Which parameter is more influential on the development of arteriosclerosis in hemodialysis patients?

Advances in Enhancing Hemocompatibility of Hemodialysis Hollow-Fiber Membranes

Hemodialysis, the most common modality of renal replacement therapy, is critically required to remove uremic toxins from the blood of patients with end-stage kidney disease. However, the chronic inflammation, oxidative stress as well as thrombosis induced by the long-term contact of hemoincompatible hollow-fiber membranes (HFMs) contribute to the increase in cardiovascular diseases and mortality in this patient population. This review first retrospectively analyzes the current clinical and laboratory research progress in improving the hemocompatibility of HFMs. Details on different HFMs currently in clinical use and their design are described. Subsequently, we elaborate on the adverse interactions between blood and HFMs, involving protein adsorption, platelet adhesion and activation, and the activation of immune and coagulation systems, and the focus is on how to improve the hemocompatibility of HFMs in these aspects. Finally, challenges and future perspectives for improving the hemocompatibility of HFMs are also discussed to promote the development and clinical application of new hemocompatible HFMs.

Graphical Abstract

Evaluation of epicardial fat tissue thickness in patients with primary hyperparathyroidism

OBJECTIVE

Primary hyperparathyroidism (pHPT) affects the cardiovascular system, and epicardial fat tissue (EFT) thickness is closely associated with cardiovascular diseases and atherosclerosis. Despite this, the association between EFT thickness and pHPT has not been studied in a clinical setting. This study aimed to assess EFT thickness in patients with pHPT.

METHODS

The study included 38 patients with pHPT and 40 healthy controls. EFT thickness, carotid intima-media thickness (CIMT), serum levels of parathormone (PTH) and calcium, and blood chemistry profiles were determined in all subjects. Correlation and regression analyses were performed with EFT thickness and CIMT as dependent variables and age; systolic and diastolic blood pressure; body mass index (BMI); presence of diabetes mellitus; and free plasma glucose (FPG), PTH, and serum calcium (Ca) levels as independent variables.

RESULTS

Both the mean EFT thickness and the mean CIMT were significantly greater in the pHPT group than the control group (P < .001 for both). Correlation analysis showed that EFT thickness was significantly correlated with CIMT, age, systolic blood pressure, and PTH and serum Ca levels. Furthermore, the regression analysis revealed that EFT thickness retained its independent and positive association with FPG and serum Ca levels.

CONCLUSIONS

The results of this study indicate that EFT thickness may be a useful marker of early atherosclerosis in patients with pHPT. Furthermore, the increase in EFT thickness appears to be due to hypercalcemia.

Carotid vascular abnormalities in primary hyperparathyroidism

CONTEXT

Data on the presence, extent, and reversibility of cardiovascular disease in primary hyperparathyroidism (PHPT) are conflicting.

OBJECTIVE

This study evaluated carotid structure and function in PHPT patients compared with population-based controls.

DESIGN

This is a case-control study.

SETTING

The study was conducted in a university hospital metabolic bone disease unit.

PARTICIPANTS

Forty-nine men and women with PHPT and 991 controls without PHPT were studied.

OUTCOME MEASURES

We measured carotid intima-media thickness (IMT), carotid plaque presence and thickness, and carotid stiffness, strain, and distensibility.

RESULTS

IMT, carotid plaque thickness, carotid stiffness, and distensibility were abnormal in PHPT patients, and IMT was higher in patients than controls (0.959 vs. 0.907 mm, P < 0.0001). In PHPT, PTH levels, but not calcium concentration, predicted carotid stiffness (P = 0.04), strain (P = 0.06), and distensibility (P = 0.07). Patients with increased carotid stiffness had significantly higher PTH levels than did those with normal stiffness (141 +/- 48 vs. 94.9 +/- 44 pg/ml, P = 0.002), and odds of abnormal stiffness increased 1.91 (confidence interval = 1.09-3.35; P = 0.024) for every 10 pg/ml increase in PTH, adjusted for age, creatinine, and albumin-corrected calcium.

CONCLUSIONS

Mild PHPT is associated with subclinical carotid vascular manifestations. IMT, a predictor of cardiovascular outcomes, is increased. Measures of carotid stiffness are associated with extent of PTH elevation, suggesting that those with more severe PHPT may have impaired vascular compliance and that PTH, rather than calcium, is the mediator.

Early detection of lesions of dorsal artery of foot in patients with type 2 diabetes mellitus by high-frequency ultrasonography

This study evaluated the value of high-frequency ultrasonograpy for early detection of dorsal artery of foot in patients with type 2 diabetes mellitus (MD). Eighty subjects including 40 patients with type 2 MD (T2DM group) and 40 healthy volunteers (NC group) were recruited. The intima-media thickness (IMT), the inner diameter and the perfusion of dorsal artery of foot were measured by using high-frequency ultrasonograpy. Meanwhile, the parameters of vascular elasticity, including stiffness parameter (beta), pressure-strain elastic modulus (Erho), arterial compliance (AC), augment index (AI), and pulse wave conducting velocity (PWVbeta) were detected by means of echo-tracking technique. The results showed that no significant difference was found in the IMT, systolic diameter (Ds), diastolic diameter (Dd) and peak systolic velocity (PSV) between T2DM and NC groups. Erho and PWVbeta were increased, and AC was decreased in T2DM group as compared with those in NC group with the differences being significant (P<0.05 for all). There was no significant difference in beta and AI between T2DM and NC groups. It was concluded that high-frequency ultrasonography in combination with echo-tracking technique is sensitive and non-invasive, and can be used for early detection of sclerosis of the lower extremity artery in patients with type 2 MD.

Serum aluminum level correlates with arterial stiffness in haemodialysis patients

BACKGROUND

In addition to pulse wave velocity (PWV), serum aluminum level is predictive of mortality in haemodialysis (HD) patients. This cross-sectional study evaluated the correlations between serum aluminum and brachial-ankle PWV (baPWV).

METHODS

One hundred twenty-seven HD patients (average age 58.46 +/- 9.95 years) were enrolled. Medical data were obtained via chart reviews and hospital database. Associations between biomarker levels and baPWV were analysed by multiple linear regression.

RESULTS

Serum aluminum, high sensitivity C-reactive protein (hsCRP), age, pulse pressure (PP), mean arterial pressure (MAP) and diabetes mellitus (DM) are important correlates of baPWV.

CONCLUSION

Further, hsCRP, PP, age and DM are positively related to arterial stiffness in HD patients.

Vascular function assessed with cardiovascular magnetic resonance predicts survival in patients with advanced chronic kidney disease

BACKGROUND

Increased arterial stiffness is associated with mortality in patients with chronic kidney disease. Cardiovascular magnetic resonance (CMR) permits assessment of the central arteries to measure aortic function.

METHODS

We studied the relationship between central haemodynamics and outcome using CMR in 144 chronic kidney disease patients with estimated glomerular filtration rate <15 ml/min (110 on dialysis). Aortic distensibilty and volumetric arterial strain were calculated from cross sectional aortic volume and pulse pressure measured during the scan.

RESULTS

Median follow up after the scan was 24 months. There were no significant differences in aortic distensibilty or aortic volumetric arterial strain between pre-dialysis and dialysis patients. Aortic distensibilty and volumetric arterial strain negatively correlated with age. Aortic distensibilty and volumetric arterial strain were lower in diabetics, patients with ischaemic heart disease and peripheral vascular disease. During follow up there were 20 deaths. Patients who died had lower aortic distensibilty than survivors. In a survival analysis, diabetes, systolic blood pressure and aortic distensibilty were independent predictors of mortality. There were 12 non-fatal cardiovascular events during follow up. Analysing the combined end point of death or a vascular event, diabetes, aortic distensibilty and volumetric arterial strain were predictors of events.

CONCLUSION

Deranged vascular function measured with CMR correlates with cardiovascular risk factors and predicts outcome. CMR measures of vascular function are potential targets for interventions to reduce cardiovascular risk.

Incidence and risk factors of coronary artery disease in patients on chronic hemodialysis

Aim of the study was to estimate the incidence of coronary heart disease (CAD) in patients (pts) with end stage renal disease (ESRD) maintained on chronic hemodialysis (HD) and its association with the presence of predisposing factors. The study included 171 dialysis pts (107 male (M) and 64 female (F)). Mean age of pts was 67+/-13 years, mean time on dialysis 52.7+/-44 months and Body Mass Index (BMI) 25.9+/-3.7 kg/m2. Fifty pts (29.2%) were clinically diagnosed with CAD. The diagnosis was established by coronary angiography in 24 (48%) and in 26 by combined dipyridamole-exercise thallium imaging (52%). Pts' data in association with the development of CAD that were recorded included age, sex, smoking habits, hypertension, obesity, the presence of diabetes mellitus (DM), hyperlipidemia, anemia, low albumin levels, secondary hyperparathyroidism (SHP), the presence of chronic inflammation, as evidenced by the presence of elevated levels of CRP and hyperhomocysteinemia. There was a statistically significant association of increasing age and CAD (p<0.0001). Relative risk (RR) was significantly increased i) in male pts compared to female pts (RR: 8.56, p<0.001), ii) in anemic pts compared to pts with hemoglobin levels< or =11 g/dL (RR: 8.26, p<0.0001), iii) in obese pts compared to pts with BMI < or =30 (RR: 5.09, p<0.005) and iv) in pts with increased levels of homocysteine compared to pts with levels of homocysteine <15 |IM (RR: 4.14, p<0.0001). Using linear regression analysis, CAD was associated with the inadequacy of HD (r = - 0.05, p<0.0001), time on HD (r =0.04, p =0.012) and increasing age (r =0.24, p<0.001). There was no statistically significant association between CAD and the presence of the other traditional risk factors. The incidence of CAD in dialysis pts is significantly increased with age, male sex, obesity, time on dialysis, the presence of anemia, hyperhomocysteinemia and inadequacy of HD.

Incidence and risk factors of coronary heart disease in elderly patients on chronic hemodialysis

AIM

To determine the incidence of coronary heart disease (CHD) in patients (pts) over 65 years (y) and its relation to common risk factors.

METHODS

We retrospectively studied 128 hemodialysis (HD) pts (80 M and 48 F), mean age 73+/-6.5 years, mean time on HD 44.4+/-26.4 months and BMI 25.4+/-3 kg/m2. They were evaluated for: age, sex, smoking, diabetes, hypertension, left ventricular hypertrophy, secondary hyperparathyroidism (SHP), inflammation, as evidence by elevated level of hsCRP, hyperhomocysteinemia (HOC), time on HD, fluid overload and adequacy of HD. Forty-eight pts (37%) had CAD diagnosed by coronary angiography in 22 (46%) and (201)TL-chloride dipyridamole stress test in 26 (54%).

RESULTS

There was a statistically significant correlation between CAD and increasing age (p<0.0001). The relative risk was significantly increased concerning: (1) male over female pts (RR: 1.95, p<0.01), (2) diabetic vs. non diabetic pts (RR: 2.09, p<0.001), (3) patients with SHP over pts with iPTH values<250 pg/ml (RR: 2.16, p<0.001), (4) hypertensive vs. non hypertensive pts (RR: 2.26, p=0.002), (5) smokers vs. non smokers (RR: 1.69, p<0.05), (6) pts with HOC over pts with normal homocysteine values (RR: 2.09, p<0.05), (7) pts with increased CRP levels over pts with normal CRP levels (RR: 1.8, p<0.01), (8) pts undergoing HD for 36 vs. 12 months (RR: 1.71, p=0.03), (9) between pts with inadequate or adequate HD (RR: 1.73, p=0.02). No significant correlation existed between CAD incidence and the other risk factors.

CONCLUSIONS

Coronary heart disease incidence in elderly HD patients increases with age, male sex, diabetes, SHP, hypertension, increased CRP levels, HOC, smoking, time on HD and inadequacy of HD.

Mineral metabolism and arterial functions in end-stage renal disease: potential role of 25-hydroxyvitamin D deficiency

In ESRD, arterial function is abnormal, characterized by decreased capacitive function (arterial stiffening) and reduced conduit function, shown by diminished flow-mediated dilation (FMD). The pathophysiology of these abnormalities is not clear, and this cross-sectional study analyzed possible relationships among arterial alterations and cardiovascular risk factors, including mineral metabolism parameters, such as serum parathormone, and vitamin D "nutritional" and "hormonal" status by measuring serum 25-hydroxyvitamin D [25(OH)D(3)] and 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] levels. Aortic stiffness (pulse wave velocity), brachial artery (BA) distensibility (echotracking; n = 42), BA FMD (hand-warming; n = 37), and arterial calcification scores (echography and plain x-rays) were measured in 52 stable and uncomplicated patients who were on hemodialysis. 25(OH)D(3) and 1,25(OH)(2)D(3) serum levels were low and weakly correlated (r = 0.365, P < 0.05). After adjustment for BP and age, multivariate analyses indicated that 25(OH)D(3) and 1,25(OH)(2)D(3) were negatively correlated with aortic pulse wave velocity (P < 0.001) and positively correlated with BA distensibility (P < 0.01) and FMD (P < 0.001). Arterial calcification scores were not independently associated with 25(OH)D(3) and 1,25(OH)(2)D(3) serum concentrations. These results suggest that nutritional vitamin D deficiency and low 1,25(OH)(2)D(3) could be associated with arteriosclerosis and endothelial dysfunction in patients who have ESRD and are on hemodialysis.

Atherosclerotic risk factors and carotid stiffness in elderly asymptomatic HD patients

Several studies showed that carotid atherosclerosis and stiffness are independent prognostic factors of cardiovascular morbidity and mortality in the general population and in end-stage renal disease patients. However, the impact of established risk factors on carotid structural and elastic properties in non-diabetic elderly hemodialysis patients with negative history for cardiovascular disease has not been fully elucidated. In this paper, we investigated the effect of established and potential risk factors on carotid atherosclerosis and stiffness. Thirty stable, non-symptomatic, non-diabetic patients, aged 65-years and older (mean age 71.4+/-4.15, range 65-79) on hemodialysis for more than 6 months, were included. All patients underwent B-mode ultrasonography of common carotid artery estimating intima-media wall thickness and wall-to-lumen ratio bilaterally and checking for the presence of plaques. Carotid elasticity was evaluated by compliance, distensibility, and the incremental elastic modulus (Einc), whereas systemic arterial stiffening was evaluated by the augmentation index provided by tonometry of radial artery. Our results showed that presence of carotid plaques and wall thickening were frequent findings in this population (76% and 73.3%, respectively) and they were positively associated with fibrinogen (P<0.005), diastolic blood pressure (P<0.004), visceral obesity (P<0.001) and bio-intact PTH (i-PTH) (P=0.03). Overall, systemic and carotid stiffness were strongly correlated with hs-CRP (P=0.018), serum ferritin (P=0.02) with age (P=0.03), lipids (P=0.03) and i-PTH (P=0.05). In conclusion, our findings show that stiffening and atherosclerosis in non-symptomatic elderly HD patients are very common and they are related not only to hemodynamic changes (diastolic blood pressure), inflammation (hs-CRP, fibrinogen, ferritin) or metabolic dysfunction (increased i-PTH, abnormal lipid profile), but also to abnormal fat deposition (increased waist to hip ratio and waist circumference). Considering the high morbidity and mortality of elderly patients, close monitoring of these parameters could be useful to prevent cardiovascular events.

Aortic stiffness in patients undergoing hemodialysis is positively related to antigen presenting cell-dependent T-lymphocyte reactivity

BACKGROUND

Aortic stiffness is increased in patients undergoing hemodialysis (HD), and it is associated with an increased cardiovascular mortality. Among others, aortic stiffness has been correlated with serum markers of inflammation, indicating a role of the immune system in its pathogenesis. The aim of this study was to evaluate the impact of antigen-presenting cell-dependent T-lymphocyte reactivity on aortic stiffness in HD patients.

PATIENTS AND METHODS

Twenty patients were enrolled in the study. Exclusion criteria were medications or conditions, other than HD, that are known to influence the immune response or aortic stiffness. Antigen-presenting cell-dependent T-lymphocyte reactivity was assessed by cell proliferation of peripheral blood mononuclear cells cultured with or without stimulation with Staphylococcal enterotoxin B (SEB). Cell proliferation was estimated by immunoenzymatic measurement of bromodeoxyuridine uptake. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (PWV) measurement.

RESULTS

Linear regression analysis revealed a strong positive relation between carotid-femoral PWV and antigen-presenting cell-dependent T-lymphocyte reactivity, when SEB at concentrations of 1 ng/mL or 10 ng/mL was used as stimulant.

CONCLUSION

The present study confirms that aortic stiffness in HD patients is positively related to antigen-presenting cell-dependent T-lymphocyte reactivity. The greater the ability of the immune system to react to a monocyte-dependent stimulant and, consequently, to provoke an inflammatory response, the greater the stiffness of the aorta. This is in agreement with the observation that aortic stiffness in HD patients is positively related to various serum inflammation markers.

Arterial stiffness in renal patients: an update

According to recent data, arterial stiffness is a major independent risk factor for cardiovascular morbidity and mortality in both the general and renal populations. Because of several factors (vascular calcifications among them), large arteries are stiffer in patients with chronic kidney disease compared with the nonrenal population, contributing to the enormous cardiovascular mortality in renal patients. This review briefly analyzes methods for determination of arterial stiffness, focusing on 2 parameters, pulse wave velocity and the augmentation index, particularly useful in assessing arterial compliance in renal patients. Effects of different methods of renal replacement therapy on arterial wall properties also are discussed. Finally, the most promising novel and/or potential therapies regarding reduction of arterial stiffness in renal patients are reviewed.