Vascular Access Outcomes and Medication Use: A USRDS Study

Mid-term cumulative patency of fistula and PTFE grafts among hemodialysis patients: A retrospective, single-center study from Palestine

BACKGROUND

Due to the long waiting time for kidney transplantation, most End-Stage renal disease patients are commenced on either hemodialysis or peritoneal dialysis. Reusable fistulas have the lowest risk for death, cardiovascular events, and infections among all vascular accesses. This study aims to report the outcomes of the arteriovenous fistulas and PTFE grafts and the related predictive clinical and demographic variables.

METHODS

This retrospective study reviewed the charts of all hemodialysis patients between January 2017 and January 2021 at the Dialysis Center of An-Najah National University Hospital, Nablus, Palestine. Our outcomes were a primary failure, primary and secondary patency, and the related factors. Survival analysis using the Kaplan-Meier method was conducted, and the log-rank test was used to compare patency rates. The Cox proportional hazards regression model tested factors relevant to primary and secondary patency rates in univariate and multivariate analyses.

RESULTS

A total of 312 procedures were performed during the study period. Primary failure was 7.1% for AVF, 13.9% for arterio-venous graft (AVG) procedures. Peripheral arterial disease and left-sided AVF were associated with more primary failure rates. AVF, primary patency rates at 1, 2, and 3 years were 82%, 69%, and 59%, respectively, while secondary patency rates at 1, 2, and 3 years were 85%, 72%, and 63%, respectively. Factors associated with increased AVF patency in a proportional hazard model were younger age and dual antiplatelet administration.

CONCLUSION

Our study adds further evidence that autogenous AVF has better results than prosthetic AVG in both primary and secondary patency rates as well as less primary failure rates. Therefore, we encourage further longitudinal studies that assess the benefits of using antiplatelet on AVF outcome versus risks of bleeding, especially with dual agents.

Factors affecting arteriovenous access patency after percutaneous transluminal angioplasty in chronic haemodialysis patients under vascular access monitoring and surveillance: a single-centre observational study

OBJECTIVES

Maintenance of vascular access (VA) patency after percutaneous transluminal angioplasty (PTA) is important and remains a challenge despite VA monitoring and surveillance. The aim of this study was to examine factors affecting the post-PTA arteriovenous access (AVA) patency in patients who have been on close VA monitoring and surveillance for access flow.

DESIGN

Retrospective cohort study.

SETTING

A single medical centre in Taiwan.

PARTICIPANTS

Records of patients who received chronic haemodialysis between 1 January 2017 and 31 December 2018 were retrospectively reviewed. Patients were divided into two groups (without or with PTA intervention on AVA).

PRIMARY AND SECONDARY OUTCOME

Patients were followed until reintervention PTA, termination or abandoned VA or end of study. In addition to routine monitoring, VA flow surveillance was performed every 3 months for detection of VA dysfunction adhering to Kidney Disease Outcomes Quality Initiative guidelines.

RESULTS

A total of 508 patients were selected for study inclusion (with PTA, n=231; without PTA, n=277). At baseline, variables that differed between groups included malignancy and levels of albumin, uric acid, potassium, phosphorous, high-density lipoprotein, total bilirubin and ferritin (all p<0.05). Significant between-group differences were observed for β-adrenergic blocking agents (with PTA, 49.8%; without PTA, 37.5%; p, 0.007) and ADP inhibitors (with PTA, 23.8%; without PTA, 11.2%; p<0.001). Among patients with PTA, those with acute myocardial infarction, high ferritin level or arteriovenous graft (AVG) had a significantly higher risk of reintervention post-PTA (p<0.05). Dipeptidyl peptidase-4 inhibitors, thiazolidinediones, ADP inhibitors, and warfarin use were predictors of post-PTA patency (p<0.05).

CONCLUSIONS

AVG access type, acute myocardial infarction, and high ferritin levels are risk factors for re-intervention post-PTA. These findings may be useful in the development of prophylactic strategies for monitoring VA function and tailoring surveillance programs for these dialysis patients.

Anticoagulation Therapy is Associated with Increased Access-related Wound Infections after Hemodialysis Access Creation

BACKGROUND

The effect of anticoagulation therapy (AC) on hemodialysis access patency and related complications is not well defined. Patients on long-term or chronic AC due to their underlying comorbid conditions may be particularly susceptible to access-related bleeding and complications from repetitive cannulation. Our goal is to assess the effect of anticoagulation therapy on outcomes after access creation.

METHODS

The Vascular Quality Initiative (VQI) database was queried for patients undergoing arteriovenous fistula (AVF) or graft (AVG) placement, from 2011 to 2019. Only patients with data on post-procedural AC status were included. Anticoagulation use was defined as patients on warfarin, dabigatran, or rivaroxaban after access creation at postoperative follow up. Demographic and procedural details were analyzed. Wound infection and patency rates at six months were assessed. Binomial logistic regression analysis was performed to assess the association of anticoagulation use with these outcomes.

RESULTS

A total of 27,757 patients underwent access creation, with the majority undergoing AVF creation (78.8%). The average age was 61.4 years and 55.3% were male. 12.9% of patients were on postoperative AC. The wound infection rate was 2.3- 3.8% in the no AC and AC cohorts, respectively (P < 0.001). At six months follow-up, patency was 85.7- 84.3% in the no AC and AC cohorts, respectively (P = 0.044). Expectedly, grafts had lower patency rates compared to AVF; those within the no AC cohort had a patency of 83.0% compared to 81.2 % in those on AC (P = 0.106). On multivariable analysis, anticoagulation use was associated with a higher risk of wound infections (odds ratio [OR] 1.513, 95% confidence interval [CI] 1.160-1.973, P = 0.002). AC use did not significantly affect access patency.

CONCLUSION

Anticoagulation therapy was associated with a higher rate of wound infections but did not affect short-term access patency within six-months. These patients warrant close surveillance of their access for signs of infection. Furthermore, long-term implications of anticoagulation needs further evaluation.

A Comparative Study Regarding Deep and Superficial Veins for Venous Outflow in Forearm Loop Arteriovenous Grafts

BACKGROUND

The purpose of the study was to compare the access patency rates of forearm loop arteriovenous grafts (AVGs) using deep veins and superficial veins for venous outflow.

METHODS

The medical records of patients on dialysis were retrospectively reviewed to identify the individual risk factors and the outcomes of forearm loop AVGs according to their outflow types.

RESULTS

Overall, 170 cases were enrolled in this study. Of these, 103 cases (60.6%) used deep veins for outflow. Most patients using deep vein outflow had their venous anastomosis above the elbow (P = 0.000). Patients with venous anastomosis above the elbow were more likely to be female (P = 0.049) and have a lower albumin level (P = 0.025). The primary patency rates for superficial vein outflow and deep view outflow were 35.5% and 29.4% at 12 months and 18.9% and 4.9% at 24 months, respectively. There was a statistically significant difference between the two groups (P = 0.013). The assisted primary patency rates for superficial venous outflow and deep vein outflow were 85.5% and 79.5% at 12 months and 73.2% and 59.6% at 24 months, respectively (P = 0.139). Primary and assisted primary patency rates did not differ according to the crossing of the elbow.

CONCLUSIONS

The primary patency rate of AVGs using deep veins for outflow was inferior to AVGs using superficial veins. But the assisted primary patency rate showed no difference. The use of a deep vein for outflow in the forearm loop AVG is a safe strategy for patients with exhausted superficial veins.

The Effect of Aspirin on Preventing Vascular Access Dysfunction in Incident Hemodialysis Patients: A Prospective Cohort Study in Korean Clinical Research Centers for End-Stage Renal Disease (CRC for ESRD)

Background: Aspirin is often prescribed empirically to improve the patency of hemodialysis (HD) vascular access. Therefore, this study aimed to investigate the impact of aspirin on the survival of vascular access in incident HD patients with arteriovenous fistula (AVF) or arteriovenous graft (AVG). Methods: A prospective cohort of 881 incident HD patients was enrolled between 2009 and 2014. The primary outcome was defined as the first AVF/AVG intervention or salvage procedure, including percutaneous transluminal angioplasty or surgery for vascular access failure. Cox analyses were performed to determine the association between aspirin usage and the occurrence of the primary outcome. Results: The mean age of the patient group was 57.9 ± 13.4, and 63.8% of the patients were male. Aspirin was prescribed in 241 (27.4%) patients, and the median follow-up duration was 30 months. During follow-up, 180 (20.4%) patients experienced the primary outcome event. Univariate analysis showed that age, gender, presence of diabetes mellitus (DM), preexisting peripheral arterial disease, and the type of vascular access used (AVG versus AVF) were significantly associated with the development of the primary outcome. However, aspirin usage from the baseline was not significantly associated with primary outcome events (hazard ratio (HR): 1.16; 95% confidence interval (CI): 0.84–1.60; p = 0.378). Multivariate analysis showed that gender, the presence of DM, and the type of vascular access were still significantly associated with the occurrence of the primary outcome. Moreover, we did not observe the protective effect of taking aspirin on primary vascular access failure, even in subgroup analyses stratified according to gender, the presence of DM, and the type of vascular access. Conclusion: Physicians should carefully consider when they prescribe aspirin for the prevention of primary vascular access failure in Korean incident HD patients. In addition, larger prospective interventional studies are needed to elucidate the effect of aspirin on vascular access failure.

Preventing arteriovenous shunt failure in hemodialysis patients: a population-based cohort study

Essentials Uncertainty remains about antiplatelets for vascular access patency in hemodialysis patients. 95 971 people under hemodialysis were followed in a claims database in Taiwan. Aspirin reduced vascular access failure rate and did not increase major bleeding rate. Clopidogrel, Aggrenox, and warfarin might increase major bleeding rate. SUMMARY: Background Dialysis adequacy is a major determinant of survival for patients with end-stage renal disease. Good vascular access is essential to achieve adequate dialysis. Objectives This study evaluated the impacts of different drugs on the vascular access failure rate of an arteriovenous fistula or an arteriovenous graft and the rate of major bleeding in hemodialysis patients. Patients and methods We studied patients with end-stage renal disease registered in the Taiwan National Health Insurance program from 1 January 1997 to 31 December 2012. A total of 95 971 patients were enrolled in our study. Vascular access dysfunction was defined as the need for thrombectomy or percutaneous angioplasty. Major bleeding was defined as emergency department visits or hospitalization with a primary diagnosis of gastrointestinal bleeding or intracerebral hemorrhage. The adjusted odds ratios between person-quarters with or without antiplatelet or oral anticoagulant use were calculated using a generalized estimating equation. Results The odds ratio of vascular access failure was 0.21 (0.11-0.39) for aspirin, 0.76 (0.74-0.79) for clopidogrel, 0.67 (0.59-0.77) for dipyridamole, 0.67 (0.53-0.86) for Aggrenox and 0.96 (0.90-1.03) for warfarin. The highest odds ratio for intracerebral hemorrhage was 5.33 (1.25-22.72) in younger patients using Aggrenox. The highest odds ratio for gastrointestinal bleeding was 1.34 (1.10-1.64) for clopidogrel. Conclusion Antiplatelet agents, but not warfarin, might reduce the vascular access thrombosis rate. The gastrointestinal bleeding rate was increased in the group using clopidogrel. Aggrenox should be used with caution in young individuals because it might increase the rate of intracerebral hemorrhage.

Antiplatelet agents maintain arteriovenous fistula and graft function in patients receiving hemodialysis: A nationwide case-control study

Background

In this study, we evaluated the effects of various medications on the patency of vascular access (VA) for hemodialysis.

Methods

We analyzed data from the Longitudinal Health Insurance Database of Taiwan. We adopted a case–control study design within a cohort of patients who had received regular hemodialysis between 2002 and 2012; 34,354 patients with first VA failure were identified, and the duration from VA creation date to the first VA failure date was calculated. We then classified these patients into two groups, namely arteriovenous fistula (AVF, n = 25,933) and arteriovenous graft (AVG, n = 8,421). Each group was further divided into two subgroups, namely short-term (<1 year) and long-term (≥1 year) patency.

Results

The risk factors for early VA failure were age ≥65 years, diabetes mellitus, hyperlipidemia, cerebral vascular disease, congestive heart failure, peripheral artery disease, and sepsis. Male sex, hypertension, cancer, and peptic ulcer were associated with early AVF failure. Antiplatelet therapy increased the AVF and AVG patency times with adjusted odds ratios of 0.748 (95% confidence interval [CI]: 0.703–0.796, p < 0.0001) and 0.810 (95% CI: 0.728–0.901, p = 0.0001), respectively. A significant decrease in the VA failure risk was observed with an increase in the cumulative defined daily dose of antiplatelet agents.

Conclusion

This nationwide study demonstrated that some risk factors were associated with early VA failure and that the use of antiplatelet agents prevented the loss of VA patency in a dose–response manner. Thus, antiplatelet drugs should be routinely administered to high-risk patients receiving dialysis.

Role of antiplatelet therapy in the durability of hemodialysis access

BACKGROUND

Antiplatelet therapy (APT) is often used on anecdotal grounds to improve vascular access patency. The aim of this study was to assess the role of APT in hemodialysis (HD) patients undergoing arteriovenous fistula (AVF) or graft (AVG) placement.

METHODS

All patients in a large HD vascular qualitative initiative database (2011-2017) were included and divided into no antiplatelet therapy (no-APT) vs. any APT [aspirin (ASA) or P2Y12 inhibitors (PI)]. Multivariate [logistic (MLR) and Cox (MCR) regression] analyses were used as appropriate.

RESULTS

A total of 24,847 patients undergoing HD access creation were identified (78% AVF). APT was noted among 49 and 46% of AVG and AVF patients, respectively. In MLR analysis, patients on no-APT vs. APT had a 12-fold increased risk of in-hospital mortality (odds ratio (OR) 11.79, [95% confidence interval 5.30-26.26]) and the risk of developing steal syndrome was higher among patients discharged on APT (OR 1.81, [1.19-2.76]). In patients undergoing AVF, primary patency (PP) was similar between APT and no-APT. However, in patients undergoing AVG, PP rates at 12 months were significantly higher for APT: ASA (47 vs. 41%) and PI (51 vs. 41%) than for no-APT (p = 0.008). At MCR analysis, the loss of PP at 12 months was 13% lower in ASA users (hazard ratio (HR) 0.87, [0.77-0.97], p = 0.02) and 24% lower in PI users (HR 0.76, [0.57-0.99], p = 0.046) compared to no-APT.

CONCLUSION

In a large national database, we showed that antiplatelet therapy was associated with lower in-hospital mortality. Aspirin and P2Y12-inhibitor use among AVG patients demonstrated improved PP rates compared to no antiplatelet therapy. We recommend the use of antiplatelet therapy especially in patients on AVG.

Effect of low dose aspirin and dipyridamole on primary patency of arteriovenous grafts in hemodialysis patients: a randomized double-blind placebo-controlled trial

Background

There is some evidence for the efficacy of antiplatelet therapies in increasing the vascular access patency duration or decreasing the thrombosis of arteriovenous grafts.

Objective

To determine the effect of low dose aspirin and dipyridamole on primary patency of arteriovenous grafts in hemodialysis patients

Methods

This randomized, double-blind, placebo-controlled trial was done at Imam Reza Hospital in Mashhad, Iran from September 10, 2015 to July 05, 2016. Sixty hemodialysis patients, after the placement of a new arteriovenous graft, were divided into three study groups which including; Group 1, who received 80 mg aspirin tablet daily, Group 2 received 80 mg aspirin plus 75 mg dipyridamole daily and Group 3 received placebo daily. Primary unassisted patency was recorded in follow-up until 12 months and the outcomes were analysed using one-way ANOVA test.

Results

Primary patency time in Group 1 (Aspirin) was 324.75±147.00 day and for Group 2 (Aspirin + Dipyridamole) was 399.05±92.09 day and for Group 3 (Placebo) was 383.55±108.23 day. There were no significant differences between the 3 groups (p>0.05). Successful dialysis was done in 16.7% in Group 1, 37.5% in Group 2 and 45% in Group 3 from brachial arteriovenous grafts after 1-year follow-up (p=0.746).

Conclusions

In treating dialysis patients, treatment with low dose aspirin and dipyridamole is not effective on increasing the synthetic grafts primary patency duration.

Trial registration

The trial was registered at the Thai Clinical Trials Registry (http://www.clinicaltrials.in.th) with the Trct id: TCTR20160920003.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Primary Thromboprophylaxis with Heparins for Arteriovenous Fistula Failure in Pediatric Patients

Background

To reduce the incidence of early arteriovenous fistula failure (AVF) due to thrombosis in pediatric hemodialysis (HD) patients, a primary thromboprophylaxis (PTP) protocol was initiated at author's institution in June 2005. The goal of this study is to report author's experience with this protocol one year later.

Methods and Results

19 AVFs (14 patients, Historical group) and 8 AVFs (7 patients, PTP group) were created prior to and after initiation of PTP respectively. PTP consisted of unfractionated heparin (5–10 units/kg/hr) infusion postoperatively, followed by subcutaneous low molecular weigh heparin (LMWH) until AVF was matured. LMWH dosing was “Prophylactic” (0.5 mg/kg/d, anti-factor Xa levels: peak 0.25–0.5 and trough < 0.3 units/mL) and “Therapeutic” (1 mg/kg/d, anti-factor Xa level: peak 0.5-1 and trough < 0.5 units/mL) based on thrombosis predisposition. In Historical group, 12 AVFs did not receive thromboprophylaxis (No-treatment group), 5 received 81 mg aspirin/day (Aspirin group), and 2 received LMWH. In No-treatment group 10/12 AVFs failed: 9 thromboses and 1 stenosis. In Aspirin group 1/5 AVFs failed due to thrombosis. In PTP group 1/8 AVFs failed due to stenosis; the first 2 AVFs developed hematoma prompting a reduction in LMWH dose and monitoring trough anti-factor Xa levels, one AVF required thrombectomy after LMWH was transiently held. The incidence of thrombosis was less in PTP group (12.5%) when comparing to No-treatment group (83%) (p < 0.05).

Conclusion

PTP is a feasible option to prevent early thrombosis at AVF. Close clinical and laboratory monitoring including trough anti-factor Xa levels is required to adjust optimum anticoagulation. Larger studies are needed to clarify safety and efficacy of our PTP protocol.

Initiation of antiplatelet medication after surgical thrombectomy jeopardized arteriovenous graft longevity

INTRODUCTION

The efficacy of antiplatelet agents in preventing thrombosis in newly formed arteriovenous graft (AVG) in hemodialysis (HD) patients has been extensively examined. The aim of this study was to investigate the possible effect of initiation of antiplatelet medications on preventing AVG thrombosis recurrence after surgical thrombectomy for acute occlusion in HD patients. Whether post-operatively antiplatelet medications have protective effects on the patency or longevity of AVG after surgical thrombectomy in HD patients has not been investigated.

METHODS

We conducted a 4-year quasi-randomized study of the unassisted patency and AVG longevity for 213 HD patients with or without initiating antiplatelet drugs after receiving surgical thrombectomy for first episode of acute AVG thrombosis.

RESULTS

From the propensity-score-matched quasi-randomized study, initiation of antiplatelet drugs after first surgical thrombectomy in HD patients did not prevent the recurrence of surgical thrombectomy (log-rank p = 0.81), but significantly decreased the longevity of the access (log-rank p = 0.034). Multivariate Cox model demonstrated that prescription of antiplatelet drugs significantly increased the risk of graft failure (adjusted hazard ratio 2.13, p = 0.025).

CONCLUSIONS

Adjunctive prescription with antiplatelet medications in HD patients after surgical thrombectomy did not prevent recurrent thrombosis of AV access, but significantly jeopardized the longevity of AVG after surgical thrombectomy.

Surgical technique determines the outcome of the Brescia/Cimino AVF

Over the past 50 years, since Dr. Appel performed the first internal vascular access procedure for hemodialysis, the distal radiocephalic arteriovenous fistula continues to be the access of choice. Over time, failure to maturation has evolved as a major problem associated with this procedure depriving its benefits to many patients with end-stage renal disease. A variable incidence of this problem within similar patients suggests that surgical technique may play an important role in the development of non-maturation. Evaluating the current surgical techniques based on the hemodynamic consequences of anatomic and physiologic alterations following this procedure highlights the role of surgical technique in mitigating or reducing complications. Piggy-back straight line on-lay, a technique that helps to tailor the blood flow and reduce the oscillatory shear stress appears to reduce the incidence of early juxta-anastomotic problems, which contribute significantly to the problem of non-maturation.

Deficiency of Endothelial Progenitor Cells Associates with Graft Thrombosis in Patients Undergoing Endovascular Therapy of Dysfunctional Dialysis Grafts

BACKGROUND

The deficiency of endothelial progenitor cells has been demonstrated to be associated with cardiovascular events in patients undergoing dialysis. However, their correlation with dialysis graft outcomes remains unknown. The objective of this study was to investigate the relationship between circulating endothelial progenitor cells and dialysis graft outcomes.

METHODS

After excluding 14 patients with acute coronary syndrome, decompensated heart failure or graft thrombosis in the prior three months, a total of 120 patients undergoing dialysis who underwent endovascular therapy of dysfunctional dialysis grafts were prospectively enrolled. Blood was sampled from study subjects in the morning of a mid-week non-dialysis day. Surface makers of CD34, KDR, and CD133 were used in combination to determine the number of circulating endothelial progenitor cells. All participants were prospectively followed until June 2013.

RESULTS

The median follow-up duration was 13 months, within which 62 patients experienced at least one episode of graft thrombosis. Patients with graft thrombosis had lower CD34⁺KDR⁺ cell counts compared with patients without graft thrombosis (median 4.5 vs. 8 per 10⁵ mononuclear cells, p = 0.02). Kaplan-Meier analysis demonstrated thrombosis-free survival was lower in the low CD34⁺KDR⁺ cell count group (30%) than in the high CD34⁺KDR⁺ cell count group (61%; p = 0.007). Univariate analysis showed diabetes, high sensitive C-reactive protein, lesion length and CD34⁺KDR⁺ cell counts associated with graft thrombosis. Multivariate analyses confirmed an independent association between low CD34⁺KDR⁺ cell counts and graft thrombosis (hazard ratio, 2.52; confidence interval, 1.43-4.44; p = 0.001).

CONCLUSIONS

Our study demonstrated an independent association between low circulating endothelial progenitor cell counts and dialysis graft thrombosis.

Distinct impact of three different statins on arteriovenous fistula outcomes: a retrospective analysis

PURPOSE

Whether statins improve arteriovenous fistula (AVF) outcomes is still a matter of debate. Taking into consideration the existing physicochemical differences between individual drugs, this study evaluates the impact of three different statins (atorvastatin, rosuvastatin and simvastatin) on one-stage and two-stage AVF outcomes.

METHODS

Using a retrospective cohort of 535 patients, we analyzed the effects of each statin on primary failure and primary patency using multivariate logistic regressions and Cox proportional hazard models.

RESULTS

Out of the three statins analyzed, only atorvastatin improved the overall primary failure of AVF (odds ratio [OR] = 0.18, p = 0.005). Comparisons between the two AVF types demonstrated that this effect was due to a prominent reduction in primary failure of one-stage (OR = 0.03; p = 0.005), but not two-stage fistulas (OR = 0.43; p = 0.25). In contrast, primary patency of two-stage (hazards ratio [HR] = 0.51; p = 0.024), but not one-stage fistulas (HR = 0.98; p = 0.95), was improved by all statins as a group, but not by individual drugs.

CONCLUSIONS

Our results suggest that the potential benefit of statins on AVF outcomes is a drug-specific and not a class effect, and that such effect is also influenced by the type of fistula.

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.

Statins Improve Long Term Patency of Arteriovenous Fistula for Hemodialysis

The protective effects of statins against stenosis for permanent hemodialysis access have been repeatedly demonstrated in animal studies, but remain controversial in human studies. This study aims to evaluate the association between statin use and permanent hemodialysis access patency using a nationwide hemodialysis cohort. A total of 9862 pairs of statin users and non-users, matched by age and gender, were selected for investigation from 75404 new hemodialysis patients during 2000-2008. The effect of statins on permanent hemodialysis access patency was evaluated using Cox proportional hazards models. Compared with non-users, statin users had an overall 18% risk reduction in the composite endpoint in which angioplasty and recreation were combined (adjusted hazard ratio = 0.82 [95%CI, 0.78-0.87]) and 21% in recreation of permanent hemodialysis access (adjusted hazard ratio = 0.79 [95%CI, 0.69-0.80]). Specifically, the protective effect was found for arteriovenous fistula (adjusted hazard ratio = 0.78[95% CI, 0.73-0.82] for composite endpoint and 0.74 [95% CI, 0.69-0.80] for vascular recreation), but not for arteriovenous grafts (adjusted hazard ratio = 1.10 [95% CI, 0.98-1.24] and 0.94 [95% CI, 0.83-1.07]). Statins possess a protective effect for arteriovenous fistula against the recreation of permanent hemodialysis access. The results provide a pharmaco-epidemiologic link between basic research and clinical evidence.

Anticoagulant and antiplatelet therapy in patients with chronic kidney disease: risks versus benefits review

PURPOSE OF REVIEW

Atrial fibrillation and cardiovascular death are increased in end-stage renal disease (ESRD) patients compared to the general population. The effect of anticoagulant and antiplatelet medications for these indications in ESRD is unclear. However, both classes of medications have been used for the preservation of vascular access. This review explores the risks and benefits of anticoagulant and antiplatelet medications in ESRD.

RECENT FINDINGS

ESRD patients with atrial fibrillation have a two and three-fold greater risk of death and stroke, respectively, than ESRD patients without atrial fibrillation. Warfarin does not appear to decrease this risk, and increases the risk of bleeding and vascular calcification. Warfarin also does not appear to be effective for vascular access preservation. In a few large observational studies, antiplatelet agents did not decrease the risk of cardiovascular death, but confounding by indication is likely. Antiplatelet agents do appear to prolong unassisted arteriovenous graft patency, but the effect is modest.

SUMMARY

The role of anticoagulant and antiplatelet agents for atrial fibrillation and cardiovascular disease in ESRD remains unclear. Well designed randomized controlled trials to determine the role of anticoagulation in ESRD patients with atrial fibrillation, and anticoagulant and antiplatelet medications in the preservation of central venous catheter function are required.

Superior in vivo compatibility of hydrophilic polymer coated prosthetic vascular grafts

PURPOSE

Protein adsorption, cell adhesion and graft patency was compared in hydrophilic versus hydrophobic polymer-coated prosthetic vascular grafts. We hypothesize that in vivo compatibility of hydrophilic polymer-coated prosthetic vascular grafts is superior to in vivo compatibility of hydrophobic grafts.

METHODS

A pairwise side-to-side common carotid artery interposition graft was placed eight female landrace goats (mean weight 55 kg). Protein adsorption was assessed using Western Blot in two hydrophilic and two hydrophobic grafts harvested after three days. Graft patency was monitored for 28 days in six goats with continuous wave Doppler ultrasonography. Adherence of endothelial cells, leukocytes and platelets was determined with ELISA and compared between the two graft types after 28 days.

RESULTS

After three days, more ApoA-I, albumin and VEGF and less fibrin adsorbed to hydrophilic grafts. After 28 days, compared to hydrophobic grafts, higher numbers of endothelial cells were present on hydrophilic grafts (P=0.016), and less thrombocytes and leukocytes (P=0.012 and 0.024, respectively). Two out of eight hydrophobic grafts lost patency, while none of the hydrophilic grafts failed (P=0.157).

CONCLUSIONS

Hydrophilic polymer-coated vascular grafts have superior in vivo compatibility when compared to hydrophobic grafts as characterized by reduced platelet and leukocyte adherence as well as higher endothelialization.

Thrombophilia and arteriovenous fistula survival in ESRD

BACKGROUND AND OBJECTIVES

The role of thrombophilia in failing arteriovenous fistula (AVF) among patients with ESRD undergoing hemodialysis is not established. This study aimed to assess whether AVF primary patency is associated with thrombophilia and coagulation abnormalities.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This observational study screened 219 patients between 2002 and 2004 for thrombophilia before AVF surgery. Thrombophilia included factor V Leiden and prothrombin G20210A mutations, protein C and antithrombin activities, and protein S. Coagulation abnormalities included high factor VIII:C, homocysteine, fibrinogen, and d-dimer levels; presence of antiphospholipid antibodies; and short thrombin time. We reviewed patient charts for comorbid conditions, AVF maturation and interventions, kidney transplantation, and patient survival (mean follow-up duration, 3.6 [range, 2.3-5.8] years). Primary patency from the AVF placement and functional primary patency from the first AVF cannulation were analyzed with Kaplan-Meier and Cox proportional hazards models.

RESULTS

Thrombophilia was present in 9% of the patients, and coagulation abnormalities occurred in 77%. One-year primary patency was 68%; 46% of the AVF failures occurred before the initiation of hemodialysis. Female sex (hazard ratio [HR], 2.6; 95% confidence interval [CI], 1.7-4.1) and thrombophilia (HR, 2.2; 95% CI, 1.2-4.2) were independent risk factors for loss of primary patency. Thrombophilia mutations or low antithrombin level (HR, 3.8), female sex (HR, 2.5), and diabetes (HR, 1.9) were associated with shortened functional primary patency of AVF.

CONCLUSIONS

Against the background of frequent coagulation abnormalities, thrombophilia and female sex predispose patients with ESRD to access failure, mostly due to thrombosis or stenosis.

The effect of statin therapy on the formation of arteriovenous fistula stenoses and the rate of reoccurrence of previously treated stenoses

Statins reduce inflammation in end-stage renal disease patients and improve endothelial function beyond cholesterol lowering. Despite this, statins do not improve the maturation rate, primary patency rate, and the cumulative survival of arteriovenous fistulas (AVFs). It is unknown if statins decrease the number of stenoses developing in AVFs or prolong the intervals between angioplasties needed to treat recurring stenoses. We conducted a retrospective chart review of our 265 active dialysis patients. The statin group was significantly more likely to be diabetic (64% vs. 43.6%) and treated with aspirin (64% vs. 40%) when compared to those not treated with statins (P=0.04 and 0.01). The mean time to first intervention (primary patency) was 16.5 months in statin users and 15.8 months in the nonstatin group (P=0.49) with standard deviations of ± 18.5 and 16.6 months, respectively. Statin use was not associated with a significant decrease in the number of stenoses diagnosed (P=0.28). The mean time between recurrent stenoses' angioplasties was 8.9 months in statin users and 7.3 months in the nonstatin patients (P=0.25). Aspirin users were more likely to have a decreased primary patency (rate ratio=1.65, P=0.03) compared with nonaspirin users. Patients who were prescribed aspirin developed 1.6 (P 0.01) times more stenoses than those not treated with aspirin. We report for the first time that statin therapy does not decrease the number of stenotic lesions developing in the AVF or prolong the interval between procedures required to treat recurrent stenoses.

Inflammation, oxidation and venous neointimal hyperplasia precede vascular injury from AVF creation in CKD patients

PURPOSE

Intimal hyperplasia (IH), a well-recognized cause of dialysis vascular access failure, is generally believed to be an acquired pathologic lesion. Recent data suggests that IH is present prior to AVF creation. We sought to determine whether pre-existing inflammation and oxidation co-exist with IH prior to their incorporation into an AVF conduit, as their presence may predispose the AVF to further IH following AVF creation.

METHODS

At the time of first AV access surgery, vein segments were collected from ten Stage 4 and 5 CKD patients undergoing AVF creation 6-12 months prior to anticipated dialysis initiation. Morphometry and immunohistochemistry was performed to detect inflammatory markers IL-6, TGF-ß1, and TNFa, and markers of DNA oxidative damage (8-Hydroxy-2'-deoxyguanosine [HNE]) and lipid peroxidation (4-Hydroxy-2-Nonenal [8OHdG]).

RESULTS

The degree of IH severity was variable. IL-6, TGF-ß1, and TNFa co-localized with a-smooth muscle actin prominently within the venous intima and media. Although more diffuse, HNE and 8OHdG were intensely expressed in parallel with the inflammatory markers. In spite of these findings, however, neither extant IH nor the intensity of inflammatory or oxidative markers were associated with primary or secondary AVF failure at 12 month follow-up.

CONCLUSIONS

Not only does venous IH pre-exist, but inflammation and oxidation markers are present within veins used for the AVF conduit prior to its creation in CKD patients as early as one year before dialysis is commenced. Nevertheless, short and long-term AVF outcomes were not associated with the inflammatory or oxidative burden, suggesting the complexity of AVF dysfunction in humans with CKD.

Statin therapy and hemodialysis vascular access--were we bringing a knife to a gunfight and were hoping to win?

Vascular access dysfunction is a major contributor to end stage renal disease patient morbidity, and the cost of maintaining it is staggering. Any intervention able to improve the vascular access maturation rate and/or patency would be significant progress. Based on the anti-inflammatory and vascular beneficial effects demonstrated in non-end stage renal disease patients, we were hoping that statin use might provide the much needed improvement in the hemodialysis vascular access outcome. The reality proved disappointing. The statins failed to improve every aspect of hemodialysis vascular access studied. The present editorial discusses the current data regarding the effect of statins on vascular access and attempts to explain their lack of success.

Angiotensin receptor blockers and antiplatelet agents are associated with improved primary patency after arteriovenous hemodialysis access placement

OBJECTIVE

Dialysis access failure is a major cause of morbidity, mortality, and cost in end-stage renal disease. We undertook a study to determine the influence of medication use on dialysis access failure.

METHODS

After institutional review board approval, we performed a retrospective analysis of all upper extremity hemodialysis accesses placed from 2005 to 2009 at the Washington DC Veterans Affairs Medical Center. For each access, the date of failure was recorded. For patients who died or were lost to follow-up, the date of the last documented functional patency (censoring) was recorded. The primary exposures were 12 medication classes. Patient demographics, behaviors, comorbidities, and access characteristics were used as covariates. Patency rates were calculated using Kaplan-Meier methods. Cox proportional hazard models controlling for patient characteristics and all medication classes, with procedures clustered within patients, were used to determine the influence of medication class on primary patency.

RESULTS

Two hundred sixty autogenous and 126 prosthetic newly placed accesses were identified. Of these, three lower extremity accesses and six accesses with unknown thrombosis date were excluded. Forty-five (18%) of the remaining 257 autogenous accesses were excluded for primary nonfunctionality (patent, but with inadequate venous dilatation for initial hemodialysis), because the primary outcome was long-term functional patency. The remaining 212 autogenous and 120 prosthetic accesses were analyzed. Primary patency rates at 1 and 2 years were 55.2% and 49.1% for autogenous accesses, and 50.2% and 29.7% for prosthetic accesses, respectively. On multivariable analysis, angiotensin receptor blockers (ARBs) were associated with reduced hazard of both autogenous (hazard ratio [HR], 0.35; 95% confidence interval [CI], 0.16-0.76; P = .008) and prosthetic (HR, 0.41; 95% CI, 0.18-0.95;P = .039) access failure. On subgroup analysis, ARBs prolonged autogenous access primary patency among patients receiving antiplatelet medication (aspirin, clopidogrel; HR, 0.16; 95% CI, 0.05-0.52;P = .002) but had no demonstrable benefit among patients not receiving antiplatelets (HR, 1.35; 95% CI, 0.34-5.31;P = .670). There were no significant drug-drug interactions in the analysis of prosthetic accesses. Weighted regression models demonstrated low multicollinearity among the model variables.

CONCLUSION

Our data suggest that therapy with an ARB plus antiplatelet agent is associated with prolonged autogenous access primary patency, and therapy with an ARB with or without antiplatelet agents is associated with prolonged prosthetic access primary patency. Randomized studies are needed to confirm the causal role of ARBs and to determine the optimal therapeutic regimen (dose, timing, and duration) to promote access patency.

Randomized controlled trial of clopidogrel to prevent primary arteriovenous fistula failure in hemodialysis patients

The optimal vascular access for chronic maintenance hemodialysis is the arteriovenous fistula (AVF). Several studies suggest a role for antiplatelet agents in the prevention of primary AVF failure. A double-blind, randomized trial was conducted to assess the efficacy and safety of clopidogrel in hemodialysis patients. Ninety three patients were randomized to receive 75 mg/daily of clopidogrel or placebo. The treatment was initiated 7–10 days prior to scheduled access surgery and continued up to six weeks postoperatively, and then patients were monitored for six months. The primary outcome was AVF failure eight weeks after fistula creation. With a permuted block randomization schedule, 46 patients received clopidogrel and 47 patients received control placebo. The primary AVF failures at two months were 21.6% in placebo group and 5.2% in clopidogrel group (P = 0.03). The hazard ratio for the incidence of primary AVF failure was 0.72 (CI 95%, 0.41–1.01). Analysis of covariables indicated that this effect occurred principally as a result of clopidogrel administration. First hemodialysis from newly created AVF in clopidogrel group was significantly more successful than placebo group (P = 0.008). No life-threatening adverse event or severe bleeding was recorded in both groups. Clopidogrel seems to be effective and safe for prevention of primary AVF failure in hemodialysis patients.

The Brachiobasilic Arteriovenous Fistula: Effect of Patient Variables

Purpose

The hemodialysis population is constantly expanding as patients on dialysis have increased longevity and the number of kidneys available for transplantation remains static (1). After radiocephalic and brachiocephalic fistulas have been exhausted the use of the autologous brachiobasilic fistula (BBAVF) should be considered prior to use of a synthetic graft. We present our single center experience of 140 brachiobasilic fistulas in a five-year period and examine any factors that influence patency and long-term function.

Methods

Patients who had undergone formation of a BBAVF between January 2004 and January 2009 were identified; a review of all case notes and databases was undertaken. Details on demographics, cause of renal failure, co-morbidities (including diabetes, cardiac morbidity, hypertension, peripheral vascular disease), dialysis status at the time of fistula creation, hemoglobin, anti-coagulation regimens, and complications from surgery were recorded.

Results

Patency (defined as use of AVF for dialysis) was 83% at 3 months, 77% at 6 months, and 69% at 12 months. Length of patency ranged from 0 to 1918 days (at study cut-off) with a mean patency of 532 days. Factors found to significantly affect fistula patency included age over 60 ( P=<0.001) and presence of peripheral vascular disease ( P=0.048).

Conclusions

Our brachiobasilic fistula patency rates are comparable with published literature and other fistulas. Within our population patient variables including age over 60 and the presence of peripheral vascular disease are associated with worse outcomes as would be expected. In spite of these factors we feel the brachiobasilic fistula is an excellent option for patients with more challenging access and should certainly be undertaken prior to the use of prosthetic grafts.

Use of aspirin associates with longer primary patency of hemodialysis grafts

Extended-release dipyridamole plus low-dose aspirin (ERDP/ASA) prolongs primary unassisted graft patency of newly created hemodialysis arteriovenous grafts, but the individual contributions of each component are unknown. Here, we analyzed whether use of aspirin at baseline associated with primary unassisted graft patency among participants in a randomized trial that compared ERDP/ASA and placebo in newly created grafts. We used Cox proportional hazards regression, adjusting for prespecified baseline comorbidities and covariates. Of all participants, 43% reported use of aspirin at baseline; of these, 82% remained on nonstudy aspirin (i.e., excluding ERDP/ASA) at 1 year. After 1 year of follow-up, the incidence of primary unassisted patency among participants using aspirin at baseline was 30% (95% CI: 24 to 35%) and among those not using aspirin was 23% (95% CI: 18 to 27%). Use of aspirin at baseline associated with a dose-dependent prolongation of primary unassisted graft patency that approached statistical significance (adjusted HR, 0.83; 95% CI: 0.68 to 1.01; P=0.06). Use of aspirin at baseline did not associate with prolongation of cumulative graft patency or participant survival. In conclusion, use of aspirin associates with a trend toward longer primary unassisted patency of newly placed hemodialysis grafts similar to that observed for ERDP/ASA.

Antiplatelet agents for the prevention of arteriovenous fistula and graft thrombosis: a meta analysis

AIMS

The aim of this study was to evaluate the impact of antiplatelet agents on the thrombosis rates of arteriovenous fistulae and grafts used for haemodialysis access.

METHODS

In this meta analysis, a systematic search of the literature was used to identify randomised controlled trials evaluating the effect of antiplatelet agents in graft or fistula thrombosis or bleeding. Two authors identified eligible trials and abstracted data on outcomes and study characteristics. The incidence of thrombosis was the primary outcome of interest and was calculated separately for studies evaluating grafts and those evaluating fistulae. A random-effects model was used for statistical pooling.

RESULTS

Ten trials were included in the analysis, nine of which reported outcomes on graft or fistula thrombosis. Antiplatelet agents reduced the rate of arteriovenous fistulae thrombosis (OR 0.54, 95% CI 0.31-0.94) but not grafts (OR 0.50, 95% CI 0.16-1.53). Both analyses had a moderate degree of statistical heterogeneity, likely because of differences in study design, antiplatelet agent and dose, as well as other possible factors. Review of bleeding events did not reveal a concerning risk of bleeding, but could not be statistically evaluated.

CONCLUSIONS

Antiplatelet agents reduce the rate of arteriovenous fistula thrombosis; however, at this time, research does not support the use of these agents for preventing arteriovenous graft thrombosis.

Stent graft versus balloon angioplasty for failing dialysis-access grafts

BACKGROUND

The leading cause of failure of a prosthetic arteriovenous hemodialysis-access graft is venous anastomotic stenosis. Balloon angioplasty, the first-line therapy, has a tendency to lead to subsequent recoil and restenosis; however, no other therapies have yet proved to be more effective. This study was designed to compare conventional balloon angioplasty with an expanded polytetrafluoroethylene endovascular stent graft for revision of venous anastomotic stenosis in failing hemodialysis grafts.

METHODS

We conducted a prospective, multicenter trial, randomly assigning 190 patients who were undergoing hemodialysis and who had a venous anastomotic stenosis to undergo either balloon angioplasty alone or balloon angioplasty plus placement of the stent graft. Primary end points included patency of the treatment area and patency of the entire vascular access circuit.

RESULTS

At 6 months, the incidence of patency of the treatment area was significantly greater in the stent-graft group than in the balloon-angioplasty group (51% vs. 23%, P<0.001), as was the incidence of patency of the access circuit (38% vs. 20%, P=0.008). In addition, the incidence of freedom from subsequent interventions at 6 months was significantly greater in the stent-graft group than in the balloon-angioplasty group (32% vs. 16%, P=0.03 by the log-rank test and P=0.04 by the Wilcoxon rank-sum test). The incidence of binary restenosis at 6 months was greater in the balloon-angioplasty group than in the stent-graft group (78% vs. 28%, P<0.001). The incidences of adverse events at 6 months were equivalent in the two treatment groups, with the exception of restenosis, which occurred more frequently in the balloon-angioplasty group (P<0.001).

CONCLUSIONS

In this study, percutaneous revision of venous anastomotic stenosis in patients with a prosthetic hemodialysis graft was improved with the use of a stent graft, which appears to provide longer-term and superior patency and freedom from repeat interventions than standard balloon angioplasty. (ClinicalTrials.gov number, NCT00678249.)

Effect of dipyridamole plus aspirin on hemodialysis graft patency

BACKGROUND

Arteriovenous graft stenosis leading to thrombosis is a major cause of complications in patients undergoing hemodialysis. Procedural interventions may restore patency but are costly. Although there is no proven pharmacologic therapy, dipyridamole may be promising because of its known vascular antiproliferative activity.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial of extended-release dipyridamole, at a dose of 200 mg, and aspirin, at a dose of 25 mg, given twice daily after the placement of a new arteriovenous graft until the primary outcome, loss of primary unassisted patency (i.e., patency without thrombosis or requirement for intervention), was reached. Secondary outcomes were cumulative graft failure and death. Primary and secondary outcomes were analyzed with the use of a Cox proportional-hazards regression with adjustment for prespecified covariates.

RESULTS

At 13 centers in the United States, 649 patients were randomly assigned to receive dipyridamole plus aspirin (321 patients) or placebo (328 patients) over a period of 4.5 years, with 6 additional months of follow-up. The incidence of primary unassisted patency at 1 year was 23% (95% confidence interval [CI], 18 to 28) in the placebo group and 28% (95% CI, 23 to 34) in the dipyridamole-aspirin group, an absolute difference of 5 percentage points. Treatment with dipyridamole plus aspirin significantly prolonged the duration of primary unassisted patency (hazard ratio, 0.82; 95% CI, 0.68 to 0.98; P=0.03) and inhibited stenosis. The incidences of cumulative graft failure, death, the composite of graft failure or death, and serious adverse events (including bleeding) did not differ significantly between study groups.

CONCLUSIONS

Treatment with dipyridamole plus aspirin had a significant but modest effect in reducing the risk of stenosis and improving the duration of primary unassisted patency of newly created grafts. (ClinicalTrials.gov number, NCT00067119.)

Variability in reasons for hemodialysis catheter use by race, sex, and geography: findings from the ESRD Clinical Performance Measures Project

BACKGROUND

Race, sex, and geographic differences in hemodialysis vascular access use have been reported, but differences in reasons for catheter use have not been assessed.

STUDY DESIGN

Cross-sectional.

SETTING & PARTICIPANTS

Data obtained from the 2005 Centers for Medicare & Medicaid Services End-Stage Renal Disease Clinical Performance Measures Project for adult hemodialysis patients.

PREDICTORS

Race, sex, and geographic region.

OUTCOMES & MEASUREMENTS

Reasons for catheter use were categorized as short term and long term. Race, sex, and geographic associations with reasons were assessed by using bivariate analyses and multivariate logistic regression.

RESULTS

Of 8,479 hemodialysis patients, 3,302 (39%) used a fistula, 2,725 (32%) used a graft, and 2,299 (27%) used a catheter. We placed 857 patients with a catheter (37%) in the short-term-reason cohort and 1,404 (61%) in the long-term-reason cohort, and 38 (2%) lacked information to be placed. Reasons for catheter use were independently associated with race, sex, and geographic region. Whites were 43%, 49%, and 34% less likely than African Americans to use a catheter because of graft maturation, graft interruption, and all vascular access sites exhausted and 70% and 40% more likely because of fistula maturation and no fistula or graft surgically planned, respectively. Men were 50% less likely than women to use a catheter because of graft interruption and 80% more likely because of fistula maturation. Geographic end-stage renal disease network was associated with catheter use because of fistula maturation (P = 0.03), no fistula or graft surgically created (P < 0.001), and no fistula or graft surgically planned (P = 0.05).

LIMITATIONS

The cross-sectional study design precludes our ability to assess trends over time in reasons for catheter use. Associations were assessed for a limited set of variables.

CONCLUSION

Race, sex, and geographic differences in reasons for hemodialysis catheter use exist. Understanding these differences may aid in developing strategies to decrease catheter initiation rates.

Stent placement versus angioplasty improves patency of arteriovenous grafts and blood flow of arteriovenous fistulae

BACKGROUND

While endovascular stent placement is the standard of care in most percutaneous coronary and peripheral artery intervention, its role in the salvage of thrombosed and stenotic hemodialysis access remains controversial.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

We compared the effects of stent versus angioplasty on primary patency rates in the treatment of stenotic arteriovenous fistulae (AVF) and arteriovenous grafts (AVGs). Moreover, we compared access flow (Qa) and urea reduction ratio (URR) between the two groups as a metric of the effect of stent placement versus angioplasty on dialysis delivery.

RESULTS

Cox regression analysis revealed that the primary assisted AVG patency was significantly longer for the stent group compared with angioplasty, with a median survival of 138 versus 61 d, respectively (aHR = 0.17; 95% confidence interval, 0.07 to 0.39; P < 0.001). The primary AVG patency for stent versus angioplasty was 91% versus 80% at 30 d, 69% versus 24% at 90 d, and 25% versus 3% at 180 d, respectively. The primary assisted AVF patency did not differ significantly between the stent and angioplasty groups. In patients dialyzing via AVF, multiple regression analysis revealed that stent placement was associated with improved after intervention peak Qa, 1627.50 ml/min versus 911.00 ml/min (beta = 0.494; P = 0.008), change in Qa from before to after intervention, 643.54 ml/min versus 195.35 ml/min (beta = 0.464; P = 0.012), and change in URR from before to after intervention, 5.85% versus 0.733% (beta = 0.389; P = 0.039).

CONCLUSIONS

Our results suggest that stent placement is associated with improved AVG primary assisted patency and improved AVF blood flow, which may significantly impact on dialysis adequacy.

Central venous lines for chronic hemodialysis: survey of the Midwest Pediatric Nephrology Consortium

Central venous lines (CVL) continue to be the most commonly used vascular access device for children on hemodialysis (HD). Despite their frequent use, little is known regarding the frequency of CVL-related intradialytic complications that could interfere with delivery of effective dialysis. To better assess this, we conducted a cross-sectional study of ten HD centers within the Midwest Pediatric Nephrology Consortium. Vascular access was provided by CVL in 61 of the 83 patients (73%) included. CVL dysfunction (defined as reduced blood flows, need for reversed lines, or frequent intradialytic alarms) occurred in 46% in the prior month. Treatment for suspected clots occurred in 16 patients. Intraluminal tissue plasminogen activator (tPA) was the preferred treatment for a suspected clot. The survey also inquired about the preferred treatment for documented clots, and intraluminal tPA was most preferred, followed by CVL stripping, CVL removal, CVL brushing, and systemic tPA. As for preventative strategies, most HD centers locked the CVL with intraluminal heparin in concentrations ranging from 1,000 to 5,000 U/ml. In conclusion, catheter usage rates and complications were highly prevalent in pediatric HD units in this study. As treatment strategies varied greatly, future prospective studies are needed to determine the effectiveness of each individual therapy.

Gender differences in vascular access in hemodialysis patients in the United States: developing strategies for improving access outcome

BACKGROUND

Patients undergoing chronic hemodialysis (HD) require placement of permanent vascular access with the creation of an arteriovenous fistula (AVF), an arteriovenous prosthetic graft (AVG), or a tunneled central venous catheter. AVFs provide greater long-term patency, fewer complications, and lower infection rates than do either AVGs or catheters. Despite these advantages, women continue to be underrepresented among AVF patients, possibly because of concerns about smaller vascular diameters and higher rates of early primary fistula failure in female HD patients. The numerous clinical benefits of AVF suggest that a greater effort should be made to promote AVF placement in women.

OBJECTIVE

This review analyzes risk factors for AVF failure in women and describes clinical strategies to improve AVF utilization and success for female HD patients.

METHODS

English-language publications were identified through a MEDLINE database search from January 1997 to March 2007, using the search terms arteriovenous fistula, vascular access, hemodialysis, female, and gender. Reference lists of identified articles were also reviewed.

RESULTS

There are significant benefits to using AVFs instead of AVGs or catheters in HD patients: greater long-term fistula patency, superior flow rates, and fewer complications. Vascular anatomical differences between the sexes contribute to the underutilization of AVF in women. AVF placement rates can be improved if patients and staff are adequately educated and provided with the tools to facilitate AVF placement. Noninvasive preoperative screening is important to identify superior access sites in women. Intraoperative monitoring of blood flow is a reliable predictor of early radiocephalic AVF patency. Routine postoperative vascular monitoring may improve overall success with AVF, and exercise may improve vascular diameter and may be even more beneficial for women, who may have smaller preoperative veins.

CONCLUSIONS

Concerns about smaller vascular diameters and reports of higher failure rates in women may prevent nephrologists and surgeons from considering AVF for female HD patients. The numerous advantages associated with AVF suggest that a greater effort should be made to increase its utilization in women. With appropriate motivation, care, and diligence by treating clinicians, the success of AVFs in women can approach the good results typically expected in men.