Peripheral Arterial Disease: A Guide for Nephrologists

Peripheral Non-Contrast MR Angiography Using FBI: Scan Time and T2 Blurring Reduction with 2D Parallel Imaging

Non-contrast magnetic resonance angiography (NC-MRA), including fresh blood imaging (FBI), is a suitable choice for evaluating patients with peripheral artery disease (PAD). We evaluated standard FBI (sFBI) and centric ky-kz FBI (cFBI) acquisitions, using 1D and 2D parallel imaging factors (PIFs) to assess the trade-off between scan time and image quality due to blurring. The bilateral legs of four volunteers (mean age 33 years, two females) were imaged in the coronal plane using a body array coil with a posterior spine coil. Two types of sFBI and cFBI sequences with 1D PIF factor 5 in the phase encode (PE) direction (in-plane) and 2D PIF 3 (PE) × 2 (slice encode (SE)) (in-plane, through-slice) were studied. Image quality was evaluated by a radiologist, the vessel's signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured, and major vessel width was measured on the coronal maximum intensity projection (MIP) and 80-degree MIP. Results showed significant time reductions from 184 to 206 s on average when using sFBI down to 98 to 162 s when using cFBI (p = 0.003). Similar SNRs (averaging 200 to 370 across all sequences and PIF) and CNRs (averaging 190 to 360) for all techniques (p > 0.08) were found. There was no significant difference in the image quality (averaging 4.0 to 4.5; p > 0.2) or vessel width (averaging 4.1 to 4.9 mm; p > 0.1) on coronal MIP due to sequence or PIF. However, vessel width measured using 80-degree MIP demonstrated a significantly wider vessel in cFBI (5.6 to 6.8 mm) compared to sFBI (4.5 to 4.7 mm) (p = 0.022), and in 1D (4.7 to 6.8 mm) compared to 2D (4.5 to 5.6 mm) (p < 0.05) PIF. This demonstrated a trade-off in T2 blurring between 1D and 2D PIF: 1D using a PIF of 5 shortened the acquisition window, resulting in sharper arterial blood vessels in coronal images but significant blur in the 80-degree MIP. Two-dimensional PIF for cFBI provided a good balance between shorter scan time (relative to sFBI) and good sharpness in both in- and through-plane, while no benefit of 2D PIF was seen for sFBI. In conclusion, this study demonstrated the usefulness of FBI-based techniques for peripheral artery imaging and underscored the need to strike a balance between scan time and image quality in different planes through the use of 2D parallel imaging.

Fast Non-contrast MR Angiography Using a Zigzag Centric ky - kz k-space Trajectory and Exponential Refocusing Flip Angles with Restoration of Longitudinal Magnetization

PURPOSE

Fresh blood imaging (FBI) utilizes physiological blood signal differences between diastole and systole, causing a long acquisition time. The purpose of this study is to develop a fast FBI technique using a centric ky - kz k-space trajectory (cFBI) and an exponential refocusing flip angle (eFA) scheme with fast longitudinal restoration.

METHODS

This study was performed on 8 healthy subjects and 2 patients (peripheral artery disease and vascular disease) with informed consent, using a clinical 3-Tesla MRI scanner. A numeric simulation using extended phase graph (EPG) and phantom studies of eFA were carried out to investigate the restoration of longitudinal signal by lowering refocusing flip angles in later echoes. cFBI was then acquired on healthy subjects at the popliteal artery station to assess the effect of varying high/low flip ratios on the longitudinal restoration effects. In addition, trigger-delays of cFBI were optimized owing to the long acquisition window in zigzag centric ky - kz k-space trajectory. After optimizations, cFBI images were compared against standard FBI (sFBI) images in terms of scan time, motion artifacts, Nyquist N/2 artifacts, blurring, and overall image quality. We also performed two-way repeated measures analysis of variance.

RESULTS

cFBI with eFA achieved nearly a 50% scan time reduction compared to sFBI. The high/low flip angle of 180/2 degrees with lower refocusing pulses shows fast longitudinal restoration with the highest blood signals, yet also more sensitive to the background signals. Overall, 180/30 degrees images show reasonable blood signal recovery while minimizing the background signal artifacts. After the trigger delay optimization, maximum intensity projection image of cFBI after systole-diastole subtraction demonstrates less motion and N/2 artifacts than that of sFBI.

CONCLUSION

Together with eFA for fast longitudinal signal restoration, the proposed cFBI technique achieved a 2-fold reduction in scan time and improved image quality without major artifacts.

The Characteristics of Dialysis Membranes: Benefits of the AN69 Membrane in Hemodialysis Patients

Patients undergoing hemodialysis (HD) experience serious cardiovascular complications, through malnutrition, inflammation, and atherosclerosis. Amputation for peripheral arterial disease (PAD) is more prevalent in patients undergoing HD than in the general population. In addition, revascularization procedures in dialysis patients are often associated with subsequent amputation and high mortality rates. To improve the prognosis of dialysis patients, malnutrition and inflammation must be properly treated, which necessitates a better understanding of the characteristics of dialysis membranes. Herein, the characteristics of several dialysis membranes were studied, with a special reference to the AN69 membrane, noting several similarities to low-density lipoprotein (LDL)-apheresis, which is also applicable for the treatment of PAD. Both systems (LDL-apheresis and AN69) have anti-inflammatory and anti-thrombogenic effects because they use a negatively charged surface for extracorporeal adsorptive filtration from the blood/plasma, and contact phase activation. The concomitant use of both these therapeutic systems may have additive therapeutic benefits in HD patients. Here, we reviewed the characteristics of dialysis membranes and benefits of the AN69 membrane in dialysis patients.

Excess all-cause and cause-specific mortality for people with diabetes and end-stage kidney disease

AIMS

Excess mortality is high in the setting of diabetes and end-stage kidney disease (ESKD), but the effects of ESKD beyond diabetes itself remains incompletely understood. We examined excess mortality in people with diabetes with versus without ESKD, and variation by age, sex and diabetes type.

METHODS

This study included 63,599 people with type 1 (aged 20-69 years; 56% men) and 1,172,160 people with type 2 diabetes (aged 30+ years; 54% men), from the Australian National Diabetes Services Scheme. Initiation of renal replacement therapy and mortality outcomes were obtained via linkage to the Australia and New Zealand Dialysis and Transplant Registry and the National Death Index, respectively. Excess mortality was measured by calculating the mortality rate ratio (MRR) for people with versus without ESKD via indirect standardisation.

RESULTS

A total of 9027 people developed ESKD during 8,601,522 person-years of follow-up. Among people with type 1 diabetes, the MRR was 34.9 (95%CI: 16.6-73.1) in men and 41.5 (20.8-83.1) in women aged 20-29 years and was 5.6 (4.5-7.0) and 7.4 (5.5-10.1) in men and women aged 60-69 years, respectively. In type 2 diabetes, MRRs were 16.6 (8.6-31.8) and 35.8 (17.0-75.2) at age 30-39 years and were 2.8 (2.6-3.1) and 3.6 (3.2-4.1) at age 80+ years in men and women, respectively. Excess cause-specific mortality was highest for peripheral artery disease, cardiac arrest, and infections, and lowest for cancer.

CONCLUSIONS

Among people with diabetes, excess mortality in ESKD is much higher at younger ages and is higher for women compared with men.

Positive Correlation of Serum Resistin Level with Peripheral Artery Disease in Patients with Chronic Kidney Disease Stage 3 to 5

Chronic kidney disease (CKD) is associated with higher risk of cardiovascular disease-related ischemic events, which includes peripheral arterial disease (PAD). PAD is a strong predictor of future cardiovascular events, which can cause significant morbidity and mortality. Resistin has been found to be involved in pathological processes leading to CVD. Therefore, we aim to investigate whether resistin level is correlated with PAD in patients with non-dialysis CKD stage 3 to 5. There were 240 CKD patients enrolled in this study. Ankle-brachial index (ABI) values were measured using the automated oscillometric method. An ABI value < 0.9 defined the low ABI group. Serum levels of human resistin were determined using a commercially available enzyme immunoassay. Thirty CKD patients (12.5%) were included in the low ABI group. Patients in the low ABI group were older and had higher resistin levels as well as higher diabetes mellitus, hypertension and habit of smoking, and lower estimated glomerular filtration rate than patients in the normal ABI group. After the adjustment for factors that were significantly associated with PAD by multivariate logistic regression analysis, age and serum resistin level were independent predictors of PAD. A high serum resistin level is an independent predictor of PAD in non-dialysis CKD stage 3 to 5.

Risk associated with estimated glomerular filtration rate and albuminuria for PAD among patients with type 2 diabetes

Chronic kidney disease (CKD) is significantly associated with peripheral arterial disease (PAD) in some studies, but data on the association of the risk of PAD across a broad range of kidney function in patients with type 2 diabetes are limited. Between October 17, 2013 and February 7, 2015, all consecutive outpatients with type 2 diabetes underwent ankle-brachial index (ABI) examination. We investigated the association of estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR) with the risk of PAD. A total of 1254 patients were cross-classified into 12 groups based on ACR category (normoalbuminuria, microalbuminuria and macroalbuminuria) and eGFR stage (≥90, 60-89, 30-59 and <30 mL/min/1.73 m²). Logistic regression analysis was used to investigate the association of eGFR and ACR with PAD. Within each ACR category, a lower eGFR stage was associated with PAD. Similarly, within each eGFR group, a higher ACR category was also associated with PAD. The OR for PAD was highest in patients with eGFR <30 mL/min/1.73 m² and macroalbuminuria (OR 14.42, 95% CI 4.60 to 45.31) when compared with the reference group of subjects with eGFR ≥90 mL/min/1.73 m² and normoalbuminuria. Our study found that cross-classification of eGFR with ACR revealed a more comprehensive association with risk of PAD than eGFR or ACR alone.

Predictive value of ankle-brachial index for long-term events of ischemic stroke in hemodialysis patients

OBJECTIVES

The ankle-brachial index is a noninvasive modality to evaluate atherosclerosis and is a predictive role for future cardiovascular events and mortality. However, few studies have evaluated its relation to long-term future ischemic stroke in hemodialysis patients. Therefore, we examined the relationship between ankle-brachial index and ischemic stroke events among hemodialysis patients in a seven-year follow-up.

METHODS

A total of 84 patients were enrolled. Ankle-brachial index was assessed in January 2009. Primary outcomes included ischemic stroke. An ankle-brachial index < 0.9 was considered abnormal and 1.4 ≥ ankle-brachial index ≥ 0.9 to be normal ankle-brachial index.

RESULTS

Mean values for ankle-brachial index were 0.98 ± 0.21at study entrance. In addition, 28 patients encountered ischemic stroke in the seven-year follow-up. In univariate Cox regression analysis, old age (hazard ratio (HR): 1.065, 95% confidence interval (CI): 1.030-1.102, p < 0.001), low seven-year averaged serum phosphate levels (HR: 0.473, 95% CI: 0.306-0.730, p = 0.001), and abnormal ankle-brachial index (HR: 0.035, 95% CI: 0.009-0.145, p < 0.001) were risk factors for ischemic stroke. In multivariate Cox regression analysis for significant variables in univariate analysis, abnormal ankle-brachial index (HR: 0.058, 95% CI: 0.012-0.279, p < 0.001) and low seven-year averaged serum phosphate levels (HR: 0.625, 95% CI: 0.404-0.968, p = 0.035) remained the risk factors for ischemic stroke. The risk of ischemic stroke was 3.783-fold in patients with abnormal ankle-brachial index compared with patients with normal ankle-brachial index (HR: 3.783, 95% CI: 1.731-8.269, p = 0.001).

CONCLUSIONS

These findings suggest that ankle-brachial index is an impressive predictor of future ischemic stroke among hemodialysis patients.

Potential of mesenchymal stem cells for bioengineered blood vessels in comparison with other eligible cell sources

Application of stem cells in tissue engineering has proved to be effective in many cases due to great proliferation and differentiation potentials as well as possible paracrine effects of these cells. Human mesenchymal stem cells (MSCs) are recognized as a valuable source for vascular tissue engineering, which requires endothelial and perivascular cells. The goal of this review is to survey the potential of MSCs for engineering functional blood vessels in comparison with other cell types including bone marrow mononuclear cells, endothelial precursor cells, differentiated adult autologous smooth muscle cells, autologous endothelial cells, embryonic stem cells, and induced pluripotent stem cells. In conclusion, MSCs represent a preference in making autologous tissue-engineered vascular grafts (TEVGs) as well as off-the-shelf TEVGs for emergency vascular surgery cases.

Prevalence of foot ulcers in dialysis-dependent patients

Hemodialysis patients are at high risk for foot ulceration. The aim of this prospective study was to describe the prevalence and risk factors for foot ulcers in hemodialysis-dependent patients. From 2012 until 2015, all hemodialysis patients (n = 66) above18 years of age, treated at the Alrijne Hospital (Leiderdorp, the Netherlands), were included. Demographics and medical history were collected and the quality of life was measured. Data were collected on common risk factors for foot ulceration: peripheral arterial disease, peripheral neuropathy with or without foot deformities, diabetes mellitus (DM), hypertension, smoking, previous foot ulcer, edema, pedicure attendance, and orthopedic footwear. Sixty-six hemodialysis patients were evaluated; the prevalence of foot ulcer was 21/66 (31.8%). Risk factors were history of foot ulceration in 27/66 (40.9%), ankle-brachial index (ABI) <0.9, and toe pressure < 80 mmHg in 38/66 (57.6%). The percentage of DM in the group of foot-ulcers was higher 13/21 (61.9%) vs. 20/45 (44.4%) in the non-ulcer group, this was not significant (p = 0.183). No differences were found in ABI, toe pressure, peripheral neuropathy and foot deformity, between the DM and non DM group. The mortality between ulcer vs. no ulcer was significant different: 13/21 (61.9%) vs. 11/45 (24.4%) (p = 0.003). Approximately, one-third of hemodialysis patient have a foot ulcer 21/66 (32%). Arterial insufficiency is associated with an increased risk of foot ulcers. In patients with a foot ulcer, survival is significantly lower than in patients without a foot ulcer; interventions to reduce foot ulceration should be implemented for all hemodialysis patients and include frequent inspection, and prompt treatment. Further research should focus on the prevention of foot ulcers in dialysis-dependent patients.

Unique aspects of peripheral artery disease in patients with chronic kidney disease

Peripheral artery disease (PAD) represents a major health care burden. Despite the advent of screening and interventional procedures, the long-term clinical outcomes remain suboptimal, especially in patients with chronic kidney disease (CKD). While CKD and PAD share common predisposing factors, emerging studies indicate that their co-existence is not merely an association; instead, CKD represents a strong, independent risk factor for PAD. These findings implicate CKD-specific mediators of PAD that remain incompletely understood. Moreover, there is a need to understand the mechanisms underlying poor outcomes after interventions for PAD in CKD. This review discusses unique clinical aspects of PAD in patients with CKD, including high prevalence and worse outcomes after vascular interventions and the influence of renal allograft transplantation. In doing so, it also highlights underappreciated aspects of PAD in patients with CKD, such as disparities in revascularization and higher peri-procedural mortality. While previous reviews have discussed general mechanisms of PAD pathogenesis, focusing on PAD in CKD, this review underscores a need to probe for CKD-specific pathogenic pathways that may unravel novel biomarkers and therapeutic targets in PAD and ultimately improve the risk stratification and management of patients with CKD and PAD.

Exercise-stimulated arterial transit time in calf muscles measured by dynamic contrast-enhanced magnetic resonance imaging

The primary goal of this study was to evaluate arterial transit time (ATT) in exercise-stimulated calf muscles as a promising indicator of muscle function. Following plantar flexion, ATT was measured by dynamic contrast-enhanced (DCE) MRI in young and elderly healthy subjects and patients with peripheral artery disease (PAD). In the young healthy subjects, gastrocnemius ATT decreased significantly (P < 0.01) from 4.3 ± 1.5 to 2.4 ± 0.4 sec when exercise load increased from 4 lbs to 16 lbs. For the same load of 4 lbs, gastrocnemius ATT was lower in the elderly healthy subjects (3.2 ± 1.1 sec; P = 0.08) and in the PAD patients (2.4 ± 1.2 sec; P = 0.02) than in the young healthy subjects. While the sensitivity of the exercise-stimulated ATT is diagnostically useful, it poses a challenge for arterial spin labeling (ASL), a noncontrast MRI method for measuring muscle perfusion. As a secondary goal of this study, we assessed the impact of ATT on ASL-measured perfusion with ASL data of multiple post labeling delays (PLDs) acquired from a healthy subject. Perfusion varied substantially with PLD in the activated gastrocnemius, which can be attributed to the ATT variability as verified by a simulation. In conclusion, muscle ATT is sensitive to exercise intensity, and it potentially reflects the functional impact of aging and PAD on calf muscles. For precise measurement of exercise-stimulated muscle perfusion, it is recommended that ATT be considered when quantifying muscle ASL data.

Abnormalities of vascular histology and collagen fiber configuration in patients with advanced chronic kidney disease

INTRODUCTION:

Several histologic features have been identified in the upper-extremity arteries and veins of patients with advanced chronic kidney disease, which may affect arteriovenous fistula maturation. However, it is unclear whether these chronic kidney disease vascular features are abnormal.

METHODS:

We obtained upper-extremity arterial and venous specimens from 125 advanced chronic kidney disease patients undergoing arteriovenous fistula creation and from 15 control subjects. We quantified medial fibrosis, micro-calcification, and intimal hyperplasia with appropriate histology stains. We characterized medial collagen fiber configuration in second-harmonic-generation microscopy images for the fiber anisotropy index and the dominant fiber direction.

RESULTS:

The advanced chronic kidney disease patients were significantly younger than control subjects (53 ± 14 years vs 76 ± 11 years, p < 0.001). After controlling for age, the chronic kidney disease patients had greater arterial medial fibrosis (69% ± 14% vs 51% ± 10%, p < 0.001) and greater arterial micro-calcification (3.03% ± 5.17% vs 0.01% ± 0.03%, p = 0.02), but less arterial intimal thickness (30 ± 25 µm vs 63 ± 25 µm, p < 0.001), as compared to control subjects. The anisotropy index of medial collagen fibers was lower in both arteries (0.24 ± 0.10 vs 0.44 ± 0.04, p < 0.001) and veins (0.28 ± 0.09 vs 0.53 ± 0.10, p < 0.001) in chronic kidney disease patients, indicating that orientation of the fibers was more disordered. The dominant direction of medial collagen fibers in chronic kidney disease patients was greater in the arteries (49.3° ± 23.6° vs 4.0° ± 2.0°, p < 0.001) and the veins (30.0° ± 19.6° vs 3.9° ± 2.1°, p < 0.001), indicating that the fibers in general were aligned more perpendicular to the lumen.

CONCLUSION:

Advanced chronic kidney disease is associated with several abnormalities in vascular histology and collagen fiber configuration. Future research is needed to investigate whether these abnormalities affect the maturation outcomes of arteriovenous fistulas.

Leveraging the Electronic Health Record to Create an Automated Real-Time Prognostic Tool for Peripheral Arterial Disease

Background Automated individualized risk prediction tools linked to electronic health records ( EHR s) are not available for management of patients with peripheral arterial disease. The goal of this study was to create a prognostic tool for patients with peripheral arterial disease using data elements automatically extracted from an EHR to enable real-time and individualized risk prediction at the point of care. Methods and Results A previously validated phenotyping algorithm was deployed to an EHR linked to the Rochester Epidemiology Project to identify peripheral arterial disease cases from Olmsted County, MN, for the years 1998 to 2011. The study cohort was composed of 1676 patients: 593 patients died over 5-year follow-up. The c-statistic for survival in the overall data set was 0.76 (95% confidence interval [CI], 0.74-0.78), and the c-statistic across 10 cross-validation data sets was 0.75 (95% CI, 0.73-0.77). Stratification of cases demonstrated increasing mortality risk by subgroup (low: hazard ratio, 0.35 [95% CI, 0.21-0.58]; intermediate-high: hazard ratio, 2.98 [95% CI, 2.37-3.74]; high: hazard ratio, 8.44 [95% CI, 6.66-10.70], all P<0.0001 versus the reference subgroup). An equation for risk calculation was derived from Cox model parameters and β estimates. Big data infrastructure enabled deployment of the real-time risk calculator to the point of care via the EHR . Conclusions This study demonstrates that electronic tools can be deployed to EHR s to create automated real-time risk calculators to predict survival of patients with peripheral arterial disease. Moreover, the prognostic model developed may be translated to patient care as an automated and individualized real-time risk calculator deployed at the point of care.

Alprostadil treatment of critical limb ischemia in hemodialysis patients : A retrospective single-center analysis

BACKGROUND

Peripheral artery disease and critical limb ischemia are common in patients undergoing chronic hemodialysis treatment and are associated with a high rate of amputation and mortality. The effect of treatment with prostanoids in this specific group of patients is unknown.

METHODS

A retrospective single-center analysis of hemodialysis patients with critical limb ischemia was performed who were treated with the prostanoid analogue alprostadil as an infusion during hemodialysis in the period from 2000 to 2013. The primary study outcome was a combined end-point including amputation and death 1 year after start of alprostadil. Kaplan-Meier curves were used to describe amputation-free survival and overall survival. A multivariable adjusted Cox proportional hazards model was calculated for the primary outcome.

RESULTS

A total of 86 patients (60 males, 69.7%) were studied. The median alprostadil treatment period was 1.8 months. The 1‑year amputation-free survival was 41%. In 36% of patients an amputation was necessary and 35% died. Despite alprostadil treatment, 36% of the study patients additionally underwent an endovascular procedure and 16% had bypass surgery. Men had a significantly higher amputation rate (45%) than women (15%) (P = 0.009). Male sex and dialysis vintage were significantly associated with an increased risk for primary outcome CONCLUSIONS: Despite treatment with alprostadil the mortality, amputation rate and the need for revascularization procedures in hemodialysis patients with critical limb ischemia remained high. The outcome, however, was comparable with that of other treatment, such as endovascular procedures and bypass surgery. The effect of any current treatment strategy on amputation rate or mortality in that patient group remains uncertain.

Assessment of Renal Function and Risk Factors for Chronic Kidney Disease in Patients With Peripheral Arterial Disease

Chronic kidney disease (CKD) and peripheral arterial disease (PAD) share common risk factors. We assessed renal function and the prevalence of CKD in patients with PAD and investigated the characteristics of the risk factors for CKD in this population. Renal function of 421 patients with PAD was evaluated. Among the participants, 194 (46.1%) patients had decreased estimated glomerular filtration rate (eGFR). The prevalence of CKD was much higher among patients with PAD. Hypertension (odds ratios [ORs] 2.156, 95% confidence interval [CI] 1.413-3.289, P < .001), serum uric acid (OR 3.794, 95% CI 2.220-6.450, P < .001), and dyslipidemia (OR 1.755, 95% CI 1.123-2.745, P = .014) were significantly associated with CKD and the independent risk factors for CKD in patients with PAD. CKD is common and has a high prevalence in a population with PAD. Patients with PAD may be considered as a high-risk population for CKD. Recognition and modification of risk factors for CKD might beneficially decrease CKD incidence and improve prognosis in patients with PAD.

Traditional and non-traditional risk factors for incident peripheral arterial disease among patients with chronic kidney disease

BACKGROUND

The risk of peripheral arterial disease (PAD) is higher in patients with chronic kidney disease (CKD) compared with those without. However, reasons for this increased risk are not fully understood.

METHODS

We studied risk factors for incident PAD among 3169 participants in the Chronic Renal Insufficiency Cohort (CRIC) Study. Patients with CKD aged 21-74 years were recruited between 2003 and 2008 and followed for a median of 6.3 years. Incident PAD was defined as a new onset ankle-brachial index (ABI) of <0.9 or confirmed clinical PAD.

RESULTS

In a multivariate-adjusted model, older age, female sex, non-Hispanic Black, current smoking, diabetes, higher pulse pressure, lower high-density lipoprotein cholesterol, higher low-density lipoprotein cholesterol, and lower estimated glomerular filtration rate were significantly associated with the increased risk of incident PAD. After adjustment for these traditional risk factors as well as use of medications and CRIC Study clinic sites, the following baseline novel risk factors were significantly associated with risk of incident PAD [hazard ratio and 95% confidence interval (CI) for a one standard deviation (SD) higher level]: log[C-reactive protein (CRP)] (1.16, 1.06-1.25, P < 0.001), white blood cell count (1.09, 1.01-1.18, P = 0.03), fibrinogen (1.15, 1.06-1.26, P = 0.002), log(myeloperoxidase) (1.12, 1.03-1.23, P = 0.01), uric acid (0.88, 0.80-0.97, P = 0.01), glycated hemoglobin (1.16, 1.05-1.27, P = 0.003), log(homeostatic model assessment-insulin resistance) (1.21, 1.10-1.32, P < 0.001) and alkaline phosphatase (1.15, 1.07-1.24, P < 0.001).

CONCLUSIONS

Among patients with CKD, inflammation, prothrombotic state, oxidative stress, glycated hemoglobin, insulin resistance and alkaline phosphatase are associated with an increased risk of PAD, independent of traditional risk factors.

Epoetin beta pegol prevents endothelial dysfunction as evaluated by flow-mediated dilation in chronic kidney disease rats

Chronic kidney disease (CKD) patients have a poor prognosis due to cardiovascular disease. Anemia and endothelial dysfunction are important risk factors for cardiovascular events in CKD patients, and treatment with erythropoiesis-stimulating agent (ESA) has been reported to improve the quality of life in CKD patients. In this study, we evaluated the effect of anemia correcting dose of epoetin beta pegol (continuous erythropoietin receptor activator; C.E.R.A.) on endothelial function in 5/6 nephrectomized rats (Nx rats). C.E.R.A. was subcutaneously administered once a fortnight, 5 times in total, from 1 week after nephrectomy. Twenty-four hours after last administration, endothelial function was evaluated by measuring flow-mediated dilation (FMD) in the femoral arteries of anesthetized Nx rats by ultrasound system. Femoral arteries were harvested for western blot analysis. C.E.R.A. significantly increased FMD of Nx rats. Endothelium-independent vasodilation induced by nitroglycerin injection was not influenced by C.E.R.A treatment. Nox4 expression and nitrotyrosine accumulation were significantly decreased, and phosphorylation of eNOS was significantly enhanced in the femoral arteries of C.E.R.A.-treated rats. C.E.R.A. normalized hemoglobin levels but did not affect body weight, systolic blood pressure, heart rate, urinary protein excretion and plasma creatinine. These results indicate that C.E.R.A. prevented endothelial dysfunction in Nx rats, possibly through reduction of local oxidative stress and enhancement of eNOS phosphorylation in the arteries. This study provides the first evidence that C.E.R.A. prevented endothelial dysfunction in CKD model rats under conditions of amelioration of anemia.

Anti-platelet factor 4/heparin antibody is associated with progression of peripheral arterial disease in hemodialysis patients

BACKGROUND

Heparin therapy may induce anti-platelet factor 4/heparin antibody (PF4-H Ab). Hemodialysis patients receive scheduled heparin and are at a risk of developing PF4-H Ab. Hemodialysis patients are also at a high risk of peripheral arterial disease (PAD). This study examines whether chronic PF4-H Ab exposure contributes to the progression of PAD measured by ankle brachial index (ABI) in hemodialysis patients.

MATERIALS AND METHODS

A total of 71 hemodialysis patients were enrolled, and the association between clinical, biochemical parameters and ABI after 3 years was studied. PF4-H Ab was evaluated by ELISA, and patients with titer ≥ 0.4 were taken as having PF4-H Ab.

RESULTS

Mean ABI was 1.04 ± 0.18 at baseline and 1.01 ± 0.17 after 3 years. Mean ΔABI (change in ABI after 3 years) was -0.04 ± 0.13. PF4-H Ab was positive in 26 patients. PF4-H Ab was not related to hemodialysis duration, DM history, smoking and age. Platelet count showed no correlation with PF4-H Ab. However, there was significance in ΔABI between PF4-H Ab-positive and PF4-H Ab-negative patients (p = 0.002). ΔABI was negatively correlated with PF4-H Ab and 3-year averaged serum Ca × P only (β = -0.378, p = 0.001; β = -0.263, p = 0.018, respectively). However, in PF4-H Ab-positive patients, the extent of ΔABI did not correlate with PF4-H Ab titers (r = -0.021, p = 0.921).

CONCLUSIONS

PF4-H Ab positivity, along with high levels of serum Ca × P, played a potential role in the progression of PAD over time.

Ankle-brachial blood pressure index predicts cardiovascular events and mortality in Japanese patients with chronic kidney disease not on dialysis

The ankle-brachial blood pressure index (ABPI) has been recognized to have a predictive value for cardiovascular (CV) events and mortality in general or dialysis populations. However, the associations between ABPI and those outcomes have not been fully investigated in predialysis patients. The present study aimed to clarify the relationships between ABPI and both CV events and mortality in Japanese chronic kidney disease (CKD) patients not on dialysis. In this prospective observational study, we enrolled 320 patients with CKD stages 3-5 who were not on dialysis. At baseline, ABPI was examined and a low ABPI was defined as <0.9. CV events and all-cause deaths were examined in each patient. A Cox proportional hazards model was applied to determine the risk factors for CV events, as well as for mortality from CV and all causes. The median follow-up period was 30 months. CV events occurred in 56 patients and all-cause deaths occurred in 48, including 20 CV deaths. Multivariate analysis showed that age and low ABPI were risk factors for CV events. It was demonstrated that age, a history of cerebrovascular disease and low ABPI were determined as independent risk factors for CV mortality. In addition, age, body mass index and low ABPI were independently associated with all-cause mortality. In patients with CKD, low ABPI during the predialysis period is independently associated with poor survival and CV events, suggesting the usefulness of measuring ABPI for predicting CV events and patient survival in CKD.

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.

Diagnosis and treatment of peripheral arterial disease in CKD patients

Peripheral arterial disease (PAD) is a cardiovascular disease risk equivalent and is a common problem in chronic kidney disease patients. Unlike in the general population, PAD in CKD occurs due to medial calcification as opposed to intimal atherosclerotic process. PAD intervention should be performed in select symptomatic patients, as described by the guidelines, and CVD risk factor modification should occur in all CKD patient, regardless of the presence of PAD. As a discipline, Interventional Nephrology has emerged out of a desire to create better outcomes for our patients and to "fix a problem." The core values of our discipline have evolved out of this fundamental desire to meet an unmet clinical need, to provide insight into a disease state specific to our patients, and to offer clinical/academic excellence in doing so. We must endeavor to follow a similar path in our approach to PAD. The purpose of this review is to educate interventional nephrologists in the diagnosis and treatment of PAD in their CKD patients.

Prevalence of risk factors for foot ulceration in a general haemodialysis population

It is well documented that diabetic foot ulceration contributes to increased morbidity and mortality associated with renal replacement therapy. Much less is known about the risk of foot ulceration and lower limb amputation in the non-diabetic dialysis population. The aim of this study was to determine if the prevalence of risks factors for lower limb amputation in a stable haemodialysis population was greater in the diabetic cohort compared with the non-diabetic cohort. The study design is a prospective observational cohort study. Sixty patients attending a satellite haemodialysis unit in Cardiff were invited to have a comprehensive foot assessment as part of a Podiatry service review. The medical notes and hospital information system were used to identify the diabetic cohort. Patients were classified according to diabetic status (diabetic versus non-diabetic). The Renal Foot Screening Tool was developed to prospectively identify risk factors associated with foot ulceration. The assessment included peripheral neuropathy (PN), peripheral arterial disease (PAD) and foot pathology (FP). Fifty-seven patients gave informed verbal consent prior to inclusion. Risk factors for foot ulceration were recorded at baseline in the diabetic (n = 24) and non-diabetic (n = 33) groups and mortality data was revisited after a 3-year period. FP was identified in 79% of patients. Eighteen per cent of the non-diabetic patients had PN. PAD was identified in 45% of diabetic and 30% of non-diabetic patients. Forty-nine per cent of the total cohort had ≥2 of the 3 independent risk factors for foot ulceration (16/24 diabetic versus 12/33 non-diabetic). The presence of PAD and PN was predictive of mortality independent of age. The limitations of this study are its small sample size and patients were from a single satellite dialysis unit. There was a high prevalence of risk factors for foot ulceration in this population, which were not confined to the diabetic cohort. These findings suggest that non-diabetic patients on haemodialysis therapy are also at risk of developing foot ulceration. Further work on strategies to monitor and prevent FP in this high-risk cohort is needed to minimize morbidity and mortality associated with foot ulceration.

Risk factors for peripheral arterial disease among patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have an increased risk for developing peripheral arterial disease (PAD). The aim of this study was to examine the cross-sectional association between novel risk factors and prevalent PAD in patients with CKD. A total of 3,758 patients with estimated glomerular filtration rates of 20 to 70 ml/min/1.73 m(2) who participated in the Chronic Renal Insufficiency Cohort (CRIC) study were included in the present analysis. PAD was defined as an ankle-brachial index <0.9 or a history of arm or leg revascularization. After adjustment for age, gender, race, cigarette smoking, physical activity, history of hypertension and diabetes, pulse pressure, high-density lipoprotein cholesterol, estimated glomerular filtration rate, and CRIC clinical sites, several novel risk factors were significantly associated with PAD. For example, odds ratios for a 1-SD higher level of risk factors were 1.18 (95% confidence interval [CI] 1.08 to 1.29) for log-transformed high-sensitivity C-reactive protein, 1.18 (95% CI 1.08 to 1.29) for white blood cell count, 1.15 (95% CI 1.05 to 1.25) for fibrinogen, 1.13 (95% CI 1.03 to 1.24) for uric acid, 1.14 (95% CI 1.02 to 1.26) for glycosylated hemoglobin, 1.11 (95% CI 1.00 to 1.23) for log-transformed homeostasis model assessment of insulin resistance, and 1.35 (95% CI 1.18 to 1.55) for cystatin C. In conclusion, these data indicate that inflammation, prothrombotic state, oxidative stress, insulin resistance, and cystatin C were associated with an increased prevalence of PAD in patients with CKD. Further studies are warranted to examine the causal effect of these risk factors on PAD in patients with CKD.

Plasma S100A12 levels and peripheral arterial disease in end-stage renal disease

Background

S100A12 is an endogenous ligand of the receptor for advanced glycation end products (RAGE). Plasma S100A12 levels are high in end-stage renal disease (ESRD) patients undergoing maintenance hemodialysis (HD). Peripheral arterial disease (PAD) is common in HD patients and is associated with increased cardiovascular morbidity and mortality rates in this population. To date, however, no study has specifically assessed the relationship between plasma S100A12 and PAD in HD patients.

Methods

We conducted a cross-sectional study of 152 HD patients in our affiliated hospital. We investigated PAD history and patient characteristics and quantified plasma S100A12 levels in all participants.

Results

HD patients with PAD (n = 26; 21.9 [13.6–33.4] ng/ml) showed significantly higher plasma S100A12 levels than HD patients without PAD (n = 126; 11.8 [7.5–17.6]ng/ml; p < 0.001). In multivariate logistic regression analysis, the plasma S100A12 level (odds ratio [OR] 5.71; 95% confidence interval [CI] 1.29–25.3; p = 0.022) was identified as an independent factor associated with PAD prevalence. Another factor associated with PAD prevalence was the ankle-brachial index (OR 0.54; 95% CI 0.40–0.74; p < 0.001).

Conclusion

These results suggest that plasma S100A12 levels are strongly associated with PAD prevalence in ESRD patients undergoing HD.

Effect of darbepoetin alfa on endothelial progenitor cells and vascular reactivity in chronic kidney disease

Endothelial progenitor cells (EPCs) are thought to be important for maintaining normal vascular function. We conducted a prospective study evaluating the effect of the erythropoiesis-stimulating agent darbepoetin alfa on EPCs and vascular function in patients with chronic kidney disease (CKD), with or without diabetes. Thirty subjects with CKD (20 subjects with type II diabetes mellitus and 10 without diabetes mellitus) received weekly subcutaneous administration of darbepoetin alfa for 4 weeks. EPCs were measured at baseline and 2 and 4 weeks after drug administration. Vascular function was measured with brachial ultrasound and cell activity was measured with a cell proliferation assay. Cells expressing CD133, CD34, CD146 and CD146/31 were significantly elevated (all p < 0.05), flow-mediated vasodilatation increased 2.1%, 95% CI: (0.4%, 3.8%) and colony-forming units increased twofold, 95% CI: (1.7, 2.3) after 4 weeks of treatment with darbepoetin alfa. Subjects with diabetes exhibited an increase in a subset of EPCs (CD133( +) and 34(+), p < 0.01 and p = 0.06, respectively), vasodilatation and proliferation. In conclusion, the administration of darbepoetin alfa for 4 weeks increased a subset of EPCs, improved endothelial function and increased cell proliferation, including those with diabetes, which is consistent with a favorable improvement in vascular health.

Geographic variation in cardioprotective antihypertensive medication usage in dialysis patients

BACKGROUND

Despite their high risk of adverse cardiac outcomes, persons on long-term dialysis therapy have had lower use of antihypertensive medications with cardioprotective properties, such as angiotensin-converting enzyme (ACE) inhibitors/angiotensin receptor blockers (ARBs), β-blockers, and calcium channel blockers, than might be expected. We constructed a novel database that permits detailed exploration into the demographic, clinical, and geographic factors associated with the use of these agents in hypertensive long-term dialysis patients.

STUDY DESIGN

National cross-sectional retrospective analysis linking Medicaid prescription drug claims with US Renal Data System core data.

SETTING & PARTICIPANTS

48,882 hypertensive long-term dialysis patients who were dually eligible for Medicaid and Medicare services in 2005.

FACTORS

Demographics, comorbid conditions, functional status, and state of residence.

OUTCOMES

Prevalence of cardioprotective antihypertensive agents in Medicaid pharmacy claims and state-specific observed to expected ORs of medication exposure.

MEASUREMENTS

Factors associated with medication use were modeled using multilevel logistic regression models.

RESULTS

In multivariable analyses, cardioprotective antihypertensive medication exposure was associated significantly with younger age, female sex, nonwhite race, intact functional status, and use of in-center hemodialysis. Diabetes was associated with a statistically significant 28% higher odds of ACE-inhibitor/ARB use, but congestive heart failure was associated with only a 9% increase in the odds of β-blocker use and no increase in ACE-inhibitor/ARB use. There was substantial state-by-state variation in the use of all classes of agents, with a greater than 2.9-fold difference in adjusted-rate ORs between the highest and lowest prescribing states for ACE inhibitors/ARBs and a 3.6-fold difference for β-blockers.

LIMITATIONS

Limited generalizability beyond study population.

CONCLUSIONS

In publicly insured long-term dialysis patients with hypertension, there were marked differences in use rates by state, potentially due in part to differences in Medicaid benefits. However, geographic characteristics also were associated with exposure, suggesting clinical uncertainty about the utility of these medications.

Detection of peripheral artery disease by duplex ultrasonography among hemodialysis patients

BACKGROUND AND OBJECTIVES

Peripheral arterial disease (PAD) is a known predictor of cardiovascular morbidity and mortality among hemodialysis patients. Although ankle-brachial BP index (ABI) is a simple and reliable test for PAD screening, its sensitivity has been suggested to decrease among dialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a cross-sectional outpatient cohort study to examine prevalence of PAD among hemodialysis patients using duplex ultrasonography of the lower extremity artery. We also evaluate the influence of increased arterial stiffness on impaired accuracy of ABI for PAD screening.

RESULTS

Of 315 total patients, 23.8% had PAD. PAD was associated with younger age, diabetes, current smoking, atherosclerotic comorbidities, increased total cholesterol levels, increased triglyceride levels, and lower Kt/V. The receiver operating characteristic analysis (area under the receiver operating characteristic curve = 0.846) showed that sensitivity and specificity of ABI values for PAD were 49.0 and 94.8%, respectively. An ABI cut-off value of 1.05 resulted in the best sensitivity (74.5%) and specificity (84.4%). There was a significant difference in sensitivity of ABI levels <0.9 for detecting PAD among patients in different brachial-ankle pulse wave velocity quartiles. In patients with the highest brachial-ankle pulse wave velocity quartile, PAD was most prevalent (46.5%), and ABI had the highest accuracy in detecting PAD (area under the curve, 0.933).

CONCLUSIONS

These results suggest that duplex ultrasonography was a useful tool for screening asymptomatic PAD among hemodialysis patients and that the diagnostic value of ABI for PAD was affected by various factors.

Evaluation of skin microcirculation during hemodialysis

BACKGROUND

Cardiovascular mortality in hemodialysis (HD) patients remains high despite improvements in HD technique such as dialysis adequacy, dialysis fluid purity, and membrane biocompatibility. Optimal fluid balance to maintain optimal hemodynamic stability during hemodialysis (HD) procedure is essential. At the present time, hemodynamic stability is conventionally assessed as stability of macrocirculation, especially as maintenance of systemic blood pressure with no attention paid to peripheral perfusion. Peripheral ischemic vascular disease represents a serious problem with high mortality and morbidity. We estimated skin microcirculation changes during HD using new device, Laser Doppler Line Scanner (Moor Instruments, Devon, UK).

AIMS

The aims were to introduce the novel method of detection of skin perfusion changes during hemodialysis and to evaluate possible relationship of these to ultrafiltration as well as to selected biochemical characteristics.

METHODS

In 36 hemodynamically stable patients, we performed paired measurements of skin blood flow in both hands before and during HD with registering the time of dialysis and the total ultrafiltration achieved.

RESULTS

We found a significant decrease in a majority of the evaluated areas. However, the skin blood flow change was not homogenous as it decreased more on the fingers.

CONCLUSION

To our knowledge, this is the first study when the microcirculatory changes during hemodialysis are demonstrated and evaluated in large skin surface area, and showing not only a decrease in a majority of areas but also the heterogeneity of the changes.

Arterial Revascularization for Upper Extremity Ischemia in Patients with Chronic Kidney Disease

Surgical revascularization of the upper extremity is uncommon, comprising only 4 to 18 per cent of all vascular surgical interventions. Patients with renal failure have higher rates of atherosclerotic cardiovascular and peripheral arterial disease resulting from chronic inflammation, endothelial damage associated with hemodialysis, and vascular trauma. Upper extremity arterial disease with chronic ischemia may be underrecognized in these patients. We reviewed our experience with upper extremity revascularization in patients with renal failure presenting with chronic ischemia. Four patients with longstanding chronic kidney disease developed chronic severe ischemia affecting the forearm or hand. All had previous dialysis access in the symptomatic arm, although none had a functional ipsilateral access at the time of presentation. All patients had successful revascularization with resolution of symptoms and patent bypass grafts at follow up. There was one death 4 months postoperatively and one patient has not returned for follow up. Patients with renal failure with symptomatic upper extremity arterial occlusion should be considered for revascularization of the infrabrachial arteries.

The association of biomarkers of iron status with peripheral arterial disease in US adults

Background

Several studies have examined the association of biomarkers of iron metabolism with measures of carotid artery atherosclerosis, with inconsistent results. Few studies, however, have evaluated the association between biomarkers of iron metabolism and peripheral arterial disease (PAD). The purpose of this study is to examine the association of ferritin and transferrin saturation with PAD.

Methods

Serum ferritin, transferrin saturation, and PAD, defined as having an ankle-brachial blood pressure index <0.9, were measured in 1,631 men and 1,031 postmenopausal women participating in the 1999-2002 National Health and Nutrition Examination Survey (NHANES).

Results

The multivariable adjusted odds ratios (95% confidence interval) for PAD associated with a two-fold increase in serum ferritin and transferrin saturation were 1.18 (1.00-1.41) and 1.45 (0.83-2.51), respectively, for men and 1.04 (0.87-1.25) and 1.55 (0.98-2.45), respectively, for women. After stratifying by cholesterol levels, the multivariable adjusted odds ratios (95% confidence intervals) for PAD associated with a two-fold increase in ferritin and transferrin saturation was 1.04 (0.78-1.39) and 0.73 (0.35-1.50), respectively, for men with total cholesterol <200 mg/dL and 1.30 (0.99-1.72) and 2.59 (0.99-6.78), respectively, for men with total cholesterol ≥ 200 mg/dL (p-value for interaction was 0.58 for ferritin and 0.08 for transferrin saturation). After stratifying by cholesterol levels, the multivariable adjusted odds ratios (95% confidence intervals) for PAD associated with a two-fold increase in ferritin and transferrin saturation was 0.66 (0.41-1.05) and 0.75 (0.44-1.28), respectively, for women with total cholesterol <200 mg/dL, and 1.20 (0.95-1.51) and 2.07 (1.01-4.22), respectively, for women with total cholesterol ≥ 200 mg/dL (p-value for interaction was 0.05 for ferritin and 0.02 for transferrin saturation).

Conclusion

In this large nationally representative sample of men and postmenopausal women, we found a modest association of ferritin and transferrin saturation with PAD, particularly among those with high cholesterol levels.

Ethnicity and peripheral artery disease

Peripheral arterial disease (PAD) is an important healthcare problem and is an indicator of widespread atherosclerosis in other vascular territories, such as the cerebral and coronary circulations. PAD is associated with considerable morbidity and mortality. Most population-based studies investigating PAD prevalence and risk factors for its development and progression have been based on predominantly White ethnic groups. Much less is known about the characteristics of this disease in other ethnic groups. Understanding the epidemiology of PAD amongst ethnic minority groups is relevant, given that the population of minority ethnic groups in countries such as the United Kingdom rose by 53% between 1991 and 2001 and is expected to rise further in the future. This article aims to provide an overview of possible pathophysiological differences between ethnic groups for PAD, focussing predominantly on South Asians (people originating from India, Bangladesh and Pakistan) and Blacks (people of Black Caribbean and Black African descent) as these groups comprise the majority of all ethnic minorities in the United Kingdom.

[Multiple obliterative vascular disease. Challenge in diagnosis and in treatment]

Currently, peripheral arterial disease is an underdiagnosed disorder. Several modifiable and non-modifiable risk factors have role in its development and progression. As system disorder it might be a part and an important predictor of fatal cardio- and cerebrovascular events.

CASE REPORT

The authors describe the case of a 73-year-old male with multilocational vascular disorder, with simultaneously occurring carotid disease, critical limb ischaemia with aorto-bifemoral bypass, multiple infarction with mechanical complication, inoperable coronary disease and with implantable cardioverter defibrillator for ventricular arrhythmia.

CONCLUSION

Peripheral arterial disease affects the whole vascular system and can progress into serious cardiac and cerebral manifestations causing the patient's death inspite of comprehensive treatment.