Hemodialysis vascular access survival: upper-arm native arteriovenous fistula

The Alpha to Omega of Dialysis Access: Arteriovenous Fistula and Graft (Part 1)

Background: Vascular access is a critical determinant of hemodialysis efficacy in patients with end-stage kidney disease (ESKD). The choice between arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) influences long-term dialysis outcomes, with AVFs offering superior patency but higher maturation failure rates and AVGs providing immediate usability at the expense of increased complications. Recent advancements in endovascular techniques and biomaterials have introduced novel approaches to optimizing vascular access. Purpose: This review examines the latest evidence on AVF and AVG creation, focusing on factors affecting maturation, long-term patency, and emerging minimally invasive techniques, such as percutaneous AVF creation, to enhance hemodialysis access outcomes. Research Design: A systematic review of current literature, clinical guidelines, and innovations in vascular access for dialysis patients was conducted. Emphasis was placed on comparative effectiveness studies, patency and complication rates, and new endovascular approaches. Study Sample: Data were sourced from clinical trials, registry reports, and systematic reviews evaluating AVF and AVG outcomes, as well as emerging endovascular fistula technologies. Data Collection and/or Analysis: Key parameters such as patency rates, infection rates, thrombosis incidence, and maturation success were analyzed. Particular attention was given to procedural innovations, including bioengineered grafts and percutaneous fistula creation, assessing their impact on long-term dialysis access viability. Results: AVFs maintain superior long-term patency but are hindered by primary failure rates, necessitating interventions for maturation. AVGs, while more prone to infection and thrombosis, offer a viable alternative when native vessels are unsuitable. Endovascular AVF creation has demonstrated high technical success and promising long-term outcomes, reducing the need for traditional surgical approaches. Advances in biomaterials and adjunctive pharmacologic therapies may further improve vascular access durability. Conclusions: Individualized vascular access planning remains essential to optimizing hemodialysis outcomes. The evolution of minimally invasive techniques, coupled with improved patient selection criteria and emerging biomaterials, offers new opportunities for enhancing dialysis access longevity. Future research should focus on refining endovascular approaches and integrating novel technologies to minimize complications and improve access patency.

Insights into the real-world practice of vascular access care pathways in Italy: data from a national survey

BACKGROUND

International guidelines issued recommendations for vascular access (VA) care for hemodialysis, but there are no registry data regarding this topic in Italy.

METHODS

A survey consisting of 17 items was sent to all Italian dialysis wards, via the Italian Society of Nephrology (SIN) website, from April to June 2021. The items were defined, discussed and approved by experts in vascular access management within the Italian Society of Nephrology. A total of 124 dialysis units answered, accounting for 14% of all dialysis units. The survey thus encompasses all regions within the country, with some regional variations in terms of adherence.

RESULTS

One hundred twenty-four facilities provided data, regarding 12,276 patients: 61% had an arteriovenous fistula (AVF), 34% had a central venous catheter (CVC), and 5% had an arteriovenous graft (AVG). Among them, two-thirds of the facilities reported having a vascular access care pathway, formally standardized in 79% of cases. Forty-six % of centers had a fully equipped vascular access care pathway, encompassing preoperative mapping (80%), vascular access setup (71%), arteriovenous fistula maturation monitoring (76%), first-level (80%) and second-level (78%) monitoring, and surgical and/or endovascular treatment of complications (66%). Vascular access monitoring was computerized in 39% of facilities. First-level monitoring (physical examination) was primarily done by nurses in two-thirds of facilities. Of note, 45% of centers had nurses who were skilled in ultrasound-guided cannulation. Quite surprisingly, facilities with less than 100 patients had a greater prevalence of arteriovenous fistulas than those with more than 100 patients (p = 0.0023). A protocolled vascular access care pathway was associated with a higher likelihood of having an arteriovenous fistula (70% AVF vs 42,1% CVC; p = 0.04). The presence in the facility of interventional nephrologists or nurses with ultrasound-guided cannulation skills significantly reduced the prevalence of central venous catheters.

CONCLUSION

These survey data further strengthen the need for formal and shared vascular access monitoring protocols.

Cardiac complications of arteriovenous access: a narrative review from a multidisciplinary team perspective

Although cardiovascular disease is common among hemodialysis patients, arteriovenous access creation has been invariably implicated in the evolution of adverse cardiac outcomes or deterioration of pre-existing cardiovascular disease. In most cases, these effects are subclinical but with potential underlying echocardiographic findings. Compared with grafts, arteriovenous fistulas are implicated more often, due to the progressively increased flow from the continuous dilatation of the venous outflow tract in the long term. The increasing flow is in the majority of patients well tolerated by cardiac adaptive alterations. However, the clinical impact is based on the balance between the amount of flow volume and the patient's cardiac reserves. Having extensively reviewed the existing English literature, we present the pathophysiology and the different types of cardiovascular complications, the indications, types, and efficacy of flow-restrictive procedures in the context of a high-flow AVF, as well as some precautions and considerations for AVF creation in high-risk patients.

Cathepsin G promotes arteriovenous fistula maturation by positively regulating the MMP2/MMP9 pathway

BACKGROUND

Arteriovenous fistula (AVF) is currently the preferred vascular access for hemodialysis patients. However, the low maturation rate of AVF severely affects its use in patients. A more comprehensive understanding and study of the mechanisms of AVF maturation is urgently needed.

METHODS AND RESULTS

In this study, we downloaded the publicly available datasets (GSE119296 and GSE220796) from the Gene Expression Omnibus (GEO) and merged them for subsequent analysis. We screened 84 differentially expressed genes (DEGs) and performed the functional enrichment analysis. Next, we integrated the results obtained from the degree algorithm provided by the Cytohubba plug-in, Molecular complex detection (MCODE) plug-in, weighted gene correlation network analysis (WGCNA), and Least absolute shrinkage and selection operator (LASSO) logistic regression. This integration allowed us to identify CTSG as a hub gene associated with AVF maturation. Through the literature search and Pearson's correlation analysis, the genes matrix metalloproteinase 2 (MMP2) and MMP9 were identified as potential downstream effectors of CTSG. We then collected three immature clinical AVF vein samples and three mature samples and validated the expression of CTSG using immunohistochemistry (IHC) and double-immunofluorescence staining. The IHC results demonstrated a significant decrease in CTSG expression levels in the immature AVF vein samples compared to the mature samples. The results of double-immunofluorescence staining revealed that CTSG was expressed in both the intima and media of AVF veins. Moreover, the expression of CTSG in vascular smooth muscle cells (VSMCs) was significantly higher in the mature samples compared to the immature samples. The results of Masson's trichrome and collagen I IHC staining demonstrated a higher extent of collagen deposition in the media of immature AVF veins compared to the mature. By constructing an in vitro CTSG overexpression model in VSMCs, we found that CTSG upregulated the expression of MMP2 and MMP9 while downregulating the expression of collagen I and collagen III. Furthermore, CTSG was found to inhibit VSMC migration.

CONCLUSIONS

CTSG may promote AVF maturation by stimulating the secretion of MMP2 and MMP9 from VSMCs and reducing the extent of medial fibrosis in AVF veins by inhibiting the secretion of collagen I and collagen III.

Prospective multicenter study of a novel endovascular venous anastomotic procedure and device for implantation of an arteriovenous graft for hemodialysis

INTRODUCTION

The traditional sutured venous anastomosis used during arteriovenous graft implantation is associated with a high incidence of subsequent stenosis that is attributed to neointimal hyperplasia. Hyperplasia results from multiple factors, including hemodynamic abnormalities and vessel trauma during implantation. A novel anastomotic connector device was designed to provide an alternative, less traumatic, endovascular venous anastomosis that may ameliorate the clinical challenges associated with a sutured anastomosis. A prospective single-arm multicenter study was performed to evaluate safety and effectiveness of graft implantation using the study device.

METHODS

Patients requiring graft creation and who met the study criteria were enrolled between February 2018 and July 2021 and observed for 6 months. Collected data included baseline characteristics, graft patency and use for hemodialysis, graft interventions, and adverse events. The primary study endpoint was cumulative graft patency, compared to a pre-specified Performance Goal of 75%. Secondary endpoints included primary unassisted patency and serious adverse events, defined as the occurrence of death, graft infection, emergent surgery, significant bleeding, and pseudoaneurysm.

RESULTS

A total of 158 patients were enrolled from 10 study sites, among which 144 subjects were evaluable at 6 months and 14 were censored with partial follow-up observation. Three patients died and the graft was abandoned in 12. The primary endpoint was met (p-value < 0.001). By Kaplan Meier survival analysis, cumulative patency was 92.08% with a lower 95% Confidence Bound of 86.98%. Primary unassisted patency was 60.21% with a lower 95% Confidence Bound of 50.84%. Graft infections occurred in six patients, all unrelated to the study device. There were no reports of emergent surgery, significant bleeding or pseudoaneurysm.

CONCLUSION

These results demonstrate that the study device can be used for successful endovascular anastomosis of a vein to a graft for hemodialysis, with acceptable cumulative patency and safety profile at 6 months.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02532621.

Heterogeneous gene expression during early arteriovenous fistula remodeling suggests that downregulation of metabolism predicts adaptive venous remodeling

Clinical outcomes of arteriovenous fistulae (AVF) for hemodialysis remain inadequate since biological mechanisms of AVF maturation and failure are still poorly understood. Aortocaval fistula creation (AVF group) or a sham operation (sham group) was performed in C57BL/6 mice. Venous limbs were collected on postoperative day 7 and total RNA was extracted for high throughput RNA sequencing and bioinformatic analysis. Genes in metabolic pathways were significantly downregulated in the AVF, whereas significant sex differences were not detected. Since gene expression patterns among the AVF group were heterogenous, the AVF group was divided into a 'normal' AVF (nAVF) group and an 'outliers' (OUT) group. The gene expression patterns of the nAVF and OUT groups were consistent with previously published data showing venous adaptive remodeling, whereas enrichment analyses showed significant upregulation of metabolism, inflammation and coagulation in the OUT group compared to the nAVF group, suggesting the heterogeneity during venous remodeling reflects early gene expression changes that may correlate with AVF maturation or failure. Early detection of these processes may be a translational strategy to predict fistula failure and reduce patient morbidity.

Short-term mortality and revisions to promote maturation after arteriovenous fistula creation

OBJECTIVE

Arteriovenous fistula (AVF) for hemodialysis access is traditionally considered superior to grafts due to infection resistance and purported improved patency. However, challenges to AVF maturation and limited patient survival may reduce AVF benefits. The objective of this study is to identify factors associated with risk of AVF requiring revision before maturation and/or mortality within 2 years of creation.

METHODS

We performed a retrospective review of 250 AVFs created between May 2017 and November 2020 at a single institution. Maturation was defined as the date the surgeon deemed the AVF ready for use or the patient successfully used the AVF for dialysis. The Risk Analysis Index was used to calculate frailty. The primary outcome was a composite of endovascular/surgical revision to promote maturation and/or mortality within 2 years of AVF creation (REVDEAD). The primary outcome was categorized as met if the patient required a revision to promote maturation or if the patient experienced mortality within 2 years of AVF creation, or if both occurred. REVDEAD was compared with those who did not meet the primary outcome and will be referred to as NOREVDEAD.

RESULTS

Survival at 2 years after AVF creation was 82%, and 54 (22%) patients underwent AVF revision. Of those, 31 (59%) patients progressed to AVF maturation. Of the 250 AVFs, 91 (36%) met the primary outcome of REVDEAD and 159 (64%) did not (NOREVDEAD). There was no difference between the REVDEAD and NOREVDEAD groups in age (P = .18), sex (P = .75), White race (P = .97), Hispanic ethnicity (P = .62), obesity (P = .76), coronary artery disease (P = .07), congestive heart failure (P = .29), diabetes mellitus (P = .78), chronic obstructive pulmonary disease (P = .10), dialysis status (P = .63), hypertension (P = .32), peripheral arterial disease (P = .34), or dysrhythmia (P = .13). There was no difference between the groups in the forearm vs the upper arm location of AVF (P = .42) or the vein diameter (P = .58). Forearm access, as opposed to upper arm AVF creation, was associated with higher rate of revision before maturation (P = .05). More patients in REVDEAD were frail or very frail (60% vs 48%, P = .05). Of the AVFs that matured, maturation required longer time in REVDEAD at 110.0 ± 9.1 days vs 78.8 ± 5.6 days (mean ± standard deviation) (P = .003). Adjusted for the vein diameter and the forearm vs the upper arm, frailty increased the odds of REVDEAD by 1.9 (95% confidence interval: 1.1, 3.3).

CONCLUSIONS

Frail patients who underwent AVF were significantly more likely to die within 2 years of AVF creation with no significant association between frailty and the need for revisions to promote maturation. Forearm AVFs were more likely to require revisions; in patients who are frail, with a high likelihood of 2-year mortality, graft may be more appropriate than AVF. If AVF is being considered in a frail patient, upper arm AVFs should be prioritized over forearm AVFs.

Fully no-touch technique without inflating the cephalic vein increase the patency rate of arteriovenous fistulas

INTRODUCTION

One of the most important problems for patients undergoing hemodialysis due to chronic renal failure is the need for a long-lasting vascular access. The patency of vascular access is affected by many factors. Factors related to surgery are also among these factors. No-touch techniques theoretically and practically prevent endothelial damage due to minimal contact on vascular structures. It is a well-known fact that surgeries performed with these methods also increase long-term survival.

METHODS

Patients who underwent distal radiocephalic arteriovenous fistula (AVF) surgery for the first time between 2017 and 2021 were included in our study. The groups, whose cephalic veins were inflated conventionally and not inflated, were compared in a prospective randomized manner.

RESULTS

There was a significant difference between both groups in terms of failure and patency rates, which is one of the study endpoints (p = 0.012). The fact that the patency period is long, and the failure rate is low stands out as the superiority of the fully no-touch technique in AVF surgery. On the other hand, no significant difference was observed in terms of failure to maturation and fistula maturation time.

CONCLUSIONS

Fully no-touch technique in AVF surgery should be considered primarily in suitable patients due to its long patency time and low failure rate.

Guidelines on vascular access for hemodialysis from the Brazilian Society of Angiology and Vascular Surgery

Chronic kidney disease is a worldwide public health problem, and end-stage renal disease requires dialysis. Most patients requiring renal replacement therapy have to undergo hemodialysis. Therefore, vascular access is extremely important for the dialysis population, directly affecting the quality of life and the morbidity and mortality of this patient population. Since making, managing and salvaging of vascular accesses falls within the purview of the vascular surgeon, developing guideline to help specialists better manage vascular accesses for hemodialysis if of great importance. Thus, the objective of this guideline is to present a set of recommendations to guide decisions involved in the referral, evaluation, choice, surveillance and management of complications of vascular accesses for hemodialysis.

Long-term patency of arteriovenous fistulas for hemodialysis: A decade's experience in a transplant unit

BACKGROUND

The heterogeneous quality of studies on arteriovenous fistulas outcome, with variable clinical settings and large variations in definitions of patency and failure rates, leads to frequent misinterpretations and overestimation of arteriovenous fistula patency. Hence, this study aimed to provide realistic and clinically relevant long-term arteriovenous fistula outcomes.

METHODS

We retrospectively analyzed all autologous arteriovenous fistulas at our center over a 10-year period (2012-2022). Primary and secondary patency analysis was conducted using the Kaplan-Meier method; multivariate analysis of variance was used to detect outcome predictors. Vascular access-specific endpoints were defined according to the European guidelines on vascular access formation.

FINDINGS

Of 312 arteriovenous fistulas, 57.5% (n = 181) were radio-cephalic (RC_AVF), 35.2% (n = 111) brachio-cephalic (BC_AVF), and 6.3% (n = 20) brachio-basilic (BB_AVF). 6, 12, and 24 months follow-up was available in 290 (92.1%), 282 (89.5%), and 259 (82.2%) patients, respectively. Primary patency rates at 6, 12, and 24 months were 39.5%, 34.8%, and 27.2% for RC_AVF, 58.3%, 44.4%, and 27.8% for BC_AVF, and 40.0%, 42.1%, and 22.2% for BB_AVF (p = 0.15). Secondary patency rates at 6, 12, and 24 months were 65.7%, 63.8%, and 59.0% for RC_AVF, 77.7%, 72.0%, and 59.6% for BC_AVF, and 65.0%, 68.4%, and 61.1% for BB_AVF (p = 0.29). Factors associated with lower primary and secondary patency were hemodialysis at time of arteriovenous fistula formation (p = 0.037 and p = 0.024, respectively) and higher Charlson Comorbidity Index (p = 0.036 and p < 0.001, respectively). Previous kidney transplant showed inferior primary patency (p = 0.005); higher age inferior secondary patency (p < 0.001).

DISCUSSION

Vascular access care remains challenging and salvage interventions are often needed to achieve maturation or maintain patency. Strict adherence to standardized outcome reporting in vascular access surgery paints a more realistic picture of arteriovenous fistula patency and enables reliable intercenter comparison.

Intimal CD31-Positive Relative Surfaces Are Associated with Systemic Inflammatory Markers and Maturation of Arteriovenous Fistula in Dialysis Patients

BACKGROUND

Arteriovenous fistula dysfunction is a widely disputed subject in the scientific literature on end-stage kidney disease (ESKD). The main cause of mortality and morbidity in these patients is the non-maturation or dysfunction of the arteriovenous fistula. Despite the many complications, the native arteriovenous fistula remains the gold standard in the treatment of these patients requiring renal replacement. This study aims to discuss the predictive role of some systemic inflammatory biomarkers (NLR, PLR, SII, IL-6), intimal hyperplasia, and neoangiogenesis (characterized by intimal-media CD31-positive relative surface) in arteriovenous fistula maturation failure.

METHODS

The present study was designed as an observational, analytical, and prospective study which included patients diagnosed with ESKD with indications of radio-cephalic arteriovenous fistula (RCAVF). Demographic data, comorbidities, preoperative laboratory data and histological/digital morphometry analysis results were processed. The patients included were divided into two groups based on their AVF maturation status at 8 weeks: "Maturation" (Group 1) and "Failed Maturation" (Group 2).

RESULTS

There was no difference in the demographic data. In terms of comorbidities, the second group had a greater incidence of heart failure (p = 0.03), diabetes (p = 0.04), peripheral artery disease (p = 0.002), and obesity (p = 0.01). Additionally, regarding the laboratory findings, these patients had higher levels of serum uric acid (p = 0.0005), phosphates (p < 0.0001), and creatinine (p = 0.02), as well as lower levels of total calcium (p = 0.0002), monocytes (p = 0.008), and lymphocytes (p < 0.0001). Moreover, all inflammatory markers (p = 0.001; p < 0.0001; p = 0.006, and p = 0.03) and Ca-P product (p < 0.0001) had higher baseline values in Group 2. Upon immunohistochemical analysis, regarding the density of neoformed vessels, there was a higher incidence of CD31-positive surfaces (p = 0.006) and CD31-positive relative surfaces (p = 0.001); the NLR (r = 0.323; p = 0.03), PLR (r = 0.381; p = 0.04), SII (r = 0.376; p = 0.03), and IL-6 (r = 0.611; p < 0.001) are all significantly correlated with vascular density, as evidenced by CD31.

CONCLUSIONS

Heart failure, peripheral artery disease, obesity, and diabetes, as well as the systemic inflammatory markers (NLR, PLR, SII, IL-6), intimal hyperplasia, and CD31-positive relative surfaces are predictors of arteriovenous fistula maturation failures.

Oversized balloon angioplasty for endovascular maturation of arteriovenous fistulae to accelerate cannulation and to decrease the duration of catheter use

BACKGROUND

The functional autologous arteriovenous fistula is considered the best vascular access for patients on hemodialysis. Some fistulae exhibit maturation problems after creation and do not reach adequate vessel diameter and flow in dialysis. The aim of this study was to describe our technique of oversized balloon angioplasty for assisted maturation of arteriovenous fistulae to accelerate the cannulation and to decrease the time of catheter use and its outcome.

METHODS

A retrospective analysis of balloon-assisted procedures for maturation failure was performed in a single center between October 2011 and January 2019. Patients underwent imaging procedures to identify stenosis, followed by angioplasty using oversized high-pressure balloons from the anastomosis to the deep venous outflow tract. The flow volume, time interval of use of the fistula and removal of the catheter, patency rates, and complications rates were evaluated.

RESULTS

Seventy-eight patients underwent 124 balloon angioplasty procedures. Technical and clinical success was achieved in 91% of the cases. In patients in whom maturation was successful, the fistula was cannulated in a mean time of 5 days after the procedure (range, 1-20 days). On average, catheter removal was performed 14 days (range, 5-33 days) after the maturation procedure. The mean flow volume in the fistula before the procedure was 276 ml/min (range, 122-488 ml/min) and 24 h after the maturation was 1014 ml/min (range, 760-1800 ml/min).The primary patency rate at 3, 6, and 12 months was 87.3%, 66.2%, and 50.7%, respectively. Assisted primary patency was 100% at 3 months, 92.9% at 6 months, and 90.0% at 12 months. Minor complications occurred in 18% of cases, and major complications in 4.8%.

CONCLUSIONS

The oversized balloon-assisted arteriovenous fistula maturation technique is safe and effective, allowing the cannulation of the fistulae a few hours or days after the procedure and decreasing the time of catheter use.

PD-L1 (Programmed Death Ligand 1) Regulates T-Cell Differentiation to Control Adaptive Venous Remodeling

OBJECTIVE

Patients with end-stage renal disease depend on hemodialysis for survival. Although arteriovenous fistulae (AVF) are the preferred vascular access for hemodialysis, the primary success rate of AVF is only 30% to 50% within 6 months, showing an urgent need for improvement. PD-L1 (programmed death ligand 1) is a ligand that regulates T-cell activity. Since T cells have an important role during AVF maturation, we hypothesized that PD-L1 regulates T cells to control venous remodeling that occurs during AVF maturation. Approach and results: In the mouse aortocaval fistula model, anti-PD-L1 antibody (200 mg, 3×/wk intraperitoneal) was given to inhibit PD-L1 activity during AVF maturation. Inhibition of PD-L1 increased T-helper type 1 cells and T-helper type 2 cells but reduced regulatory T cells to increase M1-type macrophages and reduce M2-type macrophages; these changes were associated with reduced vascular wall thickening and reduced AVF patency. Inhibition of PD-L1 also inhibited smooth muscle cell proliferation and increased endothelial dysfunction. The effects of anti-PD-L1 antibody on adaptive venous remodeling were diminished in nude mice; however, they were restored after T-cell transfer into nude mice, indicating the effects of anti-PD-L1 antibody on venous remodeling were dependent on T cells.

CONCLUSIONS

Regulation of PD-L1 activity may be a potential therapeutic target for clinical translation to improve AVF maturation.

Vascular Access and Clinical Outcomes in Underserved Hemodialysis Patients in Mexico

INTRODUCTION

Central venous catheter (CVC) as vascular access in hemodialysis (HD) associates with adverse outcomes. Early CVC to fistula or graft conversion improves these outcomes. While socioeconomic disparities between the USA and Mexico exist, little is known about CVC prevalence and conversion rates in uninsured Mexican HD patients. We examined vascular access practice patterns and their effects on survival and hospitalization rates among uninsured Mexican HD patients, in comparison with HD patients who initiated treatment in the USA.

METHODS

In this retrospective study of incident HD patients at Hospital Civil (HC; Guadalajara, MX) and the Renal Research Institute (RRI; USA), we categorized patients by the vascular access at the first month of HD and after the following 6 months. Factors associated with continued CVC use were identified by a logistic regression model. We developed multivariate Cox proportional hazards models to investigate the effects of access and conversion on mortality and hospitalization over an 18-month follow-up period.

RESULTS

In 1,632 patients from RRI, the CVC prevalence at month 1 was 64% and 97% among 174 HC patients. The conversion rate was 31.7% in RRI and 10.6% in HC. CVC to non-central venous catheter (NON-CVC) conversion reduced the risk of hospitalization in both HC (aHR 0.38 [95% CI: 0.21-0.68], p = 0.001) and RRI (aHR 0.84 [95% CI: 0.73-0.93], p = 0.001). NON-CVC patients had a lower mortality risk in both populations.

DISCUSSION/CONCLUSION

CVC prevalence and conversion rates of CVC to NON-CVC differed between the US and Mexican patients. An association exists between vascular access type and hospitalization and mortality risk. Prospective studies are needed to evaluate if accelerated and systematic catheter use reduction would improve outcomes in these populations.

Identification of the Crucial Gene in Overflow Arteriovenous Fistula by Bioinformatics Analysis

Objective: The aim was to study the preliminary screening of the crucial genes in intimal hyperplasia in the venous segment of arteriovenous (AV) fistula and the underlying potential molecular mechanisms of intimal hyperplasia with bioinformatics analysis. Methods: The gene expression profile data (GSE39488) was analyzed to identify differentially expressed genes (DEGs). We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of DEGs. Gene set enrichment analysis (GSEA) was used to understand the potential activated signaling pathway. The protein-protein interaction (PPI) network was constructed with the STRING database and Cytoscape software. The Venn diagram between 10 hub genes and gene sets of 4 crucial signaling pathways was used to obtain core genes and relevant potential pathways. Furthermore, GSEAs were performed to understand their biological functions. Results: A total of 185 DEGs were screened in this study. The main biological function of the 111 upregulated genes in AV fistula primarily concentrated on cell proliferation and vascular remodeling, and the 74 downregulated genes in AV fistula were enriched in the biological function mainly relevant to inflammation. GSEA found four signaling pathways crucial for intimal hyperplasia, namely, MAPK, NOD-like, Cell Cycle, and TGF-beta signaling pathway. A total of 10 hub genes were identified, namely, EGR1, EGR2, EGR3, NR4A1, NR4A2, DUSP1, CXCR4, ATF3, CCL4, and CYR61. Particularly, DUSP1 and NR4A1 were identified as core genes that potentially participate in the MAPK signaling pathway. In AV fistula, the biological processes and pathways were primarily involved with MAPK signaling pathway and MAPK-mediated pathway with the high expression of DUSP1 and were highly relevant to cell proliferation and inflammation with the low expression of DUSP1. Besides, the biological processes and pathways in AV fistula with the high expression of NR4A1 similarly included the MAPK signaling pathway and the pathway mediated by MAPK signaling, and it was mainly involved with inflammation in AV fistula with the low expression of NR4A1. Conclusion: We screened four potential signaling pathways relevant to intimal hyperplasia and identified 10 hub genes, including two core genes (i.e., DUSP1 and NR4A1). Two core genes potentially participate in the MAPK signaling pathway and might serve as the therapeutic targets of intimal hyperplasia to prevent stenosis after AV fistula creation.

A randomized controlled trial of the effect of post-operative hand exercise training on arteriovenous fistula maturation in patients with chronic kidney disease

OBJECTIVE

Immature arteriovenous fistula (AVF) is a critical problem in chronic kidney disease (CKD) patients after creation. Exercise with 30% maximum voluntary contraction (MVC) encourages vascular functions in other populations. It is unknown which exercise type is superior on maturation in CKD population. We compare effects of isometric- (ISM) and isotonic-hand exercise training (IST), both at 30% MVC, on AVF maturation and grip strength in CKD patients.

METHODS

Fifty CKD patients were randomized into ISM program or IST program (25 per group). Each group performed exercise program at intensity of 30% MVC every day for 10 weeks. Cephalic vein (CV) and brachial artery diameters and brachial blood flows, and grip strength were measured at weeks 0, 2, 6, and 10 of program. The number of patients meeting clinical and ultrasound (US) maturation were evaluated at weeks 2, 6, and 10.

RESULTS

At weeks 6 and 10 of the programs, ISM group had greater CV diameters (week 6, 7.1±1.2 versus 6.2±1.0 mm; week 10, 7.1±1.0 versus 6.2±1.1 mm) than the IST group. Compared to the IST, the ISM had a higher number of patients meeting US maturation at weeks 2 (IST/ISM=8/2), 6 (16/8), and 10 (21/12), and clinical maturation at week 10 (25/18). No adverse events were observed throughout the study.

CONCLUSIONS

At 30% MVC, ISM is more effective at promoting increases in cephalic vein diameter and maturation than IST. Both exercise types are feasible and safe for CKD patients after AVF creation.

Are continued policies of prioritizing native vascular access in patients on hemodialysis programs useful?

The guidelines recommend establishing native vascular access as opposed to prosthetic or catheter-based access despite information relating to its effectiveness being scarce from a patient-orientated perspective. We analyzed the effectiveness of a continued policy of native vascular access (CPNVA) in patients undergoing hemodialysis. A retrospective, observational study, including 150 patients undergoing hemodialysis between 2006 and 2012 at our center, and who underwent a CPNVA. Statistical analysis was based on treatment intention. In 138 patients (92%), the first useful access (FUA) was native, and in 12 patients (8%), it was prosthetic. In 50 patients (33.3%), more than one procedure had to be carried out in to order to achieve FUA. The probability of dialysis occurring via a FUA was 67.1% and 45.3% at 1 and 5 years respectively. Over the follow-up period (mean time = 30 months), 84 patients (56%) required repairs or new access, extending the effectiveness of the CPNVA to 88.3% and 73.2% at 1 and 5 years respectively. The effectiveness of the CPNVA was reduced if the patient: required a catheter initially (HR: 3.6, p = 0.007); in cases of initially elevated glomerular filtration rate (HR: 1.1, p = 0.040); in cases of history of previous access failure before FUA (HR: 3.9, p = 0.001); and in female patients (HR: 2.4, p = 0.031). The long-term effectiveness of a CPNVA is high. However, the percentage of patients requiring diverse procedures in order to achieve FUA and the need for re-interventions yield the necessity to optimize preoperative evaluation and postoperative follow-up.

Use of a fluoropolymer-based paclitaxel-eluting stent for arteriovenous graft outflow vein stenosis in hemodialysis patients

We implanted a fluoropolymer-based paclitaxel-eluting stent (FP-PES) in four hemodialysis patients with refractory outflow venous stenosis of their arteriovenous graft. The mean observation period after FP-PES implantation was 11.5 ± 4.7 months (range, 7.0-18.0 months). After FP-PES implantation, the patients were evaluated by ultrasound every 3 months. No of the patients experienced neointimal hyperplasia in the stents during the observation period, and no reintervention was performed. FP-PESs could be an attractive alternative to percutaneous transluminal angioplasty for patients with refractory outflow venous stenosis of arteriovenous hemodialysis grafts.

Predialysis nephrology care amongst Palestinian hemodialysis patients and its impact on initial vascular access type

Referral time for end-stage renal disease (ESRD) patients to nephrologists and initial vascular access method are considered significant factors that impact health outcomes at the time of hemodialysis (HD) initiation. Native arteriovenous fistula (AVF) is strongly recommended as initial access. However, little is known about the referral rate among ESRD receiving HD in Palestine and its correlation with AVF creation. In Ramallah Hemodialysis Center, we investigated the pre-dialysis nephrology care and AVF usage in 156 patients. Type of access at HD initiation was temporary central venous catheter (CVC) in 114 (73%), tunneled hemodialysis catheter (TDC) in 21 (13%) and AVF in 21 (13%). Out of all participants, 120 (77%) were seen by nephrologist prior to dialysis. Of the participants who initiated dialysis with a CVC, 36 (31%) had not received prior nephrology care. All participants who initiated dialysis with functional AVF had received prior nephrology care. Patients who were not seen by a nephrologist prior to HD initiation had no chance at starting HD with AVF, whereas 17% of those who had nephrology care >12 months started with AVF. In conclusion, a relatively large percentage of Palestinian HD patients who were maintained on HD did not have any predialysis nephrology care. In addition, patients who received predialysis nephrology care were significantly more likely to start their HD through AVF whereas all those without predialysis nephrology care started through CVC. More in-depth national studies focusing on improving nephrology referral in ESRD patients are needed to increase AVF utilization.

Factors Affecting the Patency of Radiocephalic Arteriovenous Fistulas Based on Clinico-Radiological Parameters

Arteriovenous fistulas are an important means of vascular access for long-term haemodialysis in patients with end-stage renal disease (ESRD). We evaluated the outcome of radiocephalic arteriovenous fistulas (RCAVFs) in 55 patients operated upon in our hospital in southern India. We studied the outcome of RCAVF surgery with the demographic factors, duration of diabetes, the diameter of the radial artery and cephalic vein, and any signs of atherosclerosis in the radial artery. We found that a small cephalic vein size of ≤ 2 mm, a negative cephalic vein tap test, a thickened, non-compressible, calcified radial artery on palpation, and evidence of atherosclerosis on radiological investigations were associated with a significant chance of RCAVF failure. A clinico-radiological grading of atherosclerosis for peripheral arteries is also proposed. Any patient presenting to the microsurgeon with a small cephalic vein size, a negative cephalic vein tap test, a thickened, non-compressible, calcified vessel on palpation, and tram-track calcification or whole vessel calcification or severely atherosclerotic vessel on radiological evaluation must be approached with caution regarding RCAVF creation and must be prepared for an arteriovenous fistula (AVF) creation at a higher level.

Contemporary outcomes of a "snuffbox first" hemodialysis access approach in the United States

OBJECTIVE

The Society for Vascular Surgery guidelines for permanent hemodialysis (HD) access creation recommend prioritizing the most distal possible autogenous access to minimize complications and preserve more proximal options. The "snuffbox" arteriovenous fistula (AVF) is the most distal radial artery-cephalic vein AVF. Despite the theoretical benefits of the snuffbox approach, recent trends have been toward upper arm access. Our study sought to investigate the feasibility of a snuffbox-first strategy for HD access in all anatomically appropriate candidates.

METHODS

From January 2016 to August 2019, all patients with end-stage renal disease (ESRD) or pre-ESRD under consideration for HD access were evaluated for a snuffbox-first approach by a team of vascular surgeons and nephrologists at a single, urban academic medical center in the United States. Data were collected prospectively and supplemented by medical record review. A survival analysis was performed to evaluate primary unassisted and secondary patency and clinical and functional maturation. Patients were censored if they had received a kidney transplant or had died. Cox proportional hazards regression was used to determine the risk factors for prolonged clinical maturation and functional maturation.

RESULTS

A total of 55 snuffbox AVFs were created. The median patient age was 60 years (interquartile range [IQR], 52-70 years), and 52.7% of the patients were men. The median follow-up was 369 days (IQR, 166-509 days). The median survival for primary unassisted patency was 90 days (95% confidence interval [CI], 79-111). Secondary patency at 1 year was 92.3% (95% CI, 85.3%-99.9%). The clinical maturation rate at 1 year was 83.7% (n = 55; 95% CI, 66.8%-91.9%), and the functional maturation rate at 1 year was 85.6% (n = 40; 95% CI, 63.3%-94.4%). Of the patients who were pre-ESRD at AVF creation and had initiated HD during the study period, 87.5% had successfully received incident HD with their snuffbox AVF. Twenty-four patients were receiving HD via a catheter at snuffbox creation. Of those patients, the functional maturation rate at 1 year was 82.5% (95% CI, 44.8%-94.4%). The patients had undergone a median of two interventions (IQR, zero to seven interventions) in the first year. Of these, 46.9% were percutaneous angioplasty and 31.2% were side-branch ligation. Diabetes was associated with slower AVF clinical maturation (multivariate hazard ratio, 0.35; 95% CI, 0.15-0.82; P = .016). A larger artery diameter was associated with earlier AVF clinical maturation (multivariate hazard ratio, 6.64; 95% CI, 2.11-20.9).

CONCLUSIONS

A snuffbox-first approach to HD access is a viable option for distal access creation in a cohort of patients requiring HD in the United States. Subsequent ancillary interventions to facilitate access maturation were required for most patients.

Inhibition of T-Cells by Cyclosporine A Reduces Macrophage Accumulation to Regulate Venous Adaptive Remodeling and Increase Arteriovenous Fistula Maturation

OBJECTIVE

Arteriovenous fistulae (AVF) are the preferred vascular access for hemodialysis, but the primary success rate of AVF remains poor. Successful AVF maturation requires vascular wall thickening and outward remodeling. A key factor determining successful AVF maturation is inflammation that is characterized by accumulation of both T-cells and macrophages. We have previously shown that anti-inflammatory (M2) macrophages are critically important for vascular wall thickening during venous remodeling; therefore, regulation of macrophage accumulation may be an important mechanism promoting AVF maturation. Since CD4+ T-cells such as T-helper type 1 cells, T-helper type 2 cells, and regulatory T-cells can induce macrophage migration, proliferation, and polarization, we hypothesized that CD4+ T-cells regulate macrophage accumulation to promote AVF maturation. Approach and Results: In a mouse aortocaval fistula model, T-cells temporally precede macrophages in the remodeling AVF wall. CsA (cyclosporine A; 5 mg/kg, sq, daily) or vehicle (5% dimethyl sulfoxide) was administered to inhibit T-cell function during venous remodeling. CsA reduced the numbers of T-helper type 1 cells, T-helper type 2, and regulatory T-cells, as well as M1- and M2-macrophage accumulation in the wall of the remodeling fistula; these effects were associated with reduced vascular wall thickening and increased outward remodeling in wild-type mice. However, these effects were eliminated in nude mice, showing that the effects of CsA on macrophage accumulation and adaptive venous remodeling are T-cell-dependent.

CONCLUSIONS

T-cells regulate macrophage accumulation in the maturing venous wall to control adaptive remodeling. Regulation of T-cells during AVF maturation may be a strategy that can improve AVF maturation. Graphic Abstract: A graphic abstract is available for this article.

Relationship between Serum YKL-40 Level and Forearm Arterial Patency after Repair

BACKGROUND

The study aimed to assess the effects of serum YKL-40 level on patency at the repair site in patients who underwent arterial repair at the level of the forearm.

METHODS

The study included 58 subjects, including 29 patients (aged 18-50 years) who had ulnar or radial artery injury secondary to cut injury to wrist between June 2015 and November 2019 and no comorbid disease and 29 age- and sex-matched healthy controls. The vascular patency was assessed using Doppler sonography in patients who underwent arterial repair at the level of the forearm. The patients were defined as flow failure if the blood flow was ≤50%, and sufficient flow if the blood flow was >50% of those in the synonymous artery on the intact extremity. The YKL-40 level differences in the patient and control groups were compared to those in the sufficient and insufficient flow groups.

RESULTS

The patients were stratified into 2 groups based on the presence of sufficient flow. The mean YKL level was 11.96 ± 8.87 in the sufficient flow groups, whereas it was 32.22 ± 15.43 in the insufficient flow groups (p= 0.038). Besides, it was found that each unit of increase in the YKL-40 level increased the likelihood of having flow failure by 1.128.

CONCLUSION

Based on our results, it was observed that over-expression of the YKL-40 level has adverse effects on patency following arterial repair.

Perceived barriers and attitudes toward arteriovenous fistula creation and use in hemodialysis patients in Palestine

In the dialysis center in Ramallah, we investigated the attitudes and perceived barriers to having arteriovenous fistula (AVF) in 156 patients. The current method of HD access was AVF in 52% and central venous catheter in 47%. Perceived causes of no or delayed AVF were: patient’s refusal of AVF in 54.5%, late referral to a surgical evaluation in 31.3% and too long to surgical appointments in 14.2%. Among those who refused AVF, reasons were: concern about the surgical procedure in 42.5%, poor understanding of disease/access in 23.3%, fear of needles in 15.1%, denial of disease or need for HD in 17.8%, and cosmetic reasons in 1.4%. Forty six percent of patients believed they received education about AVF prior to the creation of HD access, and 73.7% would recommend AVF as the method of access due to the lower risk of infection (96%), easier to care for (16%), easier showering (14%), and better-associated hygiene (3%). In conclusion, the majority would recommend an AVF as the mode of vascular access for HD. The most common barrier to having an AVF was patient’s refusal to undergo AVF creation because of their concern about the surgical procedure. A systematic evaluation of the process that precedes the creation of AVF may allow for better utilization.

A meta-analysis of traditional and functional end-to-side anastomosis in radiocephalic fistula for dialysis access

Objective

Functional vein end to arterial side (ETS) anastomosis uses vein side to arterial side (STS) anastomosis with distal vein ligation, which can achieve similar effects as those of ETS after STS anastomosis. The purpose of the study was to provide a meta-analysis to compare the clinical outcomes between traditional and functional ETS anastomosis in radiocephalic fistula for dialysis access.

Methods

Databases including PubMed, EMbase, the Cochrane Library, CNKI, Wanfang database were searched from the inception to February 6, 2020. Eligible studies comparing traditional and functional ETS anastomosis in radiocephalic fistula were included. Data were analyzed using Review Manager Version 5.3.

Results

Seven studies were included in the meta-analysis. Five randomized controlled trials and two cohort studies involving 841 patients were identified. Compared with traditional ETS anastomosis, functional ETS anastomosis had shorter anastomosis time (MD − 9.54, 95% CI − 17.96 to − 1.12, P = 0.03), higher surgical success rate (OR 3.80, 95% CI 1.76–8.22, P < 0.01), fewer complications(OR 0.18, 95% CI 0.08–0.39, P < 0.01), higher patency rate after 3 months (OR 4.91, 95% CI 1.19–20.33, P = 0.03), higher patency rate after 6 months (OR 1.90, 95%CI 1.09–3.31, P = 0.02), higher patency rate after 12 months (OR 1.70, 95% CI 1.09–2.66, P = 0.02). There was no difference after the two arteriovenous (AVF) anastomosisl methods concerning AVF maturation time (SMD − 0.48, 95% CI − 1.30–0.34, P = 0.25) and patency rate after 1 month (OR 1.77, 95% CI 0.65–4.80, P = 0.26).

Conclusion

Functional ETS anastomosis had advantages of easy operation, high surgical success rate, few complications, high patency rate of 3 months and long-term, but did not have obvious advantage in the early stages concerning AVF maturation time and 1-month patency rate.

Proximal Arteriovenous Fistulas in Hemodialysis Patients: Advantages and Disadvantages

Introduction: The main objective of the present study is to investigate the advantages and disadvantages of proximal arteriovenous native fistulas. Hemodialysis is indispensable for patients with end-stage renal disease. For this purpose, arteriovenous fistulas (AVFs) are used. Among the native fistulas, distal radiocephalic AVF is the most preferred. However, brachiocephalic AVF (BCAVF) and brachiobasilic AVF with basilic vein transposition (basilic vein transposition arteriovenous fistula [BVTAVF]) can be used for a long time in dialysis patients whose distal vascular bed is depleted.

Methods: This is a retrospective study of 117 AVFs (BCAVF and BVTAVF), in patients with end-stage chronic renal disease, that were opened with a surgical technique (2012-2018). The postoperative two-year patency rates, AVF locations, complications, and the advantages and disadvantages of these fistulas are reviewed and recorded in the light of the literature.

Results: The mean age of the patients (52 men and 65 women) was 60.6 ± 13.6 years. The percentages of primary patency rates at 3, 6, 9, 12, and 24 months were 96.6%, 93.1%, 92%, 87.4%, and 82.8% in BCAVF patients, and 96.7%, 93.3%, 90%, 86.7%, and 80% in BVTAVF patients, respectively. The percentages of secondary patency rates at 6, 12, and 24 months were 100%, 93.3%, and 86.7% in BCAVF patients, and 100%, 100% and 87.7% in BVTAVF patients, respectively. Fistula thrombosis was seen as the most common complication. The early complication was bleeding/hematoma. As late complications, we encountered steal syndrome, ischemic pain in the relevant extremity, pseudoaneurysm, and high-output heart failure.

Conclusion: Proximal AVFs are preferable fistulas with early maturation and high primary patency rates. We believe that relatively high complications can be avoided by opening fistulas with an appropriate surgical technique.

Percutaneous intervention for salvage of non-maturing arteriovenous fistulas: Which is the better approach, arterial or venous?

Objectives

To evaluate the efficacy and long-term patency of endovascular treatment for non-maturing native arteriovenous fistulas according to the approach route (arterial vs. venous).

Methods

Eighty-five patients underwent percutaneous transluminal angioplasty for non-maturing fistulas (63 radiocephalic and 22 brachiocephalic) between 2010 and 2019. Outcome variables such as procedural success, complications, and primary and secondary patency rates were analyzed from the patients’ demographic, angiographic, clinical, and hemodialysis records according to the approach route (venous access group, n = 53 and arterial access group, n = 32). The Kaplan-Meier method was used to analyze the patency rates.

Results

The mean duration from fistula creation to fistulography was 78.4±51.4 days (range, 1–180 days). The anatomical and clinical success rates were 98.8% and 83.5%, respectively. Lesions were most commonly located at the juxta-anastomosis (55.3%). Accessory cephalic veins were observed in 16 patients. The primary patency rates were 83.9%, 71.9%, and 66.3% and the secondary patency rates were 98.6%, 95.9%, and 94.2% at 3 months, 6 months, and 1 year, respectively. The degree of hypertension (P = 0.023), minimal preoperative vein size (P = 0.041), and increment in postoperative vein diameter were higher in the venous access group than in the arterial access group (P<0.01). The frequency of using cutting balloons (P = 0.026) and complication rate were higher in the arterial access group than in the venous access group (arterial access: 1 major, 8 minor; venous access: 4 minor; P = 0.015).

Conclusions

Aggressive evaluation and endovascular therapy can salvage most non-maturing fistulas. Transradial and distal radial approaches can be effective even for challenging lesions.

Cost Analysis of Dialysis Access Maintenance Interventions across Physician Specialties in U.S. Medicare Beneficiaries

Background Dialysis maintenance interventions account for billions of dollars in U.S. Medicare spending and are performed by multiple medical specialties. Whether Medicare costs differ by physician specialty is, to the knowledge of the authors, not known. Purpose To assess patency-adjusted costs of endovascular dialysis access maintenance by physician specialty. Materials and Methods In this retrospective longitudinal cohort study, patients who were beneficiaries of Medicare undergoing their first arteriovenous access placement in 2009 were identified by using billing codes in the 5% Limited Data Set. By tracking their utilization data through 2014, postintervention primary patency and aggregate payments associated with maintenance interventions were calculated. Unadjusted payments per year of access patency gain were compared across physician specialty. A general linear mixed-effects model adjusted for covariates was used, as follows: patient characteristics, access type (fistula vs graft), clinical severity, type of intervention (angioplasty, stent, thrombolysis), clinical location (hospital outpatient vs office-based laboratory), and resource utilization (operating room use, anesthesia use). Results First arteriovenous access was performed in 1479 beneficiaries (mean age, 63 years ± 15 [standard deviation]; 820 men) in 2009. Through 2014, 8166 maintenance interventions were performed in this cohort. Unadjusted mean Medicare payments for each incremental year of patency were as follows: $71 000 for radiologists, $89 000 for nephrologists, and $174 000 for surgeons. Billing for operating room (41.8% [792 of 1895], surgery; 10.2% [277 of 2709], nephrology; and 31.1% [1108 of 3562], radiology) and anesthesia (19.9% [377 of 1895], surgery; 2.6% [70 of 2709], nephrology; 4.7% [170 of 3562], radiology) varied by specialty and accounted for 407% and 132% higher payments, respectively. After adjusting for clinical severity and location, type of intervention, and resource utilization, nephrologists and surgeons had 59% (95% confidence interval: 44%, 73%; P < .001) and 57% (95% confidence interval: 43%, 72%; P < .001) higher payments, respectively, for the same patency gain compared with radiologists. Operating room use and anesthesia services were major drivers of higher cost, with 407% (95% confidence interval: 374%, 443%; P < .001) and 132% (95% confidence interval: 116%, 150%; P < .001) higher costs, respectively. Conclusion Patency-adjusted payments for hemodialysis access maintenance differed by physician specialty, driven partly by discrepant rates of billing for operating room and anesthesia use. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by White in this issue.

Higher body mass index is associated with reinterventions and lower maturation rates after upper extremity arteriovenous access creation

OBJECTIVE

A patient's body mass index (BMI) can affect both perioperative and postoperative outcomes across all surgical specialties. Given that obesity and end-stage renal disease are growing in prevalence, we aimed to evaluate the association between BMI and outcomes of upper extremity arteriovenous (AV) access creation.

METHODS

A retrospective single-institution review was conducted for AV access creations from 2014 to 2018. Patient demographics, comorbidities, and AV access details were recorded. BMI groups were defined as normal weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²), obese (30-39.9 kg/m²), and morbidly obese (>40 kg/m²). Perioperative complications and long-term outcomes including access maturation (defined as access being used for hemodialysis or the surgeon's judgment that access was ready for use in patients not yet on hemodialysis), occlusion, and reintervention were evaluated.

RESULTS

A total of 611 upper extremity AV access creations were performed on patients who were normal weight (29.6%), overweight (31.3%), obese (29.6%), and morbidly obese (9.5%). Access type included brachiocephalic (43.2%), brachiobasilic (25.5%), and radiocephalic (14.2%) fistulas and AV grafts (14.2%). Median age was 60.9 years, and 59.6% were male. Univariable analysis showed no difference between BMI groups for perioperative steal, hematoma, home discharge, or 30-day primary patency. Freedom from reintervention at 2 years on Kaplan-Meier analysis differed by BMI (44.5% ± 4.6% normal weight, 29% ± 3.8% overweight, 39.8% ± 4.3% obese, 34.7% ± 8% morbidly obese; P = .041). There was no difference in 2-year freedom from new access creation or survival. AV access maturity within 180 days differed between BMI groups (74.3% normal weight, 66% overweight, 65.7% obese, 46.6% morbidly obese; P < .001). On multivariable analysis, failure to mature within 180 days was associated with overweight (odds ratio [OR], 1.93; 95% confidence interval [CI], 1.14-3.29; P = .002), obese (OR, 2.12; 95% CI, 1.19-3.47; P = .009), and morbidly obese (OR, 3.68; 95% CI, 1.85-7.3; P < .001) relative to normal weight BMI. AV access reintervention was associated with overweight (hazard ratio [HR], 1.83; 95% CI, 1.34-2.5), obese (HR, 1.56; 95% CI, 1.12-2.16), and morbidly obese (HR, 1.69; 95% CI, 1.1-2.58; P = .02) relative to normal weight BMI. BMI was not independently associated with long-term readmission or survival.

CONCLUSIONS

Obesity is associated with higher rates of AV access failure to mature and reintervention. Surgeons performing access creation on obese patients must consider this for planning and setting expectations. Weight loss assistance may need to be incorporated into treatment algorithms.

Altered hemodynamics during arteriovenous fistula remodeling leads to reduced fistula patency in female mice

Objective

The arteriovenous fistula (AVF) is the preferred method of dialysis access because of its proven superior long-term outcomes. However, women have lower rates of AVF patency and utilization than men. We used a novel mouse AVF model that recapitulates human AVF maturation to determine whether there are differences in AVF patency in female and male mice.

Methods

Aortocaval fistulas were created in female and male C57BL/6 mice (9-10 weeks). At days 0, 3, 7, and 21, infrarenal inferior vena cava (IVC) and aortic diameters and flow velocity were monitored by Doppler ultrasound and used to calculate the vessel diameter, blood flow, and shear stress. AVF were harvested, and expression of proteins was examined by proteomic analysis and immunofluorescence and of messenger RNA by quantitative polymerase chain reaction analysis.

Results

At baseline, female mice weighed less and had lower IVC velocity and smaller magnitudes of shear stress, but there was no significant difference in IVC diameter and thickness. After AVF creation, both female and male mice had similar IVC dilation and thickening with no significant differences in IVC wall thickness at day 21. However, female mice had diminished AVF patency by day 42 (25.7% vs 64.3%; P = .039). During fistula remodeling, female mice had lower IVC mean velocity and shear stress magnitude and increased spectral broadening (days 0-21). Messenger RNA and protein expression of Krüppel-like factor 2, endothelial nitric oxide synthase, and vascular cell adhesion molecule 1 was similar at baseline in female and male mice but increased in the AVF only in male mice but not in female mice (day 21). Proteomic analysis of female and male mice detected 56 proteins expressed at significantly higher levels in the IVC of female mice and 67 proteins expressed at significantly higher levels in the IVC of male mice (day 7); function-specific analysis showed that the IVC of male mice overexpressed proteins that belong to pathways implicated in the regulation of vascular function, thrombosis, response to flow, and vascular remodeling.

Conclusions

AVF in female mice have diminished patency, preceded by lower velocity, reduced magnitudes of shear stress, and less laminar flow during remodeling. There is also sex-specific differential expression of proteins involved in thrombosis, response to laminar flow, inflammation, and proliferation. These findings suggest that hemodynamic changes during fistula maturation may play an important role underlying the diminished rates of AVF utilization in women.

Women have lower rates of arteriovenous fistula (AVF) utilization than men. Using a mouse AVF model that recapitulates human AVF maturation, we show that female mice have similar AVF remodeling but diminished patency. AVF remodeling in female mice is associated with reduced shear stress and laminar flow; lack of increased transcription and translation of several anti-inflammatory, antiproliferative, and laminar flow response proteins (endothelial nitric oxide synthase, Krüppel-like factor 2, and vascular cell adhesion molecule 1); and different patterns of expression of pathways that regulate thrombosis and venous remodeling. Identifying downstream targets involved in these mechanisms may improve AVF outcomes in female patients.

Intraoperative Ultrasound Guidance for Banding of an Arteriovenous Fistula Causing High Cardiac Output Heart Failure

The creation of an arteriovenous fistula (AVF) is the preferred mode of access for hemodialysis in patients with End-Stage Renal Disease (ESRD). High output cardiac failure is a known but rare complication of AVF resulting from high flow volume. This case report describes the use of intraoperative ultrasound as a guide for the banding of an AVF to decrease flow volume in a patient with high cardiac output failure. The access was preserved, and a gradual decline of cardiac function before and recovery after banding is demonstrated over an 18-year period.

A retrospective comparison analysis of results of drug-coated balloon versus plain balloon angioplasty in treatment of juxta-anastomotic de novo stenosis of radiocephalic arteriovenous fistulas

BACKGROUND

Juxta-anastomotic stenosis is a common issue of arteriovenous fistulas. We aimed to evaluate the results of percutaneous transluminal angioplasty with drug-coated balloon versus plain balloon for the treatment of juxta-anastomotic stenoses of mature but failing distal radiocephalic arteriovenous fistulas.

METHODS

A total of 80 patients with a juxta-anastomotic stenosis of distal radiocephalic arteriovenous fistula in our clinic between January 2016 and September 2017 were retrospectively analyzed. Patients were divided into two groups according to the type of treatment as drug-coated balloon - percutaneous transluminal angioplasty (n = 44) and plain balloon - percutaneous transluminal angioplasty (n = 43). Intra- and post-procedural data were recorded. Target lesion primary patency rate was evaluated at 6 and 12 months. Of all patients, 48 were females and 39 were males with a mean age of 56.3 ± 10.4 (range, 24-75) years. Both groups had mature fistulas, and the mean age of fistula was 11.3 ± 9.1 months in the drug-coated balloon - percutaneous transluminal angioplasty group and 10.3 ± 8.8 months in the plain balloon - percutaneous transluminal angioplasty group (p = 0.24).

RESULTS

There was no significant difference in the target lesion stenosis rate and the median lesion length between the groups. Technical and clinical success were achieved in both groups. Target lesion primary patency was similar at 6 months between the two groups (93.1% vs 81.3%, respectively; p = 0.14) but significantly higher for the drug-coated balloon - percutaneous transluminal angioplasty group at 12 months (81.8% vs 51.1%, respectively; p = 0.01).

CONCLUSION

Our study results suggest that the use of drug-coated balloon combined with percutaneous transluminal angioplasty is an effective treatment for juxta-anastomotic stenoses of mature but failing distal radiocephalic arteriovenous fistulas with significantly improved target lesion primary patency rates and reduced need for juxta-anastomotic reinterventions.

Molecular Targets for Improving Arteriovenous Fistula Maturation and Patency

The increasing prevalence of chronic and end-stage renal disease creates an increased need for reliable vascular access, and although arteriovenous fistulae (AVF) are the preferred mode of hemodialysis access, 60% fail to mature and only 50% remain patent at one year. Fistulae mature by diameter expansion and wall thickening; this outward remodeling of the venous wall in the fistula environment relies on a delicate balance of extracellular matrix (ECM) remodeling, inflammation, growth factor secretion, and cell adhesion molecule upregulation in the venous wall. AVF failure occurs via two distinct mechanisms with early failure secondary to lack of outward remodeling, that is insufficient diameter expansion or wall thickening, whereas late failure occurs with excessive wall thickening due to neointimal hyperplasia (NIH) and insufficient diameter expansion in a previously functional fistula. In recent years, the molecular basis of AVF maturation and failure are becoming understood in order to develop potential therapeutic targets to aide maturation and prevent access loss. Erythropoietin-producing hepatocellular carcinoma (Eph) receptors, along with their ligands, ephrins, determine vascular identity and are critical for vascular remodeling in the embryo. Manipulation of Eph receptor signaling in adults, as well as downstream pathways, is a potential treatment strategy to improve the rates of AVF maturation and patency. This review examines our current understanding of molecular changes occurring following fistula creation, factors predictive of fistula success, and potential areas of intervention to decrease AVF failure.

Use of dehydrated human amnion chorion membrane allograft on infected ruptured arteriovenous fistula: revision and closure

OBJECTIVE

Over two million individuals worldwide, with end-stage renal disease (ESRD), depend on dialysis therapy or a kidney transplant for survival. Every haemodialysis patient requires vascular access. The arteriovenous fistula (AVF) is preferred for long-term hemodialysis vascular access due to long-term primary patency rates. Given the limited options for haemodialysis access and placement, preservation of existing AVF sites is always a clinical priority. This case report describes a novel approach to wound closure with the application of dehydrated amnion chorion human membrane (dHACM) at an AVF surgical site known to be complicated with issues of scarring and tissue breakdown. The patient was treated successfully with the imperative preservation of his AVF given that he had few other vascular access options.

Thrombophilic risk factors in hemodialysis: Association with early vascular access occlusion and patient survival in long-term follow-up

Objective

Thrombophilic risk factors (TRFs) occur rather frequently in hemodialysis (HD) patients. However, little is known about their significance in HD patients, besides their potential impact on arteriovenous (AV) access failure, with varying results. We examined the effects of a wide variety of TRFs on both early AV fistula occlusion and survival among HD patients in long-term follow-up.

Methods

In this single-center, observational study, 70 consecutive HD patients from our dialysis center were examined with respect to shunt occlusion within the first 2 years after fistula creation and patient survival in a long-term follow-up (at least 16 years). We examined the presence of factor V, prothrombin, and MTHFR mutations using real-time fluorescence polymerase chain reaction. Furthermore, antithrombin (AT), protein C, protein S, and antiphospholipid antibodies (APL-Abs) were assessed.

Results

Among the 70 patients, 32 had MTHFR mutations, 10 had heterozygous factor V Leiden mutations, 4 had prothrombin mutations, 4 had protein S deficiency, 2 had protein C deficiency, 9 had AT deficiency, and 14 had APL-Abs. 40 patients had shunt occlusion. TRFs were associated with a significantly increased risk for shunt thrombosis (P<0.02). Kaplan–Meier analysis with a log-rank test revealed significantly shorter survival in HD patients with TRFs (P<0.02). Cox regression analysis showed that the presence of TRFs (P<0.05; hazard ratio, 1.94; 95% CI: 1.07–3.56), but not early shunt occlusion, was associated with short patient survival.

Conclusions

TRFs in hemodialysis patients have a strong impact on patient survival and early AV fistula failure; however, patient survival is not significantly affected by early shunt occlusion.

Ischemic Monomelic Neuropathy after Arteriovenous Fistula Surgery: Clinical Features, Electrodiagnostic Findings, and Treatment

Ischemic monomelic neuropathy (IMN) is a rare complication of vascular access in the hemodialysis patients, characterized by multiple mononeuropathies in the absence of clinical ischemia. Most commonly seen in the female gender, diabetes mellitus, and it must be differentiated from vascular steal syndrome, where we see clinical ischemia as the main pathognomonic feature. Early recognition of the symptoms and prompt intervention was shown to be beneficial. A delay in the treatment can lead to irreversible damage to the nerves and muscles. This article is depicting a case of an elderly male patient who presented with signs and symptoms of IMN which developed after arteriovenous (AV) fistula graft surgery.

Use of Peripherally Inserted Central Catheters in Patients With Advanced Chronic Kidney Disease: A Prospective Cohort Study

BACKGROUND

Existing guidelines, including Choosing Wisely recommendations, endorse avoiding placement of peripherally inserted central catheters (PICCs) in patients with chronic kidney disease (CKD).

OBJECTIVE

To describe the frequency of and characteristics associated with PICC use in hospitalized patients with stage 3b or greater CKD (glomerular filtration rate [GFR] <45 mL/min/1.73 m2).

DESIGN

Prospective cohort study.

SETTING

52 hospitals participating in the Michigan Hospital Medicine Safety Consortium.

PARTICIPANTS

Hospitalized medical patients who received a PICC between November 2013 and September 2016.

MEASUREMENTS

Percentage of patients receiving PICCs who had CKD, frequency of PICC-related complications, and variation in the proportion of PICCs placed in patients with CKD.

RESULTS

Of 20 545 patients who had PICCs placed, 4743 (23.1% [95% CI, 20.9% to 25.3%]) had an estimated GFR (eGFR) less than 45 mL/min/1.73 m2 and 699 (3.4%) were receiving hemodialysis. In the intensive care unit (ICU), 30.9% (CI, 29.7% to 32.2%) of patients receiving PICCs had an eGFR less than 45 mL/min/1.73 m2; the corresponding percentage in wards was 19.3% (CI, 18.8% to 19.9%). Among patients with an eGFR less than 45 mL/min/1.73 m2, multilumen PICCs were placed more frequently than single-lumen PICCs. In wards, PICC-related complications occurred in 15.3% of patients with an eGFR less than 45 mL/min/1.73 m2 and in 15.2% of those with an eGFR of 45 mL/min/1.73 m2 or higher. The corresponding percentages in ICU settings were 22.4% and 23.9%. In patients with an eGFR less than 45 mL/min/1.73 m2, PICC placement varied widely across hospitals (interquartile range, 23.7% to 37.8% in ICUs and 12.8% to 23.7% in wards).

LIMITATION

Nephrologist approval for placement could not be determined, and 2.7% of eGFR values were unknown and excluded.

CONCLUSION

In this sample of hospitalized patients who received PICCs, placement in those with CKD was common and not concordant with clinical guidelines.

PRIMARY FUNDING SOURCE

Blue Cross Blue Shield of Michigan and Blue Care Network.

Post-anastomotic venous stenosis after Optiflow deployment: An unexpected outcome

Arteriovenous fistula failure represents a major cause of hospitalization and a significant economic burden for end-stage renal disease patients on hemodialysis. The Optiflow (Bioconnect Systems Inc., Ambler, PA) is a new device developed to improve arteriovenous fistula outcomes and decrease failure rates by reducing the risk of stenosis and improving maturation rates. This case report describes a 50-year-old male with hypertensive nephropathy on dialysis who had multiple arteriovenous fistula failures in the past. He was scheduled to undergo brachiocephalic fistula construction using the Optiflow device. After 8 months of use, the new fistula developed a peri-anastomotic venous stenosis, just distal to the Optiflow device. To our knowledge, this is the first time such a complication has been reported.

Pro-inflammatory and pro-resolving mechanisms in the immunopathology of arteriovenous fistula maturation

Introduction: With high rates of arteriovenous fistula (AVF) failure, there is a continued need to predict other factors and mechanisms associated with maturation deficits. Given the central association of inflammation with AVF failure, with neointimal hyperplasia (NIH) as one such mechanism, inflammation must be considered in two endogenous ways, either pro-inflammatory or pro-resolving, resulting in inward or outward vascular remodeling. Areas covered: This review summarizes and critically evaluates the preclinical and interventional data underlying AVF failure in attempts to elucidate the necessary balance between inflammation and its resolution. Expert opinion: Understanding the pro-inflammatory and pro-resolving mechanisms underlying inward and outward vascular remodeling and NIH prevention with AVF maturation is a necessary effort to develop key diagnostic and therapeutic interventions towards the ongoing issue of long-term AVF patency. The ability for clinical application has progressed but is limited to the identification of key targets and pathways with little understanding of how they are related synergistically or antagonistically. Likewise, the balance between acute inflammation and pro-resolution requires pertinent temporal considerations necessary for timely therapeutic application and predictive measurement.

Outcomes of Primary Arteriovenous Fistula for Hemodialysis in Elderly Patients (>65 Years) with End Stage Renal Disease: A Study on Indian Population

Introduction:

The outcome of arteriovenous fistula (AVF) for hemodialysis (HD) in elderly population remains an issue. The aim of our study was to evaluate the outcomes of arteriovenous fistulas created at our institute in patients older than 65 years.

Methods:

All chronic HD patients with age >65 years who had an AVF created between January 1, 2010 and January 1, 2017 were included retrospectively. Baseline demographic information including age, gender, etiology of renal failure and comorbidities were recorded. Access characteristics including access type and anatomic location were recorded. The end point of study was primary and secondary patency. Minimum follow up period of study was 1 year.

Results:

A total of 422 AVF were created within the study period. The mean age was 69.3 years. The anatomical site of AVF creation was radiocephalic (RCF) in 74.8% (n = 316), brachiocephalic (BCF) in 18.9% (n = 80) and brachiobasilic (BBF) in 6.1% (n = 26). At one year after creation, cumulative survival of the AVF was 64.7%. At 36 months the primary and secondary patency of RCF, BCF and BBF was 43.6%, 58.6%, 42.6% and 47.3%, 62.5%, 56.9% respectively. The overall median survival did not differ between RCF and BBF fistulas. However, when both were compared with BCF (median survival 1034 days), BBF (median survival 741 days) and RCF (median survival 592 days) had significantly poorer survival (P = 0.004). The most common reason for access failure was thrombosis (28.4%) followed by failure to mature (9%) and aneurysm related complications (9%).

Conclusions:

Age should not be a limiting factor when choosing AVF as the preferred HD access. Brachiocephalic AVF has better primary and secondary patency with higher overall median survival. However RCF also provides reasonably good survival rates with acceptable complications in elderly population. Thrombosis and fistulas that fail to mature present as a primary concern to patients in elderly population, and demand further study.

Health Insurance in the First 3 Months of Hemodialysis and Early Vascular Access

BACKGROUND AND OBJECTIVES

Patients without Medicare who develop ESKD in the United States become Medicare eligible by their fourth dialysis month. Patients without insurance may experience delays in obtaining arteriovenous fistulas or grafts before obtaining Medicare coverage.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective cohort study, we used a national registry to compare uninsured patients starting in-center hemodialysis with a central venous catheter between 2010 and 2013 with similar patients with Medicare or Medicaid. We evaluated whether insurance status at dialysis start influenced the likelihoods of switching to dialysis through an arteriovenous fistula or graft and hospitalizations involving a vascular access infection. We used multivariable logistic and Cox regression models and transformed odds ratios to relative risks using marginal effects.

RESULTS

Patients with Medicare or Medicaid were more likely to switch to an arteriovenous fistula or graft by their fourth dialysis month versus uninsured patients (Medicare hazard ratio, 1.63; 95% confidence interval, 1.14 to 2.43; Medicaid hazard ratio, 1.23; 95% confidence interval, 1.12 to 1.38). There were no differences in rates of switching to arteriovenous fistulas or grafts after all patients obtained Medicare in their fourth dialysis month (Medicare hazard ratio, 1.17; 95% confidence interval, 0.97 to 1.42; Medicaid hazard ratio, 1.01; 95% confidence interval, 0.96 to 1.06). Patients with Medicare at dialysis start had fewer hospitalizations involving vascular access infection in dialysis months 4-12 (hazard ratio, 0.60; 95% confidence interval, 0.37 to 0.97).

CONCLUSIONS

Insurance-related disparities in the use of arteriovenous fistulas and grafts persist through the fourth month of dialysis, may not fully correct after all patients obtain Medicare coverage, and may lead to more frequent vascular access infections.

Skin Microcirculatory Changes in Relation to Arteriovenous Fistula Maturation

Maturation of arteriovenous fistula (AVF) involves complex vascular remodeling. In this study, we evaluated the changes of skin microvascular perfusion over the extremity with AVF maturation using the laser Doppler fluximetry (LDF). A total of 45 patients with chronic kidney disease, Stages IV-V, were included; they had undergone AVF creation from July 2014 to June 2016 at our institute. The measurement of skin microvascular perfusion was accomplished proximal and distal to the fistula anastomosis site: pre- and post-operative day 1, week 2, week 6, and week 12. Thirty-two patients with mean age of 55.6 had achieved AVF maturation. There were 40.6% radial-based and 59.4% brachial-based AVF. There was a 32.8% reduction of mean skin perfusion distal to the fistula by day 1 compared to the baseline perfusion; however, perfusion increased 47% by week 2 compared to day 1 and no dramatic change was subsequently noted. There was an increase of mean skin perfusion, proximal to fistula anastomosis, over 12 weeks with 35.8% at day 1 from the baseline. However, the changes of the mean skin perfusion were not statistically significant. There was no significant relation of skin perfusion changes with the type of fistula, diabetes mellitus, hypertension, and hyperlipidemia. LDF successfully detected the subclinical change of skin microvascular perfusion in relation to AVF creation. Reduction of skin perfusion distal to the fistula suggests that in patients with existing perfusion inadequacy of extremities, they may experience ischemic symptoms as early as day 1 postoperation, and require close monitoring for distal limb ischemic-related complications.

Early application of an intermittent pneumatic compression device is safe and results in proximal arteriovenous fistula enlargement

Introduction:

Delays in arteriovenous fistula maturation can cause care delays and increased costs. Increased distention pressure and intermittent wall shear stress may dilate veins based on prior research. Early use of non-invasive devices may help assist clinical arteriovenous fistula dilation.

Methods:

This was an Institutional Review Board approved study. After arteriovenous fistula creation, a novel, intermittent pneumatic compression device (Fist Assist®) was applied 15 cm proximal to arteriovenous fistula enabling 60 mmHg of cyclic compression for 6 h daily for 30 days. Among the patients who completed 1 month follow-up, 30 (n = 30) arteriovenous fistula patients were in the study arm to test vein dilation with Fist Assist. Controls (n = 16) used a sham device. Vein size was measured and recorded at baseline and after 30 days by duplex measurement. Clinical results (percentage increase) were recorded and tested for significance.

Results:

No patients experienced thrombosis or adverse effects. Patient compliance and satisfaction was high. After 1 month, the mean percentage increase in vein diameter in the Fist Assist treatment group was significantly larger (p = 0.026) than controls in the first 5 mm segment of the fistula after the anastomosis. All fistulas treated with Fist Assist are still functional with no reported thrombosis or extravasations.

Conclusions:

Early application of an intermittent pneumatic compression device may assist in arteriovenous fistula dilation and are safe. Non-invasive devices like Fist Assist may have clinical utility to help fistulae development and decrease costs as they may eventually assist maturation.

Which Kind of Vascular Access for Hemodialysis in Pediatric Patients?

The choice of vascular access in hemodialysis pediatric patients can be challenging, due to the small diameter of vessels. In the last 19 years, 38 arteriovenous fistulas (AVF) for hemodialysis have been created on 21 patients; 25 of them were radio-cephalic AVF. The evaluation of the vessels was, in the majority of cases, done by clinical criteria. A local anesthesia was used in all surgical procedures. The percentage of early AVF failure was 24%. Long-term AVF survival was 97%, 65% and 55% at respectively 1, 3 and 5 years. Our data indicate that even in pediatric patients the radio-cephalic fistula is the first choice surgical procedure.

Primary Patency Rates of AV Fistulae and the Effect of Patient Variables

Background

DOQI (The Dialysis Outcomes Quality Initiative) recommend 40% of prevalent renal failure patients should be undergoing hemodialysis (HD) using autogenous arteriovenous fistulae (AVF). The aim of this study is to assess the primary patency rates of wrist and elbow fistulae, and to examine how patient variables influence the success of a fistula. In addition, an attempt has been made to address the main issue of survival rates in this high risk patient population.

Methods

A retrospective study was performed on all patients in the University Hospital of North Staffordshire who underwent creation of a wrist or elbow fistula for HD. During the study period 289 primary AVFs were created. In all, 210 AVF were sited at the wrist and 79 at the elbow. Follow-up ranged from 3 months to 4 yrs. Primary patency and patient death, transplant and transfer were taken as end points. Patient survival was defined as time of fistula creation to patient death. Actuarial survival was calculated using Kaplan-Meier survival analyses, with differences between groups determined using log rank analysis, and statistical significance obtained using X2 tests.

Results

Primary patency for wrist fistulae was 49, 41 and 32% at 6, 12 and 24 months, respectively, and 57, 51 and 38% for elbow fistulae. Regression analysis showed fistula survival to be significantly greater in males than in females (p=0.023). Fistula survival rates in non-diabetics patients were higher than in patients with diabetes however, this was not significant (p=0.11); (54, 48 and 34% in diabetics compared to 45, 35 and 26% in non-diabetics at 6, 12 and 24 months, respectively). Age did not influence fistula survival; however, it did affect patient survival. Patient survival was 90, 74 and 56% at 1, 2 and 3 yrs, respectively, and in >60s fell to 86, 71 and 50%. Overall 74/245 (30%) patients died.

Conclusion

These results suggest that overall primary patency rates for wrist and elbow fistulae are comparable to similar studies at 6, 12 and 24 months. Fistula survival after this period is dictated by poor patient survival. Our findings suggest that creation of primary vascular access at the elbow in older females and diabetics may be associated with better results.