Time Of Arteriovenous Fistula Creation Research Articles

Effect of a novel cannulation device for vascular access on AVF maturation in a goat carotid-jugular fistula model.

The Ark is a 3-D printed titanium device designed to be implanted around the draining vein of an arteriovenous fistula (AVF) to facilitate vascular access. The purpose of this study was to assess AVF maturation after Ark implantation in a large animal model. End-to-side AVFs were created between the carotid artery and jugular vein in nine pygmy goats that included three control (AVF only) and six experimental (AVF and Ark device) animals. For experimental animals, an Ark device was implanted approximately 10 cm downstream of the anastomosis at the time of AVF creation. Postoperative ultrasounds and cannulations of the jugular vein fistula were performed over 12 months. At the conclusion of the study, the AVF was ligated and Ark devices along with a segment of the arterialized vein and surrounding tissues were explanted for gross and histological assessment. The control and experimental Ark groups exhibited increased dilation and flow as well as diminished depth underscoring the parallel developments in vascular attributes and AVF maturation between the two groups. Gross pathology, histology, and micro-CT imaging revealed intact endothelium, mature tissue integration throughout the porous Ark device, and no underlying stenosis. No adverse events such as foreign body reaction, skin or vessel erosion were identified. The study showed maturation without stenosis of the fistula in all animals. This study confirmed that the Ark device functions as a scaffold around the access vein, allows fistula maturation, and can be consistently cannulated without infiltrations over a 12-month period in a large animal model.

#1578 Left ventricular ejection fraction: association with risk of mortality and the incidence of AVF dysfunction

Abstract Background and Aims Ejection fraction (EF) and chronic heart failure (HF) are often considered as criteria for the possibility of arteriovenous fistula (AVF) creation in relation to an increased risk of death, without sufficient evidence for this. There is, however, rare but compelling evidence that low EF increases the risk of AVF dysfunction. Aims: to evaluate the association between EF at the time of AVF creation and the incidence of adverse cardiovascular events, all-cause mortality, as well as AVF dysfunction Method This retrospective cohort study included 962 adult patients who had a first-time created functioning AVF. Only patients with a more than three months period after AVF creation and within a five-year period were included. The mean follow-up period was 34 ± 13 months. Four groups were identified based on EF and the presence of HF at the time of AVF creation (transthoracic echocardiogram): HF with reduced EF (rEF) <40%, with mid-range (mrEF) of 40-49%, or with preserved EF (pEF) ≥50% + HF, and a “no HF” group with EF ≥50% and no HF. Results In the univariate analysis, a reduced EF was associated with an increased risk of mortality, with the hazard ratios (HRs) of 2.706 [95% CI 1.330; 5.507], p = 0.006 for mrEF and 8.250 [95% CI 2.621; 25.97], p < 0.001 for rEF, compared to the “no HF” group (here and thereafter)—Fig. 1. However, after adjusting for age, sex, and Charlson Comorbidity Index (CCI), the EF was not significantly associated with the risk of death. Only the CCI score remained a significant factor (HR = 1.748 [95% CI 1.482; 2.063], p < 0.001). A decreased EF was associated with the incidence of AVF dysfunction both in the univariate analysis and after adjustments. In the univariate analysis, the incidence rate ratios (IRRs) of 6.88 [95% CI 3.88; 12.1], p < 0.001 for mrEF, and 19.9 [95% CI 8. 64; 41.6], p < 0.001 for rEF, were shown. After adjusting for age, sex, and CCI, the IRR for mrEF was 8.96 [95% CI 5.81; 13.7], p < 0.001, and for rEF it was 23.4 [95% CI 13.8; 38.6], p < 0.001. Even in the presence of polycystic kidney disease and diabetes mellitus in the fully adjusted model, the association between EF and the incidence of AVF dysfunction remained statistically significant: the IRR was 8.61 [95% CI 5.61; 13.1], p < 0.001 for mrEF, and 33.4 [95% CI 19.5; 56.2], p < 0.001 for rEF. The findings were confirmed in a sensitivity analysis that included adjustments for unplanned onset of dialysis and competing risks survival analysis (death—outcome of interest, conversion of HD to PD or kidney transplantation and conversion of AVF to CVC—competing events). According to our results patients with EF<40% will inevitably lose AVF function for various reasons within 3.5 years—Fig. 2. Meanwhile, this approach will give the patient additional time of HD via AVF, but not CVC, without increasing the risk of death, subject to Qa monitoring. Conclusion In patients with CKD 5 who are initiating treatment with maintenance hemodialysis, a decreased EF is associated to a greater extent with a higher risk of AVF dysfunction than with an increased risk of mortality. The burden of comorbidities, rather than a standalone assessment of EF, is one of the major risk factors determining patient survival.

Risk factors for arteriovenous fistula dysfunction in hemodialysis patients: a retrospective study

Arteriovenous fistula (AVF) is the first choice of vascular access in hemodialysis (HD) patients. However, the correlations between patient factors and the arteriovenous fistula patency remain unclear. Therefore, our study investigates the risk factors associated with AVF dysfunction in HD patients. A total of 233 end-stage renal disease (ESDR) patients who met the study inclusion criteria in the Nephrology Department of Hunan Provincial People’s Hospital between December 2020 and June 2022 were included in this study. The baseline demographic, clinical and laboratory parameters were collected at the time of AVF creation and analyzed. Of the 233 ESRD patients, 146 (62.7%) were male and the mean age was 56.11 ± 12.14 (21–82) years. The patients were followed for a median time of 14 months. Kaplan–Meier analysis showed a 6-, 12- and 24-month post-placement survival of 87.1%, 82.8% and 80.7%, respectively. Univariate Cox regression analysis revealed weight (HR, 1.03; P = 0.03) as a predictor for the loss of vascular access functionality. In addition, multivariate Cox regression analysis further demonstrated that sex (HR, 3.41; P = 0.03), weight (HR 1.08; P < 0.01) and phosphorus level (HR: 3.03; P = 0.01) are independent risk factors for AVF dysfunction. AVF dysfunction is highly associated with several risk factors including weight, phosphorus level, and sex. Positive intervention strategies targeting these potential factors, such as weight loss or oral phosphate binders could improve the long-term success of AVF.

Predicting Recurrent Interventions After Radiocephalic Arteriovenous Fistula Creation with Machine Learning and the PREDICT-AVF Web App

Radiocephalic arteriovenous fistulas (AVFs) are often criticized for requiring numerous recurrent interventions to achieve and maintain hemodialysis access function. Recent Kidney Disease Outcomes Quality Initiative guidelines discourage ongoing access salvage attempts after two interventions prior to successful use or more than three interventions per year overall. This study's goal was to develop a useful prediction tool for preoperative and postoperative assessment of intervention requirements to help guide decision-making about access appropriateness and futility. The data source was patient-level data from the international multicenter PATENCY-1 and PATENCY-2 randomized controlled trials, which enrolled patients undergoing new radiocephalic AVF creation. Routine ultrasounds were performed at 4 to 6 weeks and 12 weeks from AVF creation and interpreted by a core laboratory. The outcome for the prediction models was the number of recurrent surgical or endovascular interventions required at 1 year. Cox, random survival forest, pooled logistic, and penalized pooled logistic (elastic net) recurrent event survival prediction models were built using a combination of baseline characteristics and postoperative ultrasound measurements. Models were trained with 10-fold cross-validation hyperparameter selection within a randomly split training dataset. Discrimination and calibration performance was assessed on a holdout testing dataset. An interactive web application was built, which generates patient-specific predictions at 1 year, draws cumulative hazard curves, and contextualizes the predictions with the Kidney Disease Outcomes Quality Initiative guidelines for recurrent interventions after access creation. The cohort included 914 patients; mean age was 57 ± 13 years and 22% were female. Radiocephalic AVFs were created at the snuffbox (2%), wrist (74%), or proximal forearm (24%). Patients underwent a median of 1.04 (95% confidence interval [CI], 0.95-1.13) interventions in the first year. Using only baseline characteristics, the random survival forest model performed best, with a C-statistic of 0.72 (95% CI, 0.65-0.78) at 1 year (Table). The addition of ultrasound information to baseline characteristics did not substantially improve performance; however, Cox models using either 4- to 6-week or 12-week postoperative ultrasound information alone had the best discrimination performance, with C-statistics of 0.74 (95% CI, 0.67-0.81) and 0.78 (95% CI, 0.72-0.84) at 1 year (Table). The interactive web application is deployed at PREDICT-AVF.com (Figure). When assessing candidates for radiocephalic AVF in the preoperative setting, baseline patient characteristics can predict future interventions with moderate performance. In the postoperative setting, ultrasound findings alone are sufficient to predict future interventions. A free point-of-care web application can guide patient counseling and guideline-concordant surgeon decision-making as part of a patient-centered end-stage kidney disease life plan.TableDiscrimination performance of each model and feature set, measured by the area under the receiver operating characteristic curve (C-statistic) at 1 year postoperativelyFeaturesCoxRandom survival ForestPooled logistic regressionElastic netBaseline0.704 (0.639-0.769)0.715 (0.647-0.783)0.696 (0.631-0.762)0.703 (0.638-0.769)Baseline + 4- to 6-week US0.704 (0.629-0.779)0.737 (0.666-0.808)0.702 (0.627-0.778)0.703 (0.627-0.778)Baseline + 12 week US0.737 (0.670-0.803)0.766 (0.701-0.832)0.730 (0.663-0.797)0.746 (0.680-0.812)4- to 6-Week US0.743 (0.674-0.813)0.696 (0.620-0.773)0.740 (0.670-0.810)0.742 (0.672-0.812)12-Week US0.782 (0.722-0.842)0.721 (0.652-0.791)0.774 (0.712-0.835)0.775 (0.714-0.837)US, Ultrasound.Perfect discrimination corresponds to an area under the receiver operating characteristic curve of 1. Feature sets included baseline (age, sex, race, smoking status, diabetes, heart failure, renal transplant history, anticoagulation use, antiplatelet use, statin use, hemodialysis status at the time of arteriovenous fistula creation, central venous catheter history, number of prior failed accesses, vein and artery diameter, anastomotic suture technique, access location, and access side), baseline with the addition of postoperative ultrasound measurements (flow volume, access diameter, and luminal stenosis), and ultrasound measurements alone. Open table in a new tab

High low-density lipoprotein cholesterol level is the independent risk factor of primary patency rate of arteriovenous fistula.

An arteriovenous fistula is the first choice of vascular access in dialysis patients. However, the correlations between patient factors and the arteriovenous fistula patency rate remain unclear. Therefore, we examined the effect of dialysis patient factors on arteriovenous fistula patency rate. This study included 101 patients who received maintenance dialysis and used arteriovenous fistula for vascular access at Atami Hospital, International University of Health and Welfare in July 2018. A retrospective review was performed from the time of arteriovenous fistula creation to July 2018, and the primary and secondary arteriovenous fistula patency rates were investigated. The patency rate was calculated using the Kaplan-Meier method, and risk factor analysis was performed using Cox proportional hazards regression analysis. The primary patency rate of arteriovenous fistula was 71.2% at one year and 43.0% at five years, and the secondary patency rate was 92.7% at one year and 79.8% at five years. In the multivariate analysis, high low-density lipoprotein cholesterol (LDL-C) level and a history of diabetes were considered significant risk factors (HR 1.023, p value <0.01 and HR 2.550, p value <0.01, respectively). A log rank test was conducted on the groups of patients with LDL <90 mg/dl and LDL ≥90 mg/dl, and the <90 mg/dl group resulted in a good primary patency rate (p value 0.0327). High LDL-C level was considered the independent risk factors of arteriovenous fistula primary patency rate.

Arteriovenous fistula maturation rate is not affected by ipsilateral tunneled dialysis catheter

ObjectiveThe effect that ipsilateral tunneled dialysis catheters (TDC) have on arteriovenous fistula (AVF) maturation is unclear. We sought to define this association by comparing AVF maturation rates in patients with contralateral TDC with those with ipsilateral TDC. MethodsA review of a prospectively maintained database including all AVF creation procedures between 2009 and 2016 was performed. All patients with a TDC in place at the time of AVF creation were included in this study. Clinical and functional maturation rates were compared in patients with contralateral vs ipsilateral dialysis catheters. Categorical variables were analyzed by a two-tailed Fisher's exact test. A P value of less than .05 was considered statistically significant. ResultsThere were 187 patients who underwent fistula creation with a TDC in place during the study period. Of those, 137 patients had a contralateral TDC and 50 had an ipsilateral TDC. A greater proportion of contralateral patients were first-time dialysis access patients at the time of index AVF creation (67% vs 48%; P = .03). There was no difference in clinical (contralateral 73% vs ipsilateral 78%; P = .57) and functional (contralateral 64% vs ipsilateral 74%) maturation rates between the two groups. The rate of TDC removal after AVF maturation was also not different (contralateral 64% vs ipsilateral 72%; P = .30). There was also no statistical difference in the rates of thrombosis at less than 30 days, outflow stenosis, central stenosis, and steal syndrome. ConclusionsThere was no association between TDC sidedness and AVF maturation or early failure in our cohort. Planning for AVF creation should not be influenced by attempts to avoid an ipsilateral TDC.

Autologous arteriovenous fistulas for hemodialysis using microsurgery techniques in children weighing less than 20kg.

This study aimed to describe the efficiency and longevity of arteriovenous fistula (AVF) for hemodialysis (HD) in children weighing ≤20kg. We collected data of all AVFs created using microsurgery techniques between 1988 and 2015. Success was considered as the ability to use the AVF for HD. Primary and secondary patency rates were measured. Forty-eight AVFs (35 forearm, 13 upper arm) were created in 41 children with a median weight of 13.5kg (range 5.5-20). The need for a second AVF was significantly higher in younger and thinner children at the time of AVF creation (p = 0.046 and p = 0.019, respectively). Successful use for HD occurred in 42 AVFs (87.5%), while six (12.5%) resulted in failure for early thrombosis or nonmaturation. Median time to first cannulation was 18.8weeks (range 2-166.3). Primary and secondary patency rates at 1, 5, and 10-year follow-ups were 54.2%, 29.2%, and 13.7%; and 85.4%, 57.7%, and 33%, respectively. Almost one third of thromboses after first AVF cannulation were observed at kidney transplantation (KT) perioperatively. At the end of the follow-up (median duration 5.07years, range 0-17.95), one patient was still on HD via AVF, two died of unrelated reason, and 38 were transplanted-one of whom returned to HD with a new AVF. AVF using microsurgery techniques is feasible in young children, showing an early failure rate of 12.5%. Time to first cannulation may be rather long, but secondary patency is excellent. Thrombosis rate is high during KT.

PC108 Evaluation of an ePTFE Endograft Placed at the Time of Arteriovenous Fistula Creation to Prevent Juxta-anastomotic Stenosis and Improve Maturation and Long-Term Patency Rates

PC108 Evaluation of an ePTFE Endograft Placed at the Time of Arteriovenous Fistula Creation to Prevent Juxta-anastomotic Stenosis and Improve Maturation and Long-Term Patency Rates

Asymmetric Dimethylarginine does not Predict Early Access Events in Hemodialysis Patients with Brachiocephalic Fistula Access.

Vascular access for hemodialysis is best provided by an arteriovenous fistula (AVF). AVF fail primarily because of neointimal hyperplasia. Asymmetric dimethlyarginine (ADMA) is a naturally occurring analogue of L-arginine, which is elevated in renal failure and impairs endothelial cell function. ADMA inhibits nitric oxide synthetase, leading to impaired nitric oxide production and contributing to the development of neointimal hyperplasia. ADMA was measured at the time of AVF placement to evaluate associations with access failure. ADMA was measured at the time of brachiocephalic access placement. Patients were followed for up to 12 months with end-points of access thrombosis or venous stenosis. Sixty patients with primary brachiocephalic fistulas were included in the study cohort. The median value for ADMA drawn at the time of AVF creation was 3.1 µmol/L. ADMA was not significantly associated with early thrombosis or venous stenosis events (P>0.05). Preoperative ADMA levels, as a surrogate for endothelial cell dysfunction and predictor of adverse access event (thrombosis or stenosis), were not associated with subsequent access events Future studies that identify markers of endothelial cell dysfunction are warranted.

True Brachial Artery Aneurysm after Arteriovenous Fistula for Hemodialysis: Five Cases and Literature Review

The donor artery after a long-standing arteriovenous fistula (AVF) for hemodialysis usually evolves exceptionally toward a true aneurysmal degeneration (AD). The purpose of this article was to describe true brachial artery AD in end-stage renal disease patients after AVF creation, as well as its influencing factors and treatment strategies. We present a retrospective, observational, single-center study realized in Caen University Hospital's Vascular Surgery Department from May 1996 to November 2015. The inclusion criteria were true AD of the brachial artery after a vascular access for hemodialysis. Aliterature research, using the same criteria, was performed on the articles published between 1994 and 2015. The used databases included MEDLINE (via PubMed), EMBASE via OVID, Cochrane Library Database, and ResearchGate. Our series includes 5 patients. Twenty-one articles were found in the literature: 17 case reports, 3 series, and 1 review. The same triggering factors for AD (high flow and immunosuppressive treatment) were found. The mean age at the time of AVF creation, firstrenaltransplantation, and AD's diagnosis were respectively 26 (range 15-49), 29.2, and 48.6 years (range 37-76) in our series versus 34 (range 27-39), 40.4 (range 28-55), and 55.5years (range 35-75) in cases found in the literature. The time spread after AVF creation and aneurysmal diagnosis was about 20.6years (range 18-25) in our study versus 20.5years (range 9-29) in the case reports. Our surgical attitude corresponds principally to that described in the literature. Nevertheless, we describe for the first time one case of arterial transposition to exclude the brachial aneurysm using superficial femoral artery. Arterial aneurysm is a rare, but significant complication after a long-term creation of hemodialysis access. High flow and immunosuppression may accelerate this process. Young age of the patients may act as a benefic factor and delay the AD. Arterial transposition could be an option in the absence of any venous conduit, if anatomy does not permit the use of prosthetic grafts.

IP139. Placement of Covered Stent at the Time of Arteriovenous Fistula Creation Reduces Juxta-Anstomotic Vein Stenosis: Description and Outcomes of the “JuxtaBahn Procedure”

IP139. Placement of Covered Stent at the Time of Arteriovenous Fistula Creation Reduces Juxta-Anstomotic Vein Stenosis: Description and Outcomes of the “JuxtaBahn Procedure”

Leptin, pre-existing vascular disease, and increased arteriovenous fistula maturation failure in dialysis patients

The adipocytokine leptin is an independent cardiovascular risk factor and exerts proatherogenic effect. Pre-existing vascular disease is an important cause of arteriovenous fistula (AVF) maturation failure. We explored the association between serum leptin, pre-existing vascular disease, and AVF maturation failure in incident hemodialysis patients. Vein samples from 62 patients were collected at the time of AVF creation. Pre-existing vascular disease was evaluated with histologic changes and immunohistochemical characteristics of cellular phenotypes in intima. AVF maturation failure was defined as an AVF that could not be used successfully by the third month after its creation. The prevalence of body mass index ≥30kg/m2 was 17%, and AVF maturation failure occurred in 28 (45%) patients. Patients within the highest leptin tertile showed significantly higher maturation failure rate, independent of age, gender, diabetes, and body mass index. On histologic examination, significant differences in intimal hyperplasia (13.3± 4.5 vs 18.2± 5.2 vs 30.3± 14.3μm) and medial thickening (76.8± 23.7 vs 103.9± 33.6 vs 109.3± 36.5μm) were observed across leptin tertiles. Similarly, medial fibrosis was most severe in the highest tertile. According to the immunohistochemical staining, most intimal cells were α-smooth muscle actin-positive, vimentin-positive, desmin-negative myofibroblasts. However, in the lowest tertile, desmin-positive contractile smooth muscle cells were also frequently observed, suggesting relatively slow phenotypic changes in this group. Furthermore, as leptin tertiles increased, the expression of leptin receptor in the luminal border of intima was significantly decreased. Obesity-related higher fistula maturation failure rate may be partly mediated by higher leptin level-associated pre-existing vascular diseases in end-stage renal disease patients. Decreased expression of leptin receptor may be related to this association.

Impact of preoperative ultrasonography findings on the patency rate of vascular access in Japanese hemodialysis patients.

BackgroundAlthough ultrasonography before a vascular access (VA) operation has become popular in recent years, benchmarks for the diameter or blood flow of arteries or veins are not defined in Japan. The objective of the present study is to analyze the relationship between preoperative US findings and the patency rate of VA in Japanese hemodialysis patients.Methods139 patients with end stage kidney disease were enrolled in this study. They had been given primary radiocephalic arteriovenous fistula (AVF) from February 2009 to December 2010 at the Juntendo University Hospital and were followed up over 2 years. We defined the interval from the time of AVF creation until first access thrombosis or any intervention to maintain or restore blood flow as patency time (primary patency). We examined the correlation between the 2-year primary patency rate of VA and the diameter of the radial artery (RA), brachial artery (BA), or cephalic vein at an anastomosis presumptive region by US, the blood flow of RA or BA, as measured by US, age, gender, and primary kidney diseases.ResultsThe average patency term was 448.6 ± 271.3 days, with the 1-year and 2-year patency rate as 64.0 and 51.2 %, respectively. The patency rate was significantly lower in elderly patients over the age of 75 and in patients with diabetes mellitus. US findings of 2.0 mm or less in the RA diameter also resulted in a noticeably low patency rate. A multivariate analysis indicated that those factors were risk factors for early VA failure.ConclusionsPreoperative US findings of the diameter of RA may involve the patency rate of VA, making it appears that an RA of 2.0 mm or more in diameter at an anastomosis region may be more effective for the improvement in the patency rate of VA.

Pre-existing and Postoperative Intimal Hyperplasia and Arteriovenous Fistula Outcomes

The contribution of intimal hyperplasia (IH) to arteriovenous fistula (AVF) failure is uncertain. This observational study assessed the relationship between pre-existing, postoperative, and change in IH over time and AVF outcomes. Prospective cohort study with longitudinal assessment of IH at the time of AVF creation (pre-existing) and transposition (postoperative). Patients were followed up for up to 3.3 years. 96 patients from a single center who underwent AVF surgery initially planned as a 2-stage procedure. Veins and AVF samples were collected from 66 and 86 patients, respectively. Matched-pair tissues were available from 56 of these patients. Pre-existing, postoperative, and change in IH over time. Anatomic maturation failure was defined as an AVF that never reached a diameter > 6mm. Primary unassisted patency was defined as the time elapsed from the second-stage surgery to the first intervention. Maximal intimal thickness in veins and AVFs and change in intimal thickness over time. Pre-existing IH (>0.05mm) was present in 98% of patients. In this group, the median intimal thickness increased 4.40-fold (IQR, 2.17- to 4.94-fold) between AVF creation and transposition. However, this change was not associated with pre-existing thickness (r(2)=0.002; P=0.7). Ten of 96 (10%) AVFs never achieved maturation, whereas 70% of vascular accesses remained patent at the end of the observational period. Postoperative IH was not associated with anatomic maturation failure using univariate logistic regression. Pre-existing, postoperative, and change in IH over time had no effects on primary unassisted patency. The small number of patients from whom longitudinal tissue samples were available and low incidence of anatomic maturation failure, which decreased the statistical power to find associations between end points and IH. Pre-existing, postoperative, and change in IH over time were not associated with 2-stage AVF outcomes.

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

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

Timing of Arteriovenous Fistula Creation in Patients With CKD: A Decision Analysis

The optimal time for arteriovenous fistula (AVF) referral is uncertain. Improving the timeliness of referral may reduce central venous catheter (CVC) use. Monte Carlo simulation model. Patients with chronic kidney disease (CKD) followed up in a multidisciplinary clinic, overall and stratified by age. Decision analysis, patient, patient's lifetime. AVF referral, using 1 of 2 strategies: refer when hemodialysis is anticipated to begin within a certain time frame or refer when estimated glomerular filtration rate (eGFR) drops below a certain threshold. A range of values for each strategy are compared to each other with respect to incident vascular access type (AVF or CVC), percentage of patients with an unnecessary AVF creation, and life expectancy after dialysis therapy initiation. A 15-month referral time frame gave 34% with incident CVCs, 14% with unnecessary AVFs, and a life expectancy of 1,751 days. Time frames of 12-18 months performed similarly. Referral at eGFR of 20 mL/min/1.73 m(2) gave 38% with incident CVCs, 20% with unnecessary AVFs, and life expectancy of 1,742 days. Using an eGFR threshold of 15 mL/min/1.73 m(2), 10% had an unnecessary AVF. Policy performance was affected by CKD progression rate and age. For fast progressors (ΔeGFR = -7mL/min/1.73 m(2) per year), referral at eGFR of 25 mL/min/1.73 m(2) achieved a similar incident CVC percentage (~40%) as referral at 15 mL/min/1.73 m(2) in slower progressors (ΔeGFR = -2.78 mL/min/1.73 m(2) per year). For patients aged 70-80 and 80-90 years, time frames of 15-18 months yielded 16%-22% with unnecessary AVFs (vs 9%-11% in 50- to 60-year-olds); an eGFR threshold strategy of 20 mL/min/1.73 m(2) yielded 24% unnecessary AVFs in 80- to 90-year-olds versus 16% in 50- to 60-year-olds. Our model does not consider patients with nonlinear CKD progression or acute kidney injury. We did not include arteriovenous grafts or consider cost or quality of life. In general, AVF referral within about 12 months of the estimated time to dialysis performed best among time frame strategies, and referral at eGFR < 15-20 mL/min/1.73 m(2) performed best among threshold strategies. The timing of referral should also be guided by the individual rate of CKD progression. Elderly patients with CKD could be referred later to reduce the risk of creating an AVF that is never used.

Effect of anastomosis angle on the localization of disturbed flow in ‘side-to-end’ fistulae for haemodialysis access

Early failure of the vascular access for haemodialysis (HD) after the surgical creation of a radial-cephalic arteriovenous fistula (AVF) occurs mainly due to a juxta-anastomotic stenosis. Even if elevated blood flow induces high wall shear stress, we have recently shown that disturbed flow, characterized by low and reciprocating flow, may develop in zones of the AVF where it can provide a good indication of the sites of future stenoses. The present study was aimed at investigating whether the anastomosis angle influences disturbed flow in radial-cephalic 'side-to-end' AVF. By means of a parametric AVF model we created four equivalent meshes with anastomosis angles of 30°, 45°, 60° and 90°, respectively. We then performed transient, non-Newtonian computational fluid dynamics simulations using, as boundary conditions, previously measured blood volume flow and division ratio in subjects requiring primary access. The relative residence time (RRT), a robust indicator of disturbed flow, was calculated for the overall wall surface and disturbed flow was localized as areas having RRT > 1. Quantitative characterization and statistical tests were employed to assess the difference in RRT medians between the four anastomosis angle cases. Disturbed flow was located in all AVF models in the same areas where flow recirculation and stagnation occurred, on the inner wall of the swing segment (SS) and on the arterial wall at the anastomosis floor (AF). A smaller angle AVF had smaller disturbed flow areas with lower RRT peak values, either on the venous or the arterial limb. There were significant differences in the RRT medians on the SS and on the AF between sharper (30° and 45°) and wider (60° or 90°) angles. We have found that in 'side-to-end' radial-cephalic AVFs for HD, the anastomosis angle does impact on the local disturbed flow patterns. Among the four geometries we considered in this study, the smaller angle (30°) would be the preferred choice that minimizes the development of neointima. Clinicians should consider this at the time of AVF creation because the anastomosis angle is in part amenable to surgical manipulation.

Spontaneous Bilateral Humeral Shaft Fracture Due to Severe Renal Osteodystrophia

A 41-year-old female hemodialysis patient presented with central venous catheter infection. She had been on hemodialysis for 1 year following 3 years of continuous ambulatory peritoneal dialysis. She developed spontaneous bilateral humeral shaft fractures due to severe renal osteodystrophy 4 years prior, around the time of arteriovenous fistula creation. X-ray revealed a large expansile brown tumor at the fracture site in the left humerus, which was confused with a bone malignancy (Figure 1). A parathyroid adenoma (secondary hyperparathyroidism) was detected, but she refused surgical parathyroidectomy.

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

Vascular access failure is the main cause of morbidity in hemodialysis patients. Stenosis of the arteriovenous fistula (AVF) is similar histologically to atherosclerosis. Recent studies showed that interleukin 6 (IL-6) has a key role in the pathogenesis of atherosclerosis by binding 2 specific receptors, gp80 and gp130. When activated, gp130 interacts with a tyrosine kinase, Janus kinase (JAK2), which then activates a transcription factor, signal transducers and activators of transcription (STAT3), directly turning on several proinflammatory genes. The aim of this study is to evaluate gp130 expression and JAK2/STAT3 activation within stenotic AVFs. 44 patients undergoing surgery for AVF creation were enrolled; 10 of them had AVF failure with histologically proven AVF stenosis (wall-lumen ratio > 1). A venous fragment of the AVFs was collected during creation and revision of the vascular access. gp130 and gp80 expression, as well as JAK/STAT activation, were evaluated by means of confocal microscopy. Peripheral-blood mononuclear cells were isolated at the time of AVF creation and revision. gp130 protein expression, barely detectable in native AVFs, was strikingly increased within the venous branch of stenotic AVFs. The signaling subunit of the IL-6 receptor broadly colocalized with gp80, the IL-6-binding subunit. gp130-expressing cells were mainly CD34(+), suggesting that this receptor is expressed primarily by neovasculature endothelial cells. At the same time, a significant increase in phosphorylation of JAK2/STAT3 was observed in endothelial cells of stenotic AVFs. Interestingly, peripheral-blood mononuclear cells isolated at the time of AVF failure presented strikingly greater IL-6 expression compared with dialysis age-matched controls. IL-6 receptor activation may have a role in the pathogenesis of AVF failure in hemodialysis patients and may represent a potential therapeutic target in this setting.