Cardiovascular consequences of correction of the anemia of renal failure with erythropoietin

Hypertension and cardiomyopathy associated with chronic kidney disease: epidemiology, pathogenesis and treatment considerations

Chronic kidney disease (CKD) is a complex condition with a prevalence of 10-15% worldwide. An inverse-graded relationship exists between cardiovascular events and mortality with kidney function which is independent of age, sex, and other risk factors. The proportion of deaths due to heart failure and sudden cardiac death increase with progression of chronic kidney disease with relatively fewer deaths from atheromatous, vasculo-occlusive processes. This phenomenon can largely be explained by the increased prevalence of CKD-associated cardiomyopathy with worsening kidney function. The key features of CKD-associated cardiomyopathy are increased left ventricular mass and left ventricular hypertrophy, diastolic and systolic left ventricular dysfunction, and profound cardiac fibrosis on histology. While these features have predominantly been described in patients with advanced kidney disease on dialysis treatment, patients with only mild to moderate renal impairment already exhibit structural and functional changes consistent with CKD-associated cardiomyopathy. In this review we discuss the key drivers of CKD-associated cardiomyopathy and the key role of hypertension in its pathogenesis. We also evaluate existing, as well as developing therapies in the treatment of CKD-associated cardiomyopathy.

Erythropoietin Treatment Decreases Cardiovascular Morbidity and Mortality in Capd Patients

Objective

To analyze the effects of recombinant human erythropoietin (rHuEPO) therapy on cardiovascular (CV) morbidity and mortality among continuous ambulatory peritoneal dialysis (CAPD) patients.

Design

Retrospective comparative study.

Setting

CAPD unit in a university hospital.

Patients

Forty-two patients on rHuEPO treatment for at least one year were compared with an rHuEPO nonuser group of 113 patients. Subcutaneous rHuEPO doses were adjusted to a hemoglobin objective level of 10.5 -13.5 g/ dL. Fifty-seven patients were considered as high cardiovascular risk (HCVR), 17 in the rHuEPO group and 40 in the rHuEPO nonuser group. Ninety-eight patients were classified as low cardiovascular risk (LCVR), 25 of whom were in the rHuEPO group.

Results

The incidence of cardiovascular morbidity was more frequent in the rHuEPO nonuser than in the rHuEPO user group (40% vs 22%) and in HCVR than in LCVR patients (59.6% vs 20.4%). By multiple logistic regression analysis, the best model to explain the development of cardiovascular morbidity comprises rHuEPO treatment, CV risk, and age. In the rHuEPO user group, HCVR and LCVR patients did not show significant differences in survival, while in the rHuEPO nonuser group, HCVR patients had a lower survival rate than LCVR patients (p = 0.0003). Cox proportional hazards model revealed that LCVR patients had an excellent prognosis compared with HCVR patients in the rHuEPO nonuser group, but this difference disappeared in the rHuEPO user group.

Conclusion

These data show a beneficial effect of rHuEPO treatment on cardiovascular morbidity and mortality in CAPD patients, evidenced by the elimination of the correlation between prior cardiovascular risk and subsequent mortality.

Fibroblast Growth Factor 23 and Anemia in the Chronic Renal Insufficiency Cohort Study

BACKGROUND AND OBJECTIVES

Anemia is an early complication of CKD that is associated with increased morbidity and mortality. Prior data show associations between abnormal mineral metabolism markers and decreased erythropoiesis. However, few studies have investigated elevated fibroblast growth factor 23 as a risk factor for the development of anemia in patients with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a prospective cohort study of 3869 individuals with mild to severe CKD enrolled in the Chronic Renal Insufficiency Cohort Study between 2003 and 2008 and followed through 2013. We hypothesized that elevated baseline fibroblast growth factor 23 levels are associated with prevalent anemia, decline in hemoglobin over time, and development of incident anemia, defined as serum hemoglobin level <13 g/dl in men, serum hemoglobin level <12 g/dl in women, or use of erythropoietin stimulating agents.

RESULTS

In the 1872 of 3869 individuals who had prevalent anemia at baseline, mean age was 58 (11) years old, and mean eGFR was 39 (13) ml/min per 1.73 m2. Higher levels of fibroblast growth factor 23 were significantly associated with prevalent anemia (odds ratio per 1-SD increase in natural log-transformed fibroblast growth factor 23, 1.39; 95% confidence interval, 1.26 to 1.52), decline in hemoglobin over 4 years, and risk of incident anemia (hazard ratio per 1-SD increase in natural log-transformed fibroblast growth factor 23, 1.13; 95% confidence interval, 1.04 to 1.24; quartile 4 versus quartile 1: hazard ratio, 1.59; 95% confidence interval, 1.19 to 2.11) independent of demographic characteristics, cardiovascular disease risk factors, CKD-specific factors, and other mineral metabolism markers. The results of our prospective analyses remained unchanged after additional adjustment for time-varying eGFR.

CONCLUSIONS

Elevated fibroblast growth factor 23 is associated with prevalent anemia, change in hemoglobin over time, and development of anemia. Future studies are needed to elucidate the mechanisms for these associations.

Fibronectin and transforming growth factor beta contribute to erythropoietin resistance and maladaptive cardiac hypertrophy

The use of recombinant human erythropoietin (rhEPO) to promote repair and minimize cardiac hypertrophy after myocardial infarction has had disappointing outcomes in clinical trials. We hypothesized that the beneficial non-hematopoietic effects of rhEPO against cardiac hypertrophy could be offset by the molecular changes initiated by rhEPO itself, leading to rhEPO resistance or maladaptive hypertrophy. This hypothesis was investigated using an isoproterenol-induced model of myocardial infarct and cardiac remodelling with emphasis on hypertrophy. In h9c2 cardiomyocytes, rhEPO decreased isoproterenol-induced hypertrophy, and the expression of the pro-fibrotic factors fibronectin, alpha smooth muscle actin and transforming growth factor beta-1 (TGF-β1). In contrast, by itself, rhEPO increased the expression of fibronectin and TGF-β1. Exogenous TGF-β1 induced a significant increase in hypertrophy, which was further potentiated by rhEPO. Exogenous fibronectin not only induced hypertrophy of cardiomyocytes, but also conferred resistance to rhEPO treatment. Based on these findings we propose that the outcome of rhEPO treatment for myocardial infarction is determined by the baseline concentrations of fibronectin and TGF-β1. If endogenous fibronectin or TGF-β levels are above a certain threshold, they could cause resistance to rhEPO therapy and enhancement of cardiac hypertrophy, respectively, leading to maladaptive hypertrophy.

Predictors of right ventricular systolic dysfunction in compensated and decompensated heart failure

Current understanding of the mechanisms of right ventricular (RV) systolic dysfunction in heart failure (HF) is limited. The authors analyzed a limited access dataset from the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) provided by the National Heart, Lung, and Blood Institute (NHLBI). RV systolic function was measured by echocardiography at baseline and at 3-month follow-up using fractional area change. Univariate and multivariate analysis was performed with linear regression. Of 433 patients enrolled in the ESCAPE trial, 190 had RV systolic function measured at baseline (decompensated HF) and 147 had it measured at 3-month follow-up. On both occasions, parameters of congestion were associated with RV systolic function. Interestingly, lower hematocrit level was also associated with better RV systolic function. In multivariate analysis, only wedge pressure remained a statistically significant predictor of RV dysfunction. In summary, cardiac diastolic pressures and corresponding echocardiographic parameters, as well as hematocrit level, predicted RV systolic function in both compensated and decompensated systolic HF.

Anaesthesia for renal transplant surgery

Renal transplantation is the preferred therapeutic option for patients with end-stage renal disease. Survival rates are much higher in patients who receive a transplant. Patients with renal failure have significant concomitant medical conditions, such as cardiovascular disease. This article provides an overview of the important issues to be considered in patients undergoing renal transplant, and discusses the anaesthetic management of these patients.

Anemia, renal transplantation, and the anemia paradox

Anemia is prevalent in renal transplant recipients (RTRs), as it is in all chronic kidney disease (CKD) populations. Mild anemia occurs in up to 40% of RTRs, and more severe anemia (110 g/L) occurs in about 9% to 22% of patients. As in CKD, impaired graft (renal) function is a major predictor of anemia identified in nearly all studies, suggesting a major role for erythropoietin deficiency. Chronic inflammation, malnutrition, iron deficiency, and medications (angiotensin converting enzyme inhibitors, angiotensin receptor blockers, mycophenolate, azathioprine, and sirolimus) are contributory factors seen in some, but not all, studies. Although pathophysiologic and observational data strongly support a causal association between low hemoglobin levels and cardiovascular outcomes in RTRs, no randomized controlled trial to date has been able to show a clear benefit of anemia treatment on cardiovascular outcomes or mortality in either RTR or other CKD populations. This important paradox has led some investigators to question the causal nature of the association between anemia and heart disease. Resolution of this paradox, at least for patients with stage 2/3 CKD, will depend on the outcome of randomized controlled trials currently in progress. Similar trials sorely are needed in renal transplant populations. In the interim, current opinion favors treating persistent anemia in RTRs to achieve targets similar to those recommended for dialysis and CKD patients.

General Medical Care among Patients with Chronic Kidney Disease: Opportunities for Improving Outcomes

Suboptimal health care during advancing chronic kidney disease (CKD) may result in greater morbidity and cost once dialysis is started and may preclude future transplantation. Medicare data were examined for the prevalence of selected general health, diabetes, and CKD interventions in a national cohort of patients in the 2 yr before dialysis initiation and compared with a contemporaneous non-CKD cohort. A total of 24,778 individuals who were aged > or =67 yr composed the CKD cohort, and 1,046,136 individuals who were aged > or =67 yr did not have CKD. Among patients with diabetes and CKD, fewer than two thirds had claims for eye examinations, 75% for HbA(1C) testing, and 68% for lipid testing, with similar proportions in the non-CKD cohort. Among those without diabetes, 47 and 54% of the CKD and non-CKD cohorts, respectively, had claims for lipid testing. Fewer than 50 and 15% had claims for influenza and pneumococcal vaccination, respectively, with slightly lower proportions among patients with CKD. Claims for cancer tests were found for 14 to 41% and 29 to 52% of individuals with and without CKD, respectively, depending on the type of cancer. A greater proportion of patients with diabetes tended to have claims for tests in both cohorts. In the CKD cohort, claims for anemia testing and parathyroid hormone levels were available in fewer than 50 and 15%, respectively, and claims for permanent vascular access were found for only 30% of hemodialysis patients. This study provides further evidence that patients with CKD may not be receiving general health and CKD care according to current recommendations.

Epoetin alfa's effect on left ventricular hypertrophy and subsequent mortality

BACKGROUND

Improving anemia in patients with chronic renal failure (CRF) and congestive heart failure (CHF) also improves left ventricular hypertrophy (LVH). No previous meta-analyses have been conducted to further examine this association, including the association between LVH and mortality in these patients.

METHODS AND RESULTS

Literature searches on MEDLINE, EMBASE, and OVID were performed using Cochrane Library protocols. Two hundred sixteen abstracts were reviewed preliminarily for inclusion in the meta-analysis of epoetin alfa, anemia and 5 pre-selected parameters of LVH. One hundred seventy-nine abstracts were reviewed for LVH and mortality. The predominant hematologic and left ventricular function changes observed during epoetin alfa treatment in patients with CHF and CRF are (1) increases in hemoglobin (Hb) and hematocrit (Hct); (2) decreases in left ventricular mass (LVM) and LVM index; (3) increase in ejection fraction (EF); and (4) decreases in left ventricular end-diastolic and end-systolic volume. Three independent factors-target Hb, duration of disease, and duration of follow-up-each had a statistically significant association with Hb, Hct, and EF, respectively. A separate meta-analysis using 3 risk models showed LVH is strongly and positively associated with both cardiovascular and all-cause mortality, with two- to three-fold increases in risk.

CONCLUSIONS

LVH is common in patients with CRF and CHF. Current findings indicate epoetin alfa therapy results in anemia amelioration, as evidenced by higher Hb and Hct levels, and reduction of key LVH parameters. LVM regression is associated with lower incidence of cardiovascular-related morbidity and mortality, therefore epoetin alfa therapy may provide a survival benefit.

Intractable anemia among hemodialysis patients: A sign of suboptimal management or a marker of disease?

BACKGROUND

Most incident hemodialysis (HD) patients who initiate dialysis therapy with anemia usually can achieve a hemoglobin (Hb) level of 11 g/dL or greater (> or =110 g/L) within a few months of the initiation of recombinant human erythropoietin (EPO) therapy. However, patients unable to achieve this level may be at greater risk for adverse outcomes. Whether intractable anemia is a modifiable problem or a marker for other conditions is unclear. This question was addressed in a cohort of 130,544 incident HD patients from 1996 to 2000 who were administered EPO regularly.

METHODS

Medicare claims data were used to determine demographic characteristics, comorbidities, hospitalizations, and related events. Patients who did not achieve an Hb level of 11 g/dL or greater (> or =110 g/L; n = 19,096; 14.6%) during months 4 to 9 after dialysis therapy initiation were compared with those who did.

RESULTS

Patients unable to achieve an Hb level of 11 g/dL (110 g/L) were younger and more often of nonwhite race. In addition, these patients had more comorbid conditions; experienced more hospitalizations with longer stays, more infectious hospitalizations, and more catheter insertions; and were administered more blood transfusions. EPO was administered in higher and increasing doses during the years of study among patients with intractable anemia compared with those with an Hb level of 11 g/dL or greater (> or =110 g/L), likely denoting increasing attempts to correct anemia over the years.

CONCLUSION

It is apparent that incident HD patients unable to achieve an Hb level of 11 g/dL or greater (> or =110 g/L) have a greater disease burden. The independent association of intractable anemia with such future outcomes as cardiovascular events and hospitalizations remains to be determined.

Projecting the United States ESRD population: Issues regarding treatment of patients with ESRD

In 2001, there were 406,081 patients who received treatment for end-stage renal disease (ESRD), increasing by 4.2% since 2000. The number of patients with ESRD has grown consistently over the past decade, with the greatest rate of growth occurring among patients older than 75 years of age, and patients with comorbidities such as diabetes mellitus and hypertension. Current projections indicate that the population of patients with ESRD may reach more than 2 million by 2030. The overall mortality rate has fallen by 10% since 1988, with the greatest decline among patients incident to dialysis, and an increase among patients receiving dialysis for greater than five years. While the rate of hospitalization for ESRD patients has remained relatively constant, recent improvements in mortality are temporally associated with a greater proportion of patients achieving adequate benchmarks of care in dialytic processes, such as anemia correction and dose of dialysis. The ESRD program consumes 6.4% of the Medicare budget. On a per-patient per month basis, Medicare costs have risen between 1991 and 2001. While payments fell slightly during 1998 and 1999 because of changes in Medicare policies, more recent years have seen an upswing in total expenditures, presumably related to use of injectables not included in the composite rate. Continued growth in the number of new patients reaching ESRD, as well as improved mortality rates of ESRD patients, are both contributing to the current rise and projected epidemic of ESRD over the next 25 years. The current public health strategy of identification of patients with early kidney disease to slow their progression to ESRD, in addition to aggressive treatment strategies to minimize the morbidity and mortality of patients with ESRD, is essential toward affecting the growth and health of this population.

Anemia predicts mortality in severe heart failure: the prospective randomized amlodipine survival evaluation (PRAISE)

OBJECTIVES

Our aim was to examine the relationships between serum hematocrit (Hct) and risk of all-cause mortality among patients with severe heart failure (HF).

BACKGROUND

Anemia occurs with increased frequency in severe HF. However, few studies have examined the impact of anemia on mortality in this population.

METHODS

Using a prospective cohort design, we evaluated the relationships between baseline serum Hct and mortality among 1,130 patients with left ventricular EF <30% and New York Heart Association functional class IIIB or IV HF treated with angiotensin-converting enzyme inhibitors, diuretics, and digitalis. Mortality was ascertained by centralized adjudication.

RESULTS

The mean Hct was 41.8% (range 25.4% to 58.8%). Over 15 months of mean follow-up, there were 407 deaths (29 per 100 person-years). After adjustment for potential confounders, those in the lowest quintile of Hct (range 25.4% to 37.5%) had a 52% higher risk of death (hazard ratio 1.52, 95% confidence interval 1.11 to 2.10), compared with the highest quintile (range 46.1% to 58.8%). Within the lowest quintile of Hct, each 1% decrease in Hct was associated with an 11% higher risk of death (p < 0.01), whereas within the four higher quintiles of Hct, Hct was not associated with total mortality. Evaluation of different causes of death indicated that a lower Hct was strongly associated with death from progressive HF, rather than sudden death or other deaths.

CONCLUSIONS

Among patients with severe HF, anemia is a significant independent risk factor for death, with a progressively higher risk with increasing severity of anemia. Further investigation of the etiologies, prevention, and treatment of anemia in severe HF is warranted.

Anemia treatment in the pre-ESRD period and associated mortality in elderly patients

BACKGROUND

Anemia is a common complication of advancing chronic kidney disease, yet little is known about the consistency of anemia treatment before end-stage renal disease (ESRD) and mortality on dialysis therapy.

METHODS

We studied 89,193 incident Medicare patients with ESRD in 1995 to 1997 aged 67 plus years with claims 2 years before their dialysis therapy initiation. Patients were classified as follows: no epoetin, 25% or less (least consistent), greater than 25% to 50%, greater than 50% to 75%, and greater than 75% (most consistent) epoetin treatment in the available months from the first pre-ESRD epoetin dose to the first ESRD service date. Cox regression modeled the risk for 1-year death in the post-ESRD period, adjusting for age, sex, race, diabetic status, albumin level, and incidence year.

RESULTS

Sixty percent of patients had hematocrits less than 30% at ESRD initiation, yet only 15.6% (N = 13,877) had epoetin claims before ESRD. The most consistent epoetin treatment group had hematocrits increase from 27.5% to 30.8% (P < 0.0001) by month 4 of treatment. Patients with the most consistent epoetin treatment had a greater mean hematocrit (29.2% +/- 0.11%; P < 0.0001) and albumin level (3.31 +/- 0.01 g/dL [33.1 g/L]) at initiation than those with the least consistent treatment (28.1% +/- 0.10% and 3.21 +/- 0.01 g/dL [32.1 g/L], respectively). The relative risk for death in patients with the least consistent versus the most consistent (the reference) epoetin treatment was 1.460 (95% CI, 1.245 to 1.713; P < 0.0001) 1 year after the first ESRD service date.

CONCLUSION

Elderly patients with consistent pre-ESRD epoetin treatment had lower risks for death in the first year of dialysis therapy after ESRD initiation.

Influence of the cyclic variation of hydration status on hemoglobin levels in hemodialysis patients

BACKGROUND

Maintenance hemodialysis (HD) patients were studied to assess the effect on hemoglobin (Hb) concentration induced by the cyclic variation in hydration status.

METHODS

Forty-nine HD patients were examined in three consecutive HD sessions in a 1-week treatment period. In a subgroup of 23 patients, Hb levels also were investigated during the long interdialytic interval.

RESULTS

Hb levels at the end of the long interdialytic interval were significantly lower by 0.5 to 0.6 g/dL (5 to 6 g/L) than those at the end of short intervals. Among all pre-HD and post-HD Hb values, levels measured at the end of short intervals were closest to the mean Hb value of the week, derived from calculation of the area under the curve (12.0 +/- 0.2 g/dL [120 +/- 2 g/L]). Intradialytic Hb increments were different in the three sessions (+1.6 +/- 0.1 g/dL [+16 +/- 1 g/L] after the long interval, +1.1 +/- 0.1 g/dL [+11 +/- 1 g/L] and +1.1 +/- 0.1 g/dL [+11 +/- 1 g/L] after short intervals [P < 0.001] and proportionate to weight loss [-3.4 +/- 0.1, -2.7 +/- 0.1, and -2.6 +/- 0.1 kg, respectively; P < 0.001]). Hb level increment and weight loss correlated directly (r = 0.527; P < 0.0001); each 1 L of ultrafiltration (UF) led to an increase in Hb level of approximately 0.4 g/dL (4 g/L). Plasma refilling accounted for an approximately 45% decrement in the intradialytic increase in Hb level 2 hours post-HD.

CONCLUSION

This study suggests that: (1) the end of the short interdialytic period is the most appropriate timing for anemia assessment, and (2) the remarkable hemodiluting effect of post-HD plasma refilling protects against excessive increments in Hb levels induced by UF.

Quality of prereferral care in patients with chronic renal insufficiency

BACKGROUND

Appropriate care in chronic renal insufficiency (CRI) includes blood pressure and diabetes control, as well as the investigation and management of anemia, acidosis, and bone disease. There is a lack of data on the control of these parameters at the time of referral to a nephrologist. Similarly, early referral has been emphasized in the literature, yet very little published has examined current referral patterns.

METHODS

A single-center retrospective/prospective review of all new outpatient referrals to nephrologists in Halifax, Canada, in 1998 and 1999 was conducted to identify patients with CRI (serum creatinine > 1.6 mg/dL [141 micromol/L] for men or >1.2 mg/dL [106 micromol/L] for women). Quality of prereferral care was based on data from the initial clinic visit.

RESULTS

Of 1,050 charts reviewed, 411 patients met the study criteria. Twenty-six percent of patients had diabetes mellitus, 18% were referred with a calculated glomerular filtration rate less than 15 mL/min, and blood pressure was optimally controlled (<130 mm Hg systolic and <80 mm Hg diastolic) in only 24%. Only 44% of patients were administered an angiotensin-converting enzyme inhibitor. Patients were administered an average of 1.9 antihypertensive agents. Significant anemia (hemoglobin < 10 g/dL) was present in 21%, and appropriate investigations were performed in only 35% of these patients. Calcium levels less than 8.6 mg/dL (2.15 mmol/L) were found in 19% of patients, and only 14% of these patients were started on calcium supplement therapy. Phosphate levels greater than 5.0 mg/dL (1.6 mmol/L) were seen in 20% of patients, and 14% of these patients were on phosphate-binder therapy. Parathyroid hormone levels were more than five times normal values in 18% of patients, and 25% of patients had bicarbonate levels less than 23 mmol/L.

CONCLUSIONS

A significant proportion of patients referred with CRI receive inadequate prereferral care. Continuing education programs and referral guidelines must not only emphasize the importance of early referral, but also address the related consequences of CRI to delay the progression of renal disease and avoid complications.

Alterations of left ventricular hypertrophy in and survival of patients receiving hemodialysis: follow-up of an interventional study

Left ventricular (LV) hypertrophy (LVH) is a risk factor for mortality in patients with end-stage renal disease (ESRD). Whether the attenuation of LVH has a positive effect on survival of patients with ESRD has not been documented. The aim of this study was to determine the effect of parallel treatment of hypertension and anemia on LV mass (LVM) and to determine the effect of LVM changes on survival. A cohort of 153 patients receiving hemodialysis was studied. The duration of follow-up was 54 +/- 37 mo. All patients had echocardiographic determination of LV dimensions and LVM at baseline and regular intervals until the end of the follow-up period. During the study, BP decreased from (mean +/- SD) 169.4 +/- 29.7/90.2 +/- 15.6 to 146.7 +/- 29/78 +/- 14.1 mmHg (P < 0.001), and hemoglobin increased from 8.65 +/- 1.65 to 10.5 +/- 1.45 g/dl (P < 0.001). The LV end-diastolic diameter and mean wall thickness decreased from 56.6 +/- 6.5 to 54.8 +/- 6.5 mm (P < 0.001), and from 10.4 +/- 1.6 to 10.2 +/- 1.6 mm (P < 0.05), respectively. The LVM decreased from 290 +/- 80 to 264 +/- 86 g (P < 0.01). Fifty-eight deaths occurred, 38 attributed to cardiovascular (CV) disease and 20 attributed to non-CV causes. According to Cox analyses after adjustment for age, gender, diabetes, history of CV disease, and all nonspecific CV risk factors, LVM regression positively affected the survival. The hazard risk ratio associated with a 10% LVM decrease was 0.78 (95% confidence interval, 0.63 to 0.92) for all-causes mortality and 0.72 (95% confidence interval, 0.51 to 0.90) for mortality due to CV disease. These results show that a partial LVH regression in patients with ESRD had a favorable and independent effect on patients' all-cause and CV survival.

Effect of erythropoietin on cardiovascular diseases

Cardiac diseases account for almost 50% of deaths in long-term dialysis patients. Left ventricular dysfunction is present in approximately 80% of these patients and is highly predictive of future ischemic heart disease, cardiac failure, and death. Anemia has been identified as one of several risk factors responsible for cardiac complications. Cardiovascular consequences of renal anemia begin relatively early in the course of renal failure and progress with the decline of renal function and also during dialysis therapy. In chronic renal failure patients with severe anemia (hemoglobin levels <10 g/dL), increased cardiac output, high left ventricular mass, left ventricular end-diastolic and end-systolic diameters, and cardiac symptoms improve after partial correction of anemia (hemoglobin levels >11 g/dL according to the European Best Practice Guidelines). It is disappointing that normalization of hemoglobin levels has only minor effects with respect to regression of left ventricular hypertrophy and left ventricular dilation. There is no benefit of hemoglobin normalization on all-cause mortality of dialysis patients or on survival of end-stage renal disease patients with congestive heart failure or ischemic heart disease. Therefore, prevention of renal anemia may be more efficient than its treatment. Hypertension is one of the major side effects of recombinant human erythropoietin (rHuEPO) therapy. Multiple factors are involved in rHuEPO-induced hypertension. High blood pressure can usually be controlled readily in the majority of the patients.

Risk factors for cardiovascular disease in children on maintenance dialysis

Cardiovascular disease mortality is high in children on maintenance dialysis, accounting for about 25% of patient deaths. Cardiovascular-related mortality rates for children on dialysis are higher than for children with successful kidney transplants. Data on the long-term consequences of risk factors for cardiovascular disease are lacking for pediatric end-stage renal disease patients. This article reviews pediatric data pertaining to the following risk factors: anemia, hypertension, hyperlipidemia, left ventricular hypertrophy, abnormal calcium-phosphorus metabolism, and hyperhomocysteinemia. The potential relationship of end-stage renal disease to the etiology of several functional disorders of the cardiovascular system is discussed. Clinical studies are needed to assess the prevalence of cardiovascular disease and of cardiovascular disease risk factors in the pediatric end-stage renal disease population. Possible preventive and therapeutic guidelines need to be developed for at-risk children on maintenance dialysis.

A randomized study of oral vs intravenous iron supplementation in patients with progressive renal insufficiency treated with erythropoietin

BACKGROUND

Correction of anaemia as a result of renal failure improves cardiovascular function and also provides significant cognitive and emotional benefits. The most appropriate route for iron supplementation has not been determined for patients with chronic renal failure who are not yet on dialysis.

METHODS

Forty-five anaemic patients with progressive renal insufficiency (PRI) were prospectively randomized to receive oral (ferrous sulphate 200 mg tds) or intravenous (300 mg iron sucrose monthly) iron treatment. Erythropoietin (rHuEpo) was simultaneously commenced and the dose adjusted according to a pre-established protocol.

RESULTS

There were no significant differences in baseline patient characteristics between the two groups. The average follow-up was 5.2 months. Three patients suffered possible allergic reactions to iron sucrose. Haemoglobin response and changes in red cell hypochromasia were similar in the two groups, but serum ferritin was significantly higher in the intravenous group. The starting dose of rHuEpo could be temporarily discontinued in 43% of patients on oral iron and 33% of patients receiving iron sucrose (NS). rHuEpo was increased after 3 months in 9% of patients on oral iron and 19% of patients receiving iron sucrose (NS). Final doses of rHuEpo were 33.5 (0-66) and 41.6 (0-124) U/kg/week respectively in the oral and intravenous groups (NS). Although gastro-intestinal symptoms were more commonly reported in patients taking oral iron, these were mild according to scores on visual analogue scales. Dietary protein and energy intake were not significantly different in the two groups at 0, 3 and 6 months.

CONCLUSIONS

In pre-dialysis patients, the efficacy of monthly 300 mg iron sucrose given intravenously is not superior with regard to haemoglobin response and rHuEpo dose as compared with a daily oral dose of 600 mg of ferrous sulphate or equivalent. Where intravenous iron is preferred, lower doses may help to reduce the incidence of allergic or "free iron" reactions, especially in patients with low body mass.

Defining a renal anemia management period

Estimates of the prevalence of anemia during chronic renal insufficiency (CRI) vary depending on how anemia is defined. An analysis of patients beginning dialysis in the United States found that 67% had a hematocrit of less than 30% and 51% had a hematocrit of less than 28%. The anemia of CRI, therefore, appears to be prevalent even as it is underrecognized and undertreated-despite the widespread realization that there is much to be gained by treatment with recombinant human erythropoietin, with little risk of accelerating the progression of kidney disease. It is difficult to separate the effects of anemia in CRI from those of other comorbid conditions, but it is clear that anemia is a strong predictor of mortality and cardiac morbidity. Correction of anemia would be expected to negate the contribution of anemia to the mortality and cardiac morbidity associated with CRI. While this hypothesis is well-validated in hemodialysis patients, data in the population with CRI are preliminary but encouraging. Recent small prospective studies have established that treatment of anemia with recombinant human erythropoietin can reverse some degree of the cardiac morphological changes seen in CRI. While awaiting the results of large long-term clinical trials, the concept of the renal anemia management period (RAMP) draws attention and focus to the need for proactive and aggressive treatment of anemia among patients with CRI. The RAMP is defined as the period of time after the onset of CRI during which anemia develops, requiring diagnosis and treatment. Treatment of anemia during the RAMP has the potential to ameliorate, or even prevent, significant future morbidity in patients with CRI.

Anemia management in patients with chronic renal insufficiency

The introduction of recombinant human erythropoietin (rHuEPO) more than a decade ago provided the first effective treatment for the anemia of chronic renal insufficiency (CRI). The use of rHuEPO in the treatment of anemia has been associated with partial regression of left ventricular hypertrophy among both dialysis and nondialysis patients, and has been shown to reduce the frequency of cardiac complications such as congestive heart failure and number of days of hospitalization among dialysis patients. Despite this evidence, the anemia of CRI remains highly prevalent, underrecognized, and undertreated. A number of considerations arise regarding the management of anemia among patients with CRI. In this article, we review the rationale for treatment of anemia, current management practices, proposed treatment strategies, and the economic implications of improved anemia treatment.

Erythropoietin protects against brain ischemic injury by inhibition of nitric oxide formation

Erythropoietin prevents in vitro glutamate-induced neuronal death and could play a role in the central nervous system. We investigated the in vivo effects of recombinant human erythropoietin after intraperitoneal (i.p.; 25-100 U) or intracerebroventricular (i.c.v.; 0.25-25 U) administration on survival, brain malonildialdehyde (MDA) levels, brain edema, hippocampal neuronal death and brain nitric oxide (NO) synthesis after bilateral carotid occlusion (5 min), followed by reperfusion in the Mongolian gerbil. Peripheral posttreatment with recombinant human erythropoietin reduced postischemic MDA levels, brain edema and increased survival. Either peripheral or i.c.v. posttreatment with recombinant human erythropoietin significantly reduced hippocampal CA1 neuronal loss, observed 7 days after the ischemic event. Increase of nitrite and nitrate (as an index of NO formation) in the hippocampus, as observed after ischemia, was reduced in animals treated with recombinant human erythropoietin. These data suggest that in vivo recombinant human erythropoietin effects on brain ischemic injury could be due to inhibition of NO overproduction.

Pathophysiology of cardiovascular disease in hemodialysis patients

Cardiovascular disease is the principal cause of morbidity and mortality in dialysis patients. The principal alterations responsible are left ventricular hypertrophy and arterial disease characterized by an enlargement and hypertrophy of arteries and the high prevalence of atheromatous plaques. Left ventricular hypertrophy is the consequence of combined effects of chronic hemodynamic overload and nonhemodynamic biochemical and neurohumoral factors characteristic of uremia. The hemodynamic overload is due to flow and pressure overload. The flow overload is tightly related to hyperkinetic circulation caused by anemia, arteriovenous fistula, or overhydration and is characterized by an enlargement of the left ventricular cavity. The pressure overload in these patients is more tightly related to abnormal geometry and function of large conduit arteries, principally the stiffening of arterial tree. The flow overload is also in large part responsible for remodeling of arterial tree, and as the heart and vessels are a coupled interactive physiological system, cardiac and vascular alterations occur in parallel, being induced to a great extent by the same hemodynamic abnormalities. The principal clinical consequences of left ventricular hypertrophy and arterial alterations are heart failure, ischemic heart disease, and peripheral artery disease. Cardiovascular alterations are only partly reversible, and efforts should be directed toward early prevention.

Serial change in echocardiographic parameters and cardiac failure in end-stage renal disease

Echocardiographic abnormalities are the rule in patients starting dialysis therapy and are associated with the development of cardiac failure and death. It is unknown, however, whether regression of these abnormalities is associated with an improvement in prognosis. As part of a prospective cohort study with mean follow-up of 41 mo, 227 patients had echocardiography at inception and after 1 yr of dialysis therapy. Improvements in left ventricular (LV) mass index, volume index, and fractional shortening were seen in 48, 48, and 46%, respectively. Ninety patients had developed cardiac failure by 1 yr of dialysis therapy. Twenty-six percent of the remaining 137 patients subsequently developed new-onset cardiac failure. The mean changes in LV mass index were 17 g/m(2) in those who subsequently developed cardiac failure compared with 0 g/m(2) among those who did not (P = 0.05). The corresponding values were -8 versus 0% for fractional shortening (P < 0.0001). The associations between serial change in both LV mass index and fractional shortening and subsequent cardiac failure persisted after adjusting for baseline age, diabetes, ischemic heart disease, and the corresponding baseline echocardiographic parameter. Regression of LV abnormalities is associated with an improved cardiac outcome in dialysis patients. Serial echocardiography adds prognostic information to one performed at baseline.

Flow patterns in the radiocephalic arteriovenous fistula: an in vitro study

A significant number of late failures of arteriovenous fistulae for haemodialysis access are related to the progression of intimal hyperplasia. Although the aetiology of this process is still unknown, the geometry of the fistula and the local haemodynamics are thought to be contributory factors. An in-vitro study was carried out to investigate the local haemodynamics in a model of a Cimino-Brescia arteriovenous (AV) fistula with a 30 degrees anastomotic angle and vein-to-artery diameter ratio of 1.6. Flow patterns were obtained by planar illumination of micro-particles suspended in the fluid. Steady and pulsatile flow studies were performed over a range of flow conditions corresponding to those recorded in patients. Quantitative measurements of wall shear stress and turbulence were made using laser Doppler anemometry. The flow structures in pulsatile flow were similar to those seen in steady flow with no significant qualitative changes over the cardiac cycle. This was probably the result of the low pulsatility index of the flow waveform in AV fistulae. Turbulence was the dominant feature in the vein, with relative turbulence intensity > 0.5 within 10 mm of the suture line decreasing to a relatively constant value of about 0.10-0.15 between 40 and 70 mm from the suture line. Peak and mean Reynolds shear stress of 15 and 20 N/m2, respectively, were recorded at the suture line. On the floor of the artery, peak values of temporal mean and oscillating wall shear stress of 9.22 and 29.8 N/m2, respectively. In the vein, both mean and oscillating wall shear stress decreased with distance from the anastomosis.

Erythropoietin therapy in chronic uremia: the impact of normalization of hematocrit

The target hematocrit to be achieved when treating anemia in hemodialysis patients with erythropoietin is controversial. Current evidence-based recommendations suggest a target hematocrit range of 33% to 36%. Small studies suggest that normalization of hematocrit with erythropoietin may benefit hemodialysis patients in terms of brain function, physical performance, quality of life, and prevention of progressive left ventricular dilatation. However a recent study of the effects of erythropoietin-induced normalization of hematocrit in hemodialysis patients with symptomatic heart disease has shown an increase in both mortality and the rate of vascular access thrombosis. Currently, normalization of hematocrit in patients with symptomatic heart disease is not recommended, nor is it possible to conclude that possible benefits of normalization of hematocrit will outweigh risks in hemodialysis patients without symptomatic heart disease.

Worsening of left ventricular diastolic function during long-term correction of anemia with erythropoietin in chronic hemodialysis patients--an assessment by radionuclide ventriculography at rest and exercise

We studied the effect of correction of anemia with erythropoietin on left ventricular systolic and diastolic function at rest and exercise in 17 chronic hemodialysis patients by means of maximum exercise testing and equilibrium gated radionuclide angiocardiography on three occasions: 1) initial--before erythropoietin administration, 2) intermediate--at the time when the target hemoglobin level reached 100 g/l, and 3) long-term--after 12 months of therapy. After correction of anemia, the patients showed a significant improvement in their response to exercise regarding maximal work load achieved, exercise duration and recovery time. Ejection fraction and peak ejection rate remained unchanged during therapy. At rest, peak filling rate was reduced from 2.62 +/- 1.0 (baseline) to 2.28 +/- 0.9 (intermediate) end-diastolic volume per second, p < 0.01, while no significant difference was observed during exercise. The time to peak filling rate was prolonged significantly during EPO therapy from 157 +/- 30 to 177 +/- 28 ms at rest, p < 0.05, and from 101 +/- 24 to 130 +/- 27 ms during exercise, p < 0.01. By the time of the late study, there were no significant differences between the late and intermediate study. In conclusion, amelioration of anemia with erythropoietin in hemodialysis patients produced improvement in exercise capacity, but diastolic function worsened with therapy and this effect was maintained during the long-term treatment, while systolic function at rest and exercise remained unchanged.

Blood pressure, left ventricular hypertrophy and long-term prognosis in hemodialysis patients

Cardiovascular events are the main cause of death in patients with chronic renal failure who are treated with hemodialysis. Hypertension is frequent among dialysis patients and may be a major cause of mortality, although epidemiological studies are controversial in this regard. This disparity in results may be the consequence of an inadequate definition of hypertension in dialysis patients as well as the interaction with hypertension with other risk factors such as malnutrition or left ventricular hypertrophy (LVH), which are strong predictors of death. Although the goal of blood pressure in dialysis has not been established yet, it seems that predialysis blood pressure levels lower than 150/90 mm Hg must be achieved for patients to avoid complications. LVH is very frequent among dialysis patients and starts early in the progression of chronic renal failure. Hypertension is the main cause for its development, but other potentially reversible factors such as anemia, volume overload, secondary hyperparathyroidism, dose of dialysis or malnutrition may also be implicated. Hence, an adequate management of patients on hemodialysis must include the strict control of blood pressure, preferably with angiotensin converting enzyme (ACE) inhibitors, together with those early measures in order to avoid the development of the other causes of LVH or to treat them when they already exist.

Long-term evolution of cardiomyopathy in dialysis patients

BACKGROUND

Left ventricular enlargement is very common at the inception of dialysis therapy, and highly predictive of future cardiac morbidity and mortality. It is not known whether cardiac size increases further while on dialysis therapy and whether potentially reversible risk factors for later progression can be identified. METHODS; Baseline and yearly echocardiograms were performed in a prospective inception cohort of 433 dialysis patients. The mean patient follow-up was 41 months; 29 patients had four consecutive echocardiograms at yearly intervals.

RESULTS

The patient subset with four echocardiograms was older (58 vs. 51 years, P = 0.02) and had a lower mass ventricular mass index (128 vs. 149 g/m2, P = 0.02) than the parent group. Using repeated measures analysis of variance, applied to those with four echocardiograms, there were progressive increases over time in posterior wall thickness (P = 0.015), left ventricular end-diastolic diameter, left ventricular mass index (P = 0.001), and cavity volume index (P = 0. 001). Mass-to-volume ratios did not change. The biggest changes in mass (18 g/m2 - 14%)and volume index (13 ml/m2 - 18%) occurred between baseline and year 1, although increases in both were seen after year 1. Hemodialysis versus peritoneal dialysis (41 g/m2, P = 0.008) and anemia (10 g/m2 per 1 g/dl drop in hemoglobin, P = 0.02) were associated with progressive left ventricular enlargement, but only within the first year of dialysis therapy. The left ventricular enlargement seen after year 1 was independent of anemia, blood pressure, serum albumin and mode of dialysis.

CONCLUSIONS

Progressive cardiac enlargement, particularly left ventricular dilation with compensatory hypertrophy, continues after starting dialysis therapy. Most of the additional cardiac enlargement seems to occur in the first year of dialysis therapy, suggesting that intervention beyond one year may be relatively ineffective.

Cardiac disease in chronic uremia: pathophysiology

In chronic uremia, apart from frequent coronary lesions, further abnormalities of the heart recently reported include (1) left ventricular hypertrophy, not completely explained by hypertension, (2) interstitial myocardial fibrosis, for which parathyroid hormone is a permissive factor, (3) reduced myocardial perfusion reserve, secondary to functional and structural changes of intramyocardial arteries and to reduced capillary density, (4) abnormalities of myocardial metabolism, which act in concert with restriction of blood flow by microvascular abnormalities to reduce ischemic tolerance. Such metabolic abnormalities include diminished responsiveness to beta-adrenergic stimulation, abnormal control of intracellular calcium concentration, impaired maintenance of energy-rich nucleotide concentrations under conditions of ischemia, impaired insulin-mediated glucose uptake, and abnormalities of myocardial oxidative metabolism.

Cardiac disease in chronic uremia: pathogenesis

Cardiomyopathy in chronic uremia results from pressure and volume overload. The former causes concentric left ventricular [LV] hypertrophy, results from hypertension and aortic stenosis, and is also associated with diabetes mellitus and anemia. Volume overload causes LV dilatation, results from arteriovenous shunting, salt and water overload, and anemia, and is also associated with ischemic heart disease, hypertension, and hypoalbuminemia. Decreased major arterial compliance and an early return of arterial wave reflections are also associated with the extent of LV hypertrophy. Cardiomyopathy predisposes to diastolic and systolic dysfunction. The latter results from myocyte death, and predisposing factors include ischemic heart disease and the uremic environment. Ischemic heart disease may be atherosclerotic or nonatherosclerotic in origin. Multiple factors contribute to the vascular pathology of chronic uremia, including injury to the vessel wall, dyslipidemia, prothrombotic factors, increased oxidant stress, and hyperhomocysteinemia. Ischemic risk factors include hypertension, LV hypertrophy, hypoalbuminemia, and perhaps hyperparathyroidism. The clinical consequences of cardiomyopathy include heart failure, ischemic heart disease, dialysis hypotension, and arrhythmias. The adverse impact of ischemic heart disease is probably mediated through the development of cardiac failure.

Cardiac disease in chronic uremia: clinical outcome and risk factors

Cardiac disease is common and is the major killer in end-stage renal disease (ESRD). Cardiac failure is a highly malignant condition in ESRD patients. Cardiac failure mediates most of the adverse prognostic impact of ischemic heart disease. Left ventricular (LV) abnormalities are already present at initiation of dialysis therapy in approximately 80% of patients. These abnormalities (ie, systolic dysfunction in approximately 15%, LV dilatation with preserved systolic function in 30%, concentric LV hypertrophy [LVH] in 40%) independently predict ischemic heart disease and cardiac failure, and are the largest baseline predictor of mortality after 2 years on dialysis therapy. The associations between classical risk factors (eg, hyperlipidemia, smoking, hypertension) and cardiac outcomes in ESRD are inconsistent. "Uremic" risk factors represent a nascent, but potentially important field. In our prospective 10-year study of 433 patients starting renal replacement therapy, we identified the following as major independent risk factors for cardiac disease: (1) hypertension (concentric LVH, LV dilatation, ischemic heart disease, cardiac failure, inverse relationship with mortality); (2) anemia (LV dilatation, cardiac failure, death); and (3) hypoalbuminemia (ischemic heart disease, cardiac failure, death). Transplantation dramatically improved LV abnormalities, suggesting that a uremic environment is cardiotoxic. Multiple risk factors act in concert to produce cardiac disease in ESRD; many of these are avoidable, suggesting that the enormous burden of disease can be reduced considerably.

Cardiovascular effects of recombinant human erythropoietin in predialysis patients

Treatment with recombinant human erythropoietin (rHuEPO) has solved the problem of anemia in patients on dialysis. However, its application to predialysis patients has raised some doubts about its effects on the progression of renal disease and on blood pressure (BP) and hemodynamic regulation. We have prospectively studied over at least 6 months a group of 11 predialysis patients receiving rHuEPO treatment (initial dose, 1,000 U subcutaneously three times a week). Clinical assessment and biochemical and hematologic measurements were made once every 2 weeks. Twenty-four-hour ambulatory BP monitoring, echocardiography, and determination of neurohumoral mediators of hemodynamics were performed once every 3 months. An adequate hematologic response was found (hemoglobin, 11.7 +/- 0.4 g/dL v 9 +/- 0.3 g/dL) without changes in the progression of renal disease. A decrease in cardiac output and an increase in total peripheral resistance was seen as anemia improved. A trend toward decreased left ventricular (LV) thickness and a significant decrease in LV mass index (from 178.2 +/- 20.6 g/m2 to 147.3 +/- 20.6 g/m2) were observed. Blood pressure control did not improve; moreover, in some patients an increase in systolic values was detected by ambulatory BP. Casual BP remained seemingly stable. Sequential determinations of neurohumoral mediators of hemodynamic substances (endothelin, renin, norepinephrine, epinephrine, dopamine) failed to explain these results. Ambulatory BP reveals a worse control in some patients who were previously hypertensive and confirms the utility of this technique in the assessment of patients under erythropoietin treatment. The trend toward LV hypertrophy regression without improved BP control confirms the role of anemia among the multiple factors leading to LV hypertrophy in end-stage renal disease (ESRD), and opens therapeutic possibilities. Better control of BP may avoid a potential offsetting of beneficial effects that correcting anemia would have on the cardiovascular system.

Aortic changes in experimental renal failure: hyperplasia or hypertrophy of smooth muscle cells?

Cardiovascular complications are a well-known feature of chronic renal failure. Increased wall thickness of intramyocardial arterioles and elastic (aorta) and peripheral (mesenteric) arteries is seen even after normalization of blood pressure. It is currently unknown whether such increases result from hyperplasia of vascular smooth muscle cells, hypertrophy, or a combination of both or from an increase in aortic extracellular matrix. Using a recently developed unbiased stereological technique (the dissector), we investigated the aortas of subtotally nephrectomized rats and sham-operated controls after perfusion fixation. We determined aortic wall thickness, cross-sectional area of aortic media, total number of vascular smooth muscle cells per unit aortic length (1 mm), mean cell and nuclear volumes, volume density of elastic fibers, extracellular matrix, vascular smooth muscle cells, and total volumes of these structures per unit of aortic length (1 mm). Blood pressure was not significantly increased in subtotally nephrectomized rats. In contrast, wall thickness, cross-sectional media, total number of aortic vascular smooth muscle cells, and volume of extracellular matrix including collagen were significantly increased after subtotal nephrectomy, whereas cellular hypertrophy was only modest and an increase in elastic fibers did not occur. In conclusion, increased aortic wall thickness in experimental renal failure results primarily from an increase in aortic extracellular matrix. In addition, however, proliferation of aortic vascular smooth muscle cells resulting in cell hyperplasia also contributed to aortic wall thickening to a minor degree. It appears that aortic wall thickening is caused by secretory stimulation of the proliferating vascular smooth muscle cells, resulting in increased matrix production. The nature of the underlying stimulus requires further investigation.