Lipid abnormalities in end stage renal disease

Correlation of Serum Magnesium with Dyslipidemia in Maintenance Hemodialysis Patients

One of the factors involved in accelerated atherosclerosis in hemodialysis patients is dyslipidemia. In this study we considered factors involved in intensification of dyslipidemia in hemodialysis patients.This study was done on 36 maintenance hemodialysis patients. Serum lipoprotein (a), Triglyceride, Cholesterol, HDL-C,LDL-C and also serum Intact parathormone( iPTH), Calcium, Phosphorus, Magnesium were measured. In statistical analysis there was not any correlation between serum lipids and iPTH. There was not correlation between serum calcium with serum lipids (p>0.05). There was not correlation between CaxP product with serum lipids (p>0.05). There was a positive correlation between serum Magnesium and Lipoprotein(a) (P<0.05) and also positive correlation between serum magnesium with triglyceride level (P<0.05) was seen too. Magnesium doesn’t increase the lipoprotein synthesis. It may involve in the regulation of some enzymes responsible for lipoprotein synthesis. Correlation of serum magnesium with serum triglycerides can be due to changes in hepatic triglyceride metabolism. Lipoprotein(a) is a non traditional factor of premature atherosclerosis, its association with serum magnesium needs more attention in hemodialysis patients.

Resistance training downregulates macrophages infiltration in the kidney of 5/6 nephrectomized rats

INTRODUCTION

Chronic kidney disease (CKD) is considered a significant world health problem with elevated mortality rates. Patients with CKD are restricted to mild physical activity, present chronic inflammatory state and loss of muscle strength. Currently, the influence of resistance exercise (RE) on the progression of renal disease has not being fully elucidated.

PURPOSE

To evaluate the effects of RE on the progression of CKD in a remnant kidney model (5/6Nx) in rats.

METHODS

Eight-week-old Wistar rats were submitted to 5/6 nephrectomy and were divided into four groups: Sham sedentary (Sham SD); Sham RE (Sham RE); 5/6Nx SD and 5/6Nx RE. The animals were trained for 8 weeks in a vertical climbing ladder for 3 days per week, on non-consecutive days.

RESULTS

As expected, 5/6Nx SD group presented a markedly loss of renal function, increased plasma inflammatory cytokines and increased oxidative stress with a reduced activity of nitric oxide. The higher macrophage infiltration and fibrosis confirmed these conditions. RE attenuated systolic blood pressure and renal function decrease and also improved serum lipid parameters in 5/6 Nx animals. It was evident the increase of muscle strength and mass in the trained groups while the sedentary group showed reduced muscle weight and strength compared to Sham SD.

CONCLUSIONS

RE implemented following 5/6Nx retard the progression of chronic kidney injury while simultaneously allowed the maintenance of skeletal muscle strength.

Cardiorenal syndrome type 4: From chronic kidney disease to cardiovascular impairment

Cardiorenal syndrome type 4 (CRS type 4), or chronic renocardiac syndrome, has been defined as "chronic abnormalities in renal function leading to cardiac disease" and recognizes the extreme burden of cardiovascular disease (CVD) risk in patients with chronic kidney disease (CKD). CKD is common and increasingly recognized as a risk factor for CVD. Even though the treatment for CVD has dramatically improved over the past decades, it still takes responsibility for up to 50% of deaths in CKD patients. For this reason, patients with CKD should be thoroughly evaluated for cardiovascular risk factors that require careful management, given the significant burden of CRS type 4 on the healthcare system. This review focuses on the most significant conventional and non-conventional CVD risk factors related to CKD.

Carotid intima-media thickness as a marker of atherosclerosis in hemodialysis patients

Atherosclerotic changes in carotid arteries of hemodialysis (HD) patients reflect global atherosclerotic changes in vasculature. Carotid intima-media thickness (CIMT) can be used for atherosclerosis prediction and assessment of cardiovascular risks in HD patients, and thus screening high-risk patients. In this cross-sectional study, CIMT was measured using ultrasonography (B-mode with 5-10-MHz multifrequency linear probe) in HD patients in our hospitals. Additionally, we assessed the relationship between their CIMT and some cardiovascular risk factors. A total of 62 HD patients (64.5% male) were included. Age, body mass index, low-density lipoprotein, fasting blood sugar, history of diabetes mellitus and cardiovascular disease, serum albumin, and duration and adequacy of HD in study patients had significant association with their CIMT. There were no significant relationships between CIMT and patient's gender, smoking, serum calcium, phosphate, calcium x phosphate product, hemoglobin, and uric acid level. More diagnostic modalities must be performed for detecting the impact of atherosclerosis on HD patients with high CIMT.

Up-regulation of liver Pcsk9 gene expression as a possible cause of hypercholesterolemia in experimental chronic renal failure

Dyslipidemia commonly present in patients with chronic kidney disease (CKD) has been recently linked to increased proprotein convertase subtilisin/kexin type 9 (PCSK9) serum concentration. We tested a hypothesis that increased liver PCSK9 biosynthesis could be partially responsible for the elevated circulating PCSK9 level, and subsequently contribute to hypercholesterolemia observed in subjects with CKD. Rat model of chronic renal failure (CRF) was used in the study. Animals underwent a 5/6 nephrectomy or a sham operation. Liver expression of Pcsk9, sterol regulatory element-binding transcription factor 2 (Srebf-2), and β-actin were quantified by real-time RT-PCR. Liver protein levels of PCSK9, LDL-receptor (LDL-R), and SREBF-2 were analyzed using Western blotting. Serum PCSK9 concentration was estimated by immunoassay. Rats with an experimental CRF as compared to pair-fed and control ones were characterized by: (a) an up-regulation of liver Pcsk9 and Srebf-2 genes expression with parallel increase of serum PCSK9 concentration; (b) a decrease in liver LDL-R protein level, and (c) an increase of serum total and LDL-cholesterol concentrations. We also found significant correlations between serum creatinine and liver PCSK9 mRNA levels (r = 0.88, p < 0.001) and between serum creatinine and circulating PCSK9 levels (r = 0.73, p < 0.001). The results suggest that a rat model of CRF is associated with an increased liver Pcsk9 gene expression. The coordinated up-regulation of Pcsk9 and Srebf-2 genes expression suggests that SREBF-2 may play a key role in regulation of Pcsk9 gene expression, circulating PCSK9 level, and hypercholesterolemia in experimental CRF.

Benefits of a continuous ambulatory peritoneal dialysis (CAPD) technique with one icodextrin-containing and two biocompatible glucose-containing dialysates for preservation of residual renal function and biocompatibility in incident CAPD patients

In a prospective randomized controlled study, the efficacy and safety of a continuous ambulatory peritoneal dialysis (CAPD) technique has been evaluated using one icodextrin-containing and two glucose-containing dialysates a day. Eighty incident CAPD patients were randomized to two groups; GLU group continuously using four glucose-containing dialysates (n=39) and ICO group using one icodextrin-containing and two glucose-containing dialysates (n=41). Variables related to residual renal function (RRF), metabolic and fluid control, dialysis adequacy, and dialysate effluent cancer antigen 125 (CA125) and interleukin 6 (IL-6) levels were measured. The GLU group showed a significant decrease in mean renal urea and creatinine clearance (-Δ1.2 ± 2.9 mL/min/1.73 m(2), P=0.027) and urine volume (-Δ363.6 ± 543.0 mL/day, P=0.001) during 12 months, but the ICO group did not (-Δ0.5 ± 2.7 mL/min/1.73 m(2), P=0.266; -Δ108.6 ± 543.3 mL/day, P=0.246). Peritoneal glucose absorption and dialysate calorie load were significantly lower in the ICO group than the GLU group. The dialysate CA125 and IL-6 levels were significantly higher in the ICO group than the GLU group. Dialysis adequacy, β2-microglobulin clearance and blood pressure did not differ between the two groups. The CAPD technique using one icodextrin-containing and two glucose-containing dialysates tends to better preserve RRF and is more biocompatible, with similar dialysis adequacy compared to that using four glucose-containing dialysates in incident CAPD patients. [Clincal Trial Registry, ISRCTN23727549].

Effectiveness of omega-3 supplement on lipid profile and lipid peroxidation in kidney allograft recipients

BACKGROUND

Omega-3 fatty acids carry major roles in mediating inflammation, immune response, lipid peroxidation and lipoprotein metabolism. Diversity of health benefits have been attributed to dietary supplementation with omega-3 fatty acids in transplant and nontransplant settings. Several studies in renal transplantation have suggested that supplementation with omega-3 fatty acids may lead to significant clinical benefits. However, the extents of these benefits are variable and published data had not coincided with positive findings.

OBJECTIVES

The aim of this study was to evaluate the effectiveness of omega-3 supplementation on the lipid profile and lipid peroxidation in patients underwent kidney transplant.

PATIENTS AND METHODS

Thirty cases had been selected with stable allograft function following at least six months of transplantation. The serum levels of lipids including triglyceride, low density lipoprotein (LDL), high density lipoprotein (HDL), very low density lipoprotein (VLDL), total cholesterol and indices of lipid peroxidation (malondialdehyde and APO a1) were measured by biochemical techniques at the baseline. Two months following prescription of oral omega-3 (3 g/day), the biochemical measurements were repeated and the differences were analyzed.

RESULTS

Of thirty patients, 12 were male and 18 were female with the mean age of 45.3 ± 13.0 (18-65) years. At the baseline, the serum levels of MDA and APO B were 3.5 ± 1.3 and 148.3 ± 20.4 ng/dL respectively. At the end of two months following intervention, they were 3.2 ± 1.2 and 145.7 ± 19.0 ng/dL, respectively (P > 0.05). Correspondingly, at the baseline the serum levels of triglyceride, LDL, VLDL and total cholesterol were 171.1 ± 58.7, 106.9 ± 31.8, 42.2 ± 4.0, 145.7 ± 33.2 and 181.2 ± 35.1 mg/dL and after intervention they were 162.4 ± 82.5, 99.4 ± 35.1, 44.6 ± 6.3, 140.3 ± 33.1 and 170.9 ± 38.3 mg/dL, respectively (P > 0.05). There was no significant difference between the males and females in this instance.

CONCLUSIONS

Our results seem to indicate that oral omega-3 may promote the lipid profile and indices of lipid peroxidation in patients following kidney transplantation however extents of these effects are not significant.

Carotid intima-media thickness in children with end-stage renal disease on dialysis

Cardiovascular morbidity and mortality are common in end stage renal disease (ESRD) patients. There is scarce data on carotid and bulb intima-media thickness (IMT-C and IMT-B) as an early marker of atherosclerosis and related factors in children on hemodialysis (HD) and peritoneal dialysis (PD). Since we did not have enough information about our patients, this study was carried on all ESRD children (hemodialysis and peritoneal dialysis) in a referral center. Data was collected from 16 ESRD children under 18 years with seven patients on PD and nine on HD. Lab tests and biochemical parameters including serum von Willebrand factor (vWF), homocystein, apo lipoprotein A, apo lipoprotein B and quantitative CRP were measured in fasting patients just before initiating dialysis. IMT-C and IMT-B were measured by gray scale ultrasound using 7.5 MHZ probe. The mean of age was 12.76±4.5 years. The mean duration of dialysis in HD and PD patients were not significantly different; 11.88±3.25 months and 10.14±2.4 months respectively. Mean of systolic blood pressure in HD group was significantly higher than PD group, 135.55±25.54 mmHg versus 121.42±12.14 mmHg, P<0.05. Significant differences among all following parameters in ESRD patients, with normal laboratory values, were clarified: cholesterol, triglycerides, apo A, apo B, quantitative CRP, VWF, homocystein and IMT-C. However, we could not demonstrate any difference between IMT-B in case and control group. After adjusting for age, partial correlation showed significant correlation between IMT-C and following factors: N-PTH and serum alkaline phosphatase. Longitudinal studies with large size samples are needed to clarify the contributing factors with intima-media thickness in ESRD children.

Lipids in chronic kidney disease

Patients with chronic kidney disease (CKD) develop premature cardiovascular disease. In the general population (without CKD), there are strong associations between cholesterol fractions and the risk of coronary disease and weaker associations with stroke. Randomised trials in the general population demonstrate that lowering blood cholesterol (chiefly with a statin) reduces the risk of vascular events. Patients with CKD differ significantly from the general population. They have markedly disturbed lipid metabolism manifesting as elevated triglyceride concentrations, reduced HDL cholesterol concentrations and a preponderance of small, dense LDL particles that are potentially more atherogenic; the observed association between lipids and vascular disease is bizarre, and is confounded by co-morbidity; the nature of the vascular disease appears less strongly associated with classical atherosclerosis. Randomised trials are required to determine the relevance of blood lipids to the development of vascular disease in CKD patients, but the results of such studies have been inconclusive to date. CKD patients are at risk of end-stage renal disease. Lipids may be involved in the progression of renal disease. Modifying them may delay the progression of CKD. The current data are based on effects on markers of progression (e.g. proteinuria). The ongoing SHARP (Study of Heart and Renal Protection) trial should provide reliable information about the effects of statins on both vascular and renal risk.

Icodextrin: an alternative peritoneal dialysis fluid

Peritoneal dialysis is a home dialysis therapy in which a fluid known as dialysate is placed into the patient's peritoneal cavity. The standard dialysate consists of a concentrated dextrose solution. Icodextrin is a glucose polymer that can be substituted for dextrose with avoidance of some of the glucose-dependant effects. The efficacy and safety of this compound was evaluated and compared with the standard dialysate solutions. It seems to be well-tolerated overall and may offer benefits in select populations of patients with kidney failure. This seems to be especially relevant in patients with more permeable peritoneal membranes who are known as 'high-transporters'.

Subclinical Peripheral Artery Disease in Patients Undergoing Peritoneal Dialysis: Risk Factors and Outcome

Background

Peripheral artery disease (PAD) is highly prevalent among patients in end-stage renal disease. The ankle–brachial index (ABI) is believed to be highly correlated with the subclinical PAD of lower extremities but little is known about the associated risk factors and outcome for PAD and ABI in patients on peritoneal dialysis (PD).

Methods

We performed a cohort study of 153 patients from a single center receiving stable PD for more than 3 months. These patients were screened for subclinical PAD using the ABI measurement. The ABI was measured and a ratio of <0.9 was considered abnormal. Clinical outcomes included actuarial patient and technique survival in this study.

Results

30 patients were classified into a subclinical PAD group. The prevalence of PAD (subclinical and overt) in our PD center was 19.61% (30/153). Advanced age, preexisting diabetes, preexisting cardiovascular and/or cerebrovascular disease (CVD), lower renal Kt/V urea, lower renal creatinine clearance (WCrCl), lower serum albumin level, and higher serum triglyceride level were risk factors for PAD in our PD center. Bivariate analysis showed that ABI was positively correlated with residual renal Kt/V urea and WCrCl, but was not correlated with peritoneal Kt/V urea and WCrCl. Patient and technique survival rates were significantly lower in the low ABI group than in the normal ABI group.

Conclusions

ABI is highly correlated with advanced age, preexisting diabetes, preexisting CVD, serum albumin, serum triglyceride, and residual renal clearance in PD patients. Also, lower ABI is independently associated with a high risk of patient mortality and PD technique failure.

Increased gene expression of liver SREBP-2 in experimental chronic renal failure

Sterol regulatory element-binding protein-2 (SREBP-2) is a transcription factor regarded as the main regulator of cholesterol homeostasis. Therefore, increased level of SREBP-2 could be responsible for hypercholesterolemia, which is observed in experimental chronic renal failure (CRF). This study was designed primary to evaluate the impact of experimental CRF (5/6 nephrectomy model) on rat liver SREBP-2 gene expression. In CRF rats, a twofold increase in SREBP-2 mRNA level, as well as in mature SREBP-2 protein abundance was found, when compared to control animals. It was associated with enhanced activity and mRNA abundance of liver HMG-CoA reductase, a rate-limiting enzyme for cholesterol biosynthesis. A twofold increase in liver cholesterologenesis rate was also noted. We conclude that experimental CRF is associated with increased liver SREBP-2 gene expression. This is probably the cause for enhanced HMG-CoA reductase gene expression and, consequently, for increase in liver cholesterol synthesis in CRF rats. Despite increased SREBP-2 gene expression we found LDL-receptor mRNA level to be lower than in controls, suggesting SREBP-2 independent mechanisms of LDL-receptor transcriptional regulation in CRF rats. Enhanced cholesterol synthesis and decreased LDL-receptor mRNA level are probably responsible for an almost fourfold increase in serum cholesterol concentration in CRF rats.

Endocrinology and Dialysis Jean L. HolleySeries Editor: Lipid Abnormalities Associated with End-Stage Renal Disease

Patients undergoing chronic renal replacement therapy have a high incidence of dyslipidemia. In general, there are increased concentrations of triglyceride-rich apolipoprotein B-containing particles. These elevations lead to increased levels of non-high-density lipoprotein (HDL) levels. This pattern is further modified by the method of dialysis (peritoneal versus hemodialysis) and comorbidities such as diabetes. End-stage renal disease patients also demonstrate increased levels of lipoprotein(a) (Lp(a)) and oxidized low-density lipoprotein (LDL)both of which are highly atherogenic. This review focuses on the pathogenesis of these lipid abnormalities and their role in the atherosclerotic process.

Chronic Kidney Disease: A Risk Factor for Cardiovascular Disease

The goal of risk stratification of CVD inpatients with CKD is to lead to effective and early intervention and to prevent the adverse outcomes associated with this complex multisystem disease that is characteristic of growing number of patients with CKD in the general population and of patients receiving dialysis therapy or kidney transplantation. By 2030, there will be 2.24 million patients with ESRD in the United States, and approximately 1.3 million of these cases of ESRD will be caused by diabetes mellitus. Thus, CVD in this high-risk population presents a challenge for the nephrology and the cardiology community.

Ability of non-high-density lipoprotein cholesterol and calculated intermediate-density lipoprotein to identify nontraditional lipoprotein subclass risk factors in dialysis patients

BACKGROUND

Non-high-density lipoprotein cholesterol (non-HDL-C) and calculated intermediate-density lipoprotein cholesterol (IDL-C) have been proposed as surrogate markers to estimate apolipoprotein B-containing lipoproteins. The purpose of this study was to determine the validity of non-HDL-C and calculated IDL-C to predict nontraditional lipoprotein risk factors among dialysis patients and to compare the prevalence of these nontraditional risk factors between dialysis modalities.

METHODS

The authors performed a cross-sectional analysis comparing standard lipid profile with lipoprotein analysis via nuclear magnetic resonance (NMR) spectroscopy among 186 hemodialysis (HD) and peritoneal dialysis (PD) patients on modern lipid-lowering therapy.

RESULTS

The PD group had a significantly higher low-density lipoprotein (LDL) particle concentration (P < 0.005), higher large very low-density lipoprotein (VLDL; P < 0.001), greater small dense LDL (P < 0.001), and lower protective large HDL (P < 0.005). Forty-six (40%) of 118 subjects with LDL-C below goal had at least 1 nontraditional risk factor by NMR spectroscopy. The sensitivity of non-HDL-C method together with triglyceride (TG) value greater than 200 mg/dL (>2.26 mmol/L) to predict nontraditional risk was 13% and increased to 20% if TG values were excluded. A negative correlation was observed between LDL particle size and HDL-C (r2 = 0.269; P < 0.001); the sensitivity of HDL-C to predict LDL size was 92%. There was no relationship between measured IDL by NMR and calculated IDL-C (r2 = 0.005; P = 0.69).

CONCLUSION

Non-HDL-C greater than 130 mg/dL (3.4 mmol/L) independent of TG values and HDL-C lower than 40 mg/dL (1.0 mmol/L) may predict nontraditional lipoprotein risk factors among dialysis patients. This is especially applicable to patients on PD, a modality associated with a more atherogenic lipoprotein profile.

Assessment of Coronary Artery Calcification in Hemodialysis Patients Using Multi-Detector Spiral CT Scan

Cardiovascular disease in association with coronary artery calcification (CAC) is the leading cause of death in patients with end-stage renal disease (ESRD). The evaluation of CAC has been performed by electron beam CT scan. The purpose of the present study was to assess CAC using multi-detector spiral CT (MDCT) and to evaluate contributors to CAC in these patients. Fifty-three patients on chronic hemodialysis participated in this study. Their mean age was 61.0+/-9.6 years, and the mean duration of dialysis therapy was 6.7+/-5.4 years. We used an automatic device to measure arterial pulse wave velocity (PWV) as an index of arterial wall stiffness. The aortic calcification index (ACI) was quantified morphometrically by CT scan. The CAC score correlated positively with ACI score (r =0.863, p <0.0001). Linear regression analysis indicated that the CAC scores correlated positively with age (r =0.406, p =0.0023), C-reactive protein (r =0.38, p =0.0047) and PWV (r =0.303, p =0.0271). Stepwise regression analysis indicated that ACI (beta-coefficient=0.862, p <0.0001) and arterial PWV (beta-coefficient=0.303, p <0.0001) were independently associated with CAC score. The mean CAC score of patients with cardiac events (2,568.5+/-2,575.1 mm3) was significantly higher than that (258.0+/-409.2 mm3) of patients without cardiac events. In conclusion, our results showed clearly that assessment of CAC score using MDCT may be predictive for detecting the presence of coronary artery disease. CAC is indirectly associated with increased arterial stiffness and the extent of aortic calcification in hemodialysis patients. We did not find a significant correlation between CAC score and parameters of mineral metabolism, including serum levels of calcium, phosphorus and parathyroid hormone. A longitudinal prospective study is required to assess the predictive value of this technique in determining cardiac events in large numbers of hemodialysis patients.

Dyslipidemia, oxidative stress and cardiac dysfunction in children with chronic renal failure: effects of L-carnitine supplementation

BACKGROUND

Secondary carnitine deficiency may develop in chronic renal failure (CRF) patients undergoing long-term hemodialysis (HD), with a resulting higher incidence of cardiovascular diseases, dyslipidemia and oxidative stress. We studied the efficacy of 12 months of L-carnitine supplementation on the amelioration of dyslipidemia, oxidative stress and cardiac dysfunction in 24 CRF children undergoing long-term HD compared with 24 age- and sex-matched controls.

METHODS

Plasma samples were analyzed spectrophotometerically before and after dialysis sessions and after 2-month supplementation with oral L-carnitine (50 mg/kg/day) for free carnitine (FC), the lipid profile, and oxidative stress markers. Echocardiography the day following dialysis measured cardiac diameters, wall thicknesses, left ventricular mass index (MI), end diastole and systole volume indices and functions.

RESULTS

The pre-dialysis FC concentration was substantially lower than controls and decreased significantly at the end of the dialysis session. Pre- and post-dialysis plasma levels of free fatty acids (FFAs), trigyleride (TG), total cholesterol (TC) and oxidative stress markers significantly increased while high-density lipoprotein cholesterol (HDL-C) and phospholipids significantly decreased compared to controls. Echocardiography detected a significant increase in cardiac diameters and thickness, and systolic and diastolic cardiac dysfunction. After L-carnitine supplementation, plasma levels of FC increased to normal levels. FFAs, TC and HDL-C returned to control levels while TG, phospholipids, and the oxidative stress markers decreased but remained significantly higher than controls. There was a significant decrease in cardiac diameters and an increase in left ventricular diastolic function (E/A ratio), but no correlation between FC levels and echocardiographic parameters. Pre-dialysis, post-dialysis and after treatment, plasma FC level showed a significant positive correlation with HDL-C and phospholipids and a significant negative correlation with each of oxidative stress markers, FFAs, TG and TC. On the other hand, FFAs showed a significant positive correlation with TG, TC, DC, NO and a significant negative correlation with HDL-C and phospholipids.

CONCLUSION

This study demonstrates that CRF children under regular HD suffer from a decrease in the level of plasma FC, dyslipidemia, oxidative stress, and an increase in cardiac diameters and thickness with impairment of cardiac functions. Oral L-carnitine supplementation at a dose of 50 mg/kg for 2 months can increase plasma FC level, improve dyslipidemia, decrease oxidative stress with reduction of cardiac diameters and increase in diastolic function.

Management of selected lipid abnormalities: hypertriglyceridemia, isolated low HDL-cholesterol, lipoprotein(a), and lipid abnormalities in renal diseases and following solid organ transplantation

Although the focus in treating lipid disorders is on reducing LDL-C levels, additional lipid-related independent risk factors, such as TG, HDL-C, and Lp(a) levels, should be used clinically to assess cardiovascular risk. Decisions to initiate drug therapy for LDL-C reduction may be influenced by levels of these other lipoprotein fractions. Data supporting intervention to modify these factors are less abundant than for LDL-C reduction, but in certain circumstances. drug therapy targeted at TGs or HDL-C may be appropriate. Patients who have nephrotic syndrome and end-stage renal disease are at particularly high risk for the development of CVD and should be treated aggressively for their lipid disorders. Finally, solid organ transplant recipients are almost always hyperlipidemic and appropriate therapy could reduce cardiovascular events.

Ultrasound evaluation of intima media thickness of carotid arteries in dialysis patients and correlation with proposed risk factors

Atherosclerosis is significant risk factor for cardiovascular morbidity and mortality in dialysis patients. Aim of the study was ultrasound evaluation of intima media thickness on carotid arteries (as a marker of atherosclerosis), in dialysis patients and its correlation with proposed risk factors. Intima media thickness was measured in 45 dialysis patients with no signs of cardiovascular diseases (15 on peritoneal dialysis, group I,30 on hemodialysis, group II) and 20 healthy controls. The mean carotid artery intima media thickness was significantly higher in dialysis patients than in control group. According to intima media thickness, dialysis patients were divided in group A (patient with intima media thickness less or equal 0,720 mm) and group B (intima media thickness higher then 0,720mm). Intima media thickness in bout group was correlated with proposed risk factors. In group A there was not significant correlation of intima media thickness with risk factors. In group B significant correlation have been found between intima media thickness and LDL, VLDL cholesterol, body mass index and systolic, diastolic and mean blood pressure. Although atherosclerosis was not the only cause for cardiovascular morbidity and mortality, it has a dominant role in dialysis patients. Augmented intima media thickness could be early marker of atherosclerosis. The risk factors of great influence on intima media thickness are lipid disturbances, obesity and hypertension.

[Dialysis as a risk factor for development of atherosclerosis]

INTRODUCTION

Atherosclerosis is a major risk factor for increased cardiovascular morbidity and mortality in dialysis patients. First clinical symptoms are usually associated with initial atherosclerotic changes of blood vessels. The aim of this study was ultrasound evaluation of intima media thickness (IMT) of carotid arteries in dialysis patients and its correlation with certain risk factors.

PATIENTS AND METHODS

IMT was measured in 45 dialysis patients with no signs of cardiovascular diseases: 15 continuous ambulatory peritoneal dialysis (CAPD) patients, 30 hemodialysis (HD) patients and in 20 healthy controls. IMT was correlated with certain risk factors for atherosclerosis (general parameters--age, gender, duration of dialysis, cause of renal diseases, parameters of nutrition, parameters of calcium and phosphorus metabolism, lipid parameters, blood pressure and smoking).

RESULTS

The mean carotid artery IMT was significantly higher in dialysis patients than in the control group (p < 0.05). In addition, the mean IMT was statistically significantly higher in PD than in HD patients (p < 0.05). In CAPD patients there was a significant correlation between IMT and total and LDL cholesterol. In the second group (HD patients) IMT significantly correlated with diastolic blood pressure, BMI and smoking.

CONCLUSION

Although atherosclerotic cardiovascular disease may not manifest in dialysis patients, IMT of carotid arteries significantly increases. Major risk factors affecting IMT are lipid disturbances in patients on peritoneal dialysis and hypertension, obesity and smoking in HD patients.

Sevelamer attenuates the progression of coronary and aortic calcification in hemodialysis patients

BACKGROUND

Cardiovascular disease is frequent and severe in patients with end-stage renal disease. Disorders of mineral metabolism may contribute by promoting cardiovascular calcification.

METHODS

We conducted a randomized clinical trial comparing sevelamer, a non-absorbed polymer, with calcium-based phosphate binders in 200 hemodialysis patients. Study outcomes included the targeted concentrations of serum phosphorus, calcium, and intact parathyroid hormone (PTH), and calcification of the coronary arteries and thoracic aorta using a calcification score derived from electron beam tomography.

RESULTS

Sevelamer and calcium provided equivalent control of serum phosphorus (end-of-study values 5.1 +/- 1.2 and 5.1 +/- 1.4 mg/dL, respectively, P = 0.33). Serum calcium concentration was significantly higher in the calcium-treated group (P = 0.002), and hypercalcemia was more common (16% vs. 5% with sevelamer, P = 0.04). More subjects in the calcium group had end-of-study intact PTH below the target of 150 to 300 pg/mL (57% vs. 30%, P = 0.001). At study completion, the median absolute calcium score in the coronary arteries and aorta increased significantly in the calcium treated subjects but not in the sevelamer-treated subjects (coronary arteries 36.6 vs. 0, P = 0.03 and aorta 75.1 vs. 0, P = 0.01, respectively). The median percent change in coronary artery (25% vs. 6%, P = 0.02) and aortic (28% vs. 5%, P = 0.02) calcium score also was significantly greater with calcium than with sevelamer.

CONCLUSIONS

Compared with calcium-based phosphate binders, sevelamer is less likely to cause hypercalcemia, low levels of PTH, and progressive coronary and aortic calcification in hemodialysis patients.

Risk factors for the development and progression of dyslipidemia after heart transplantation

BACKGROUND

Hyperlipidemia is an important complication after organ transplantation and contributes to the development of posttransplant accelerated coronary artery diseases.

METHODS

We have retrospectively evaluated the relative contribution of various risk factors associated with the development and progression of hyperlipidemia in 194 heart transplant recipients by the use of mixed effects multiple linear regression analysis. The demographic characteristics evaluated were primary diagnosis of ischemic heart disease (IHD), gender, and age. Postoperative characteristics included number of treated rejections, dosage of cyclosporine (CYA), tacrolimus (TAC), prednisolone and azathioprine, and concentration of serum creatinine and glucose. The effects of administration of antihypertensive agents, diuretics, and lipid lowering agents were also studied.

RESULTS

The total cholesterol concentration increased significantly in the first 3 months posttransplant but gradually decreased thereafter. Total cholesterol and the ratio of low density lipoprotein (LDL) cholesterol to high density lipoprotein (HDL) cholesterol (LDL-C/HDL-C) increased to a greater extent in patients with IHD although female transplant recipients had a greater increase in the total cholesterol concentration. Each episode of rejection increased serum cholesterol by 0.306 mmol/liter (0.258, 0.355) [mean (95% C.I.)] and serum triglyceride by 0.164 mmol/liter (0.12, 0.209) although switching to TAC improved total cholesterol and LDL-C/HDL-C. Administration of frusemide, increased the total cholesterol and LDL-C/HDL-C whereas administration of bumetanide or metolazone increased the concentration of serum triglyceride. Serum glucose was associated with hypertriglyceridemia whereas serum creatinine was associated with increases in the total cholesterol, LDL-C/HDL-C and triglyceride.

CONCLUSIONS

We have identified demographic and postoperative covariables that predispose heart transplant recipients to hyperlipidemia. Some of these risk factors, such as the effect of diuretics, have not been identified before in this group of patients and may be amenable to modification or closer control. TAC rather than CYA may be the immunosuppressive of choice for patients who are at greater risk of developing hyperlipidemia.

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and rhabdomyolysis: considerations in the renal failure patient

An intense debate has developed as to the risk-benefit ratio of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) following the withdrawal of cerivastatin. The development of rhabdomyolysis in cerivastatin-treated patients should have surprised few since myotoxicity is an accepted class effect of statins. What has sprung from the cerivastatin experience though is a concern for other members of this class. Such misgivings, although understandable, are ill advised. Without question, differences exist in the risk of rhabdomyolysis occurrence amongst the various statins. In this regard, pravastatin and fluvastatin are least likely to produce rhabdomyolysis, which, in part, relates to the fact they are not metabolized by the cytochrome P450 3A4 pathway. When muscle damage occurs with statins it is most often the result of a drug-drug interaction rather than a specific adverse response to statin monotherapy. Such drug-drug interactions increase plasma concentrations of a statin and thereby increase the risk of myotoxicity. A growing consensus exists which supports an expanded use of statins in a range of patient groups including the renal failure patient. Polypharmacy and altered drug metabolism increase the risk of myotoxicity, albeit to an ill-defined degree, in this population. Many factors should enter into the choice of a statin in the multiply medicated renal failure patient.

Accelerated atherosclerosis, dyslipidemia, and oxidative stress in end-stage renal disease

Premature atherosclerosis is a major cause of morbidity and mortality in end-stage renal disease patients. Dyslipidemia and increased oxidative stress contribute to premature atherogenesis in these patients. The dyslipidemia of end-stage renal disease consists of both quantitative and qualitative abnormalities in serum lipoproteins. Qualitative changes include hypertriglyceridemia (increased remnant lipoproteins), low high-density lipoprotein-cholesterol, and increased lipoprotein (a). In addition to quantitative changes, lipoproteins in end-stage renal disease undergo compositional and qualitative changes that make them pro-atherogenic, such as various modifications of apolipoprotein B, including oxidation, and modification by advanced glycation end-products. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and low-dose fibrates could be effective therapies for lipid disorders. The best evidence for increased oxidative stress in end-stage renal disease is the demonstration of increased plasma F2-isoprostanes. Confirmation of the positive findings with high-dose alpha-tocopherol in the Secondary Prevention with Antioxidants of Cardiovascular Disease in End-stage Renal Disease Study is urgently needed. Clinical trials with statins and other drugs that improve dyslipidemia also need to be undertaken. These therapies could clearly lead to a reduction in cardiovascular morbidity and mortality in these patients.

Cardiac calcification in adult hemodialysis patients. A link between end-stage renal disease and cardiovascular disease?

OBJECTIVES

We sought to determine clinical and laboratory correlates of calcification of the coronary arteries (CAs), aorta and mitral and aortic valves in adult subjects with end-stage renal disease (ESRD) receiving hemodialysis.

BACKGROUND

Vascular calcification is known to be a risk factor for ischemic heart disease in non-uremic individuals. Patients with ESRD experience accelerated vascular calcification, due at least in part to dysregulation of mineral metabolism. Clinical correlates of the extent of calcification in ESRD have not been identified. Moreover, the clinical relevance of calcification as measured by electron-beam tomography (EBT) has not been determined in the ESRD population.

METHODS

We conducted a cross-sectional analysis of 205 maintenance hemodialysis patients who received baseline EBT for evaluation of vascular and valvular calcification. We compared subjects with and without clinical evidence of atherosclerotic vascular disease and determined correlates of the extent of vascular and valvular calcification using multivariable linear regression and proportional odds logistic regression analyses.

RESULTS

The median coronary artery calcium score was 595 (interquartile range, 76 to 1,600), values consistent with a high risk of obstructive coronary artery disease in the general population. The CA calcium scores were directly related to the prevalence of myocardial infarction (p < 0.0001) and angina (p < 0.0001), and the aortic calcium scores were directly related to the prevalence of claudication (p = 0.001) and aortic aneurysm (p = 0.02). The extent of coronary calcification was more pronounced with older age, male gender, white race, diabetes, longer dialysis vintage and higher serum concentrations of calcium and phosphorus. Total cholesterol (and high-density lipoprotein and low-density lipoprotein subfractions), triglycerides, hemoglobin and albumin were not significantly related to the extent of CA calcification. Only dialysis vintage was significantly associated with the prevalence of valvular calcification.

CONCLUSIONS

Coronary artery calcification is common, severe and significantly associated with ischemic cardiovascular disease in adult ESRD patients. The dysregulation of mineral metabolism in ESRD may influence vascular calcification risk.

Premature cardiovascular disease in chronic renal failure

There is a remarkable lack of reliable information about the determinants of risk of cardiovascular disease (CVD) among patients with chronic renal failure. Indeed, such patients have often been deliberately excluded from randomised trials of treatments of CVD, perhaps because of concerns about drug safety. But the absolute risk of CVD among them may be large, so the potential absolute benefits of treatments may also be large, and may well exceed any increased hazards. Hence, as well as further investigation of the underlying mechanisms of cardiac disease, it would be helpful to have some large-scale randomised trials in a wide range of renal patients of interventions (such as cholesterol-lowering drugs, antihypertensives, aspirin, B-vitamins, and antioxidant vitamins) that are of proven or suspected benefit in other settings. If safe and effective treatments can be identified, and started early in the natural history of renal failure, the exceptionally high risk of CVD experienced by these patients could be decreased before and after end-stage renal failure has occurred.

Survival after acute myocardial infarction in patients with end-stage renal disease: results from the cooperative cardiovascular project

Cardiovascular disease (CVD) is the most common cause of death in patients with end-stage renal disease (ESRD). The optimal management strategy in this population is unknown. We studied 640 patients with ESRD and acute myocardial infarction during 1994 to 1995 as part of the Health Care Financing Administration's Cooperative Cardiovascular Project. The majority of patients were treated with medical therapy alone, 46 patients (7%) were treated with percutaneous transluminal coronary angioplasty (PTCA), and 29 patients (5%) underwent coronary artery bypass grafting (CABG). Patient characteristics and comorbid conditions were similar among the three groups. The overall 1-year mortality rate was 53%. Advanced age, low or high body mass index, history of peripheral vascular disease or stroke, the inability to walk independently, and several indicators of cardiac dysfunction were associated with an increased relative risk (RR) for death. Survival curves differed significantly by treatment modality, with 1-year survival rates of 45%, 54%, and 69% in the medical therapy alone, PTCA, and CABG groups, respectively (P = 0.03). After adjustment for confounding variables, the RR for death was less (but not significantly so) in the CABG group (RR, 0.6; 95% confidence interval, 0.3 to 1.1). There are no randomized clinical trial data to guide therapy of CVD in patients with ESRD. On the basis of these and other available data, CABG may be the optimal therapy for CVD in ESRD. In light of the exceptionally poor outcomes observed for patients treated with medical therapy alone, it may be premature to dismiss PTCA as a therapeutic option in this population.

Atherogenic lipoprotein phenotype in end-stage renal failure: origin and extent of small dense low-density lipoprotein formation

End-stage renal failure (ESRF) is associated with dyslipidemia and accelerated atherosclerosis. Triglyceride-rich lipoproteins accumulate and qualitative changes take place in low-density lipoprotein (LDL), with a predominance of the small dense LDL phenotype. Increased small dense LDL (LDLIII) is a known risk factor for cardiovascular disease. To assess the extent of LDLIII formation in ESRF and identify factors contributing to LDLIII production, we analyzed LDL subfractions by density-gradient ultracentrifugation, very low-density lipoprotein subfractions, and lipase activity in 75 patients with ESRF (25 hemodialysis [HD], 25 peritoneal dialysis [PD], and 25 predialysis patients) and 40 age- and sex-matched controls. The percentage of LDLIII was increased in all three patient groups compared with controls (PD, 33% +/- 29% [mean +/- SD]; P < 0.005; HD, 30% +/- 22%; P < 0.01; predialysis, 26% +/- 26%; P < 0.01; all versus controls, 14% +/- 10%). Plasma LDLIII concentration was increased only in PD patients (median, 84 mg/dL; interquartile range [IQR], 29 to 160 mg/dL versus controls; median, 31 mg/dL; IQR, 26 to 54 mg/dL). In other patient groups, total LDL level was less, with heterogeneity in LDLIII concentrations. Forty percent of PD patients and 28% of HD and predialysis patients had LDLIII concentrations greater than 100 mg/dL compared with 2.5% of controls (P = 0.002). Plasma triglyceride levels (r(2) = 38.4%; P < 0.001) and hepatic lipase activity (r(2) = 6.7%; P < 0.03) were independent predictors of LDLIII concentration. The strong association between LDLIII concentration and triglyceride level was present in all three patient groups (HD, r(2) = 47.9%; PD, r(2) = 45. 2%; predialysis, r(2) = 25.8%); plasma triglyceride levels greater than 177 mg/dL (2.0 mmol/L) had an 86% specificity and 79% sensitivity for predicting an LDLIII concentration greater than 100 mg/dL. We conclude that the atherogenic lipoprotein phenotype predominates in ESRF, with excess LDLIII particularly prominent in PD patients. Atherogenic levels of LDLIII are found in patients with triglyceride levels greater than 177 mg/dL. This is likely to represent a further cardiovascular risk factor in this population.

Management of selected lipid abnormalities. Hypertriglyceridemia, low HDL cholesterol, lipoprotein(a), in thyroid and renal diseases, and post-transplantation

Although the focus in treating lipid disorders is on reducing LDL cholesterol levels, triglycerides, HDL cholesterol, and Lp(a) are all independent risk factors that can be used clinically to assess cardiovascular risk. Decisions to initiate drug therapy for LDL cholesterol reduction may be influenced by levels of these other lipoprotein fractions. Data supporting intervention to modify these factors is less abundant than for LDL cholesterol reduction, but in certain circumstances drug therapy targeted at triglycerides or HDL cholesterol may be appropriate. Patients with nephrotic syndrome and end-stage renal disease are at particularly high risk for the development of cardiovascular disease and should be treated aggressively for lipid disorders. Finally, solid organ transplant recipients are almost always hyperlipidemic, and appropriate therapy could reduce cardiovascular events.

Apolipoprotein E polymorphism and renal disease

BACKGROUND

Lipid abnormalities are frequently found in end-stage renal disease (ESRD), and abnormal lipid metabolism may contribute to the progression of renal disease. Previous investigators have reported that apolipoprotein E (apoE) has an important role in lipoprotein metabolism and that the process of lipoprotein catabolism varies according to the apoE phenotype. In addition, the relative frequency of the apoE alleles is different among the races. In this study, we investigated the allele frequency of apoE phenotypes and evaluated the impact of apoE polymorphism on lipid profile in Japanese patients with renal disease.

METHODS

ApoE phenotypes were determined using isoelectric focusing and Western blotting in 592 Japanese patients with renal disease [86 out of 107 patients with glomerulonephritis had proteinuria of not less than 0.25 g per 24 hr and 485 with ESRD; 448 were on hemodialysis (HD), and 37 were on continuous ambulatory peritoneal dialysis (CAPD)]. The allele frequency and apoE phenotype distribution were estimated by the gene-counting method. Serum lipid parameters related to lipid metabolism were measured after at least a 12-hour fast.

RESULTS

The allele frequency of the three major apoE phenotypes (apoE2, apoE3, and apoE4) in 107 glomerulonephritis patients (epsilon 2; 0.037, epsilon 3; 0.860, epsilon 4; 0.103) was almost identical to that in the normal control population (epsilon 2; 0.036, epsilon 3; 0.848, epsilon 4; 0.115). However, 86 glomerulonephritis patients with proteinuria had higher allele frequency of apoE2 (epsilon 2; 0.052, P < 0.01) and apoE4 (epsilon 4; 0.140, P < 0.001) and lower allele frequency of apoE3 (epsilon 3; 0.808, P < 0.001) than the controls. Furthermore, ESRD patients had higher allele frequency of apoE2 (epsilon 2; 0.058, P < 0.01) and lower allele frequency of apoE4 (epsilon 4; 0.091, P < 0.05) than the controls. Higher prevalence of nephrotic syndrome was found in proteinuric glomerulonephritis patients with apoE2. The impact of apoE polymorphism on serum lipid profile in patients with glomerulonephritis, HD, and CAPD was different from that generally expected.

CONCLUSIONS

The higher frequency of apoE2 in ESRD patients suggests that apoE2 is a possible genetic predisposition to ESRD in a Japanese population. The impact of apoE2 and apoE4 on lipid profile in patients with renal disease was unique and different from that in the normal population.