Use of the Viabahn stent graft for the treatment of recurrent cephalic arch stenosis in hemodialysis accesses.

OBJECTIVE: Cephalic arch stenosis (CAS) is a frequent and challenging failure mode of brachiocephalic fistulas. Natural tortuosity of the cephalic arch requires special consideration in selecting a treatment modality. Typical percutaneous angioplasty and bare-metal stent (BMS) treatments provide a short-term treatment solution for CAS without a durable effect. This study assessed Viabahn (W. L. Gore & Associates, Flagstaff, Ariz) stent grafts (SGs) as a first-line percutaneous option to provide a durable treatment for CAS. METHODS: SG data were collected at a free-standing physician office between July 10, 2009, and January 26, 2011. A single-arm, prospective, observational study was conducted of 50 consecutive CAS patients treated with angioplasty followed by deployment of Viabahn SGs. Outcomes included target lesion primary patency and reintervention rates as well as secondary access patency. Results were compared with historic cohorts of percutaneous balloon angioplasty (N = 50) and angioplasty followed by BMS deployment (N = 50). The cohorts were treated between May 5, 2005, and May 20, 2010, and assessed in chronologic order. RESULTS: The SG cohort target lesion primary patency reported at 3, 6, and 12 months was 90% ± 7%, 74% ± 12%, and 60% ± 14% (±95% confidence interval), respectively. Compared with historic cohorts, the SG cohort demonstrated statistically superior target lesion primary patency (P < .001), with a reduced reintervention rate per access-year (P < .001). Secondary access patency was statistically superior compared with the percutaneous balloon angioplasty cohort (P = .034) but not statistically different from the BMS cohort when assessed during a 2.5-year period. The secondary access patency for the SG cohort at 5 years was 80% ± 15%. CONCLUSIONS: In treatment of a CAS, the Viabahn SG study group demonstrated superior target lesion primary patency and required fewer subsequent interventions compared with historic cohorts treated with angioplasty or angioplasty followed by BMS placement. Given the significant improvement in target lesion primary patency, future studies should challenge Viabahn SGs as a primary percutaneous treatment modality vs durable surgical alternatives.

Hand ischemia associated with dialysis vascular access: an individualized access flow-based approach to therapy.

With the rise in the median age of hemodialysis patients, the increasing numbers of patients with multiple risk factors for vascular disease, and the efforts being made to increase the creation of autogenous arteriovenous fistulas (AVFs), dialysis access-related steal syndrome (DASS) has become a growing problem. This syndrome, caused by arterial insufficiency distal to the arteriovenous access due to diversion of blood into the access, is a potentially devastating complication. It is crucial that physicians who manage hemodialysis patients and perform vascular access procedures have a comprehensive understanding of the pathophysiology, symptoms, diagnostic maneuvers, and treatment options for DASS. The goals of management must be twofold-relieve the ischemia and preserve the access. The choice of any intervention, if such is necessary, should be based upon the clinical features presented by that individual patient; the clinical condition and prognosis of the patient, stage of the disease, location of the arterial anastomosis, and the level of blood flow within the access. This review presents information that supports an individualized, physiologic approach to this condition.

Fistula first breakthrough initiative: targeting catheter last in fistula first.

An arteriovenous fistula (AVF) is the optimal vascular access for hemodialysis (HD), because it is associated with prolonged survival, fewer infections, lower hospitalization rates, and reduced costs. The AVF First breakthrough initiative (FFBI) has made dramatic progress, effectively promoting the increase in the national AVF prevalence since the program's inception from 32% in May 2003 to nearly 60% in 2011. Central venous catheter (CVC) use has stabilized and recently decreased slightly for prevalent patients (treated more than 90 days), while CVC usage in the first 90 days remains unacceptably high at nearly 80%. This high prevalence of CVC utilization suggests important specific improvement goals for FFBI. In addition to the current 66% AVF goal, the initiative should include specific CVC usage target(s), based on the KDOQI goal of less than 10% in patients undergoing HD for more than 90 days, and a substantially improved initial target from the current CVC proportion. These specific CVC targets would be disseminated through the ESRD networks to individual dialysis facilities, further emphasizing CVC avoidance in the transition from advanced CKD to chronic kidney failure, while continuing to decrease CVC by prompt conversion of CVC-based hemodialysis patients to permanent vascular access, utilizing an AVF whenever feasible.

Has the Fistula First Breakthrough Initiative caused an increase in catheter prevalence?

The use of central venous hemodialysis catheters (CVC) continues to be high among the incident as well as the prevalent HD patients. Whereas many strategies have been implemented to decrease the use of CVCs, their placement rates have doubled since 1996. While many factors, including late referral, are responsible for the increased use of CVCs, the arteriovenous Fistula First Breakthrough Initiative (known as "Fistula First" [FF]) has also been implicated in the increased use of CVCs. It has been suggested that while the FF initiative has resulted in a substantial increase in arteriovenous fistulae placement and use, it has also resulted in an increase in the use of CVCs. This report argues that catheter rates have remained unchanged and provides data regarding the impact of the FF initiative on catheter use.

The Society for Vascular Surgery: clinical practice guidelines for the surgical placement and maintenance of arteriovenous hemodialysis access.

Recognizing the impact of the decision making by the dialysis access surgeon on the successful placement of autogenous arteriovenous hemodialysis access, the Society for Vascular Surgery assembled a multispecialty panel to develop practice guidelines in arteriovenous access placement and maintenance with the aim of maximizing the percentage and functionality of autogenous arteriovenous accesses that are placed. The Society commissioned the Knowledge and Encounter Research Unit of the Mayo Clinic College of Medicine, Rochester, Minnesota, to systematically review the available evidence in three main areas provided by the panel: timing of referral to access surgeons, type of access placed, and effectiveness of surveillance. The panel then formulated practice guidelines in seven areas: timing of referral to the access surgeon, operative strategies to maximize the placement of autogenous arteriovenous accesses, first choice for the autogenous access, choice of arteriovenous access when a patient is not a suitable candidate for a forearm autogenous access, the role of monitoring and surveillance in arteriovenous access management, conversion of a prosthetic arteriovenous access to a secondary autogenous arteriovenous access, and management of the nonfunctional or failed arteriovenous access. For each of the guidelines, the panel stated the recommendation or suggestion, discussed the evidence or opinion upon which the recommendation or suggestion was made, detailed the values and preferences that influenced the group's decision in formulating the relevant guideline, and discussed technical remarks related to the particular guideline. In addition, detailed information is provided on various configurations of autogenous and prosthetic accesses and technical tips related to their placement.

Secondary arteriovenous fistulas: converting prosthetic AV grafts to autogenous dialysis access.

As existing arteriovenous grafts (AVGs) fail, the National Kidney Foundation KDOQI Guidelines and the AV Fistula First Breakthrough Initiative ("Fistula First") project recommend that each patient be re-evaluated for conversion to an arteriovenous fistula (AVF). AVFs created following failure of an AVG have been termed secondary fistulas (SAVF). We review our experience and outcomes converting AVGs to SAVFs, utilizing the mature outflow vein of the AVG when possible, otherwise creating a new AVF at a remote site. We reviewed two groups of consecutive patients undergoing operations for vascular access at different centers. Group 1 had a SAVF protocol in place during the study period with specific criteria for timing SAVF construction. Patients from group 2 were referred for evaluation by nephrologists or dialysis nurses as access problems were recognized, without a formal protocol in place. All patients had preoperative ultrasound or contrast imaging in addition to physical examination. Indications for creating a SAVF were AVG thrombosis, dysfunction, erosion, bleeding, or steal syndrome involving the existing AVG. The simple presence of a functional AVG without evidence of dysfunction was not an indication for conversion to a SAVF. SAVFs were classified according to location and the potential for utilizing the existing mature AVG outflow vein. Group 1: 40 consecutive patients, age 26-78 (mean = 62), 42% were female; 55% were diabetic. These patients had 1-22 previous access operations (mean = 3). 92.5% underwent SAVF surgery prior to loss of the AVG, minimizing catheter use. Cumulative patency was 92.5% at 1 year and 87.5% at 2 years. Group 2: 102 consecutive patients, age 24-87 (mean = 55), 52% were female; 50% were diabetic. These patients had 1-50 previous access operations (mean = 3). Only 19.3% were referred for SAVF surgery prior to loss of the AVG or outflow vein. Cumulative patency was 94.4% at 1 year and 91.6% at 2 years. Failure, dysfunction, or complications of AVGs may be resolved by conversion to a SAVF. Further, the limited lifespan of AVGs and the superiority of AVFs dictates that a plan be in place to transition the AVG patient to an AVF. Most, if not all, hemodialysis patients whose access is an AVG will have one or more anatomic sites and vessels suitable for an autogenous SAVF. Vessel mapping is critical in the evaluation of failing AVGs and in preparation for a SAVF. Cumulative patency rates exceeded 90% at 12 months for SAVFs in both patient groups in this report. The need for catheters was dramatically less in the patient group with an established SAVF conversion plan.

Primary and staged transposition arteriovenous fistulas.

BACKGROUND: The use of catheters or prosthetic grafts for vascular access has significantly higher mortality and morbidity risks, in addition to higher costs, than arteriovenous fistulas (AVF). Many patients have a difficult access extremity due to complex medical illnesses, previous vascular access procedures, intravenous catheters, diabetes, vascular disease, female sex, age, and other complicating factors. Transposition AVFs (AVF-T) have been used for these individuals to avoid catheters and grafts. We report our experience with primary and staged basilic vein AVF-Ts and staged brachial vein AVF-Ts. METHODS: From our database of consecutive vascular access operations, we reviewed patients from May 2003 to September 2006 for all upper extremity AVF-Ts. A primary AVF-T was used when the basilic vein was continuous with a minimum diameter of 4 mm and of adequate length. When the basilic vein was 2.5 to 4 mm, the procedure was staged. The proximal radial artery was used for inflow, if possible. When the basilic vein was not suitable, a radial vein or brachial vein anastomosis was performed as the first stage of a planned brachial vein AVF-T. The second stage operations of staged AVF-Ts were generally done 4 to 6 weeks after the primary AVF construction. All patients were evaluated with preoperative ultrasound imaging by the operating surgeon. RESULTS: From a database of 412 consecutive vascular access patients, 78 upper extremity transposition procedures were identified. Of these, 57 patients (73.1%) were women, 44 (56.4%) were diabetic, and 46 (59.0%) had previous access surgery. Fifty-eight operations were staged procedures. The basilic vein was used in 68 AVF-T, the brachial vein in six, and cephalic vein in four. The anastomosis was based on the proximal radial artery in 60 patients. Mean follow-up was 18 months (range, 3-48 months). Primary patency, primary assisted patency, and cumulative patency were 45.7%, 93.5%, and 96.0% at 12 months and 27.6%, 86.5%, and 88.9% at 24 months, respectively. No prosthetic grafts were used in the study period. CONCLUSION: Both primary and staged AVF-T procedures were successfully used in patients with difficult access extremities. AVF-Ts were durable, although many required an interventional procedure for maturation or maintenance. Cumulative (secondary) patency was 96.0% at 12 months and 88.9% at 24 months. The absence of an adequate basilic vein does not preclude the use of a staged AVF-T because the brachial vein offers a suitable alternative.

Surgical salvage of the autogenous arteriovenous fistula (AVF).

Numerous studies have shown that the native arteriovenous fistula (AVF) has better long-term outcomes than other forms of access for hemodialysis. However, complications may require challenging salvage procedures. The present review summarizes and discusses surgical solutions for AVF salvage recently proposed within the Fistula First Breakthrough Initiative. These include strategies to salvage primary failed fistulae due to early thrombotic events or lack of maturation, ischemia, venous hypertensive problems, aneurysms and infections.

Interventional nephrology: from episodic to coordinated vascular access care.

In recent years, nephrologists have taken the initiative of performing vascular access-related procedures themselves. Because of their unique clinical perspective on dialysis access and better understanding of the intricacies of renal replacement therapy, nephrologists are ideally suited for this activity. This approach has minimized delays, decreased hospitalizations and decreased the use of temporary catheters, thereby improving medical care, decreasing costs and increasing patient convenience. Vascular access interventions commonly employed by nephrologists include vascular access education, vascular mapping, percutaneous balloon angioplasty, thrombectomy, intravascular coil and stent insertion and tunneled hemodialysis catheter-related procedures. While the performance of these procedures by nephrologists offers many advantages, appropriate training to develop the necessary procedural skills is critical. Recent data have emphasized that a nephrologist can be successfully trained to become a competent interventionalist. In addition to documenting excellent outcome data, multiple reports have demonstrated the safety and success of an interventional nephrology approach. The last decade has been a period of significant advances in this new field. This has been driven in part by the formation of the American Society of Diagnostic and Interventional Nephrology (ASDIN), whose mission includes training, quality assurance and certification. Recently, the ASDIN has published guidelines for training in nephrology-related procedures and has begun certifying physicians in specific procedures related to chronic kidney disease. It is anticipated that this will promote the skillful performance of these procedures by nephrologists and lead to substantial improvements in the care of renal patients. Challenges for the future include awareness of this subspecialty and development of training programs at academic centers on a larger scale.

Autogenous arteriovenous fistula options.

The Fistula First Breakthrough Initiative (FFBI) shows that development of multidisciplinary teams with designated vascular access coordinators is the key to success in increasing the appropriate use of the arteriovenous fistula as access for hemodialysis. Since nephrologists should communicate expectations to surgeons regarding fistula placement and their ability to use the access repeatedly, current surgical techniques based on KDOQI guidelines and best practices are summarized in this review. These may serve also as bases for the education of the surgical community. Autogenous fistula options include primary native fistula creation in the forearm, arm and lower extremity which can be direct or based on transposed or translocated venous vessels. Optimizing autogenous options for hemodialysis requires vessel mapping and a surgeon's willingness to invest additional time and effort.

Vascular mapping techniques: advantages and disadvantages.

At present, an arteriovenous fistula is the best available access when compared with an arteriovenous graft or a tunneled hemodialysis catheter. Preoperative vascular mapping has been shown to result in an increased placement of arteriovenous fistulae. In general, 3 modalities (physical examination, ultrasound examination and angiographic evaluation) are available for vascular evaluation. Both arterial as well as venous examination can be conducted using physical examination. However, this technique is known to miss veins, especially in the obese, and result in exclusion of patients who do not show adequate veins on clinical inspection, but who have suitable veins (proven by the other modalities) for AVF construction. Ultrasound examination of the vessels is an objective assessment. It provides an excellent evaluation of both arteries and veins for creation of an arteriovenous fistula. The technique is limited by its inability to directly visualize the central veins. Although imaging of the veins by the administration of radiocontrast dye optimally visualizes peripheral as well as central veins, it exposes the patient to the risk of radiocontrast-induced nephropathy. This article presents advantages and disadvantages of the 3 mapping techniques and proposes a strategy to conduct vascular mapping in patients with chronic kidney disease.

Biology of arteriovenous fistula failure.

Although arteriovenous (AV) fistulae are the preferred form of dialysis access, they continue to have significant problems with both early and late failures. Despite the magnitude of the clinical problem, however, there are unfortunately no effective therapies for AV fistula failure. We believe that this inability to intervene is partly due to a lack of understanding about the pathology and pathogenesis of AV fistula failure. Therefore, in the current review we will initially explore novel concepts about the pathology and pathogenesis of AV fistula failure. This information will then be used to suggest potential therapeutic interventions for this important, yet unmet clinical need. Finally, we will end with a brief description of some state-of-the-art clinical trials that are attempting to apply some of these novel therapeutic concepts to the recalcitrant clinical problem of AV fistula failure.

Clinical epidemiology of arteriovenous fistula in 2007.

The native arteriovenous fistula (AVF) is considered the best access for hemodialysis due to its longer survival and lower complication rates as compared with other forms of vascular access. However, broad practice variation exists in the use of AVF among different countries and even within the same country among different regions and centers. Several barriers to AVF placement have been identified in the last decade that might explain its suboptimal use among both prevalent and incident patients. The present review summarizes and discusses recent findings from epidemiological studies on practice patterns and risk factors for AVF failure. Special emphasis is devoted to drawbacks and payoffs consequent upon the choice of the AVF as access for dialysis. In fact the AVF requires major investments in the short run but far less assistance and rework thereafter. Primary AVF failure, due to early failure or lack of maturation, is currently considered a key area of investigation to improve vascular access outcomes. The main challenge for the nephrologist today is to minimize the risk of primary failure while attempting to provide most patients with a native AVF. Improving vascular access outcomes is clearly a complex and difficult task. Recent experience from the United States suggests that multidisciplinary management is the most appropriate approach to deal with all the multifaceted aspects of end-stage renal disease care and to increase the likelihood of success.

Static intra-access pressure ratio does not correlate with access blood flow.

BACKGROUND: Access flow (Qa) measurement is recommended by Kidney Disease Outcomes Quality Initiative (K/DOQI) as the preferred method for access surveillance. Static intra-access pressure ratio (SIAPR) measurement is the second surveillance method of choice. The purpose of this prospective multicenter study was to investigate the relationship between SIAPR and Qa and to examine the premise upon which SIAPR surveillance is based-namely, that high SIAPR is a surrogate for low Qa associated with hemodynamically significant stenosis. METHODS: SIAPR and Qa (HD01; Transonic Systems, Inc., Ithaca, NY, USA) were simultaneously measured monthly in 242 patients [146 prosthetic arteriovenous bridge grafts (AVG), 96 autogenous arteriovenous fistulas (AVF)] from three centers. SIAPR was measured according to the K/DOQI protocol. RESULTS: There was no correlation between Qa and venous or arterial SIAPR in AVGs (R(2)= 0.0037 and R(2)= 0.006, respectively, N= 730), or in AVFs (R(2)= 0.0247 and R(2)= 0.0329, respectively, N= 431). Of the high SIAPR measurements in AVGs, 81% and 50% were associated with Qa > or =600 and Qa > or =1000 mL/min, respectively. Of the AVGs studied, 41% (60/146) had consistently high Qa > or =1000 mL/min. Seventy percent (42/60) of these high-Qa AVGs had at least two consecutive sessions with high SIAPR measurements, thereby meeting the K/DOQI SIAPR criteria for referral. In addition, 78% (14/18) of new AVGs with Qa > or =1000 mL/min, and 86% (6/7) of AVGs with the highest Qa (> or =2000 mL/min), had high SIAPR. As a result, these high-Qa AVGs, which represented the best functioning AVGs by K/DOQI Qa standards, were erroneously targeted for referral based on SIAPR measurements. CONCLUSION: SIAPR does not correlate with Qa or discriminate between high and low Qa. Therefore, because the utility of SIAPR surveillance for detection of clinically significant stenosis depends on a correlation with Qa, the current use of absolute K/DOQI SIAPR thresholds for intervention based on the presumption that such thresholds are indicative of low Qa is not justified, and should be discontinued. Studies need to be done to examine the utility of SIAPR for trend analysis.