Effect of preoperative sonographic mapping on vascular access outcomes in hemodialysis patients

Preoperative ultrasound still valuable for radio-cephalic arteriovenous fistula creation?

Radio-cephalic arteriovenous fistula is a prototype hemodialysis access with small incidences of infection and distal ischemia, it spares proximal veins for future access use and it helps in the maturation of veins that may be used for more proximal access creations. This access type is prone to higher early failure rates compared to more proximal fistulas and there are unsolved uncertainties regarding exact ultrasound parameters predictive of fistula outcome. Evolution of ultrasound use has yielded several functional parameters that can be measured in addition to anatomical lumen sizes, which remain core parameters on which the decision to construct fistula in radio-cephalic forearm position is based. We propose to use arterial hyperemic response and wall morphology to aid in this decision when radial artery diameter falls in the interval with predictive uncertainty of 1.6-1.9 mm and to use venous flow pattern, respiratory variation, radial artery status and possibly venous distensibility when cephalic vein augmented diameter lies in the borderline interval of 2-2.4 mm. Ultrasound preoperative mapping and planning should be followed by expert surgical technique and several technique modifications of the classical end-to-side approach are possible to enhance operation outcome and diminish the incidence of stenosis most often present at juxta-anastomotic location. In our experience radio-cephalic arteriovenous fistula remains the golden standard for hemodialysis access and preoperative ultrasound the single best imaging modality to plan the operation and predict its success.

Sonography of Arteriovenous Fistulas and Grafts

Arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) are the vascular accesses of choice for long-term hemodialysis. Strategies to establish and maintain functioning AVFs and AVGs are essential. In addition to clinical evaluation, ultrasound plays a critical role in the evaluation and maintenance of AVFs and AVGs. AVFs have a high rate of failure to mature which can be reliably diagnosed with ultrasound. Treatable etiologies of the failure to mature can often be diagnosed with ultrasound. Causes of secondary AVG failure can also be diagnosed with ultrasound and treated. AVGs have a relatively short functional life expectancy due to a high rate of AVG thrombosis. Ultrasound is a safe, noninvasive way to diagnose vascular stenosis in both AVFs and AVGs prior to thrombosis, potentially saving the access. Routine surveillance ultrasound of asymptomatic AVFs and AVGs is controversial with conflicting studies on its benefit. Routine surveillance ultrasound of AVFs and AVGs is not common practice.

Arteriovenous Grafts: Much Maligned But in Need of Reconsideration?

There are substantial variations in arteriovenous fistula (AVF) use among hemodialysis patients in different countries, in different regions of the U.S., and even in different hemodialysis units within a single metropolitan area. These variations persist after adjustment for patient demographics and comorbidities, suggesting that practice patterns play a major role in determining the frequency of AVF use. These observations led to vascular access guidelines urging nephrologists and surgeons to increase AVF creation in patients with chronic kidney disease. Over the past 20 years, as clinicians have adopted these guidelines, the prevalence of AVF use in hemodialysis patients has increased substantially. At the same time, clinicians have recognized important limitations of an unwavering "Fistula First" approach. First, a substantial proportion of AVFs fail to mature even when routine preoperative vascular mapping is used, leading to prolonged catheter dependence. Second, certain patient subgroups are at high risk for AVF nonmaturation. Third, nonmaturing AVFs frequently require interventions to promote their maturation. Fourth, AVFs that require such interventions have shortened cumulative patency. Fifth, arteriovenous grafts (AVG) have several advantages over AVFs, including lower primary failure rates, fewer interventions prior to successful cannulation, and shorter duration of catheter dependence with its associated risk of bacteremia. All these observations have led nephrologists to propose an individualized approach to vascular access, with AVG being preferred in patients who initiate hemodialysis with a catheter, particularly if they are at high risk for AVF nonmaturation and have a relatively short life expectancy.

Effects of Cardiac Function with Postoperative Arteriovenous Fistula Blood Flow in Patients with Hemodialysis

Background/Aims: This study was aimed at evaluating the effect of cardiac function with postoperative arteriovenous fistula (AVF) blood flow in hemodialysis (HD) patients. Methods: A total of 45 HD patients were examined at the Juntendo University Hospital. The AVF blood flow was measured using ultrasonography, and the cardiac function was measured using echocardiography. Correlation between these parameters and the rate of change in body weight (BW) was analyzed. Results: The number of postoperative days significantly correlated with the AVF blood flow, and it positively correlated with the stroke volume (SV). The postoperative AVF blood flow in patients with reduced ejection fraction (EF) was lower than that in patients with normal EF. The rate of change of BW negatively correlated with that of SV, positively correlated with cardiac output (CO), and positively correlated with CO in patients with an AVF blood flow of more than 1,000 mL/min. Conclusion: It appears that the cardiac function can be improved by controlling the BW even in patients with high AVF blood flow.

Establishing patient-specific criteria for selecting the optimal upper extremity vascular access procedure

OBJECTIVE

The Kidney Disease Outcome Quality Initiative and Fistula First Breakthrough Initiative call for the indiscriminate creation of arteriovenous fistulas (AVFs) over arteriovenous grafts (AVGs) without providing patient-specific criteria for vascular access selection. Although the U.S. AVF rate has increased dramatically, several reports have found that this singular focus on increasing AVFs has resulted in increased AVF nonmaturation/early failure and a high prevalence of catheter dependence. The objective of this study was to determine the appropriateness of vascular access procedures in clinical scenarios constructed with combinations of relevant factors potentially influencing outcomes.

METHODS

The RAND/UCLA Appropriateness Method was used. Accordingly, a comprehensive literature search was performed and a synthesis of results compiled. The RAND/UCLA Appropriateness Method was applied to 2088 AVF and 1728 AVG clinical scenarios with varying patient characteristics. Eleven international vascular access experts rated the appropriateness of each scenario in two rounds. On the basis of the distribution of the panelists' scores, each scenario was determined to be appropriate, inappropriate, or indeterminate.

RESULTS

Panelists achieved agreement in 2964 (77.7%) scenarios; 860 (41%) AVF and 588 (34%) AVG scenarios were scored appropriate, 686 (33%) AVF and 480 (28%) AVG scenarios were scored inappropriate, and 542 (26%) AVF and 660 (38%) AVG scenarios were indeterminate. Younger age, larger outflow vein diameter, normal or obese body mass index (vs morbidly obese), larger inflow artery diameter, and higher patient functional status were associated with appropriateness of AVF creation. Older age, dialysis dependence, and smaller vein size were associated with appropriateness of AVG creation. Gender, diabetes, and coronary artery disease were not associated with AVF or AVG appropriateness. Dialysis status was not associated with AVF appropriateness. Body mass index and functional status were not associated with AVG appropriateness. To simulate the surgeon's decision-making, scenarios were combined to create situations with the same patient characteristics and both AVF and AVG options for access. Of these 864 clinical situations, 311 (36%) were rated appropriate for AVG but inappropriate or indeterminate for AVF.

CONCLUSIONS

The results of this study indicate that patient-specific situations exist wherein AVG is as appropriate as or more appropriate than AVF. These results provide patient-specific recommendations for clinicians to optimize vascular access selection criteria, to standardize care, and to inform payers and policy. Indeterminate scenarios will guide future research.

Postoperative Day 1 Access Blood Flow and Resistive Index can Predict Patency in Distal Forearm Arteriovenous Fistula

Introduction

Early access failure is an important complication of autogenous arteriovenous fistulas (AVFs). We prospectively monitored patients who underwent AVF creation using ultrasonography.

Methods

Color flow imaging was used to assess access blood flow in patients undergoing creation of a new AVF in the distal forearm preoperatively and at 1 day and 1 week postoperatively. We measured the flow volume (FV) and resistive index (RI) of the brachial artery, and the internal diameter of the brachial artery and outflow vein. The primary outcome was the primary patency of the AVF without percutaneous angioplasty (PTA) or surgical revision 40 days after access creation.

Results

We recruited 35 patients with newly created AVFs (men, 21; mean age, 73 years). Within one day of operation, the overall FV increased from 62 to 352 mL/min (p<0.0001) while the overall RI decreased from 1.0 to 0.63 (p<0.001). Five patients required PTA or surgical revision (intervention group [IG]), whereas 30 patients did not (non-intervention group [NIG]). The FV increased while the RI decreased from day 1 to week 1 in the NIG, but not in the IG (p<0.0001). The diameter of the brachial artery and outflow vein significantly increased in the NIG at 1 week. The FV of 235 mL/min and RI of 0.63 at 1 day were the thresholds for predicting early fistula failure.

Conclusions

Access FV and RI at 1 day after AVF creation can predict primary patency and help plan intervention.

Vascular imaging for hemodialysis vascular access planning

INTRODUCTION

Central venous catheters (CVC) increase risks associated with hemodialysis (HD), but may be necessary until an arteriovenous fistula (AVF) or graft (AVG) is achieved. The impact of vascular imaging on achievement of working AVF and AVG has not been firmly established.

METHODS

Retrospective cohort of patients initiating HD with CVC in 2010-2011, classified by exposure to venography or Doppler vein mapping, and followed through December 31, 2012. Standard and time-dependent Cox models were used to determine hazard ratios (HRs) of death, working AVF, and any AVF or AVG. Logistic regression was used to assess the association of preoperative imaging with successful AVF or AVG among 18,883 individuals who had surgery. Models were adjusted for clinical and demographic factors.

FINDINGS

Among 33,918 patients followed for a median of 404 days, 39.1% had imaging and 55.7% had surgery. Working AVF or AVG were achieved in 40.6%; 46.2% died. Compared to nonimaged patients, imaged patients were more likely to achieve working AVF (HR = 1.45 [95% confidence interval [CI] 1.36, 1.55], P < 0.001]), any AVF or AVG (HR = 1.63 [1.58, 1.69], P > 0.001), and less likely to die (HR = 0.88 [0.83-0.94], P < 0.001). Among patients who had surgery, the odds ratio for any successful AVF or AVG was 1.09 (1.02-1.16, P = 0.008).

DISCUSSION

Fewer than half of patients who initiated HD with a CVC had vascular imaging. Imaged patients were more likely to have vascular surgery and had increased achievement of working AV fistulas and grafts. Outcomes of surgery were similar in patients who did and did not have imaging.

Predictors of Initiation for Predialysis Arteriovenous Fistula

BACKGROUND AND OBJECTIVES

The optimal timing of predialysis arteriovenous fistula surgery remains uncertain. We evaluated factors associated with hemodialysis initiation in patients undergoing predialysis arteriovenous fistula surgery and derived a model to predict future initiation of dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our study retrospectively identified 308 patients undergoing predialysis arteriovenous fistula creation at a large medical center in 2006-2012 to determine whether they initiated hemodialysis. Multiple variable logistic regression analyzed which demographic and clinical factors predicted initiation of dialysis within 2 years of arteriovenous fistula surgery. A receiver operating characteristic area under the curve was used to quantify the predictive value of preoperative factors on the likelihood of initiating hemodialysis within 2 years.

RESULTS

Overall, hemodialysis was initiated within 6 months, 1 year, and 2 years in 119 (39%), 175 (57%), and 211 (68%) patients, respectively. Using multiple variable logistic regression, four factors were associated with hemodialysis initiation at 2 years: eGFR at access surgery (odds ratio, 0.45; 95% confidence interval, 0.31 to 0.64 per 5 ml/min per 1.73 m2; P<0.001), diabetes (odds ratio, 2.51; 95% confidence interval, 1.22 to 5.15; P=0.003), GFR trajectory (odds ratio, 1.54; 95% confidence interval, 1.09 to 2.17 per 3 ml/min per 1.73 m2 per year; P=0.01), and spot urine protein-to-creatinine ratio (odds ratio, 1.39; 95% confidence interval, 1.14 to 1.71 per 1 U; P<0.001). eGFR alone had a moderate predictive value for dialysis initiation (area under the curve =0.69; 95% confidence interval, 0.63 to 0.76; P<0.001), whereas the full model had a higher predictive value (area under the curve =0.83; 95% confidence interval, 0.77 to 0.88; P<0.001).

CONCLUSIONS

The likelihood of initiating hemodialysis within 2 years of predialysis arteriovenous fistula surgery is associated with eGFR at access surgery, diabetes, GFR trajectory, and magnitude of proteinuria. The combined use of all four variables improves the ability to predict future hemodialysis compared with the use of eGFR alone.

Transjugular Access for Endovascular Treatment of Immature Autogenous Arteriovenous Fistulae

PURPOSE

To assess the feasibility and outcome of transjugular access for endovascular treatment of immature arteriovenous fistulae (AVFs).

MATERIALS AND METHODS

Between August 2013 and January 2016, 90 patients (mean age, 64.5 y ± 12.8) underwent endovascular treatment of immature AVFs via transjugular access. The mean age of fistulae was 3.3 months ± 1.8. Total procedure time and technical and clinical success rates of endovascular procedures were assessed. Primary and secondary patency rates were calculated according to the Kaplan-Meier method, and complications were assessed.

RESULTS

All patients had inflow lesions, among which 19 (21.1%) had occlusions. The juxtaanastomotic segment was the most common site (44.3%). Transjugular access was successful in 83 patients (92.2%), and 7 required additional standard or transarterial access. The mean procedure time was 36.5 minutes. Technical and clinical success rates were 98.9% and 90.5%, respectively. Mean primary and secondary patency durations were 14.3 months ± 1.7 and 31.0 months ± 0.7, respectively. Primary patency rates at 3, 6, and 12 months were 84.4%, 67.3%, and 48.8%, respectively. Secondary patency rates at 6 and 18 months were 98.6% and 95.5%, respectively. Venous rupture occurred as a result of balloon inflation in 9 patients (10%), and was managed by balloon tamponade. There were no complications related to transjugular access during a mean follow-up period of 12.6 months.

CONCLUSIONS

Transjugular access for angioplasty of immature AVFs is feasible and safe. Potential problems associated with access in the outflow vein could be avoided by transjugular access.

Racial and Gender Differences in Arterial Anatomy of the Arm

Prior studies have shown racial and gender differences with respect to maturation of arteriovenous fistulas. Women and minorities have lower maturation rates for unclear reasons. Small arterial diameter and high brachial artery bifurcation (HBB) are also implicated in reduced maturation rates. We sought to correlate differences in upper extremity arterial anatomy to race and gender. All upper extremity vascular mapping ultrasounds from 2013 to 2014 were retrospectively reviewed. A total of 509 arms in 284 patients were evaluated. Men had significantly higher mean arterial diameters than women at the elbow brachial (4.7 vs 3.9 mm, P < 0.01) and wrist radial arteries (2.1 vs 1.9 mm, P = 0.03). There were 20 (7%) patients with HBB of at least one arm, and 7 (2.5%) patients with bilateral HBB. African-American patients had significantly higher rates of both unilateral HBB (15.9% vs 5.4%, P = 0.02) and bilateral HBBs (9.1% vs 1.3%, P = 0.01). In conclusion, men had significantly larger arteries than women, and African-Americans had a higher rate of HBB than non-African-Americans. Consideration should be given for routine preoperative ultrasound to assess arterial anatomy before arteriovenous fistulas creation, particularly in women and in African-Americans.

Duplex Ultrasound for the Prediction of Vascular Events Associated with Arteriovenous Fistulas in Hemodialysis Patients

Objective

To determine if duplex ultrasound (US) for arteriovenous fistulas (AVFs) can predict vascular events (VEs; thrombosis and stenosis).

Methods

Duplex US was performed for vascular access evaluation in 2557 maintenance hemodialysis (HD) patients between October 1, 2013 and March 31, 2016. Of these patients, 2184 patients were finally included in this study. AVF dysfunction was assessed using the brachial artery blood flow volume (Qa; mL/min), arterial blood flow resistance index (RI), and residual diameter of the fistula vein (RD; mm). Proximal, midpoint, and distal aspects of the fistulas were measured. The baseline measurements were the US assessments, and the endpoint was VEs requiring vascular access intervention therapy or vascular surgery. Associations of US findings and VEs were assessed with receiver operating characteristic curve analysis, log-rank analysis, and multivariate Cox hazard models.

Results

The mean Qa was 772.8 ± 441.4 mL/min; RI, 0.56 ± 0.1; and RD, 2.37 ± 1.0 mm. The optimal Qa cut-off point was calculated as 581.5 mL/min, RI cut-off as 0.56, and RD cut-off as 1.85 mm. VEs were more frequent in patients with a Qa <581.5 mL/min than in those with a Qa >581.5 mL/min (p<0.001). In multivariate analysis, Qa, ferritin, transferrin saturation, and warfarin use were significantly associated with VEs.

Conclusions

US evaluation of AVFs in HD patients is a simple method to predict the risks of thrombosis and fistula dysfunction. Qa, ferritin, transferrin saturation, and warfarin use might be associated with VEs.

Arteriovenous Vascular Access Selection and Evaluation

When making decisions regarding vascular access creation, the clinician and vascular access team must evaluate each patient individually with consideration of life expectancy, timelines for dialysis start, risks and benefits of access creation, referral wait times, as well as the risk for access complications. The role of the multidisciplinary team in facilitating access choice is reviewed, as well as the clinical evaluation of the patient.

Does pre- and post-angioplasty Doppler ultrasound evaluation help in predicting vascular access outcome?

BACKGROUND

Kidney Disease - Improving Global Outcomes (KDIGO) recommends post-percutaneous transluminal angioplasty (PTA) <30% residual stenosis (RS) and hemodynamic parameters improvement. Primary end point: how post-PTA access blood flow (ABF) improvement predicts vascular access (VA) outcome. Secondary: compare Doppler ultrasound (DU) and angiography diagnostic accuracy; determine how other factors predict outcome.

METHODS

Eighty patients. DU evaluation performed pre- and post-PTA. Several parameters recorded. Secondary patency verified after 6 months.

RESULTS

Initial ABF 537 ± 248 mL/min; final ABF 1013 ± 354 mL/min. Number and location of stenosis was highly correlated between DU and angiography (p<0.001); central vessels mismatching. First semester overall survival was 63%; significantly better for fistulas (76%) than grafts (51.7%), p 0.044. Final RS>30% associated to better survival, p 0.038. Initial ABF<500 mL/min and multiple stenosis did not affect outcome (p>0.05). A >2-fold ABF increase had no significant impact on fistulas (p>0.05) but was significantly associated with worst outcomes in grafts (23.1% vs. 73.5%, p 0.009). Grafts had lower survival (HR 3.3, p 0.034).

CONCLUSIONS

Although less accurate for central lesions, DU has a key role on VA surveillance, allowing a morphologic and hemodynamic assessment. Angioplasty is effective in preserving VA; however, it may increase restenosis due to accelerated neointimal hyperplasia. Current parameters are not useful. Trials addressing this issue are needed.

Maturation and Failure Rates in a Large Series of Arteriovenous Dialysis Access Fistulas

The objective of this study was to document maturation and failure rates in a large homogeneous series of arteriovenous fistulas (AVFs). Between January 1, 1996, and December 31, 2001 (60 months), a single surgeon (AFS) in 1 academic medical center, constructed 374 AVFs. In this series, all AVFs were developed in vessels that had not undergone previous vascular access surgery. Recently, a retrospective review of these records revealed that 291 subjects had had complete follow-up for at least 3 months, and they constitute the material for this study. AVFs were considered a failure if an early occlusion/thrombosis occurred, if in 3 months the AVF had not matured on clinical examination, or if cannulation in the dialysis center was not feasible. A total of 91 AVFs did not mature, for an overall failure rate of 31%. An evaluation of failure rates indicated rates in females were higher than in males (41% versus 27%). Other risk factors, including HIV+ status, hypertension, and diabetes, demonstrated minimal failure differences (33%, 31%, and 36%, respectively).

New Insights into Dialysis Vascular Access: What Is the Optimal Vascular Access Type and Timing of Access Creation in CKD and Dialysis Patients?

Optimal vascular access planning begins when the patient is in the predialysis stages of CKD. The choice of optimal vascular access for an individual patient and determining timing of access creation are dependent on a multitude of factors that can vary widely with each patient, including demographics, comorbidities, anatomy, and personal preferences. It is important to consider every patient's ESRD life plan (hence, their overall dialysis access life plan for every vascular access creation or placement). Optimal access type and timing of access creation are also influenced by factors external to the patient, such as surgeon experience and processes of care. In this review, we will discuss the key determinants in optimal access type and timing of access creation for upper extremity arteriovenous fistulas and grafts.

An update of the effect of far infrared therapy on arteriovenous access in end-stage renal disease patients

The life qualities of end-stage renal disease (ESRD) patients rely largely on adequate dialysis, and a well-functioning vascular access is indispensable for high quality hemodialysis. Despite the advancement of surgical skills and the optimal maintenance of arteriovenous fistula (AVF), malfunction of AVF is still frequently encountered and has great impact on the life of ESRD patients. Several medical, mechanical and genetic prognostic factors are documented to affect the patency of AVF and arteriovenous graft (AVG). Heme oxygenase-1 (HO-1) is one of the genetic factors reported to play a role in cardiovascular disease and the patency of vascular access. Far infrared (FIR), a novel therapeutic modality, can not only conduct heat energy to AVF but also stimulate the non-thermal reactions mediated by HO-1. The use of FIR therapy significantly enhances the primary patency rate and maturation of AVF with fewer unfavorable adverse effects, and also achieves higher post-angioplasty patency rate for AVG. The only limitation in proving the effectiveness of FIR therapy in enhancing patency of AVF is that all the studies were conducted in Chinese people in Taiwan and thus, there is a lack of evidence and experience in people of other ethnicities.

Prospective Evaluation of Factors Associated with Early Failure of Arteriovenous Fistulae in Hemodialysis Patients

Recent guidelines have recommended performing native arteriovenous fistulae (AVF) in hemodialysis patients rather than synthetic grafts whenever possible. However, early failure of AVF may reach up to 50%. The purpose of this study was to assess the factors associated with early failure of such procedures in hemodialysis patients.

A prospective study was performed on all patients with end-stage renal disease who had an AVF between June 2003 and March 2005. Data including patient characteristics and the type of AVF were recorded. The internal diameter of the vein and artery and intraoperative blood flow were measured. Patients were followed up for 3 months.

One hundred twenty-six AVF were included in this study. Early failure was in 14 (9%) patients. The internal diameter of the vein and artery and intraoperative blood flow were significantly lower in the failure group than in the patent group. The failure rate was not significantly related to other parameters.

Our data showed that intraoperative blood flow is a reliable parameter that determines the early failure of an AVF. Careful selection of the vein and the artery may reduce the rate of failure.

Preoperative vessel mapping in chronic kidney disease patients - a center experience

PURPOSE

Hemodialysis (HD) is the main treatment modality in stage 5 chronic kidney disease, and vascular access planning is a crucial step in the path to dialysis treatment. Beyond detailed patient history and physical examination, duplex ultrasound (DU) evaluation is essential in preoperative vascular mapping.

METHODS

A retrospective descriptive nonrandomized study was performed and included 108 end-stage kidney disease patients referred from eight HD centers to be assessed for creation of an arteriovenous (AV) access (AV fistula or AV graft). We assessed primary failure, primary unassisted patency (PP) and primary assisted patency (PAP) rates and cumulative survival of AV accesses at 6 and 12 months.

RESULTS

We created 86 AV accesses of which 79 (91.9%) were AV fistulas (AVFs) (29 distal AVFs, 49 proximal AVFs and 1 femorofemoral AVF) and 7 (8.1%) arteriovenous grafts (AVGs). Fifteen percent (15%) (n = 12) of primary failure occurred in the AVF group. Any case of primary failure was observed between AVGs.In the AVF group, PP at 6 months was 63.8 % and at 12 months was 48.3%, PAP was 80.7% at 6 and 12 months. PP excluding primary failures was 73.0% and 55.3% at 6 and 12 months, respectively. The cumulative survival at 6 and 12 months was 80.7%.In the AVG group, PP at 6 months and 12 months was 66.7%, PAP and cumulative survival at 6 and 12 months were of 100%.

CONCLUSIONS

This study demonstrates that preoperative vascular mapping with a patient-centered approach may be critical to achieve good outcomes allowing the increase in AVF access.

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

Background

Although ultrasonography before a vascular access (VA) operation has become popular in recent years, benchmarks for the diameter or blood flow of arteries or veins are not defined in Japan. The objective of the present study is to analyze the relationship between preoperative US findings and the patency rate of VA in Japanese hemodialysis patients.

Methods

139 patients with end stage kidney disease were enrolled in this study. They had been given primary radiocephalic arteriovenous fistula (AVF) from February 2009 to December 2010 at the Juntendo University Hospital and were followed up over 2 years. We defined the interval from the time of AVF creation until first access thrombosis or any intervention to maintain or restore blood flow as patency time (primary patency). We examined the correlation between the 2-year primary patency rate of VA and the diameter of the radial artery (RA), brachial artery (BA), or cephalic vein at an anastomosis presumptive region by US, the blood flow of RA or BA, as measured by US, age, gender, and primary kidney diseases.

Results

The average patency term was 448.6 ± 271.3 days, with the 1-year and 2-year patency rate as 64.0 and 51.2 %, respectively. The patency rate was significantly lower in elderly patients over the age of 75 and in patients with diabetes mellitus. US findings of 2.0 mm or less in the RA diameter also resulted in a noticeably low patency rate. A multivariate analysis indicated that those factors were risk factors for early VA failure.

Conclusions

Preoperative US findings of the diameter of RA may involve the patency rate of VA, making it appears that an RA of 2.0 mm or more in diameter at an anastomosis region may be more effective for the improvement in the patency rate of VA.

Outcomes of arteriovenous fistulas and grafts with or without intervention before successful use

OBJECTIVE

Arteriovenous fistulas (AVFs) are considered superior to arteriovenous grafts (AVGs) because of longer secondary patency after successful cannulation for dialysis. We evaluated whether access interventions before successful cannulation affect the relative longevity of AVFs and AVGs after successful use.

METHODS

This retrospective study of a prospective database identified patients who initiated dialysis with a catheter and subsequently had a permanent access (289 AVFs and 310 AVGs) placed between January 1, 2006, and December 31, 2011, and were successfully cannulated for dialysis at a large medical center. Patients were monitored until June 30, 2014, and we evaluated the clinical outcomes (secondary patency and frequency of interventions) of the vascular accesses.

RESULTS

An intervention before successful cannulation was required more frequently with AVFs than with AVGs (50.5% vs 17.7%; odds ratio, 4.74; 95% confidence interval [CI], 3.26-6.86; P < .0001). Compared with AVFs that matured without interventions, those that required intervention had shorter secondary patency after successful cannulation (hazard ratio, 1.84; 95% CI, 1.30-2.60; P < .0001) and required more interventions per year after successful use (rate ratio [RR], 1.81; 95% CI, 1.49-2.20; P < .0001). Similarly, AVGs that required intervention before successful cannulation had shorter secondary patency than those without prior intervention (odds ratio, 1.98; 95% CI, 1.52-4.02; P < .0001) and required more interventions per year after successful use (RR, 1.49; 95% CI, 1.27-1.74; P < .0001). AVFs requiring intervention before maturation had inferior secondary patency compared with AVGs that were cannulated without prior intervention (hazard ratio, 1.45; 95% CI, 1.08-2.01; P = .01), but required fewer annual interventions after successful use (RR, 0.57; 95% CI, 0.49-0.66; P < .0001).

CONCLUSIONS

The patency advantage of AVFs over AVGs is no longer evident in patients requiring an AVF intervention before successful cannulation, but the AVFs require fewer interventions after successful use.

Surgical Approach to Hemodialysis Access

With the increasing incidence of end-stage renal disease, hemodialysis vascular access presents an ongoing struggle, and a multidisciplinary approach must be considered to provide long-term durable access for patients on chronic hemodialysis. Surgeons must be very thoughtful in planning the steps of access for these patients and consider fistula first and catheter last, without forgetting that prosthetic grafts may be a legitimate first option for patients. This article provides a review of surgical management of dialysis access, including primary access options and follow-up of this difficult patient population.

Arteriovenous fistula in dialysis patients: Factors implicated in early and late AVF maturation failure

Increasing numbers of patients are being diagnosed with end-stage renal disease (ESRD), and the demand for on haemodialysis (HD) is rising. Arteriovenous fistulae (AVFs) remain the best conduit for adequate HD, with fewer complications associated with long-term use compared to bypass grafts and central venous catheters. However, it is known that many newly formed fistulae do not mature to provide useful HD access. The paper provides a narrative overview of factors influencing the process of AVF maturation failure.

Importance of monitoring and treatment of failed maturation in radiocephalic arteriovenous fistula in predialysis: Role of ultrasound

The aim of the study was to analyse outcomes of AVF-RC in predialysis stage in which a clinical and radiological follow up of its maturation had been done and primary failure had been treated.

MATERIAL AND METHODS

We studied 127 RC-AVF in 117 predialysis patients. All cases had a preoperative map. The RC-AVF was considered mature if it had a brachial artery flow ≥500ml/min and a cephalic vein diameter of ≥4mm. Primary failure was treated radiologically or surgically depending on the type of lesion. Fifty-eight patients started dialysis at the time of the study.

RESULTS

In 106 RC-AVF without thrombosis, 72 (68%) were mature and 34 (32%) were immature. A total of 97% of the immature had at least one lesion, and the most common site was the post-anastomotic vein. Lesions were found in 31% of mature RC-AVF, and 18% of patients required treatment. Radiological treatment was the most frequent for maturation failure. After 6 months, primary and secondary patency were 59% and 78%, while after 12 months they were 48% and 77%, respectively. The 80% of patients started dialysis with a distal AVF (76% RC-AVF and 4% ulnar basilic). None of the patients with treated immature RC-AVF started dialysis with CVC, while 78% of the patients started with said AVF.

CONCLUSION

Ultrasonography for monitoring maturation provides advantages over clinical monitoring. With our management of RC-AVF in predialysis, 80% of patients start dialysis with an adequate distal AVF.

Three-dimensional MDCT angiography for the assessment of arteriovenous grafts and fistulas in hemodialysis access

Arteriovenous grafts and fistulas are placed for long-term hemodialysis access, and their associated complications can lead to considerable morbidity. Multi-detector computed tomography (MDCT) images provide accurate delineation of hemodialysis access anatomy and show potential complications. This review makes the reader more familiar with vascular access anatomy and configurations, describes the appearance of access complications encountered on MDCT, and discusses endovascular and surgical treatment options for complications, which should aid in post-treatment evaluation.

A Patient-Centered Approach to Hemodialysis Vascular Access in the Era of Fistula First

The primary vascular access options for the hemodialysis population are arteriovenous fistulas (AVF), arteriovenous grafts, and cuffed central venous catheters (CVC). AVFs are associated with the most favorable outcomes with respect to complications, interventions required to maintain functionality and patency, and overall cost. These population-based outcomes, in conjunction with the efforts of the Fistula First Breakthrough Initiative, have propelled the prevalence of AVFs in the US hemodialysis population. While this endeavor remains steadfast in assuring the continued dominance of this policy for AVF preference, it fails to take into account a subset of the dialysis population who will fail to see the benefits of an AVF. This subset of patients may include the elderly, those with poor vasculature anatomy, those with slowly progressive CKD who are more likely to die than progress to ESRD, and those with an overall poor long-term prognosis and shortened life expectancy. Thus, in an effort to avoid numerous unnecessary surgical and interventional procedures with minimal to no gains in clinical outcomes, an individualized patient approach must be adopted. The Centers for Medicare and Medicaid Services-instituted quality incentive program is designed to reward high AVF prevalence while also penalizing high CVC prevalence. The current model is devoid of case-based adjustment, thus penalties are disbursed to dialysis providers in accordance with a "one-size-fits-all" fistula only approach. The most suitable access for a patient remains the one that takes into account the characteristics unique to the individual patient with a primary focus on patient comfort, satisfaction, quality of life, and clinical outcomes.

Arteriovenous Fistula Development in the First 6 Weeks after Creation

PURPOSE

To assess the anatomic development of native arteriovenous fistula (AVF) during the first 6 weeks after creation by using ultrasonographic (US) measurements in a multicenter hemodialysis fistula maturation study.

MATERIALS AND METHODS

Each institutional review board approved the prospective study protocol, and written informed consent was obtained. Six hundred and two participants (180 women and 422 men, 459 with upper-arm AVF and 143 with forearm AVF) from seven clinical centers underwent preoperative artery and vein US mapping. AVF draining vein diameter and blood flow rate were assessed postoperatively after 1 day, 2 weeks, and 6 weeks. Relationships among US measurements were summarized after using multiple imputation for missing measurements.

RESULTS

In 55% of forearm AVFs (68 of 124) and 83% of upper-arm AVFs (341 of 411) in surviving patients without thrombosis or AVF intervention prior to 6 weeks, at least 50% of their 6-week blood flow rate measurement was achieved at 1 day. Among surviving patients without thrombosis or AVF intervention prior to week 2, 70% with upper-arm AVFs (302 of 433) and 77% with forearm AVFs (99 of 128) maintained at least 85% of their week 2 flow rate at week 6. Mean AVF diameters of at least 0.40 cm were seen in 85% (389 of 459), 91% (419 of 459), and 87% (401 of 459) of upper-arm AVFs and in 40% (58 of 143), 73% (104 of 143), and 77% (110 of 143) of forearm AVFs at 1 day, 2 weeks, and 6 weeks, respectively. One-day and 2-week AVF flow rates and diameters were used to predict 6-week levels, with 2-week prediction of 6-week measures more accurate than those of 1 day (flow rates, R(2) = 0.47 and 0.61, respectively; diameters, R(2) = 0.49 and 0.82, respectively).

CONCLUSION

AVF blood flow rate at 1 day is usually more than 50% of the 6-week blood flow rate. Two-week measurements are more predictive of 6-week diameter and blood flow than those of 1 day. US measurements at 2 weeks may be of value in the early identification of fistulas that are unlikely to develop optimally.

Interrupting Rivaling Access-flow with Nonsurgical Image-guided ligation: the "IRANI" Procedure

The presence of collateral veins is one of the most common causes of fistula failure to mature. The traditional approach to eliminate collateral vessel flow is coil embolization under fluoroscopy or surgical cut down and branch vessel ligation. However, both approaches are expensive and time consuming. Here, we described an image-guided nonsurgical method to ligate collateral veins. The collateral veins were ligated using Hawkins-Akins needle under ultrasound guidance. The average time for one ligation procedure was 17 minutes. There was a significant increase of blood flow in the venous outflow postligation procedure. Four weeks postprocedure ultrasound demonstrated occlusion of the target vessels. This procedure was well tolerated without major complications. In summary, the novel procedure described here offers an image-guided nonsurgical approach for collateral vein occlusion.

Preoperative and Intraoperative Factors for Early Failure of Native Arteriovenous Fistulas

The aim of the study was to assess the potential predictive factors for early arteriovenous fistula (AVF) failure following the fistula first initiative. We retrospectively reviewed the data of 159 end-stage renal disease (ESRD) patients who underwent AVF creation. The preoperative factors such as demographic, comorbidity condition, laboratory parameters and medication, and intraoperative or surgical-related factors were assessed. In multivariate logistic regression analysis, significant predictive factors of early AVF failure were female gender (odds ratio (95% confidence interval): 2.63 (1.19-5.81); P = 0.017), higher body mass index (P = 0.038), and lower hemoglobin level (P = 0.048), while adjusting for preoperative factors or all factors. For adjusting of intraoperative factors, reduced venous diameter (P = 0.056) tended to be associated with early AVF failure. In conclusion, female gender, higher body mass index and lower hemoglobin level predicted the occurrence of early AVF failure in ESRD patients.

Preoperative vascular access evaluation for haemodialysis patients

BACKGROUND

Haemodialysis treatment requires reliable vascular access. Optimal access is provided via functional arteriovenous fistula (fistula), which compared with other forms of vascular access, provides superior long-term patency, requires few interventions, has low thrombosis and infection rates and cost. However, it has been estimated that between 20% and 60% of fistulas never mature sufficiently to enable haemodialysis treatment. Mapping blood vessels using imaging technologies before surgery may identify vessels that are most suitable for fistula creation.

OBJECTIVES

We compared the effect of conducting routine radiological imaging evaluation for vascular access creation preoperatively with standard care without routine preoperative vessel imaging on fistula creation and use.

SEARCH METHODS

We searched Cochrane Kidney and Transplant's Specialised Register to 14 April 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that enrolled adult participants (aged ≥ 18 years) with chronic or end-stage kidney disease (ESKD) who needed fistulas (both before dialysis and after dialysis initiation) that compared fistula maturation rates relating to use of imaging technologies to map blood vessels before fistula surgery with standard care (no imaging).

DATA COLLECTION AND ANALYSIS

Two authors assessed study quality and extracted data. Dichotomous outcomes, including fistula creation, maturation and need for catheters at dialysis initiation, were expressed as risk ratios (RR) with 95% confidence intervals (CI). Continuous outcomes, such as numbers of interventions required to maintain patency, were expressed as mean differences (MD). We used the random-effects model to measure mean effects.

MAIN RESULTS

Four studies enrolling 450 participants met our inclusion criteria. Overall risk of bias was judged to be low in one study, unclear in two, and high in one.There was no significant differences in the number of fistulas that were successfully created (4 studies, 433 patients: RR 1.06, 95% CI 0.95 to 1.28; I² = 76%); the number of fistulas that matured at six months (3 studies, 356 participants: RR 1.11, 95% CI 0.98 to 1.25; I² = 0%); number of fistulas that were used successfully for dialysis (2 studies, 286 participants: RR 1.12, 95% CI 0.99 to 1.28; I² = 0%); the number of patients initiating dialysis with a catheter (1 study, 214 patients: RR 0.66, 95% CI 0.42 to 1.04); and in the rate of interventions required to maintain patency (1 study, 70 patients: MD 14.70 interventions/1000 patient-days, 95% CI -7.51 to 36.91) between the use of preoperative imaging technologies compared with standard care (no imaging).

AUTHORS' CONCLUSIONS

Based on four small studies, preoperative vessel imaging did not improve fistula outcomes compared with standard care. Adequately powered prospective studies are required to fully answer this question.

Effect of a Rapid Clinical Protocol to the Conversion from Central Venous Hemodialysis Catheter to Arteriovenous Access

Purpose

Evaluation of the rapid conversion protocol that includes an ambulatory dialysis access center (DAC), and a three-step clinical pathway, to the conversion rate from central venous hemodialysis (HD) catheter to functioning arteriovenous (AV) access.

Methods

Prospective data were collected on 97 consecutive catheter-dependent HD patients. DAC is defined as an ambulatory unit, able to accommodate clinic visits, ultrasound examinations, surgical, interventional and hybrid procedures. Step I: initial evaluation, vein mapping and creation of AV access. Step II: clinical evaluation in two weeks and if failure identified, secondary procedure to restore function. Step III: evaluation in four weeks after creation, and additional procedure to promote maturation if indicated. The success rate, time to conversion and time to catheter removal were recorded.

Results

From the 97 consecutive referred patients, eight patients were excluded. From the remaining 89 patients, 99% were successfully converted to AV access. Seventy-three percent of the patients were converted to native arteriovenous fistulae and 27% of the patients to prosthetic arteriovenous shunts. The median time from creation to HD catheter removal was 63 (SD 41) days. Fifty-two percent of the patients required at least one additional secondary procedure to accomplish successful conversion

Conclusions

High rates of timely conversion from catheter to AV access, primarily AV fistulae, can be accomplished within the context of the rapid conversion protocol.

Preoperative arterial microcalcification and clinical outcomes of arteriovenous fistulas for hemodialysis

BACKGROUND

Arteriovenous fistulas (AVFs) often fail to mature, but the mechanism of AVF nonmaturation is poorly understood. Arterial microcalcification is common in patients with chronic kidney disease (CKD) and may limit vascular dilatation, thereby contributing to early postoperative juxta-anastomotic AVF stenosis and impaired AVF maturation. This study evaluated whether preexisting arterial microcalcification adversely affects AVF outcomes.

STUDY DESIGN

Prospective study.

SETTING & PARTICIPANTS

127 patients with CKD undergoing AVF surgery at a large academic medical center.

PREDICTORS

Preexisting arterial microcalcification (≥1% of media area) assessed independently by von Kossa stains of arterial specimens obtained during AVF surgery and by preoperative ultrasound.

OUTCOMES

Juxta-anastomotic AVF stenosis (ascertained by ultrasound obtained 4-6 weeks postoperatively), AVF nonmaturation (inability to cannulate with 2 needles with dialysis blood flow ≥ 300mL/min for ≥6 sessions in 1 month within 6 months of AVF creation), and duration of primary unassisted AVF survival after successful use (time to first intervention).

RESULTS

Arterial microcalcification was present by histologic evaluation in 40% of patients undergoing AVF surgery. The frequency of a postoperative juxta-anastomotic AVF stenosis was similar in patients with or without preexisting arterial microcalcification (32% vs 42%; OR, 0.65; 95% CI, 0.28-1.52; P=0.3). AVF nonmaturation was observed in 29%, 33%, 33%, and 33% of patients with <1%, 1% to 4.9%, 5% to 9.9%, and ≥10% arterial microcalcification, respectively (P=0.9). Sonographic arterial microcalcification was found in 39% of patients and was associated with histologic calcification (P=0.001), but did not predict AVF nonmaturation. Finally, among AVFs that matured, unassisted AVF maturation (time to first intervention) was similar for patients with and without preexisting arterial microcalcification (HR, 0.64; 95% CI, 0.35-1.21; P=0.2).

LIMITATIONS

Single-center study.

CONCLUSIONS

Arterial microcalcification is common in patients with advanced CKD, but does not explain postoperative AVF stenosis, AVF nonmaturation, or AVF failure after successful cannulation.

Persistent Median Artery As A Cause Of Nonmaturing AV Fistula

A 68-year-old right handed male with End-Stage Renal Disease with a left radiocephalic fistula created 8 months ago was referred for the evaluation of a nonmaturing access. Patient had an arterial anastomosis lesion that underwent successful angioplasty. Diagnostic arteriogram of the AV access extremity revealed the presence of a short radial artery and dominant common interosseous artery manifesting as a persistent median artery in the distal forearm and was anastomosed to the fistula and then continues as the median-ulnar superficial arch in the palm. Balloon angioplasty of the common interosseous artery led to a complication when the distal 30 cm of the 0.018 guide wire fractured and had to be retrieved using a snare device. In addition to anticipating and treating the common complications of vascular access procedures, it is also important to be aware of the anomalies of the distal forearm arterial anatomy and perform a detailed arterial evaluation prior to creating the arterio-venous anastomosis.

Predictive parameters of arteriovenous fistula functional maturation in a population of patients with end-stage renal disease

INTRODUCTION

With increasing numbers of patients diagnosed with ESRD, arteriovenous fistula (AVF) maturation has become a major factor in improving both dialysis related outcomes and quality of life of those patients. Compared to other types of access it has been established that a functional AVF access is the least likely to be associated with thrombosis, infection, hospital admissions, secondary interventions to maintain patency and death.

AIM

Study of demographic factors implicated in the functional maturation of arteriovenous fistulas. Also, to explore any possible association between preoperative haematological investigations and functional maturation.

METHODS

We performed a retrospective chart review of all patients with ESRD who were referred to the vascular service in the University Hospital of Limerick for creation of vascular access for HD. We included patients with primary AVFs; and excluded those who underwent secondary procedures.

RESULTS

Overall AVF functional maturation rate in our study was 53.7% (52/97). Female gender showed significant association with nonmaturation (P = 0.004) and was the only predictor for non-maturation in a logistic regression model (P = 0.011). Patients who had history of renal transplant (P = 0.036), had relatively lower haemoglobin levels (P = 0.01) and were on calcium channel blockers (P = 0.001) showed better functional maturation rates.

CONCLUSION

Female gender was found to be associated with functional non-maturation, while a history kidney transplant, calcium channel-blocker agents and low haemoglobin levels were all associated with successful functional maturation. In view of the conflicting evidence in the literature, large prospective multi-centre registry-based studies with well-defined outcomes are needed.

Factors influencing maturation time of native arteriovenous fistulas

BACKGROUND

To determine the factors influencing the maturation time of native arteriovenous fistulas.

METHODS

A retrospective review was performed of hemodialysis patients from a single university-associated dialysis center from 2004 to 2009. Demographics, comorbidities, and insurance status were recorded. Maturation time was defined as the time from access creation until the access was able to be used regularly for hemodialysis for a period of 2 weeks.

RESULTS

A total of 249 patients were identified during the study period who had an arteriovenous fistula created that successfully matured; 104 (42%) patients were women and 145 (58%) were men. Most of the patients were Hispanic (82%). Ninety-seven (39%) of the patients had Medicaid-type insurance and 133 (53%) had Medicare. The mean age was 51 years, and 190 (76%) of the patients had diabetes. The overall mean maturation time was 79 days. Women had a significantly longer time to fistula maturation than males (91.9 days vs. 70.5 days, P = 0.0028). Diabetics also had a significantly longer maturation time than nondiabetics (92.5 days vs. 75.4 days, P = 0.0004). Age did not have an effect on maturation time. On multivariable analysis, sex remained significant (P = 0.007), however, diabetes lost its significance.

CONCLUSIONS

In this predominantly Hispanic hemodialysis population, women require longer fistula maturation times than men. The exact reasons for this are unknown based on this data. More study is required to determine the etiology of this gender discrepancy.