Computational fluid-structure interaction analysis of the end-to-side radio-cephalic arteriovenous fistula.

BACKGROUND AND OBJECTIVE: In the current work, we present a descriptive fluid-structure interaction computational study of the end-to-side radio-cephalic arteriovenous fistula. This allows us to account for the different thicknesses and elastic properties of the radial artery and cephalic vein. METHODS: The core of the work consists in simulating different arteriovenous fistula configurations obtained by virtually varying the anastomosis angle, i.e. the angle between the end of the cephalic vein and the side of the radial artery. Since the aim of the work is to understand the blood dynamics in the very first days after the surgical intervention, the radial artery is considered stiffer and thicker than the cephalic vein. RESULTS: Our results demonstrate that both the diameter of the cephalic vein and the anastomosis angle play a crucial role to obtain a blood dynamics without re-circulation regions that could prevent fistula failure. CONCLUSIONS: When an anastomosis angle close to the perpendicular direction with respect to the radial artery is combined with a large diameter of the cephalic vein, the recirculation regions and the low Wall Shear Stress (WSS) zones are reduced. Conversely, from a structural point of view, a low anastomosis angle with a large diameter of the cephalic vein reduces the mechanical stress acting on the vessel walls.

Arteriovenous Access for Hemodialysis: A Review.

Importance: Hemodialysis requires reliable vascular access to the patient's blood circulation, such as an arteriovenous access in the form of an autogenous arteriovenous fistula or nonautogenous arteriovenous graft. This Review addresses key issues associated with the construction and maintenance of hemodialysis arteriovenous access. Observations: All patients with kidney failure should have an individualized strategy (known as Patient Life-Plan, Access Needs, or PLAN) for kidney replacement therapy and dialysis access, including contingency plans for access failure. Patients should be referred for hemodialysis access when their estimated glomerular filtration rate progressively decreases to 15 to 20 mL/min, or when their peritoneal dialysis, kidney transplant, or current vascular access is failing. Patients with chronic kidney disease should limit or avoid vascular procedures that may complicate future arteriovenous access, such as antecubital venipuncture or peripheral insertion of central catheters. Autogenous arteriovenous fistulas require 3 to 6 months to mature, whereas standard arteriovenous grafts can be used 2 to 4 weeks after being established, and "early-cannulation" grafts can be used within 24 to 72 hours of creation. The prime pathologic lesion of flow-related complications of arteriovenous access is intimal hyperplasia within the arteriovenous access that can lead to stenosis, maturation failure (33%-62% at 6 months), or poor patency (60%-63% at 2 years) and suboptimal dialysis. Nonflow complications such as access-related hand ischemia ("steal syndrome"; 1%-8% of patients) and arteriovenous access infection require timely identification and treatment. An arteriovenous access at high risk of hemorrhaging is a surgical emergency. Conclusions and Relevance: The selection, creation, and maintenance of arteriovenous access for hemodialysis vascular access is critical for patients with kidney failure. Generalist clinicians play an important role in protecting current and future arteriovenous access; identifying arteriovenous access complications such as infection, steal syndrome, and high-output cardiac failure; and making timely referrals to facilitate arteriovenous access creation and treatment of arteriovenous access complications.

Differential expression of serum TM, PAF, and CD62P in patients with autologous arteriovenous fistula and the correlation with vascular access function.

BACKGROUND: End-stage renal disease (ESRD) is the final stage of chronic kidney disease (CKD). AIMS: We aimed to analyze the expression differences of serum thrombomodulin (TM), platelet-activating factor (PAF), and P-selectin (CD62P) in patients with autologous arteriovenous fistula (AVF) and the correlation with vascular access function. METHODS: The case data were retrospectively analyzed. Moreover, 160 patients with AVF maintenance hemodialysis were selected as the AVF group, and 150 healthy participants were selected as the healthy control group. According to the function of vascular access, patients in the AVF group were divided into Group A (n = 50, after the first establishment of AVF), Group B (n = 64, normal vascular access function after hemodialysis treatment), and Group C (n = 46, vascular access failure). Pearson analysis was conducted to explore the correlation between serum TM, PAF, CD62P content, and vascular pathological examination indicators, to evaluate the value of TM, PAF, and CD62P levels in predicting vascular access failure in patients with AVF. RESULTS AND DISCUSSION: The serum levels of TM, PAF, and CD62P were positively correlated with the expressions of CD68 and MCP-1, respectively (p < .001). Serum TM was positively correlated with the levels of PAF and CD62P (p < .001), and PAF was positively correlated with the levels of CD62P (p < .001), respectively. Serum levels of TM, PAF and CD62P were risk factors for vascular access failure in AVF patients (p < .05). The area under the curve of serum TM, PAF and CD62P levels in predicting vascular access failure in AVF patients was 0.879. CONCLUSION: The serum levels of TM, PAF, and CD62P in AVF patients were correlated with the vascular access function of AVF patients, which was very important for maintaining the stability of vascular access function, and had certain value in predicting vascular access failure/disorder in AVF patients, and could be popularized and applied.

Arteriovenous Fistula Closure Using a Simple Ligation Technique After Kidney Transplantation.

BACKGROUNDS: There are advantages and disadvantages with closure of an arteriovenous fistula (AVF) after kidney transplantation, but some cases require closure. The general procedure for closure is angioplasty with exposure of the anastomotic site, but this is often time-consuming and complicated. We have developed a simpler, less invasive, and shorter procedure for AVF closure, in which the anastomotic site itself is not peeled off and the outflow vein close to this site is ligated using 1-0 silk. In this study, we examined the utility of this procedure. METHODS: A retrospective case series study was conducted by review of electronic medical records of patients and surgeries. All patients (n = 52) who underwent AVF closure after kidney transplantation at our hospital between January 2008 and April 2021 were reviewed. Perioperative and long-term postoperative results were examined. This study was carried out following the ethical standards of the Declaration of Helsinki and Istanbul. Donors were not from prisoners, or from those individuals who are coerced of paid. RESULTS: Simple ligation was performed for 46 patients (88.5%). The median time after renal transplantation was 40 (24.5-66.5) months. Median operative time and blood loss were 20 (12.2-30) minutes and 10 (5-15) mL, respectively. Two patients (4.3%) developed the aneurysm after the AVF closure using the simple ligation. CONCLUSION: The simple ligation technique had a relatively shorter operative time and only 2 cases had aneurysm formation. These results suggest that this technique is an option for closure of an AVF after kidney transplantation.

Percutaneous Management of Dialysis Access Steal Syndrome: Interventions and Outcomes from a Single Institution's 20-Year Experience.

PURPOSE: To determine safety and effectiveness of percutaneous interventions performed by interventional radiologists at a single institution over 2 decades in patients with dialysis access steal syndrome (DASS). MATERIALS AND METHODS: A retrospective review of fistulograms from 2001 to 2021 (N = 11,658) was performed. In total, 286 fistulograms in 212 patients with surgically created dialysis accesses met inclusion criterion of fistulography for suspected DASS. Chart review collected data regarding patient demographics, comorbidities, access characteristics, fistulography findings, intervention(s) performed, and outcomes. Procedures with and without DASS intervention were compared. Odds ratios (ORs), adjusted for age, sex, comorbidities, access characteristics, and multiple within-patient events, were calculated using logistic regression to determine associations between steal intervention status and outcome variables: (a) major adverse events, (b) access preservation, and (c) follow-up surgery. A percutaneously treatable cause of DASS was present in 128 cases (45%). Treatment of DASS lesions was performed in 118 cases. Fifteen embolizations were also performed in patients without DASS lesions. RESULTS: Technical success of DASS interventions, defined by the Society of Interventional Radiology (SIR) reporting standards, was 94%; 54% of interventions resulted in DASS symptom improvement at a median follow-up of 15 days. Patients with steal intervention had 60% lower odds of follow-up surgery (OR, 0.4; P = .007). There was no difference in major adverse events (P = .98) or access preservation (P = .13) between groups. CONCLUSIONS: In this retrospective cohort study, approximately half of DASS fistulograms revealed a percutaneously treatable cause of steal. Over half of DASS interventions resulted in symptomatic relief. Percutaneous intervention was associated with lower odds of follow-up surgery without compromising access preservation.

Comparative analysis of RADAR vs. conventional techniques for AVF maturation in patients with blood viscosity and vessel elasticity-related diseases through fluid-structure interaction modeling: Anemia, hypertension, and diabetes.

PURPOSE: This study aims to compare two surgical techniques, the standard Vein-to-Artery and the newer Artery-to-Vein (Radial Artery Deviation And Reimplantation; RADAR), for enhancing the success of Arterio-Venous Fistula maturation in end-stage renal disease patients. The impact of diseases like anemia, diabetes, hypertension, and chronic kidney disease were considered. The goals are to advance Arterio-Venous Fistula (AVF) surgery, improve patient outcomes, and contribute to evidence-based surgical guidelines. METHODS: Fluid-structure interaction modeling was employed to investigate how hemodynamic and mechanical stresses impact arteriovenous fistula maturation, with a particular focus on the role of wall shear stress in determining maturation outcomes. The critical threshold for vessel injury was identified as wall shear stress values exceeding 35 N/m2, while stenosis formation was projected to occur at levels below 1 N/m2. This work introduced a novel approach by considering disease-related factors, including blood viscosity (anemia), and vessel elasticity (diabetes, hypertension, and chronic kidney diseases), which directly influence hemodynamics and the generation of wall shear stress. Furthermore, the model was designed to incorporate varying thicknesses and elasticities for both the vein and artery, accurately representing authentic vascular anatomy. RESULTS: The RADAR technique has demonstrated superior performance compared to the standard technique by providing appropriate wall shear stress in critical regions and minimizing the risk of wall damage. Its use of a thicker vessel also reduces the risk of vessel injury, making it particularly effective for patients with Chronic Kidney Disease (CKD), hypertension, anemia, and diabetes, ensuring optimal blood flow and fewer complications. However, there are minor concerns about stenosis formation in hypertension and anemia cases, which could be mitigated by adjusting the anastomosis angle to be lower than 30°. CONCLUSION: Diabetes and hypertension have significant physiological effects that increase the risks associated with arteriovenous fistula maturation. The anemic condition resulting from CKD may help reduce vessel injury but raises concerns about potential stenosis formation. Despite these co-morbidities, the RADAR technique has demonstrated its ability to induce more favorable hemodynamic changes, promoting arteriovenous fistula maturation.

Logistic regression analysis of risk factors for hematoma after autologous arteriovenous fistula in hemodialysis patients.

To determine the risk factors and nursing countermeasures for post-operative hematoma in hemodialysis patients with autogenous arteriovenous fistula by logistic regression analysis. A retrospective analysis of 240 chronic hemodialysis patients admitted to our hospital from January 2019 to October 2022 was performed. Physical and vascular examinations of the patients were performed by surgeons. Continuous care measures were implemented for all patients. The patient serum creatinine (Scr) and blood urea nitrogen (BUN) were measured on the day of inclusion and after the implementation of care measures. Self-management scales were used to analyze patients' self-management. Fatigue symptoms were assessed using the Fatigue Scale 14. The WHO Quality of Life Scale (WHOQOL-BREF score) was used to assess patients' quality of life. Self-Rating Depression Scale and Self-Rating Anxiety Scale (SAS) were used to assess negative affect. Treatment compliance was assessed according to 3 levels: complete compliance, compliance, and noncompliance. In all, 240 patients underwent 240 initial and 48 repeat procedures; 18 of the 240 patients experienced fistula failure, with an overall success rate of 92.5% (222/240). There were no significant differences in renal function, self-management, General Self-Efficacy Scale, fatigue symptom scores, and WHOQOL-BREF scores between the postoperative hematoma group and no-hematoma group before the continuous care. After continuous care, renal function, self-management, General Self-Efficacy Scale, fatigue symptom scores, and WHOQOL-BREF scores were better in the postoperative no-hematoma group than in the hematoma group, and the difference was statistically significant (P < .05). Logistic regression analysis of risk factors for postoperative hematoma showed that elevated Scr and BUN levels, decreased self-management and SAS scores and poor treatment compliance were independent risk factors for postoperative hematoma in hemodialysis patients with autologous arteriovenous fistulas (P < .05). Elevated Scr levels, elevated BUN levels, decreased self-management scores, decreased SAS scores, and poor treatment compliance were independent risk factors for postoperative hematoma in hemodialysis patients with autogenous arteriovenous fistulas. By providing continuous care to hemodialysis patients based on timing theory, the negative emotions can be alleviated and the self-efficacy, quality of life, and treatment compliance of the patients can be improved.

Percutaneous ecoguided endovascular lithotripsy to recruit failed-to-mature arteriovenous fistula due to completely calcified radial artery.

The first-choice vascular access for starting dialysis is autogenous distal forearm arteriovenous-fistula (AVF); the increasing demand to create more fistulas may lead to their creation in borderline vessels and, in this setting, the early failure (EF) and failure of maturation (FTM) remain the main issues. The size of vessels or preexisting stenotic lesions of artery or vein are no longer considered absolute exclusion criteria for the creation of distal AVF, but huge arterial calcification still represents an indication to create upper arm AVF. A novel approach to treat arterial calcifications is represented by intravascular lithotripsy (IVL). This technique could represent a valid option to save failed to mature AVF due to extended calcified artery. We describe a case of a male patient, 43 years old with middle forearm AVF failed to mature with a completely calcified radial artery, low brachial flow (Qa) and small efferent vein. We treated the patient AVF with less invasive, percutaneous, endovascular, eco-guided IVL on the entire radial artery. After the procedure was observed a rapid increase of Qa, with reduction of calcification in the arterial wall, increase of arterial caliper and flow. This procedure could represent a valid alternative to surgical upper-arm AVF creation in patient with functioning but failed to mature fistula due to spread artery calcification, with a rapid, less invasive procedure.

Creating hemodialysis autogenous access in children and adolescents.

OBJECTIVE: End-stage renal disease (ESRD) in childhood and adolescence is rare, with relatively few published reports of pediatric ESRD vascular access. This study analyzes a 10-year experience creating arteriovenous fistulas (AVFs) in children and adolescents. Our goal is to review our strategy for creating functional autogenous vascular access in younger patients and report our results. METHODS: We retrospectively reviewed data and outcomes for consecutive vascular access patients aged ≤19 years during a 10-year period. Each patient had preoperative vascular ultrasound mapping by the operating surgeon in addition to physical examination. A distal forearm radiocephalic AVF was the first access choice when feasible, and a proximal radial artery inflow AVF was the next option. Demographic data, inflow artery, venous outflow target, and required transposition vs direct AVFs were variables included in the analysis. Primary and cumulative patency were calculated by Kaplan-Meier analysis. RESULTS: Thirty-seven AVFs were created in 35 patients. No grafts were used. Ages were 6 to 19 years (mean, 15 years), and 20 were male. Causes of ESRD included glomerular disease (n = 18) and urinary obstruction or reflux (n = 7), among others. Three had previous AVFs, and 10 were obese. The proximal radial artery supplied AVF inflow in 25 patients and the brachial artery in only seven. Eleven individuals required a transposition and one a vein translocation to the contralateral arm. No patients developed hand ischemia, although two later required banding procedures for high flow. Eleven patients had successful transplants. A single patient died, unrelated to the vascular access. Five AVFs failed. Of these, two had new successful AVFs created, two regained renal function, one was transplanted, and one declined other procedures. Primary and cumulative patency rates were 75% and 85% at 12 months, 70% and 85% at 24 months, and 51% and 85% at 36 months, respectively. Median follow-up was 16 months. CONCLUSIONS: Creating an AVF for hemodialysis is a successful vascular access strategy for pediatric and adolescent patients. Proximal radial artery AVFs provided safe and functional access when a distal AVF was not feasible. Cumulative AVF patency was 85% at 36 months.

Hemodialysis Access: US for Preprocedural Mapping and Evaluation of Maturity and Access Dysfunction.

Patients with kidney failure require kidney replacement therapy. While renal transplantation remains the treatment of choice for kidney failure, renal replacement therapy with hemodialysis may be required owing to the limited availability and length of time patients may wait for allografts or for patients ineligible for transplant owing to advanced age or comorbidities. The ideal hemodialysis access should provide complication-free dialysis by creating a direct connection between an artery and vein with adequate blood flow that can be reliably and easily accessed percutaneously several times a week. Surgical arteriovenous fistulas and grafts are commonly created for hemodialysis access, with newer techniques that involve the use of minimally invasive endovascular approaches. The emphasis on proactive planning for the placement, protection, and preservation of the next vascular access before the current one fails has increased the use of US for preoperative mapping and monitoring of complications for potential interventions. Preoperative US of the extremity vasculature helps assess anatomic suitability before vascular access creation, increasing the rates of successful maturation. A US mapping protocol ensures reliable measurements and clear communication of anatomic variants that may alter surgical planning. Postoperative imaging helps assess fistula maturation before cannulation for dialysis and evaluates for early and late complications associated with arteriovenous access. Clinical and US findings can suggest developing stenosis that may progress to thrombosis and loss of access function, which can be treated with percutaneous vascular interventions to preserve access patency. Vascular access steal, aneurysms and pseudoaneurysms, and fluid collections are other complications amenable to US evaluation. ©RSNA, 2023 Supplemental material is available for this article. Test Your Knowledge questions for this article are available through the Online Learning Center.

An effective AI model for automatically detecting arteriovenous fistula stenosis.

In this study, a novel artificial intelligence (AI) model is proposed to detect stenosis in arteriovenous fistulas (AVFs) using inexpensive and non-invasive audio recordings. The proposed model is a combination of two new input features based on short-time Fourier transform (STFT) and sample entropy, as well as two associated classification models (ResNet50 and ANN). The model's hyper-parameters were optimized through the use of the design of the experiment (DOE). The proposed AI model demonstrates high performance with all essential metrics, including sensitivity, specificity, accuracy, precision, and F1-score, exceeding 0.90 at detecting stenosis greater than 50%. These promising results suggest that our approach can lead to new insights and knowledge in this field. Moreover, the robust performance of our model, combined with the affordability of the audio recording device, makes it a valuable tool for detecting AVF stenosis in home-care settings.

Temporal serum metabolomic and lipidomic analyses distinguish patients with access-related hand disability following arteriovenous fistula creation.

For end-stage kidney disease (ESKD) patients, hemodialysis requires durable vascular access which is often surgically created using an arteriovenous fistula (AVF). However, some ESKD patients that undergo AVF placement develop access-related hand dysfunction (ARHD) through unknown mechanisms. In this study, we sought to determine if changes in the serum metabolome could distinguish ESKD patients that develop ARHD from those that have normal hand function following AVF creation. Forty-five ESKD patients that underwent first-time AVF creation were included in this study. Blood samples were obtained pre-operatively and 6-weeks post-operatively and metabolites were extracted and analyzed using nuclear magnetic resonance spectroscopy. Patients underwent thorough examination of hand function at both timepoints using the following assessments: grip strength manometry, dexterity, sensation, motor and sensory nerve conduction testing, hemodynamics, and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. Nineteen of the forty-five patients displayed overt weakness using grip strength manometry (P < 0.0001). Unfortunately, the serum metabolome was indistinguishable between patients with and without weakness following AVF surgery. However, a significant correlation was found between the change in tryptophan levels and the change in grip strength suggesting a possible role of tryptophan-derived uremic metabolites in post-AVF hand-associated weakness. Compared to grip strength, changes in dexterity and sensation were smaller than those observed in grip strength, however, post-operative decreases in phenylalanine, glycine, and alanine were unique to patients that developed signs of motor or sensory disability following AVF creation.

Hemodynamics in AVF over time: A protective role of vascular remodeling toward flow stabilization.

The mechanisms underlying vascular stenosis formation in the arteriovenous fistula (AVF) for hemodialysis (HD) remain mostly unknown. Several computational fluid dynamics (CFD) studies have suggested a potential role for unsteady flow in inducing intimal hyperplasia and AVF stenosis, but the majority of these observations have been limited to a single time point after surgical creation. The aim of the present study was to investigate the relation between hemodynamic conditions and AVF vascular remodeling through a CFD longitudinal study. Non contrast-enhanced MR images and Doppler Ultrasound (US) examinations were acquired at 3 days, 40 days, 6 months, 1 year, and 1.5 years after surgery in a 72-year male referred for native radio-cephalic AVF. Three-dimensional AVF models were generated and high fidelity CFD simulations were performed using pimpleFoam, setting patient-specific boundary conditions derived from US. Morphological and hemodynamic changes over time were then analyzed. Analysis of vessel morphology and hemodynamics during follow-up showed that the AVF had a successful maturation process, characterized by a massive arterial and venous dilatation within the 6 months after surgery, a corresponding increase in blood flow volume and important flow instabilities. Between 6 months and 1 year, a stenosis developed in the juxta-anastomotic vein and caused AVF failure at 1.5 years. The development of stenosis was paralleled by the regularization of blood flow velocity pattern and consequent decrease in the near-wall disturbed flow metrics. These results suggest that development of intimal hyperplasia and vessel stenosis, triggered by unsteady flow, could be the result of vascular inward remodeling toward regularization of turbulent-like flow.

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.

Impact of simulation-based training in addition to theoretical training versus theoretical training of nurses alone in the occurrence of adverse events related to arteriovenous fistula puncture in chronic hemodialysis patients: study for a cluster randomized controlled trial (SIMFAV2).

BACKGROUND: The technique of arteriovenous fistula (AVF) puncture is currently taught by colleagues within hemodialysis units. Even if the main principles of the technique are well known and common to all hemodialysis units, strong rationales are still missing to standardize fine practices such as the relative position of the needles, the angle of the needle at puncture, and the position of the bevel at the time of puncture and after the needle is in the vascular lumen. METHODS: We are conducting a prospective, comparative, center-randomized, multicenter study involving 8 hemodialysis centers. The primary objective is to compare the number of adverse events related to AVF puncture between a group receiving theoretical training plus simulation-based training (4 centers) and a group receiving only theoretical training (4 centers). The study will include all adult patients who are scheduled to have an AVF puncture performed by a hemodialysis-trained nurse during a scheduled chronic dialysis session. DISCUSSION: We hypothesize that a training program for nurses on the AVF approach in procedural simulation versus theoretical input alone would decrease the adverse events related to AVF punctures and would be beneficial for the patient. This study is innovative for several reasons. First, simulation-based training in continuing education among professionals is not widely used. Furthermore, training allows for the standardization of practices within the team, both technically and relationally. TRIAL REGISTRATION: ClinicalTrials.gov NCT05302505 . Registered on March 17, 2022.

Obesity drives secondary procedures to achieve access maturation in end-stage renal disease.

BACKGROUND: Establishing long-term arteriovenous access is an important component in the long-term care of a patient with end-stage renal disease. The increasing frequency of obesity is reported to impact the access management of end-stage renal disease patients. This study aims to evaluate the outcomes of arteriovenous fistulae (AVF) in obese and nonobese patients. METHODS: A retrospective review of all patients over ten years with primary autogenous AVF (radiocephalic, brachiocephalic, and brachial-basilic) was undertaken at a single center. Patients were subcategorized by body mass index into nonobese, class I, II, and III obesity. Outcomes of maturation (successful progression to hemodialysis), reintervention, functional dialysis (continuous hemodialysis for 3 consecutive months), and patency were examined. RESULTS: From January 1999 to December 2019, 2311 patients (67% female; mean age, 61 ± 15 years) underwent primary AVF placement (12% radiocephalic, 53% brachiocephalic, and 35% brachial basilic). Forty-one percent were nonobese, 29% had class I obesity, 19% had class II obesity, and 11% had class III obesity. The majority of patients were diabetic and Hispanic. The 30-day major adverse cardiovascular event rate was elevated in class II (0.20%) and class III (0.50%) obesity compared with class I obesity (0.15%) and nonobese (0.05%). The 30-day morbidity rate was higher in all classes of obesity (0.5% vs0.3% vs 0.2% vs 0.05% for class III vs class II vs class I obesity and nonobese, respectively). Early thrombosis was significantly increased in class II (9%) and class III obesity (12%) compared with class I obesity (5%) and nonobese (3%). There was a two-fold increase in procedures to effect maturation in class II (51%) and class III (74%) obesity compared with class I obesity (22%) and nonobese (34%). Secondary patency at 3 years was significantly lower in class III (62 ± 4%) and class II (79 ± 3%) compared with class I obesity (87 ± 2%) and nonobese (93 ± 4%). All classes of obesity required significantly more secondary Interventions per year compared with nonobese (3.9 vs 3.1 vs 2.5 vs 1.4 secondary interventions per year for class III vs class II vs class I obesity and nonobese, respectively). CONCLUSIONS: Advancing obesity class is associated with an increased number of procedures to achieve AVF maturation and is associated with poorer patency and functionality as the category of obesity advances.

Effects of a More Selective Arteriovenous Fistula Strategy on Vascular Access Outcomes.

SIGNIFICANCE STATEMENT: The optimal choice of vascular access for patients undergoing hemodialysis-arteriovenous fistula (AVF) or arteriovenous graft (AVG)-remains controversial. In a pragmatic observational study of 692 patients, the authors found that among patients who initiated hemodialysis with a central vein catheter (CVC), a strategy that maximized AVF placement resulted in a higher frequency of access procedures and greater access management costs for patients who initially received an AVF than an AVG. A more selective policy that avoided AVF placement if an AVF was predicted to be at high risk of failure resulted in a lower frequency of access procedures and access costs in patients receiving an AVF versus an AVG. These findings suggest that clinicians should be more selective in placing AVFs because this approach improves vascular access outcomes. BACKGROUND: The optimal choice of initial vascular access-arteriovenous fistula (AVF) or graft (AVG)-remains controversial, particularly in patients initiating hemodialysis with a central venous catheter (CVC). METHODS: In a pragmatic observational study of patients who initiated hemodialysis with a CVC and subsequently received an AVF or AVG, we compared a less selective vascular access strategy of maximizing AVF creation (period 1; 408 patients in 2004 through 2012) with a more selective policy of avoiding AVF creation if failure was likely (period 2; 284 patients in 2013 through 2019). Prespecified end points included frequency of vascular access procedures, access management costs, and duration of catheter dependence. We also compared access outcomes in all patients with an initial AVF or AVG in the two periods. RESULTS: An initial AVG placement was significantly more common in period 2 (41%) versus period 1 (28%). Frequency of all access procedures per 100 patient-years was significantly higher in patients with an initial AVF than an AVG in period 1 and lower in period 2. Median annual access management costs were significantly higher among patients with AVF ($10,642) versus patients with AVG ($6810) in period 1 but significantly lower in period 2 ($5481 versus $8253, respectively). Years of catheter dependence per 100 patient-years was three-fold higher in patients with AVF versus patients with AVG in period 1 (23.3 versus 8.1, respectively), but only 30% higher in period 2 (20.8 versus 16.0, respectively). When all patients were aggregated, the median annual access management cost was significantly lower in period 2 ($6757) than in period 1 ($9781). CONCLUSIONS: A more selective approach to AVF placement reduces frequency of vascular access procedures and cost of access management.

Use of Basilic vein in arteriovenous fistulas construction for hemodialysis access. Is it a good option alternative to prosthetic arteriovenous grafts?

PURPOSE: For patients with a failed forearm autogenous fistula (AF) and an exhausted cephalic vein, there is controversy about whether a brachial basilic AF with transposition or an arteriovenous prosthetic bridging graft (BG) must be the second vascular access option. This work measured and compared these two modalities according to patency rates, complications, and revisions. PATIENTS AND METHODS: A retrospective study of 104 cases that had either a brachial basilic AF (72) or an Arteriovenous BG (32). Technical success, operative complications, procedurerelated mortality, maturation time, functional primary, secondary, and overall patency rates were all assessed. RESULTS: Technical success was obtained in all participants. No procedure-linked mortality. Maturation time for BGs was significantly shorter than AFs. The complication rate was significantly higher in BGs than in AFs. The most prevalent complication was access thrombosis. The functional primary patency rate was significantly higher in AF than in BG at 12-month followup: 77.7% vs 53.1% (p < 0.012). secondary patency rate was higher in AF than in BG at 1-year follow-up 62.5% vs 42.8% (p = 0.063), respectively. In addition, BGs required more interventions to preserve patency. CONCLUSIONS: AF had higher primary, secondary and overall functional patency rates and needed fewer procedures to keep patency than BGs. Cases that need early vascular access as a result of central venous catheter complications or who have a reduced life expectancy may benefit from BGs.

Chronic Kidney Disease Transdifferentiates Veins into a Specialized Immune-Endocrine Organ with Increased MYCN-AP1 Signaling.

Most patients with end-stage renal disease (ESRD) and advanced chronic kidney disease (CKD) choose hemodialysis as their treatment of choice. Thus, upper-extremity veins provide a functioning arteriovenous access to reduce dependence on central venous catheters. However, it is unknown whether CKD reprograms the transcriptome of veins and primes them for arteriovenous fistula (AVF) failure. To examine this, we performed transcriptomic analyses of bulk RNA sequencing data of veins isolated from 48 CKD patients and 20 non-CKD controls and made the following findings: (1) CKD converts veins into immune organs by upregulating 13 cytokine and chemokine genes, and over 50 canonical and noncanonical secretome genes; (2) CKD increases innate immune responses by upregulating 12 innate immune response genes and 18 cell membrane protein genes for increased intercellular communication, such as CX3CR1 chemokine signaling; (3) CKD upregulates five endoplasmic reticulum protein-coding genes and three mitochondrial genes, impairing mitochondrial bioenergetics and inducing immunometabolic reprogramming; (4) CKD reprograms fibrogenic processes in veins by upregulating 20 fibroblast genes and 6 fibrogenic factors, priming the vein for AVF failure; (5) CKD reprograms numerous cell death and survival programs; (6) CKD reprograms protein kinase signal transduction pathways and upregulates SRPK3 and CHKB; and (7) CKD reprograms vein transcriptomes and upregulates MYCN, AP1, and 11 other transcription factors for embryonic organ development, positive regulation of developmental growth, and muscle structure development in veins. These results provide novel insights on the roles of veins as immune endocrine organs and the effect of CKD in upregulating secretomes and driving immune and vascular cell differentiation.