ASDIN white paper: Management of cephalic arch stenosis endorsed by the American Society of Diagnostic and Interventional Nephrology.

Brachiocephalic arteriovenous fistulas (AVF) makeup approximately one third of prevalent dialysis vascular accesses. The most common cause of malfunction with this access is cephalic arch stenosis (CAS). The accepted requirement for treatment of a venous stenosis lesion is ⩾50% stenosis associated with hemodynamically abnormalities. However, the correlation between percentage stenosis and a clinically significant decrease in access blood flow (Qa) is low. The critical parameter is the absolute minimal luminal diameter (MLD) of the lesion. This is the parameter that exerts the key restrictive effect on Qa and results in hemodynamic and functional implications for the access. CAS is the result of low wall shear stress (WSS) resulting from the effects of increased blood flow and the unique anatomical configuration of the CAS. Decrease in WSS has a linear relationship to increased blood flow velocity and neointimal hyperplasia exhibits an inverse relationship with WSS. The result is a stenotic lesion. The presence of downstream venous stenosis causes an inflow-outflow mismatch resulting in increased pressure within the access. Qa in this situation may be decreased, increased, or within a normal range. Over time, the increased intraluminal pressure can result in marked aneurysmal changes within the AVF, difficulties with cannulation and the dialysis treatment, and ultimately, increasing risk of access thrombosis. Complete characterization of the lesion both hemodynamically and anatomically should be the first step in developing a strategy for management. This requires both access flow measurement and angiographic imaging. Patients with CAS present a relatively broad spectrum as relates to both of these parameters. These data should be used to determine whether primary treatment of CAS should be directed toward the anatomical lesion (small MLD and low Qa) or the pathophysiology (large MLD and high Qa).

Comparison of Ellipsys Percutaneous and Proximal Forearm Gracz-Type Surgical Arteriovenous Fistulas.

RATIONALE & OBJECTIVE: Percutaneous arteriovenous fistulas (AVF) are created by establishing a proximal forearm anastomosis and offer a safe and reliable vascular access. This study compares the Ellipsys percutaneous AVF with a proximal forearm Gracz-type surgical AVF, chosen for comparison as it is constructed at the same anatomical site. STUDY DESIGN: Retrospective study of prospectively collected clinical data. SETTING & PARTICIPANTS: All vascular access procedures conducted during a 34-month period were reviewed. The study groups comprised 89 percutaneous AVFs and 69 surgical AVFs. EXPOSURE: Percutaneous or surgical AVF placement. OUTCOME: AVF patency, function, and complications. ANALYTICAL APPROACH: Patency rates for each AVF group were evaluated by competing risk survival analysis using a cumulative incidence function. Association of primary, primary assisted, and secondary patency with the AVF groups was examined by Cox proportional hazard models. RESULTS: Technical success was 100% for both groups. Average procedure times were 14 minutes for percutaneous AVFs and 74 minutes for surgical AVFs (P < 0.001). Proximal radial artery (PRA) was used in all percutaneous AVF cases. Inflow for surgical AVFs included radial (30%), ulnar (12%), and brachial (58%) arteries. Outflow veins for both groups were the cephalic and/or basilic veins. Access flow volumes, times to maturation, and overall numbers of interventions per patient-year were not significantly different. Cumulative incidence of primary patency failure at 12 months was lower for surgical AVF (47% vs 64%, P = 0.1), but secondary patency failure was not different between groups (20% vs 12%, P = 0.3). PRA surgical AVFs had similar primary patency (65% vs 64%, P = 0.8) but higher secondary patency failure rates than percutaneous AVFs at 12 months (34% vs 12%, P = 0.04). LIMITATIONS: Retrospective study with a relatively short follow-up period, and not all patients required hemodialysis at the end of study. CONCLUSIONS: Both percutaneous and surgical AVFs demonstrated high rates of technical success and secondary patency. Percutaneous AVFs required shorter procedure times. The rate of intervention was similar. When a distal radial artery AVF is not feasible, percutaneous AVF might offer an appropriate procedure for creating a safe and functional access, maintaining further proximal forearm surgical AVF creation options.

Interventional Nephrology: Opportunities and Challenges.

The nephrologist has a pivotal role as the leader of multidisciplinary teams to optimize vascular access care of the patient on dialysis and to promote multidisciplinary collaboration in research, training, and education. The continued success of interventional nephrology as an independent discipline depends on harnessing these efforts to advance knowledge and encourage innovation. A comprehensive curriculum that encompasses research from bench to bedside coupled with standardized clinical training protocols are fundamental to this expansion. As we find ourselves on the threshold of a much-awaited revolution in nephrology, there is great opportunity but also formidable challenges in the field - it is up to us to work together to realize the enormous potential of our discipline.

Comparison of Outcomes of Percutaneous Arteriovenous Fistulae Creation by Ellipsys and WavelinQ Devices.

PURPOSE: The purpose of this study was to compare the clinical outcomes of Ellipsys with those of WavelinQ-4F percutaneous arteriovenous fistulae (pAVF) devices in a single center by a single operator. MATERIALS AND METHODS: A retrospective review was conducted in 100 patients who underwent pAVFs procedures (65 Ellipsys and 35 WavelinQ patients) and created between December 2017 and December 2019. A total of 69% were male and 37% were diabetic. Median age was 64.1 years (range: 28-86), and median body mass index was 27.2 (range: 15-45.1) kg/m2. A procedure sequence algorithm was followed for selecting all vascular accesses created. RESULTS: Ellipsys outcomes were compared to WavelinQ outcomes. Technical success was 100% versus 97%, respectively, and median procedure times were 14 versus 63 minutes, respectively (P < .001), with 183 (1-487) versus 185 (0-760) days follow-up, respectively. Maturation at 4 weeks was 68.3% versus 54.3%, respectively, and median times to cannulation were 60 (1-164) versus 90 (1-180) days, respectively. Successful pAVF dialysis was established in 31 of 39 patients (79.5%) versus 14 of 24 patients (58%), respectively (P = .071), dialysis patients with access-related adverse events observed in 4 individuals (1 Ellipsys versus 3 WavelinQ). Six patients (5 versus 1) with matured outflow from previous AVFs underwent first-day cannulations. Interventions were performed in 27.7% (33 Ellipsys) and 26.5% (15 WavelinQ) patients, and the number of interventions per patient-years was 0.96 versus 0.46, respectively. pAVF failure was seen in 15.4% versus 37.1% patients, respectively (P = .0137). Secondary patency at 12 months was significantly higher among patients who had an Ellipsys procedure (82%) than among those who underwent the WavelinQ procedure (60%). CONCLUSIONS: pAVFs were created with high technical success and low complications with both devices. Ellipsys pAVFs demonstrated significantly shorter procedure times without a need for radiation exposure and with superior secondary patency.

The effect of angioplasty of single arteriovenous fistula-associated stenosis on arteriovenous fistula blood flow rate.

INTRODUCTION: Percutaneous balloon angioplasty of arteriovenous fistula-associated stenosis is performed for a variety of indications. Successful percutaneous transluminal angioplasty (PTA) is expected to increase in arteriovenous fistula blood flow rate (Qa). A validated approach to predicting changes in Qa based upon stenosis characteristics is not available. METHODS: Three baseline parameters were determined in a group of patients with a single arteriovenous fistula-associated stenosis undergoing PTA. These were percent estimated stenosis, stenosis minimum luminal diameter, and baseline Qa. The relationship between these parameters and changes in Qa following PTA was analyzed using Spearman's rank correlation and linear regression. RESULTS: 113 patients (total group) were studied. Of these,106 had peripheral stenosis (total peripheral subgroup) and 7 had central stenosis. For the total group and total peripheral subgroup, a highly significant inverse correlation was seen between changes in Qa and baseline Qa. A weaker correlation was seen between changes in Qa and minimum luminal diameter, but no correlation was seen with percent estimated stenosis. A minimum luminal diameter ⩽2.0 mm was predictive of ⩾300-mL/min increases in Qa, whereas a minimum luminal diameter >4.5 mm was associated with <300-mL/min increases in Qa. PTA of Central vein stenosis was not associated with significant changes in Qa. CONCLUSION: Baseline Qa is the best predictor for change in Qa following PTA. Stenosis minimum luminal diameter cutoffs of ⩽2.0 and >4.5 mm are useful in predicting the magnitude of changes in Qa. Percent estimated stenosis is not predictive of change in Qa. PTA of central veins does not seem to change Qa.

ASDIN white paper: Assessment and management of hemodialysis access-induced distal ischemia by interventional nephrologists.

Although not common, hemodialysis access-induced distal ischemia is a serious condition resulting in significant hemodialysis patient morbidity. Patients with signs and symptoms suggestive of hand ischemia frequently present to the general and interventional nephrologist for evaluation. In order to care for these cases, it is necessary to understand this syndrome and its management. Most cases can be managed conservatively without intervention. Some cases requiring intervention may be treated using techniques within the scope of practice of the interventional nephrologists while other cases require vascular surgery. In order for the interventional nephrologists to evaluate and manage these cases in a timely and appropriate manner, practice guidelines are presented.

Exploring correlations between anatomic characteristics of dialysis arteriovenous fistula stenosis and arteriovenous fistula blood flow rate (Qa).

BACKGROUND: Radiologic justification for endovascular treatment of a dialysis arteriovenous fistula circuit stenosis is currently based on ⩾50% severity. However, the clinical significance of any given stenosis is not always clear. The minimum luminal diameter of any stenotic lesion in the arteriovenous fistula circuit might exert a more predictive effect on the arteriovenous fistula blood flow rate (Qa). METHODS: To investigate relationships between anatomic parameters of stenosis and Qa, this study was conducted in a cohort of patients with a variety of arteriovenous fistula stenotic lesions. The goals were to determine (1) the degree of correlation between arteriovenous fistula stenosis estimated during the procedure, and that which is measured, and (2) the correlations between two anatomic stenosis parameters (percent stenosis and stenosis minimum luminal diameter) and Qa. RESULTS: The cohort comprised 113 patients. Only a moderate correlation between estimated and measured stenosis was seen. A correlation between measured stenosis and Qa for the whole cohort was not seen, but a weak correlation between estimated stenosis and Qa was seen. Correlations between stenosis minimum luminal diameter and Qa were superior. The superiority of stenosis minimum luminal diameter to percent stenosis in correlating with a Qa of <500 mL/h was also demonstrated by receiver operating characteristics curve analysis. Stenosis minimum luminal diameter cutoffs of ⩽2.5 mm or >4 mm seemed to have a good predictive value of Qa. CONCLUSIONS: Percent stenosis determination is fraught with uncertainty and exhibits a weak correlation with Qa. Compared with percent stenosis, the minimum luminal diameter of the stenosis demonstrates a superior correlation with Qa.

Early cannulation of percutaneously created arteriovenous hemodialysis fistulae.

INTRODUCTION: The optimal vascular access for most dialysis patients is an arteriovenous fistula and the recognized appropriate process of care for the chronic kidney disease patient is to have the access in place ready for use when renal replacement therapy is required. Unfortunately, as a result of multiple barriers, most patients start dialysis with a catheter and many experience multiple interventions. The recent advent of the percutaneous arteriovenous fistula may offer at least a partial solution to these problems. The purpose of this study was to report of the results of early cannulation of the percutaneous arteriovenous fistula. MATERIALS AND METHODS: Early cannulation, less than 14 days post creation, was performed in 14 cases in order to avoid an initial catheter or continued use of a problematic catheter for dialysis. Immediately post access creation, blood flow ranged from 491 to 1169 mL/min (mean = 790 mL/min). Ultrasound was used to map potential cannulation sites prior to use. Cannulation was performed using plastic fistula cannulas. RESULTS: Early cannulation was successful in this cohort of cases except for one cannulation complication. Dialysis treatments were otherwise uncomplicated. Primary patency at 3, 6, and 12 months was 76%, 76%, and 66%, respectively. Assisted primary patency for the same intervals was 100%, 100%, and 91%, respectively. Cumulative patency was 100% at all three-time intervals. CONCLUSION: The results of this study suggest that the possibility of successful early cannulation with a percutaneous arteriovenous fistula can be considered as an additional factor in making this access a reasonable alternative for a surgically created arteriovenous fistula in appropriate patients.

Two-year cumulative patency of endovascular arteriovenous fistula.

BACKGROUND AND OBJECTIVES: The recent advent of a device to create a proximal radial artery arteriovenous fistula using an endovascular approach to create the anastomosis represents a significant advance in dialysis access creation. This endovascular arteriovenous fistula offers the beneficial attributes of the proximal radial artery arteriovenous fistula while adding the advantages of avoiding a surgical procedure. The endovascular arteriovenous fistula can be created safely, functions well, has excellent patency, and has a high degree of patient satisfaction. The purpose of this study is to report the 2-year cumulative patency rate for a large multicenter cohort of endovascular arteriovenous fistula cases. DESIGN: An endovascular arteriovenous fistula was created in 105 patients using either local or regional anesthesia and conscious sedation. Patient data were obtained from each program's electronic health record system. Data collection was truncated at 2 years postprocedure and used to calculate cumulative patency. Post-access creation patient satisfaction was assessed. RESULTS: A physiologically mature arteriovenous fistula (blood flow ⩾500 mL/min and a target vein internal diameter ⩾4 mm) was obtained in 98%. A clinically functional arteriovenous fistula (supporting two-needle dialysis according to the patient's dialysis prescription) was demonstrated in 95%. Access failure resulting in the loss of access occurred in eight cases during the study period. The cumulative patency rate at 6, 12, 18, and 24 months was 97.1%, 93.9%, 93.9%, and 92.7%, respectively. The post-procedure patient evaluation emphasized a high level of patient satisfaction. CONCLUSION: The proximal radial artery arteriovenous fistula created using an endovascular approach for the anastomosis is associated with excellent 2-year cumulative patency and is associated with a high level of patient satisfaction.

Definitions and End Points for Interventional Studies for Arteriovenous Dialysis Access.

This paper is part of the Clinical Trial Endpoints for Dialysis Vascular Access Project of the American Society of Nephrology Kidney Health Initiative. The purpose of this project is to promote research in vascular access by clarifying trial end points which would be best suited to inform decisions in those situations in which supportive clinical data are required. The focus of a portion of the project is directed toward arteriovenous access. There is a potential for interventional studies to be directed toward any of the events that may be associated with an arteriovenous access' evolution throughout its life cycle, which has been divided into five distinct phases. Each one of these has the potential for relatively unique problems. The first three of these correspond to three distinct stages of arteriovenous access development, each one of which has been characterized by objective direct and/or indirect criteria. These are characterized as: stage 1-patent arteriovenous access, stage 2-physiologically mature arteriovenous access, and stage 3-clinically functional arteriovenous access. Once the requirements of a stage 3-clinically functional arteriovenous access have been met, the fourth phase of its life cycle begins. This is the phase of sustained clinical use from which the arteriovenous access may move back and forth between it and the fifth phase, dysfunction. From this phase of its life cycle, the arteriovenous access requires a maintenance procedure to preserve or restore sustained clinical use. Using these definitions, clinical trial end points appropriate to the various phases that characterize the evolution of the arteriovenous access life cycle have been identified. It is anticipated that by using these definitions and potential end points, clinical trials can be designed that more closely correlate with the goals of the intervention and provide appropriate supportive data for clinical, regulatory, and coverage decisions.

What is the best setting for receiving dialysis vascular access repair and maintenance services?

INTRODUCTION: Advances in dialysis vascular access (DVA) management have changed where beneficiaries receive this care. The effectiveness, safety, quality, and economy of different care settings have been questioned. This study compares patient outcomes of receiving DVA services in the freestanding office-based center (FOC) to those of the hospital outpatient department (HOPD). It also examines whether outcomes differ for a centrally managed system of FOCs (CMFOC) compared to all other FOCs (AOFOC). METHODS: Retrospective cohort study of clinically and demographically similar patients within Medicare claims available through United States Renal Data System (USRDS) (2010-2013) who received at least 80% of DVA services in an FOC (n = 80,831) or HOPD (n = 133,965). Separately, FOC population is divided into CMFOC (n = 20,802) and AOFOC (n = 80,267). Propensity matching was used to control for clinical, demographic, and functional characteristics across populations. RESULTS: FOC patients experienced significantly better outcomes, including lower annual mortality (14.6% vs. 17.2%, p<0.001) and DVA-related infections (0.16 vs. 0.20, p<0.001), fewer hospitalizations (1.65 vs. 1.91, p<0.001), and lower total per-member-per-month (PMPM) payments ($5042 vs. $5361, p<0.001) than HOPD patients. CMFOC patients had lower annual mortality (12.5% vs. 13.8%, p<0.001), PMPM payments (DVA services) ($1486 vs. $1533, p<0.001) and hospitalizations ($1752 vs. $1816, p<0.001) than AOFOC patients. CONCLUSIONS: Where nephrologists send patients for DVA services can impact patient clinical and economic outcomes. This research confirmed that patients who received DVA care in the FOC had better outcomes than those treated in the HOPD. The organizational culture and clinical oversight of the CMFOC may result in more favorable outcomes than receiving care in AOFOC.

Management of transposed arteriovenous fistula swing point stenosis at the basilic vein angle of transposition by stent grafts.

INTRODUCTION: Transposed basilic vein arteriovenous fistulas suffer from stenosis at their basilic angle of transposition (BAT). This lesion exhibits frequent recurrence after angioplasty. The primary goal of this study was to determine the effect of stent-graft placement on BAT lesion- and access-patency. The secondary goals were to determine the frequency of intervention pre- and post-stent placement and stent-associated stenosis. METHODS: Thirty-seven cases had stent-grafts placed at their BAT to manage stenosis. Cases served as their own controls by analyzing their lesion- and access-patency pre- and post-stent placement. Student's t-test was used for analysis of continuous variables. Categorical variables were evaluated by Fisher's exact test. Tests were considered significant when p was ≤0.05. RESULTS: At 6 and 12 months, pre-stent lesion primary patency rates were 29% and 3%, and post-stent were 57% and 40%, respectively. Lesion primary assisted patency rates were 39% and 13%, and post-stent were 91% and 80%, respectively. At 6 and 12 months, pre-stent access primary patency rates were 29% and 3%, and post-stent were 26% and 19%, respectively. Pre-stent primary access assisted patency rates were 36% and 10%, and post-stent were 82% and 75%, respectively. Lesion intervention rates averaged 0.47/month pre-stent and 0.13/month post-stent. Access intervention rate averaged 0.50/month pre-stent, and 0.15/month post-stent. Stent-associated stenosis was seen in 23 cases. CONCLUSIONS: Treatment of BAT stenosis with stent-grafts had positive impact on the target lesion and the dialysis access circuit.

Angiography of Hemodialysis Fistulas and Grafts.

Angiography of the dialysis access is an important procedure in dealing with dialysis arteriovenous access (AVA) dysfunction. It is an integral part and the initiating procedure for all the interventional procedures performed for the management and salvage of dialysis AVA. The performance of this procedure and normal dialysis access-related anatomy including anatomical variants are discussed. In addition, pathology commonly encountered in association with the anatomy is reviewed.

Changes in the Profile of Endovascular Procedures Performed in Freestanding Dialysis Access Centers over 15 Years.

BACKGROUND AND OBJECTIVES: Marked changes occurred in the vascular access profile of patients receiving hemodialysis in the United States over the 15-year period of 2001-2015. This study was undertaken to evaluate how these changes have affected dialysis access maintenance and salvage procedures performed in freestanding dialysis access centers and to examine the effectiveness, efficiency, and safety of these procedures in this setting. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Data were collected from freestanding, dedicated dialysis access centers operating under a common system of management. Data were available on 689,676 dialysis access procedures. Data relating to case mix, procedure outcome, procedural time, and intraprocedural and immediate postprocedural complications were analyzed. RESULTS: The arteriovenous procedure profile changed from one characterized by approximately equal numbers of angioplasties and thrombectomies performed on arteriovenous grafts (AVGs) to one characterized primarily by angioplasties performed on arteriovenous fistulas. The percentage of angioplasties performed throughout the study was significantly greater than thrombectomies, with a mean of 67.9% versus 32.1% (P<0.001). Interventional procedures did not decrease with increasing arteriovenous fistula utilization in prevalent patients receiving dialysis. The incidence roughly paralleled the increasing prevalence of this type of access. A decreasing percentage of AVG utilization resulted in a progressive, roughly parallel, but disproportionately higher, decrease in the percentage of AVG procedures (P<0.001). A progressive improvement in procedure outcomes and a decrease in complication rates and procedure times were observed (P<0.001 for each). A progressive decrease in tunneled dialysis catheter placement was also observed. CONCLUSIONS: The procedure profile treated in freestanding, dedicated dialysis access centers changed significantly over 15 years, reflecting the changes that have occurred in the vascular access profile of the dialysis population.

The DRIL procedure for arteriovenous access ischemic steal: a controversial approach.

The DRIL procedure first described in 1988 has long been considered the preferred treatment for arteriovenous access ischemic steal (AVAIS). At the time it was a brilliant concept and breakthrough. In the last decade, the DRIL procedure has become less used. With the increasing age of the dialysis population, patients developing AVAIS are more likely to be elderly with advanced peripheral arterial disease, making the distal revascularization anastomosis difficult and risky if not impossible to perform. In addition, the distal ligation of the main artery to the arm is something most surgeons are reluctant to do. The occlusion of the arterial bypass over time is not uncommon with recurrence of hand ischemia. The multistep DRIL procedure requires general anesthesia and the need to harvest the saphenous vein for the bypass, add to the surgical risk in patients with multiple co-morbidities. For these reasons, some surgeons prefer to do only the DR (distal re-vascularization) portion of the procedure omitting the IL (interval ligation). Increasing the bypass distance from the original anastomosis, makes this modification similar to the less invasive proximal arterial inflow (PAI) procedure. Because of changes in the patient population clinical presentation, most notably forearm atherosclerosis and with new technologies, this editorial addresses the current validity of the DRIL procedure as a safe option in treating AVAIS.

The risk of bleeding with tunneled dialysis catheter placement.

PURPOSE: The purpose of this study was to evaluate the risk of bleeding associated with tunneled dialysis catheter (TDC) placement in a large population of hemodialysis patients who were either anticoagulated or were taking antithrombotic medications. METHODS: Medical records obtained over a two-year period were queried in order to select two groups of study cases. The first was a Med group (n = 458), cases which had a TDC placed while taking the antithrombotic medications (warfarin, clopidogrel or acetylsalicylic acid [ASA]) which were not discontinued or held. The second was a Declot Failure (DF) group (n = 941) and consisted of cases in which a TDC had been placed immediately following a failed arteriovenous access thrombectomy procedure in which they had been anticoagulated using unfractionated heparin. The results obtained in these two groups were compared to the incidence of bleeding observed in a cohort of 6555 TDC placements that had been performed previously referred to as the Control group. RESULTS: The incidence of bleeding in the Control group was 0.46%. The incidence of bleeding in the DF group was 0.44% and in the Med group was 0.36%. No patient had bleeding that required transfusion, hospitalization, or catheter removal. CONCLUSIONS: Based upon these data, it seems reasonable to classify the TDC placement procedure as having a very low risk of bleeding and to not require preprocedure laboratory testing. The value of suspending antithrombotic medications prior to TDC placement cannot be supported.

We Refuse to Give up on Nonmaturing Fistulas.

The nonmaturing arteriovenous fistula (AVF) is a major problem and can lead to significant patient morbidity and mortality because the patient is exposed to the risk of dialysis with a central venous catheter (CVC). Access planning should include a strategy to decrease the incidence of AVF nonmaturation. All newly created AVFs should be evaluated for maturation at 4-6 weeks. If it is judged to not be usable at that time, it should be evaluated for salvage. However, if multiple procedures over a prolonged period of time are necessary for salvage, the decreasing chances of long-term success with the increasing risks of CVC-based dialysis must be considered. Giving up on the nonmaturing AVF may be in the best interest of the patient.

Chronically Occluded Arteriovenous Fistula Salvaged by Sharp Needle Recanalization.

Salvage of a failed arteriovenous access with occlusion of the venous outflow and no alternative for a secondary arteriovenous fistula that would provide for immediate dialysis is a difficult problem for which there is no ideal solution. The present report is such a patient. The patient had a radial-cephalic fistula represented by only a very short segment, inadequate for effective dialysis. Salvage was accomplished using the sharp needle revascularization technique in order to avoid a prolonged period of central venous catheter use.

Role of interventional nephrology in the multidisciplinary approach to hemodialysis vascular access care.

Dialysis vascular access planning, creation, and management is of critical importance to the dialysis patient population. It requires a multidisciplinary approach involving patients and their families, dialysis facility staff, the nephrologist, the surgeon, and the interventionalist. With the emergence of interventional nephrology as a subspecialty of nephrology, the nephrologist is increasingly providing both the nephrology and interventional aspects of care, and in some areas, the surgical functions as well. Most of these interventional nephrologists work in freestanding outpatient dialysis access centers (DACs). Large clinical studies published over the past 10 years demonstrate that the interventional nephrologist can manage the problems associated with dialysis access dysfunction effectively, safely, and economically. A recently published study based upon United States Medicare claims data in which a DAC patient group (n = 27,613) and a hospital outpatient department patient group (HOPD group; n = 27,613) were compared using propensity score matching techniques showed that patients treated in the DACs had significantly better clinical outcomes (P<0.001). This included fewer vascular access-related infections (0.18 vs. 0.29), fewer septicemia-related hospitalizations (0.15 vs. 0.18), and a lower mortality rate (47.9% vs. 53.5%).