenous Fistula Maturation

OBJECTIVE

Arteriovenous fistulae (AVF) remain the optimal conduit for hemodialysis access but continue to demonstrate poor patency and poor rates of maturation. We hypothesized that CD44, a widely expressed cellular adhesion molecule that serves as a major receptor for extracellular matrix components, promotes wall thickening and extracellular matrix deposition during AVF maturation.

APPROACH AND RESULTS

AVF were created via needle puncture in wild-type C57BL/6J and CD44 knockout mice. CD44 mRNA and protein expression was increased in wild-type AVF. CD44 knockout mice showed no increase in AVF wall thickness (8.9 versus 26.8 μm; P=0.0114), collagen density, and hyaluronic acid density, but similar elastin density when compared with control AVF. CD44 knockout mice also showed no increase in vascular cell adhesion molecule-1 expression, intercellular adhesion molecule-1 expression, and monocyte chemoattractant protein-1 expression in the AVF compared with controls; there were also no increased M2 macrophage markers (transglutaminase-2: 81.5-fold, P=0.0015; interleukin-10: 7.6-fold, P=0.0450) in CD44 knockout mice. Delivery of monocyte chemoattractant protein-1 to CD44 knockout mice rescued the phenotype with thicker AVF walls (27.2 versus 14.7 μm; P=0.0306), increased collagen density (2.4-fold; P=0.0432), and increased number of M2 macrophages (2.1-fold; P=0.0335).

CONCLUSIONS

CD44 promotes accumulation of M2 macrophages, extracellular matrix deposition, and wall thickening during AVF maturation. These data show the association of M2 macrophages with wall thickening during AVF maturation and suggest that enhancing CD44 activity may be a strategy to increase AVF maturation.

Future research directions to improve fistula maturation and reduce access failure

With the increasing prevalence of end-stage renal disease, there is a growing need for hemodialysis. Arteriovenous fistulae (AVF) are the preferred type of vascular access for hemodialysis, but maturation and failure continue to present significant barriers to successful fistula use. AVF maturation integrates outward remodeling with vessel wall thickening in response to drastic hemodynamic changes in the setting of uremia, systemic inflammation, oxidative stress, and pre-existent vascular pathology. AVF can fail due to both failure to mature adequately to support hemodialysis and development of neointimal hyperplasia that narrows the AVF lumen, typically near the fistula anastomosis. Failure due to neointimal hyperplasia involves vascular cell activation and migration and extracellular matrix remodeling with complex interactions of growth factors, adhesion molecules, inflammatory mediators, and chemokines, all of which result in maladaptive remodeling. Different strategies have been proposed to prevent and treat AVF failure based on current understanding of the modes and pathology of access failure; these approaches range from appropriate patient selection and use of alternative surgical strategies for fistula creation, to the use of novel interventional techniques or drugs to treat failing fistulae. Effective treatments to prevent or treat AVF failure require a multidisciplinary approach involving nephrologists, vascular surgeons, and interventional radiologists, careful patient selection, and the use of tailored systemic or localized interventions to improve patient-specific outcomes. This review provides contemporary information on the underlying mechanisms of AVF maturation and failure and discusses the broad spectrum of options that can be tailored for specific therapy.

Tracking and Therapeutic Value of Human Adipose Tissue-derived Mesenchymal Stem Cell Transplantation in Reducing Venous Neointimal Hyperplasia Associated with Arteriovenous Fistula

PURPOSE

To determine if adventitial transplantation of human adipose tissue-derived mesenchymal stem cells (MSCs) to the outflow vein of B6.Cg-Foxn1(nu)/J mice with arteriovenous fistula (AVF) at the time of creation would reduce monocyte chemoattractant protein-1 (Mcp-1) gene expression and venous neointimal hyperplasia. The second aim was to track transplanted zirconium 89 ((89)Zr)-labeled MSCs serially with positron emission tomography (PET) for 21 days.

MATERIALS AND METHODS

All animal experiments were performed according to protocols approved by the institutional animal care and use committee. Fifty B6.Cg-Foxn1(nu)/J mice were used to accomplish the study aims. Green fluorescent protein was used to stably label 2.5 × 10(5) MSCs, which were injected into the adventitia of the outflow vein at the time of AVF creation in the MSC group. Eleven mice died after AVF placement. Animals were sacrificed on day 7 after AVF placement for real-time polymerase chain reaction (n = 6 for MSC and control groups) and histomorphometric (n = 6 for MSC and control groups) analyses and on day 21 for histomorphometric analysis only (n = 6 for MSC and control groups). In a separate group of experiments (n = 3), animals with transplanted (89)Zr-labeled MSCs were serially imaged with PET for 3 weeks. Multiple comparisons were performed with two-way analysis of variance, followed by the Student t test with post hoc Bonferroni correction.

RESULTS

In vessels with transplanted MSCs compared with control vessels, there was a significant decrease in Mcp-1 gene expression (day 7: mean reduction, 62%; P = .029), with a significant increase in the mean lumen vessel area (day 7: mean increase, 176% [P = .013]; day 21: mean increase, 415% [P = .011]). Moreover, this was accompanied by a significant decrease in Ki-67 index (proliferation on day 7: mean reduction, 81% [P = .0003]; proliferation on day 21: mean reduction, 60%, [P = .016]). Prolonged retention of MSCs at the adventitia was evidenced by serial PET images of (89)Zr-labeled cells.

CONCLUSION

Adventitial transplantation of MSCs decreases Mcp-1 gene expression, accompanied by a reduction in venous neointimal hyperplasia.

Adipose phenotype predicts early human autogenous arteriovenous hemodialysis remodeling

OBJECTIVE

Substantial proportions of autogenous arteriovenous fistulas (AVFs) for hemodialysis access fail to mature for unclear reasons. AVFs develop in a large mass of surrounding adipose tissue that is increasingly recognized as an active participant in the vascular response to injury via paracrine and endocrine mechanisms. We thus hypothesized that baseline phenotypic characteristics of the adipose tissue juxtaposed to the developing AVF associate with subsequent inward or outward vein wall remodeling.

METHODS

Clinical data and subcutaneous adipose tissue were collected from 22 consented patients undergoing AVF creation. Tissue was assayed (protein levels) for interleukin (IL)-6, IL-8, leptin, tumor necrosis factor-α, monocyte chemoattractant protein-1 (MCP-1), resistin, and adiponectin. Vein dimensions were acquired by duplex ultrasound imaging, preoperatively and at 4 to 6 weeks postoperatively, 1 cm cephalad to the arteriovenous anastomosis, which is the most common location of AVF stenosis).

RESULTS

The vein at the assayed location outwardly remodeled 55.7% on average (median before, 3.7 mm; median after, 4.7 mm; P = .005). The preoperative vein diameter failed to correlate with postoperative size at the point of assay (R = 0.31; P = .155) unless two outliers were excluded (R = 0.64; P = .002). After removal of the same outliers, the correlation coefficient between venous diameter change (preoperative vs postoperative) and IL-8, tumor necrosis factor-α, MCP-1, resistin, and adiponectin was -0.49, -0.79, -0.66, -0.64, and -0.69, respectively (P < .05). Postoperative AVF flow volume correlated with MCP-1 (R = -0.53; P < .05) and adiponectin (R = -0.47; P < .05).

CONCLUSIONS

These data reveal a novel relationship between local adipose phenotype and the eventual venous wall response to hemodynamic perturbation in humans. The predictive value of these mediators generally equaled or exceeded that of preoperative vein size. Beyond providing mechanistic insights into vascular wall adaptations due to flow perturbations, this discovery suggests that strategies focused on altering adipose tissue biology may improve AVF maturation.

The Eternal Tale of Dialysis Access Vessels and Restenosis: Are Drug-Eluting Balloons the Solution?

In dialysis access fistulas and grafts, percutaneous transluminal angioplasty (PTA) is frequently followed by restenosis development, which results in repeated periodical re-interventions. The technique of drug-eluting balloon (DEB) angioplasty has shown promising results in the treatment of femoropopliteal arteriosclerotic lesions. In contrast to arteriosclerotic arteries, dialysis access vessels host unfavorable hemodynamics due to the direct conduction of high-pressure fluid into a low-pressure system. Hence, the beneficial effect of DEB angioplasty may be limited in this system. However, a first prospective randomized trial on 40 patients with arteriovenous fistula or graft stenoses exhibited a significantly higher 6-month primary patency of the treated lesions after DEB angioplasty than after uncoated balloon angioplasty. Despite such a positive reference, general recommendations regarding the value of DEBs in dialysis access vessels cannot be considered as serious unless large randomized controlled trials have been performed.

Sclerostin as a new key player in arteriovenous fistula calcification

BACKGROUND

The osteocyte-derived sclerostin has been shown to play a key inhibitor role in determining the normal extent of bone formation, and it consequently protects against the deleterious effects of uncontrolled bone growth. Sclerostin has been demonstrated to be upregulated during vascular smooth muscle cell calcification in vitro and has recently been identified in the human aorta at the protein level. Whether the effects of sclerostin on bone turnover and its vascular expression also translate into clinically significant changes in arteriovenous fistula patency is unknown.

PATIENTS AND METHODS

The primary outcome was loss of unassisted arteriovenous fistula patency, defined as arteriovenous fistula thrombosis or need for intervention. In this prospective cohort study, 350 prevalent hemodialysis patients were followed up for 12 months. Serum sclerostin levels were measured and arteriovenous fistula calcification was detected using a 64-detector computerized tomographic scanner.

RESULTS

Patients with calcified arteriovenous fistula had higher serum sclerostin levels than patients without. Overall, 26 % of the patients reached the outcome during the follow-up. The 12-month arteriovenous fistula survival was reduced in patients with calcified arteriovenous fistulas. Patients with serum sclerostin levels above median levels at the start of the observation period had a worse arteriovenous fistula survival. Multivariable-adjusted Cox regression analyses revealed that only presence of arteriovenous fistula calcification and serum C-reactive protein level independently predicted loss of unassisted arteriovenous fistula patency.

CONCLUSION

Our study suggests that the detection of arteriovenous fistula calcification and serum C-reactive protein levels might be useful for identifying patients at an increased risk for loss of unassisted arteriovenous fistula patency.

The impact of inflammatory factors associated with primary arteriovenous failure

PURPOSE

Very scarce data exist regarding the relationship between differential white blood cell (WBC) counts and primary arteriovenous fistula (AVF) failure. Thus, the current study aimed to investigate the specific relationship between primary AVF failure and differential WBC counts.


METHODS

Sociodemographic, clinical, and laboratory parameters including automatically determined complete blood counts of the patients (from medical records and hospital charts) prior to AVF fistula surgery were recorded. Primary AVF failure was described as a complication of the AVF before the first successful cannulation for HD treatment.


RESULTS

In total 94 patients (Male/Female: 49/45, Aged: 50.9 ± 15.0 years) were included. Ferritin, high sensitive C-reactive protein (hs-crp), total WBC count, neutrophil count, red cell distribution width (RDW) were higher in patients with primary AVF failure compared to patients without primary AVF failure. Logistic regression analysis showed that presence of diabetes (OR = 3.654, p = 0.035), RDW (OR = 0.449, p = 0.033) and ferritin (OR = 1.097, p = 0.021) were independently related with primary AVF failure.


CONCLUSIONS

Neither total WBC counts nor WBC subtypes were related with primary AVF failure. Higher RDW and ferritin levels had a prognostic value for development of primary AVF failure.

Interleukin-6 -634 C/G and -174 G/C polymorphisms in Korean patients undergoing hemodialysis

BACKGROUND/AIMS

Chronic inflammatory status is a possible risk factor for vascular access dysfunction in hemodialysis (HD) patients, but susceptibility differences appear among individuals. Interleukin (IL)-6 is a well-known inflammatory cytokine with various polymorphisms. We examined whether IL-6 polymorphisms are associated with vascular access dysfunction in HD patients.

METHODS

A total of 80 HD patients (including 42 diabetic patients) were enrolled. Polymorphisms in the IL-6 gene promoter (-634 C/G and -174 G/C) were studied using restriction length polymorphism polymerase chain reaction analysis. Vascular access patency was compared between the patient groups with respect to IL-6 polymorphisms. An additional 89 healthy individuals were enrolled in the control group. Plasma IL-6 levels were determined by enzyme-linked immunosorbent assay.

RESULTS

The GG genotype and G allele at position -634 in the IL-6 promoter were more frequently observed in HD patients than in controls. Furthermore, the distribution of the -634 polymorphism differed according to vascular access patency in non-diabetic HD patients. However, the G allele was not a significant risk factor for early access failure. No significant association appeared between the IL-6 -634 C/G polymorphism and plasma IL-6 levels. The C allele of the IL-6 -174 G/C polymorphism was not detected in our study population.

CONCLUSIONS

The IL-6 -634 G allele appears with greater frequently in patients with end-stage renal disease and may be associated with vascular access dysfunction in non-diabetic HD patients.

Paclitaxel-coated balloon angioplasty vs. plain balloon dilation for the treatment of failing dialysis access: 6-month interim results from a prospective randomized controlled trial

PURPOSE

To report the 6-month results of a prospective randomized trial investigating angioplasty with paclitaxel-coated balloons (PCB) vs. plain balloon angioplasty (BA) for the treatment of failing native arteriovenous fistulae (AVF) or prosthetic arteriovenous grafts (AVG).

METHODS

The enrollment criteria for this non-inferiority hypothesis trial included clinical signs of failing dialysis access with angiographic documentation of a significant venous stenotic lesion in patients with AVF or AVG circuits. From March to December 2010, 40 patients (29 men; mean age 64.1 ± 14.3 years) were randomized to undergo either PCB dilation (n = 20) or standard BA (n = 20) of a stenosed venous outflow lesion. Regular angiographic follow-up was scheduled bimonthly. Study outcome measures included device success (<30% residual stenosis without postdilation), procedural success (<30% residual stenosis), and primary patency of the treated lesion (<50% angiographic restenosis and no need for any interim repeat procedures).

RESULTS

Baseline and procedural variables were comparably distributed between both groups. Device success was 9/20 (45%) for the PCB device vs. 20/20 (100%) for standard control BA (p<0.001). Procedural success was 100% in both groups after further high-pressure post-dilation as necessary. There were no major or minor complications in either group. At 6 months, cumulative target lesion primary patency was significantly higher after PCB application (70% in PCB group vs. 25% in BA group, p<0.001; HR 0.30, 95% CI 0.12 to 0.71, p<0.006).

CONCLUSION

PCB angioplasty improves patency after angioplasty of venous stenoses of failing vascular access used for dialysis.

Advances and new frontiers in the pathophysiology of venous neointimal hyperplasia and dialysis access stenosis

Hemodialysis vascular access dysfunction is a major cause of morbidity and mortality in hemodialysis patients. The most common cause of this vascular access dysfunction is venous stenosis as a result of venous neointimal hyperplasia within the perianastomotic region (arteriovenous fistula) or at the graft-vein anastomosis (polytetrafluoroethylene, or PTFE, grafts). There have been few effective treatments to date for venous neointimal hyperplasia, in part, because of the poor understanding of the pathogenesis of venous neointimal hyperplasia. Therefore, this article will (1) describe the pathology of hemodialysis access stenosis in arteriovenous fistulas and grafts, (2) review and describe both current and novel concepts in the pathogenesis of neointimal hyperplasia formation, (3) discuss current and future novel therapies for treating venous neointimal hyperplasia, and (4) suggest future research areas in the field of hemodialysis vascular access dysfunction.