Significant correlation between ankle-brachial index and vascular access failure in hemodialysis patients

Factors Affecting the Early Maturation of Arteriovenous Fistulae Created at a Tertiary Centre in Oman

Objectives

This study aimed to determine the risk factors associated with the failure of arteriovenous fistulae (AVF) maturation.

Methods

This retrospective cohort study was conducted from January 2014 to December 2018 in Sultan Qaboos University Hospital, Muscat, Oman. Patients were followed-up 3 months after surgery, and their electronic medical records were accessed for demographic and clinical data. Univariate analysis was used to determine the risk factors associated with early AVF maturation and multivariant analysis was used to determine the predictive factors for AVF failure.

Results

A total of 269 patients were included. Female gender was a significant factor affecting AVF maturity (P = 0.049), while age (P = 0.626), diabetes (P = 0.954), hypertension (P = 0.378), dyslipidaemia (P = 0.907), coronary artery disease (P = 0.576), cerebrovascular accident (P = 0.864), congestive heart failure (P = 0.685), previous central venous catheterisation (P = 0.05), fistula type (P = 0.863) and fistula site (P = 0.861) did not affect AVF maturation. Binary logistic regression showed that all the risk factors were insignificant. Failure of early AVF maturation affected 11.5% in the cohort.

Conclusion

This study found that the proportion of early AVF maturation at our hospital is at par with that in the international literature. Failure of AVF maturation was significantly associated with the female gender. These findings can help nephrologists and vascular surgeons prognosticate AVF maturation rates. However, a larger study is needed for definitive conclusions.

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.

Bridge of Tunneled Cuffed Catheter as a Risk for Future Arteriovenous Fistulae Failure

Background: A clinically tunneled cuffed catheter (TCC) for hemodialysis (HD) is often inserted into end-stage renal disease patients, who have an immature or no arteriovenous fistula (AVF), for the performance of HD to relieve uremic syndrome or to solve uncontrolled fluid overload, hyperkalemia, or metabolic acidosis. The catheter is primarily regarded as a bridge until the AVF matures and can be cannulated for HD. However, the effect of the bridge of the TCC on the future patency of AVFs remains elusive. Methods: This nationwide population-based observational study compared the hazards of AVF failure and the time to AVF failure. We enrolled 24,142 adult incident patients on HD, who received HD via AVFs for at least 90 days between 1 January 2010 and 31 December 2015. The subjects were divided into two groups, according to the history of TCC, and were followed-up until the failure of the AVF, mortality, or the end of the study. A propensity score-matched analysis based on 1:1 matching of age, sex, and baseline comorbidities was utilized to reduce bias and confounding variables. Results: A Kaplan−Meier survival curve revealed that patients with and without a history of TCC had significantly better AVF survival rates (log-rank test; p < 0.001). A history of TCC was independently associated with a higher risk of new AVF or AVG creation due to AVF failure, after the adjustment of the Charlson comorbidity index score (corresponding adjusted hazard ratios of 2.17 and 1.52; 95% confidence intervals of 1.77−2.67 and 1.15−1.99). For the impact of time on AVF failure, patients with a TCC bridge had a significantly higher incidence of new AVF creation during the first year after the AVF cannulation. Conclusion: A history of a TCC bridge was an independent risk factor for AVF failure and the time of AVF failure was significantly higher during the first year after the fistula cannulation in the TCC bridge group.

Timing of the first cannulation and survival of arteriovenous grafts in hemodialysis patients: a multicenter retrospective cohort study

Arteriovenous graft (AVG) is an important vascular access route in hemodialysis patients. The optimal waiting time between AVG creation and the first cannulation is still undetermined, therefore the current study investigated the association between ideal timing for cannulation and AVG survival. This retrospective cohort study used data from the Taiwan National Health Insurance Database, which included 6,493 hemodialysis patients with AVGs between July 1^st 2008 and June 30^th 2012. The waiting cannulation time was defined as the time from the date of shunt creation to the first successful cannulation. Patients were categorized according to the waiting cannulation time of their AVGs as follows: ≤30 days, between 31 and 90 days, between 91 and 180 days, and >180 days. The primary outcome was functional cumulative survival, measured as the time from the first cannulation to shunt abandonment. The AVGs which were cannulated between 31 and 90 days (reference group) after construction had significantly superior functional cumulative survival compared with those cannulated ≤30 days (adjusted HR = 1.651 with 95% CI 1.482–1.839; p < 0.0001) and >180 days (adjusted HR = 1.197 with 95% CI 1.012–1.417; p = 0.0363) after construction. An analysis of the hazard ratios in patients with different demographic characteristics, revealed that the functional cumulative survival of AVGs in most groups was better when they received cannulation >30 days after construction. Consequently, in order to achieve the best long-term survival, AVGs should be cannulated at least 1 month after construction, but you should avoid waiting for >3 months.

The Role of Oxidative Stress Markers in Predicting Acute Thrombotic Occlusion of Haemodialysis Vascular Access and Progressive Stenotic Dysfunction Demanding Angioplasty

Haemodialysis vascular access (VA) dysfunction is a major cause of morbidity in haemodialysis (HD) patients. Primary venous outflow occlusion and restenosis after percutaneous transluminal angioplasty (PTA) are two major obstacles for the long-term use of dialysis VA. It remains unclear whether oxidative stress markers can be used as predictors for thrombotic occlusion of VA and progressive stenosis dysfunction demanding PTA. All routine HD patients at one teaching hospital participated in this study including ankle-brachial index (ABI) examinations and serum oxidative stress markers. The serum oxidative stress markers (high-sensitivity C-reactive protein (hs-CRP), matrix metalloproteinase-2 (MMP-2), MMP-9, homocysteine, asymmetrical dimethylarginine (ADMA), nitrate oxidase (NO), tumour necrosis factor-α (TNF-α), monocyte chemotactic protein 1 (MCP-1), interleukin-1β (IL-1β), and transforming growth factor-β (TGF-β)) were measured using immunosorbent assays in 159 HD patients (83 men and 76 women; mean age: 65 ± 12 years). The participants met the following criteria: (1) received regular HD treatment for at least 6 months, without clinical evidence of acute or chronic inflammation, recent myocardial infarction, unstable angina or circulatory congestion; and (2) received an arteriovenous fistula (AVF)/arteriovenous graft (AVG: polytetrafluoroethylene, PTFE) as the current VA for more than 6 months, without interventions within the last 6 months. All the participants were followed up clinically for up to 12 months to estimate the amount of primary thrombotic occlusion and VA dysfunction demanding PTA. During the 12-month observation, 24 patients (15.1%) had primary thrombotic occlusion of VAs. Another 24 patients (15.1%) required PTA because of clinical dysfunction of access. Additionally, during the follow-up period, restenosis occurred in 12 patients (50% of 24 patients). The access types of arteriovenous grafts (AVGs) and a diagnosis of peripheral arterial occlusive disease (PAOD) were two strong predictors for acute thrombotic events of VA (hazard ratio (HR): 16.93 vs. 2.35; p < 0.001 vs. 0.047). Comparing dysfunctional with non-dysfunctional VAs, up to 27.7% of patients with high levels of ADMA (>0.6207 μM, N = 65) received required PTA compared with 4.4% of those with low levels (≤0.6207 μM; N = 90; p < 0.001). In multivariate analysis, the plasma baseline levels of ADMA independently conferred nearly 4.55 times the risk of primary stenotic dysfunction of HD VA (HR: 4.55; 95% confidence interval: 1.20 to 17.26; p = 0.026). In conclusion, our findings suggest the role of ADMA in the development of symptomatic VA dysfunction. Additionally, PAOD severity can be used in clinical practice to predict whether acute thrombotic occlusion of VA will easily occur in HD patients.

Prognostic Significance of Abnormal Ankle-Brachial Index Among Long-term Hemodialysis Patients in Kinshasa, the Democratic Republic of the Congo

OBJECTIVE

Early identification of atherosclerosis using a non-invasive tool like ankle-brachial index (ABI) could help reduce the risk for cardiovascular disease among long-term hemodialysis patients. The study objective was to assess the frequency and impact of abnormal ABI as a marker of subclinical peripheral artery disease (PAD) in chronic hemodialysis patients.

METHODS

This was a historic cohort study of kidney failure patients on long-term hemodialysis for at least 6 months. The ABI, measured with two oscillometric blood pressure devices simultaneously, was used to assess subclinical atherosclerosis of low limb extremities. Abnormal ABI was defined as ABI <0.9 or >1.3 (PAD present). Survival was defined as time to death. Independent factors associated with abnormal ABI were assessed using multiple logistic regression analysis. Kaplan-Meier method (log-rank test) was used to compare cumulative survival between the two groups; a P value <0.05 was statistically significant.

RESULTS

Abnormal ABI was noted in 50.6% (n=43) of the 85 kidney failure patients included in the study; 42.4% (n=36) had a low ABI, and 8.2% (n=7) had a high ABI. Factors associated with PAD present were cholesterol (adjusted odds ratio [AOR], 1.02; 95% confidence interval [CI], 1.01-1.04; P=0.019), inflammation (AOR, 9.44; 95% CI, 2.30-18.77; P=0.002), phosphocalcic product (AOR, 6.25; 95% CI, 1.19-12.87; P=0.031), and cardiac arrhythmias (AOR, 3.78; 95% CI, 1.55-7.81, P=0.009). Cumulative survival was worse among patients with PAD present (log-rank; P=0.032).

CONCLUSION

The presence of PAD was a common finding in the present study, and associated with both traditional and emerging cardiovascular risk factors as well as a worse survival rate than patients without PAD.

Targeting Uremic Toxins to Prevent Peripheral Vascular Complications in Chronic Kidney Disease

Chronic kidney disease (CKD) exhibits progressive kidney dysfunction and leads to disturbed homeostasis, including accumulation of uremic toxins, activated renin-angiotensin system, and increased oxidative stress and proinflammatory cytokines. Patients with CKD are prone to developing the peripheral vascular disease (PVD), leading to poorer outcomes than those without CKD. Cumulative evidence has showed that the synergy of uremic milieu and PVD could exaggerate vascular complications such as limb ischemia, amputation, stenosis, or thrombosis of a dialysis vascular access, and increase mortality risk. The role of uremic toxins in the pathogenesis of vascular dysfunction in CKD has been investigated. Moreover, growing evidence has shown the promising role of uremic toxins as a therapeutic target for PVD in CKD. This review focused on uremic toxins in the pathophysiology, in vitro and animal models, and current novel clinical approaches in reducing the uremic toxin to prevent peripheral vascular complications in CKD patients.

Plasma Leucine-Rich α-2-Glycoprotein 1 Predicts Cardiovascular Disease Risk in End-Stage Renal Disease

Plasma leucine-Rich α-2-glycoprotein 1 (LRG1) is an innovative biomarker for inflammation and angiogenesis. Many adverse pathophysiological changes including inflammation, atherosclerosis, and premature mortality is associated with End-stage renal disease (ESRD). However, whether levels of plasma LRG1 correlate with the co-morbidities of ESRD patients is unknown. Plasma LRG1 and high-sensitivity C-reactive protein (hsCRP) were analyzed by ELISA in 169 hemodialysis patients from the Immunity in ESRD (iESRD) study. Patient demographics and comorbidities at the time of enrollment were recorded. Peripheral blood monocyte and T cell subsets were assessed by multicolor flow cytometry. In the univariate analysis, a higher level of LRG1 was associated with the presence of cardiovascular disease (CVD) and peripheral arterial occlusive disease (PAOD). In multivariate logistic regression models, higher LRG1 tertile was significantly associated with PAOD (odds ratio = 3.49) and CVD (odds ratio = 1.65), but not with coronary artery disease, history of myocardial infarction, or stroke after adjusting for gender, diabetes, hemoglobin, albumin, calcium-phosphate product, and level of hsCRP. In addition, the level of LRG1 had a positive correlation with IL-6, hsCRP, and also more advanced T cell differentiation. The association suggests that LRG1 participates in the progression of atherosclerosis by inducing inflammation. Therefore, the role of LRG1 in coexisting inflammatory response should be further investigated in the pathogenesis of cardiovascular morbidity and mortality in patients with ESRD.

Predictors of Primary Functional Maturation of Autogenous Radiocephalic Arteriovenous Fistula in a Cohort of Asian Patients

BACKGROUND

The aim of this study was to investigate the predictors of autogenous radiocephalic arteriovenous fistula (RCAVF) maturation.

METHODS

This was a retrospective analysis of patients undergoing RCAVF creation from June 2013 to December 2018 at a single medical center. Comparison of the variables between the matured and nonmatured group was performed.

RESULTS

A total of 277 patients (men, 173; 62.5%) with a mean age of 56.6 ± 16.9 years underwent primary RCAVF creation during the study period. The mean diameter of the cephalic vein and radial artery were 2.4 ± 0.6 mm (range 1.5 to 4.3 mm) and 2.3 ± 0.5 mm (range 1.5 to 4.0 mm), respectively. Primary functional maturation was achieved in 236 patients (236/277, 85%). There was no statistical significance between the matured and nonmatured group in terms of age (56.4 ± 14.8 vs. 58.1 ± 15.1, respectively; P = 0.498), coronary arterial disease (12% vs. 17%, respectively; P = 0.449), diabetes mellitus (42% vs. 39%, respectively; P = 0.864), smoking (26% vs. 22%, respectively; P = 0.699), or antiplatelet therapy (23% vs. 24%, respectively; P = 0.844). However, female gender (35% vs. 54%, respectively; P = 0.024), peripheral arterial disease (9% vs. 22%, respectively; P = 0.025), and small vein (2.4 ± 0.5 mm vs. 2.0 ± 0.5 mm, respectively; P < 0.01) and artery (2.4 ± 0.5 vs. 2.1 ± 0.4, respectively; P < 0.01) diameter were associated with the failure of maturation. The best cutoff diameter for the cephalic vein and radial artery was 1.85 mm and 2.05 mm, respectively.

CONCLUSIONS

In this cohort of patients undergoing RCAVF creation, vein and artery diameter on preoperative ultrasound mapping was the predictor of functional maturation. Female gender and presence of peripheral arterial disease were associated with failure of maturation.

Association of Race and Ethnicity with Vascular Access Type Selection and Outcomes

BACKGROUND

Black patients with end-stage renal disease (ESRD) represent 30.5% of the prevalent ESRD population in the United States, despite only accounting for 18% of the total population. Black patients are less likely to have pre-ESRD care compared with their white counterparts and are 3-4 times more likely to progress from chronic kidney disease to ESRD than whites, suggesting that black patients are particularly vulnerable to disparities in outcomes related to hemodialysis and ESRD. The objective of this study is to examine the association of race with outcomes of hemodialysis access and selection of arteriovenous fistula (AVF) versus arteriovenous graft (AVG).

METHODS

Patients with chronic kidney disease who initiated dialysis through a tunneled hemodialysis catheter (THC) were identified in the Optum's De-identified Clinformatics® Data Mart (OptumInsight, Eden Prairie, MN) claims database (2011-2017). The odds of AVF versus AVG creation and the odds of repeat vascular access creation were analyzed using logistic regression. Time from initial AVF/AVG to THC removal and time to repeat AVF/AVG were analyzed using Cox proportional hazards.

RESULTS

About 7,584 vascular access patients met the inclusion criteria: 5,852 (77%) AVF and 1,732 (23%) AVG. Median follow-up was 583 days overall (range, 1-2,543), 589 days among AVF patients (range, 1-2,543), and 260 days among AVG patients (range, 1-2,529). Between races, there was no clinically significant variation in characteristics or comorbidities, with the exception of a much lower rate of obesity among Asians. Black patients had 36% lower odds of AVF index versus AVG index (P < 0.001). Patients 70 years or older and patients with diabetes had lower odds of AVF index, whereas men and obese patients had greater odds of receiving AVF. Overall, graft patients were 73% more likely to have a shorter time to THC removal than fistula patients, but Hispanic graft patients were 25% more likely to have a shorter time to THC removal than whites. Patients with diabetes, patients with cardiac arrhythmia, and obesity were more likely to have a longer time to THC removal. About 1,589 (21%) patients underwent a repeat vascular access creation during the follow-up period: 19% of whites (n = 802), 26% of blacks (n = 483), 19% of Hispanics (n = 250), and 19% of Asians (n = 54) (P < 0.001). Multivariate analysis demonstrated that black patients had 58% greater odds of requiring a second access than white patients (P < 0.001). Graft patients, patients 70 years or older, and men had lower odds of repeat access. Black patients were 45% more likely to have a shorter time until second access creation. Graft patients, patients aged 70 years or older, and men were more likely to have a longer time until second access. Patients with obesity were more likely to have a shorter time until second access.

CONCLUSIONS

This study's findings suggest that after initial vascular access, compared with whites, blacks have no difference in time to index access success, but their access fails earlier and more frequently, independent of access type, age, and comorbidities. Given blacks constitute 30.5% of the hemodialysis population in the United States, it is imperative that future research investigate the root causes of these disparities.

Hemodialysis vascular access in the elderly-getting it right

Choosing the optimal hemodialysis vascular access for the elderly patient is best achieved by a patient-centered coordinated multidisciplinary team approach that aligns the patient's end-stage kidney disease Life-Plan, i.e., the individual treatment approach (supportive care, time-limited or long-term kidney replacement therapy, or combination thereof) and selection of dialysis modality (peritoneal dialysis versus hemodialysis) with the most suitable dialysis access. Finding the right balance between the patient's preferences, the likelihood of access function and survival, and potential complications in the context of available resources and limited patient survival can be extremely challenging. The framework for choosing the most appropriate vascular access for the elderly presented in this review considers the individual end-stage kidney disease Life-Plan, the patient life expectancy, the likelihood of access function and survival, the timing of dialysis relative to access placement, prior access history, and patient preference. This complex decision-making process should be dynamic in order to accommodate patients' changing needs and life and health circumstances. Effective and timely communication between the patient, their caregivers, and treating team is key to delivering truly patient-centered care. Delivering this care also requires overcoming the limitations of the currently available evidence that is predominantly based on observational data with its inherent risks of bias. While challenging, future randomized controlled studies exploring the risks, benefits, costs, and timing of placement of available access types in the elderly are required to help us "get it right" for our patients.

Atherosclerosis in Chronic Kidney Disease: More, Less, or Just Different?

Patients with chronic kidney disease (CKD) are at an increased risk of premature mortality, mainly from cardiovascular causes. The association between CKD on hemodialysis and accelerated atherosclerosis was described >40 years ago. However, more recently, it has been suggested that the increase in atherosclerosis risk is actually observed in early CKD stages, remaining stable thereafter. In this regard, interventions targeting the pathogenesis of atherosclerosis, such as statins, successful in the general population, have failed to benefit patients with very advanced CKD. This raises the issue of the relative contribution of atherosclerosis versus other forms of cardiovascular injury such as arteriosclerosis or myocardial injury to the increased cardiovascular risk in CKD. In this review, the pathophysiogical contributors to atherosclerosis in CKD that are shared with the general population, or specific to CKD, are discussed. The NEFRONA study (Observatorio Nacional de Atherosclerosis en NEFrologia) prospectively assessed the prevalence and progression of subclinical atherosclerosis (plaque in vascular ultrasound), confirming an increased prevalence of atherosclerosis in patients with moderate CKD. However, the adjusted odds ratio for subclinical atherosclerosis increased with CKD stage, suggesting a contribution of CKD itself to subclinical atherosclerosis. Progression of atherosclerosis was closely related to CKD progression as well as to the baseline presence of atheroma plaque, and to higher phosphate, uric acid, and ferritin and lower 25(OH) vitamin D levels. These insights may help design future clinical trials of stratified personalized medicine targeting atherosclerosis in patients with CKD. Future primary prevention trials should enroll patients with evidence of subclinical atherosclerosis and should provide a comprehensive control of all known risk factors in addition to testing any additional intervention or placebo.

Prevalence, clinical characteristics, and predictors of peripheral arterial disease in hemodialysis patients: a cross-sectional study

Background

Peripheral arterial disease (PAD) is common in patients with end-stage renal disease on hemodialysis, but is frequently underdiagnosed. The risk factors for PAD are well known within the general population, but they differ somewhat in hemodialysis patients. This study aimed to determine the prevalence of PAD and its risk factors in patients on hemodialysis.

Methods

This cross-sectional study included 156 hemodialysis patients. Comorbidities and laboratory parameters were analyzed. Following clinical examinations, the ankle-brachial index was measured in all patients. PAD was diagnosed based on the clinical findings, ankle-brachial index < 0.9, and PAD symptoms.

Results

PAD was present in 55 of 156 (35.3%; 95% CI, 27.7–42.8%) patients. The patients with PAD were significantly older (67 ± 10 years vs. 62 ± 11 years, p = 0.014), more likely to have diabetes mellitus (p = 0.022), and anemia (p = 0.042), and had significantly lower serum albumin (p = 0.005), total cholesterol (p = 0.024), and iron (p = 0.004) levels, higher glucose (p = 0.002) and C-reactive protein (p < 0.001) levels, and lower dialysis adequacies (p = 0.040) than the patients without PAD. Multivariate analysis showed higher C-reactive protein level (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.00–1.06; p = 0.030), vascular access by Hickman catheter (OR, 4.66; 95% CI, 1.03–21.0; p = 0.045), and symptoms of PAD (OR, 5.20; 95% CI, 2.60–10.4; p < 0.001) as independent factors associated with PAD in hemodialysis patients.

Conclusion

The prevalence of PAD was high among patients with end-stage renal disease on hemodialysis. Symptoms of PAD, higher C-reactive protein levels, and Hickman vascular access were independent predictors of PAD in patients on hemodialysis.

Association between albumin and C-reactive protein and ankle-brachial index in haemodialysis

AIM

Peripheral artery occlusive disease (PAOD) is associated with increased rates of cardiovascular mortality, morbidity and hospitalization in patients undergoing dialysis. An ankle-brachial index (ABI) less than 0.9 has been used to diagnose PAOD. The aim of this study was to evaluate associations among inflammation, malnutrition and their interactions on the risk of PAOD.

METHODS

Two hundred and twenty-two haemodialysis patients (mean age 61.0 ± 11.7 years, 56.8% men) were enrolled and stratified into four groups according to median values of albumin (3.87 g/dL) and logarithm of C-reactive protein (CRP) (0.48 mg/L). Associations between the study groups and an ABI less than 0.9 were assessed using multiple logistic regression analysis. Receiver operating characteristic curves were constructed to predict an ABI less than 0.9.

RESULTS

A lower level of albumin and higher level of CRP were significantly associated with an ABI less than 0.9 in multivariate analysis (odds ratio, 5.688; 95% confidence interval, 1.369-23.626; P = 0.017) after adjusting for demographic, clinical, biochemical and medication data. The interaction between albumin and CRP in relation to an ABI less than 0.9 was significant in multivariate analysis (odds ratio, 1.797; 95% confidence interval, 1.258-2.568; P = 0.001). The areas under the curve for albumin, CRP and albumin + CRP for the prediction of ABI less than 0.9 were 0.311, 0.654 and 0.733, respectively.

CONCLUSION

Patients undergoing haemodialysis with a lower albumin level and higher CRP level have an increased risk of PAOD. A combination of malnutrition and inflammation may be associated with PAOD in haemodialysis patients.

Maturation of arteriovenous fistula: Analysis of key factors

The growing proportion of individuals suffering from chronic kidney disease has considerable repercussions for both kidney specialists and primary care. Progressive and permanent renal failure is most frequently treated with hemodialysis. The efficiency of hemodialysis treatment relies on the functional status of vascular access. Determining the type of vascular access has prime significance for maximizing successful maturation of a fistula and avoiding surgical revision. Despite the frequency of arteriovenous fistula procedures, there are no consistent criteria applied before creation of arteriovenous fistulae. Increased prevalence and use of arteriovenous fistulae would result if there were reliable criteria to assess which arteriovenous fistulae are more likely to reach maturity without additional procedures. Published studies assessing the predictive markers of fistula maturation vary to a great extent with regard to definitions, design, study size, patient sample, and clinical factors. As a result, surgeons and specialists must decide which possible risk factors are most likely to occur, as well as which parameters to employ when evaluating the success rate of fistula development in patients awaiting the creation of permanent access. The purpose of this literature review is to discuss the role of patient factors and blood markers in the development of arteriovenous fistulae.

Association of Ankle-Brachial Index and Aortic Arch Calcification with Overall and Cardiovascular Mortality in Hemodialysis

Peripheral artery occlusive disease and vascular calcification are highly prevalent in hemodialysis (HD) patients, however the association of the combination of ankle-brachial index (ABI) and aortic arch calcification (AoAC) with clinical outcomes in patients undergoing HD is unknown. In this study, we investigated whether the combination of ABI and AoAC is independently associated with overall and cardiovascular mortality in HD patients. The median follow-up period was 5.7 years. Calcification of the aortic arch was assessed by chest X-ray. Forty-seven patients died including 24 due to cardiovascular causes during the follow-up period. The study patients were stratified into four groups according to an ABI < 0.95 or ≥0.95 and an AoAC score of >4 or ≤4 according to receiver operating characteristic curve. Those with an ABI < 0.95 and AoAC > 4 (vs. ABI ≥ 0.95 and AoAC score ≤ 4) were associated with overall (hazard ratio [HR], 4.913; 95% confidence interval [CI], 1.932 to 12.497; p = 0.001) and cardiovascular (HR, 3.531; 95% CI, 1.070 to 11.652; p = 0.038) mortality in multivariable analysis. The combination of a low ABI and increased AoAC was associated with increased overall and cardiovascular mortality in patients undergoing HD.

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.

Unequal Arterial Stiffness With Overall and Cardiovascular Mortality in Patients Receiving Hemodialysis

BACKGROUND

Pulse wave velocity is a marker of arterial stiffness. Unequal arterial stiffness has been associated with increased risk of cardiovascular events. This study calculated bilateral brachial-ankle pulse wave velocity (baPWV) differences and investigated the associations of unequal bilateral baPWV with overall and cardiovascular mortality in patients receiving hemodialysis (HD).

MATERIALS AND METHODS

A total of 205 patients receiving HD were enrolled in this study. The mean follow-up period was 4.4 ± 1.5 years. The baPWV was measured using an ankle-brachial index-form device, and bilateral baPWV difference was calculated and defined as ΔbaPWV.

RESULTS

The median value of ΔbaPWV was 88cm/second. ankle-brachial index < 0.95 and high baPWV were independently associated with a ΔbaPWV ≥ 88cm/s. Furthermore, patients with a ΔbaPWV ≥ 88cm/s demonstrated poorer overall (log-rank P = 0.035) and cardiovascular (log-rank P = 0.036) survival than did those with a ΔbaPWV < 88cm/s. After multivariate analysis, this difference was independently associated with overall (hazard ratio = 1.006; 95% CI: 1.001-1.011; P = 0.024) and cardiovascular (hazard ratio = 1.006; 95% CI: 1.000-1.013; P = 0.049) mortality.

CONCLUSIONS

ΔbaPWV was associated with an increased risk of cardiovascular and overall mortality in patients receiving HD. Earlier evaluation of ΔbaPWV may facilitate the identification of patients receiving HD who have an increased risk of cardiovascular and overall mortality.

Link between Peripheral Artery Disease and Heart Rate Variability in Hemodialysis Patients

Peripheral artery disease (PAD) and low heart rate variability (HRV) are highly prevalent in hemodialysis patients, and both are associated with increased cardiovascular morbidity and mortality. This study aims to examine the suggested relationship between PAD and HRV, and the relationship of parameters before and after hemodialysis. This study enrolled 161 maintenance hemodialysis patients. PAD was defined as ABI < 0.9 in either leg. HRV was performed to assess changes before and after hemodialysis. The change in HRV (△HRV) was defined as post-hemodialysis HRV minus pre-hemodialysis HRV. Patients’ clinical parameters were collected from the dialysis records. All HRV parameters except high frequency (HF) % were lower in patients with PAD than patients without PAD, though not achieving significant level. In patients without PAD, HF (P = 0.013), low frequency (LF) % (P = 0.028) and LF/HF (P = 0.034) were significantly elevated after hemodialysis, whereas no significant HRV parameters change was noted in patients with PAD. Serum intact parathyroid hormone was independently associated with △HF (β = -0.970, P = 0.032) and △LF% (β = -12.609, P = 0.049). Uric acid level (β = -0.154, P = 0.027) was negatively associated with △LF/HF in patients without PAD. Our results demonstrated that some of the HRV parameters were significantly increased after hemodialysis in patients without PAD, but not in patients with PAD, reflecting a state of impaired sympatho-vagal equilibrium. Severity of secondary hyperparathyroidism and hyperuricemia contributed to lesser HRV parameters increase after hemodialysis in patients without PAD.

Features of atherosclerosis in hemodialysis patients

Background

Cardiovascular disease is the main cause of mortality in dialysis patients. Carotid intima–media thickness (CIMT) is used as a surrogate marker of early atherosclerosis. Atherosclerosis can cause vascular access failure. The purpose of this study was to define the clinical features of atherosclerosis in hemodialysis patients based on CIMT and to define the relationship between CIMT and access failure.

Methods

In this cross-sectional study, the CIMT of 60 patients on hemodialysis was examined using B-mode Doppler ultrasonography between May 2012 and November 2012. Carotid atherosclerosis was defined as a CIMT≥0.9 mm or the incidence of atherosclerotic plaques.

Results

The patients’ mean age was 54.5±10.6 years, and 60% of the patients were male. The CIMT was 0.81±0.47 mm (range, 0.35–2.50 mm). The group with atherosclerosis was characterized by older age compared with those without atherosclerosis. Patients with atherosclerosis showed much shorter durations of access patency than their counterparts in the nonatherosclerosis group (hazard ratio, 2.822; 95% confidence interval, 1.113–7.156; P=0.029). Moreover, being overweight was associated with a 2.47-fold (95% confidence interval, 1.101–5.548) increased primary access failure.

Conclusion

This study shows that atherosclerosis is associated with older age. Patients who are overweight and have atherosclerosis may have shortened access patency.

Peripheral arterial disease in the Middle East: Underestimated predictor of worse outcome

Peripheral arterial disease (PAD) is a common manifestation of systemic atherosclerosis and is associated with significant morbidity and mortality. The prevalence of PAD in the developed world is approximately 12% among adult population, which is age-dependent and with men being affected slightly more than women. Despite the strikingly high prevalence of PAD, the disease is underdiagnosed. Surprisingly, more than 70% of primary health care providers in the US were unaware of the presence of PAD in their patients. The clinical presentation of PAD may vary from asymptomatic to intermittent claudication, atypical leg pain, rest pain, ischemic ulcers, or gangrene. Claudication is the typical symptomatic expression of PAD. However, the disease may remains asymptomatic in up to 50% of all PAD patients. PAD has also been reported as a marker of poor outcome among patients with coronary artery disease. Despite the fact that the prevalence of atherosclerotic disease is increasing in the Middle East with increasing cardiovascular risk factors (tobacco use, diabetes mellitus and the metabolic syndrome), data regarding PAD incidence in the Middle East are scarce.

Índice tornozelo-braço em pacientes hemodialíticos

INTRODUÇÃO: Apesar da elevada mortalidade dos pacientes em hemodiálise devido às doenças cardiovasculares, é incomum a realização de exames diagnósticos para doença arterial obstrutiva periférica e artérias pouco compressíveis. OBJETIVOS: Analisar a prevalência de doença arterial obstrutiva periférica e artérias pouco compressíveis em hemodialisados, comparando-os com o Grupo Controle. MÉTODOS: Tratou-se de um estudo transversal, com 78 hemodialisados e 88 pacientes que não faziam hemodiálise com, pelo menos, dois fatores de risco para doença arterial obstrutiva periférica (Grupo Controle). Para aferição da pressão arterial sistólica, utilizou-se Doppler vascular portátil e esfigmomanômetro. Esta foi aferida somente nos membros que não possuíam fístula arteriovenosa. O índice tornozelo-braço foi calculado utilizando cada artéria do membro inferior. Foram considerados normais os valores de 0,9 a 1,3. RESULTADOS: Diagnosticou-se doença arterial obstrutiva periférica e artérias pouco compressíveis em 26,9 e 30,8%, dos hemodialisados, e em 33 e 22,7%, do Grupo Controle. Nos hemodialisados, verificou-se o índice tornozelo-braço alterado em 75% dos sintomáticos (p=0,005), em 67,3% dos homens e 31% das mulheres (p<0,005), em 78,6% dos idosos, 34,8% dos adultos jovens (p<0,01) e em 76,9% dos diabéticos (p<0,005 versus não diabéticos). Esses pacientes apresentaram maior prevalência de doença arterial obstrutiva periférica grave do que o Grupo Controle (p<0,01). CONCLUSÕES: O índice tornozelo-braço anormal foi muito prevalente nos grupos estudados; entretanto, os hemodialisados apresentaram alterações mais graves quando comparados ao Grupo Controle. Diabetes melito, sexo masculino e idade avançada foram fatores de risco importantes para a alteração do índice tornozelo-braço nos hemodialisados. O índice tornozelo-braço foi um bom método de rastreio para alterações pesquisadas. Portanto, a utilização deste na rotina de manejo de pacientes em hemodiálise é sugerida.

Decrease in ankle-brachial index over time and cardiovascular outcomes in patients with hemodialysis

INTRODUCTION

Abnormal ankle-brachial index (ABI) is associated with increased morbidity and mortality in hemodialysis patients. However, whether the decrease in ABI over time carries the prognostic value is unknown. The aim of this study was to assess whether the decrease in ABI over time was a good predictor of poor cardiovascular (CV) prognosis in hemodialysis patients.

METHODS

This study enrolled 234 routine hemodialysis patients and 173 patients completed the follow-up. The ABI was measured by an ABI-form device at baseline and at the first year follow-up. The ΔABI was defined as ABI measured at the first year follow-up minus ABI measured at baseline. Progressors of ABI were defined as patients with ΔABI < -0.3. CV events were defined as CV death, hospitalization for unstable angina, nonfatal myocardial infarction, hospitalization for arrhythmia, hospitalization for congestive heart failure and stroke.

RESULTS

The follow-up period was 37.8 ± 11.1 months. In the multivariate analysis, progressors of ABI (hazard ratio, 2.71; 95% confidence interval, 1.10-6.68, P = 0.03), decreased albumin and increased high-sensitivity C-reactive protein were associated with increased CV events.

CONCLUSIONS

This longitudinal study showed ΔABI < -0.3 was independently associated with an increase in CV events. Hence, a great decrease in ABI over time might be a useful indicator of poor CV prognosis in hemodialysis patients.

The role of protein-bound uremic toxins on peripheral artery disease and vascular access failure in patients on hemodialysis

OBJECTIVE

p-Cresyl sulfate (PCS) and indoxyl sulfate (IS) have been reported to predict poor clinical outcomes in hemodialysis (HD) patients. However, little is known about the effect of the two toxins on peripheral arterial disease (PAD) and vascular access dysfunction. Our objective was to explore the association between the two toxins and PAD and vascular access failure (VAF) in a hemodialysis-based cohort.

METHODS

We enrolled 100 stable and eligible HD patients from a single medical center. These patients were screened for PAD by machine and recorded as ABI (ankle brachial index) and brachial-ankle PWV (pulse wave velocity). Serum levels of PCS, IS and biochemical data were also collected concurrently. In addition, we also recorded the first event of VAF and frequency of PTA and thrombectomy during 3-year follow-up.

RESULTS

Total and free PCS were correlated to right and left ABI and PWV (p < 0.01), and total IS was associated with right and left ABI (p < 0.01) by Pearson's analysis. Repeated measuring by mixed model analysis revealed that serum albumin (p = 0.003), cholesterol (p = 0.01) and total PCS (p = 0.031) had significant correlation with ABI after adjusting other confounding factors. As for brachial-ankle PWV, serum triglyceride (p = 0.002), total IS (p = 0.04) and total PCS (p = 0.050) reached significance finally. In addition, multivariate Cox regression analysis revealed dialysis length and total PCS were related to AV-shunt failure event (Hazard Ratio: 1.14, p = 0.01, and Hazard Ratio: 1.04, p = 0.04, respectively). Both of total and free PCS and IS were also positively linked to numbers of PTA and thrombectomy. Further, the Kaplan-Meier analysis showed only total PCS was significantly associated with vascular access failure event (log rank P = 0.02).

CONCLUSION

This study shows that the serum levels of PCS and IS were associated with PAD and total PCS could be a valuable determinant of access viability other than traditional or nontraditional risk factors in HD patients.

Increasing prevalence of peripheral artery occlusive disease in hemodialysis patients: a 2-year follow-up

INTRODUCTION

Peripheral artery occlusive disease (PAOD) has been reported to be prevalent in hemodialysis patients and influence their mortality. Ankle-brachial index (ABI) <0.9 is a reliable marker for PAOD. The aims of the 2-year longitudinal study were to assess whether there was a progression in PAOD and to find out the determinants of ABI progression in hemodialysis patients.

METHODS

This study enrolled 237 routine hemodialysis patients and 154 patients completed the 2-year follow-up. The ABI was measured by an ABI-form device at baseline and at the first and second year follow-up. The change in ABI (ΔABI) was defined as ABI measured at the second year follow-up minus ABI measured at baseline.

RESULTS

The prevalence of ABI <0.9 increased yearly (10.4%, 22.7% and 27.9%, respectively; P < 0.001) and the values of ABI decreased yearly (1.11 ± 0.16, 0.97 ± 0.17 and 0.96 ± 0.19, respectively; P < 0.001) in the 154 follow-up patients. Multiple stepwise analysis identified fasting glucose level, calcium-phosphorous product, high-sensitivity C-reactive protein and homocysteine level as independent determinants of ΔABI.

CONCLUSIONS

Our results demonstrated the prevalence of PAOD increased and the values of ABI decreased yearly in hemodialysis patients. The ABI progression was associated with high fasting glucose level, high calcium-phosphorous product, high-sensitivity C-reactive protein and low homocysteine levels.

Association of interleg BP difference with overall and cardiovascular mortality in hemodialysis

BACKGROUND AND OBJECTIVES

An interarm BP difference has been associated with atherosclerosis and adverse cardiovascular outcomes. This study investigated whether an interleg BP difference was associated with peripheral vascular disease and overall and cardiovascular mortality in hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study enrolled 210 hemodialysis patients from December 2006 to January 2007. Bilateral leg BPs were measured simultaneously by an ankle-brachial index (ABI)-form device before hemodialysis.

RESULTS

The mean follow-up period was 4.4±1.5 years. ABI <0.9 and high brachial-ankle pulse wave velocity were independently associated with an interleg difference in systolic BP of ≥15 mmHg or diastolic BP of ≥10 mmHg. Furthermore, this difference was an independent predictor for overall mortality (hazard ratio [HR], 3.36; 95% confidence interval [CI], 1.68-6.72; P<0.01) and cardiovascular mortality (HR, 4.84; 95% CI, 1.84-12.71; P<0.01) after adjustment for demographic, clinical, and biochemical parameters. After further adjustment for ABI <0.9 and brachial-ankle pulse wave velocity, the relation remained significant to overall mortality (HR, 2.91; 95% CI, 1.28-6.64; P=0.01) and cardiovascular mortality (HR, 3.15; 95% CI, 1.05-9.44; P=0.04).

CONCLUSIONS

A difference in systolic BP of ≥15 mmHg or diastolic BP of ≥10 mmHg between legs was associated with peripheral vascular disease and increased risk for overall and cardiovascular mortality in hemodialysis patients. Detection of an interleg BP difference may identify hemodialysis patients at increased risk of peripheral vascular disease and overall and cardiovascular mortality.

Factors affecting the patency of arteriovenous fistulas for dialysis access

BACKGROUND

The autologous arteriovenous fistula (AVF) is the accepted gold standard mode of repeated vascular access for hemodialysis in terms of access longevity, patient morbidity, and health care costs. This review assesses the current evidence supporting the role of various patient and surgeon factors on AVF patency.

METHODS

The literature was searched to identify the current evidence available for patient characteristics, methods of AVF planning, and anatomic factors that may affect patency outcomes after AVF formation. The use of adjuvant medications, surgical techniques, and policies for AVF maintenance are discussed in relation to AVF patency.

RESULTS

Current literature supports patient factors, such as increasing age, presence of diabetes, smoking, peripheral vascular disease, predialysis hypotension, and vessel characteristics, as directly influencing AVF patency. Vessels of small caliber (<2 mm) or demonstrating reduced distensibility are unlikely to create a functional AVF. Current evidence does not support altered patency due to sex or raised body mass index (<35 kg/m(2)). Factors such as early referral for AVF, preoperative ultrasound vessel mapping, use of vascular staples, and intraoperative flow measurements affected AVF patency, but the use of medical adjuvant therapies did not. Programs of surveillance and various needling techniques to maintain patency are not supported by current evidence. Novel techniques of infrared radiotherapy and topical glyceryl trinitrate are possible future strategies to increase AVF patency rates. The limitations of available evidence include a lack of large, randomized controlled trials and meta-analysis data to support current practice.

CONCLUSIONS

There is a complex interaction of factors that may affect the patency of an individual AVF. These need to be carefully considered when selecting surgical site or technique, adjuvant treatments, and follow-up protocols for AVFs.

Ankle--brachial index, vascular calcifications and mortality in dialysis patients

BACKGROUND

The ankle-brachial index (ABI) is a noninvasive method to evaluate peripheral artery disease (PAD). ABI <0.9 diagnoses PAD; ABI >1.3 is a false negative caused by noncompressible arteries. The aim of this study is to evaluate the association between ABI with vascular calcifications (VC) and with mortality, in haemodialysis (HD) patients.

METHODS

We studied 219 HD patients (60% male; 20% diabetic). At baseline, ABI was evaluated by a Doppler device. VCs were evaluated by two methods: the abdominal aorta calcification score (AACS) in a lateral plain X-ray of the abdominal aorta and the simple vascular calcification score (SVCS) in plain X-rays of the pelvis and hands. VC were also classified by their anatomical localization in main vessels (aorta and iliac-femoral axis) and in peripheral or distal vessels (pelvic, radial or digital). The cutoff values for the different VC scores in relation with ABI were determined by receiver operating characteristic curve analysis. Biochemical parameters were time averaged for the 6 months preceding ABI evaluation.

RESULTS

An ABI <0.9, an ABI >1.3 or a normal ABI were found, respectively, in 90 (41%), in 42 (19%) and in 87 (40%) patients. AACS ≥6 and SVCS >3 were found, respectively, in 98 (45%) and 95 (43%) patients. The adjusted odds ratio (OR) for having an ABI <0.9 was 2.5 (P = 0.007) for AACS ≥6 and 4.5 (P < 0.001) for iliac-femoral calcification score (CS) ≥2. The adjusted OR for having an ABI >1.3 was 4.2 (P = 0.003) for pelvic CS and 3.7 (P = 0.006) for hand CS ≥2. During an observational period of 28.9 months, all-cause and cardiovascular mortality occurred, respectively, in 50 (23%) and in 29 (13%) patients. Adjusting for age, diabetes, P levels, HD duration and cardiovascular disease at baseline, an ABI <0.9 [hazard ratio (HR) = 3.9, P < 0.001] and an ABI >1.3 (HR = 2.7, P = 0.038) were associated with all-cause mortality; an ABI <0.9 (HR = 7.2, P = 0.002) and an ABI >1.3 (HR = 5.1, P = 0.028) were associated with cardiovascular mortality.

CONCLUSIONS

Both low and high ABI were independent predictors of all-cause and cardiovascular mortality. VC in main arteries were associated with an ABI <0.9. VC in peripheral and distal arteries were associated with an ABI >1.3. ABI is a simple and noninvasive method that allows the identification of high cardiovascular risk patients.

Surrogate markers of cardiovascular disease in CKD: what's under the hood?

Although clinical cardiovascular outcomes, such as heart attack, stroke, and sudden cardiac death, have a dramatic onset, they result from prolonged exposure to an ever-growing array of risk factors. Several noninvasive procedures are available to assess the cumulative effect of these exposures with the goal of more precisely estimating a person's cardiovascular risk. These include ankle-brachial index, which provides an estimation of obstruction in major-vessel lumen caliber; carotid ultrasound, which evaluates carotid intima-media thickness and plaque, visibly quantifying atherosclerotic burden; aortic pulse wave velocity, which provides a measure of large-artery stiffness; and echocardiography, which measures left ventricular mass, providing a measure of subclinical hypertensive heart disease. In this narrative review, we discuss the role of each of these measures, with a particular emphasis on patients with chronic kidney disease.

The Association Between Ankle-Brachial Index and Quality of Life in Chronic Hemodialysis Patients

Ankle-brachial index (ABI) is an important indicator of peripheral arterial disease (PAD) and PAD has a negative impact on quality of life (QOL). However, the correlation between ABI and QOL is unknown among chronic hemodialysis patients. Ankle-brachial index was measured, and WHOQOL-BRIEF (TW) questionnaire was completed. The association between ABI and QOL was analyzed using linear regression. A total of 54 chronic hemodialysis patients (mean age of 56.2 ± 14.6 years) were included. Ankle-brachial index was positively associated with QOL (r = .448, P = .001). The QOL scores were 3.1 ± 2.9 and 2.6 ± 0.4 for 37 patients with an ABI more than 0.9 and 17 patients with an ABI less than 0.9 or more than 1.3 (p < .001). In linear regression, only ABI was significantly associated with QOL scores with a β of .448 (95% CI: 0.443 to 1.55, P = .001). Ankle-brachial index is positively correlated to QOL among chronic hemodialysis patients.