The regulation and measurement of plasma volume in heart failure

Association of fluid retention with anemia and clinical outcomes among patients with chronic kidney disease

Background

Observational studies have demonstrated an association between anemia and adverse outcomes in patients with chronic kidney disease (CKD). However, randomized trials failed to identify a benefit of higher hemoglobin concentrations, suggesting that the anemia‐outcome association may be confounded by unknown factors.

Methods and Results

We evaluated the influence of fluid status on hemoglobin concentrations and the cardiovascular and renal outcomes in a prospective cohort of 326 patients with stage 3 to 5 CKD. Fluid status, as defined by overhydration (OH) level measured with bioimpedance, was negatively correlated with hemoglobin concentrations at baseline (r=−0.438, P<0.001). In multivariate regression analysis, OH remained an independent predictor of hemoglobin, second only to estimated glomerular filtration rate. Patients were stratified into 3 groups: no anemia (n=105), true anemia (n=82), and anemia with excess OH (n=139) (relative OH level ≥7%, the 90th percentile for the healthy population). During a median follow‐up of 2.2 years, there was no difference in cardiovascular and renal risks between patients with true anemia and those with no anemia in the adjusted Cox proportional hazards models. However, patients with anemia with excess OH had a significantly increased risk of cardiovascular morbidity and mortality and CKD progression relative to those with true anemia and those with no anemia, respectively.

Conclusions

Fluid retention is associated with the severity of anemia and adverse cardiovascular and renal outcomes in patients with CKD. Further research is warranted to clarify whether the correction of fluid retention, instead of increasing erythropoiesis, would improve outcomes of CKD‐associated anemia.

A comparison of continuous intravenous insulin and subcutaneous insulin among patients with type 2 diabetes and congestive heart failure exacerbation

BACKGROUND

The study aims to determine whether the route of insulin administration influences glycaemic variability and inflammatory or neurohormonal markers in patients with type 2 diabetes and congestive heart failure (CHF) exacerbation.

METHODS

Patients (n = 65) were randomized to intravenous (IV) insulin (duration 48 h) or subcutaneous (SQ) insulin. Inflammatory cytokines and markers of lipid oxidation, high-frequency heart rate variability (n = 27) and cardiac impedance (pre-ejection period, n = 28) were used to estimate parasympathetic and sympathetic tone in patients with valid cardiac data. Glycaemic variability was measured using a continuous glucose monitor.

RESULTS

Mean glucose was lower (7.7 ± 1.2 vs 9.4 ± 2.7 mmol/L, p = 0.004), coefficient of variation was higher (p = 0.03) and glycaemic lability index was similar on day 1 in the IV group compared with the SQ group, but groups were similar by day 2. The IV group had more confirmed hypoglycaemia (p = 0.005). There were no differences in hospital readmission or hospital length of stay between groups. There were no differences in CHF biomarkers, heart rate variability or pre-ejection period between groups. Increasing log glycaemic lability index was associated with lower on-treatment pre-ejection period (p = 0.03) while increasing coefficient of variation was associated with increasing brain natriuretic peptide (p = 0.004) and paroxonase-1 (p = 0.02). Other univariable analyses were not significant.

CONCLUSIONS

There were modest, transient differences in glucose control between IV and SQ insulin in hospitalized CHF patients. However, the analyses do not support a link between insulin route and inflammatory markers or autonomic tone. Further study is needed to assess outcomes in hospitalized CHF patients.

Calculated plasma volume status and prognosis in chronic heart failure

AIMS

Plasma volume (PV) expansion hallmarks worsening chronic heart failure (CHF) but no non-invasive means of quantifying volume status exists. Because weight and haematocrit are related to PV, they can be used to calculate relative PV status (PVS). We tested the validity and prognostic utility of calculated PVS in CHF patients.

METHODS AND RESULTS

First, we evaluated the agreement between calculated actual PV (aPV) and aPV levels measured using (125)Iodine-human serum albumin. Second, we derived PVS as: [(calculated aPV - ideal PV)/ideal PV] × 100%. Third, we assessed the prognostic implications of PVS in 5002 patients from the Valsartan in Heart Failure Trial (Val-HeFT), and validated this in another 246 routine CHF outpatients. On analysis, calculated and measured aPV values correlated significantly in 119 normal subjects and 30 CHF patients. In the Val-HeFT cohort, mean (+SD) PVS was -9 ± 8% and related to volume biomarkers such as brain natriuretic peptide (BNP). Over 2 years, 977 (20%) patients died. Plasma volume status was associated with death and first morbid events in a 'J-shaped' fashion with the highest risk seen with a PVS > -4%. Stratification into PVS quartiles confirmed that a PVS > -4% was associated with increased mortality (unadjusted hazard ratio 1.65, 95% confidence interval 1.44-1.88, χ(2)  = 54, P < 0.001) even after adjusting for 22 variables, including brain natriuretic peptide. These results were mirrored in the validation cohort.

CONCLUSIONS

Relative PVS calculated from simple clinical indices reflects the degree to which patients have deviated from their ideal PV and independently relates to outcomes. The utility of PVS-driven CHF management needs further evaluation.

Cost-utility of ferric carboxymaltose (Ferinject®) for iron-deficiency anemia patients with chronic heart failure in South Korea

BACKGROUND

Iron-deficiency anemia (IDA) is prevalent in patients with advanced chronic heart failure (CHF). It affects the patients' overall physical condition and is suggested as a strong outcome predictor in CHF. Recent clinical trials suggested that intravenous iron supplementation improves CHF functional status and quality of life. The aim of this study was to assess the cost-effectiveness of ferric carboxymaltose(FCM) in CHF patients with IDA.

METHODS

Ferric carboxymaltose, an intravenous iron preparation, was compared with placebo. The target population comprised CHF patients with IDA in hospital and outpatient care settings. We conducted this study from the Korean healthcare payers' perspective with a time horizon of 24 weeks. One clinical trial provided the clinical outcomes of ferric carboxymaltose therapy. The improvement rates of the New York Heart Association (NYHA) functional class in the placebo and ferric carboxymaltose groups were used to estimate effectiveness in the base-case model. We also conducted a scenario 2 analysis using quality of life investigated in the clinical trial. A panel survey was conducted to obtain the ratio of healthcare resource use based on NYHA class in Korea. Cost-effectiveness was expressed as incremental cost (US dollars) per quality-adjusted life-year (QALY) gained.

RESULTS

In the base-case analysis, the incremental cost-effectiveness ratio (ICER) of ferric carboxymaltose compared with placebo was $22,192 (₩25,010,451) per QALY gained. The sensitivity analysis showed robust results, with the ICERs of ferric carboxymaltose ranging from $5,156 to $29,796 per QALY gained. In the scenario 2 analysis, ICER decreased to $12,598 (₩14,198,501) per QALY gained.

CONCLUSIONS

Iron repletion with ferric carboxymaltose for IDA in CHF patients was cost-effective compared with placebo.

Natriuretic peptides and cardio-renal disease

The natriuretic peptide (NP) system is an important endocrine, autocrine and paracrine system, consisting of a family of peptides which provide cardiac, renal and vascular effects that, through their beneficial physiological actions, play a key role in maintaining overall cardiovascular health. Traditionally, the pathophysiological origins of cardio-renal disease have been viewed as the domain of the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS), with inappropriate activation of both systems leading to deleterious changes in cardio-renal function and structure. Therapies designed to suppress the RAAS and the SNS have been routinely employed to address the consequences of cardio-renal disease. However, it is now becoming increasingly apparent that enhancing the beneficial physiological effects of the NP system may represent an attractive alternative therapeutic approach to counter the pathophysiological effects of disease. In particular, innovative therapeutic strategies aimed at enhancing the physiological benefits afforded by NPs while simultaneously suppressing the RAAS are generating increasing interest as potential treatment options for the management of cardio-renal disease.

Fluid distribution kinetics during cardiopulmonary bypass

OBJECTIVE

The purpose of this study was to examine the isovolumetric distribution kinetics of crystalloid fluid during cardiopulmonary bypass.

METHODS

Ten patients undergoing coronary artery bypass grafting participated in this prospective observational study. The blood hemoglobin and the serum albumin and sodium concentrations were measured repeatedly during the distribution of priming solution (Ringer's acetate 1470 ml and mannitol 15% 200 ml) and initial cardioplegia. The rate of crystalloid fluid distribution was calculated based on 3-min Hb changes. The preoperative blood volume was extrapolated from the marked hemodilution occurring during the onset of cardiopulmonary bypass. Clinicaltrials.gov: NCT01115166.

RESULTS

The distribution half-time of Ringer's acetate averaged 8 minutes, corresponding to a transcapillary escape rate of 0.38 ml/kg/min. The intravascular albumin mass increased by 5.4% according to mass balance calculations. The preoperative blood volume, as extrapolated from the drop in hemoglobin concentration by 32% (mean) at the beginning of cardiopulmonary bypass, was 0.6-1.2 L less than that estimated by anthropometric methods (p<0.02). The mass balance of sodium indicated a translocation from the intracellular to the extracellular fluid space in 8 of the 10 patients, with a median volume of 236 ml.

CONCLUSIONS

The distribution half-time of Ringer's solution during isovolumetric cardiopulmonary bypass was 8 minutes, which is the same as for crystalloid fluid infusions in healthy subjects. The intravascular albumin mass increased. Most patients were hypovolemic prior to the start of anesthesia. Intracellular edema did not occur.

The effect of congestive heart failure on sensor accuracy among hospitalized patients with type 2 diabetes

BACKGROUND

Congestive heart failure (CHF) features disturbances in the interstitial environment that may affect the accuracy of subcutaneous continuous glucose monitoring (CGM).

SUBJECTS AND METHODS

A pooled analysis of two studies of hospitalized patients with type 2 diabetes randomized to intravenous or subcutaneous insulin was conducted. One study enrolled patients with CHF exacerbation, whereas history of CHF was an exclusion criterion in the other. All patients wore a professional CGM device for at least 24 h. Intravenous insulin was administered according to the institution's nursing-run protocol (duration of 12 and 48 h in non-CHF and CHF protocols, respectively). Subcutaneous insulin was delivered similarly in both groups.

RESULTS

Subjects with CHF (n=43) had higher admission glucose and hemoglobin A1c compared with non-CHF subjects (n=32), but the sensor glucose values were similar. Overall mean absolute relative difference (MARD) was similar between CHF and non-CHF subjects (0.11 vs. 0.08, respectively; P=0.12). MARD was higher in the 100-149 mg/dL (P=0.003) and >199 mg/dL (P = 0.02) strata among CHF subjects. Static glucose and continuous glucose error grid analyses favored the non-CHF group. In multivariable analyses, only glucose coefficient of variation and log sensor time were independent predictors of elevated overall MARD >0.10. After adjustment for other factors, only increasing log sensor time was a significant predictor of elevated MARD in the 100-149 mg/dL strata.

CONCLUSIONS

Among hospitalized subjects with type 2 diabetes, CHF exacerbation is not associated with lower sensor accuracy after adjustment for other factors, but this requires confirmation over a wider glucose range.

Determinants of the accuracy of continuous glucose monitoring in non-critically ill patients with heart failure or severe hyperglycemia

BACKGROUND

The accuracy of continuous glucose monitoring (CGM) in non-critically ill hospitalized patients with heart failure or severe hyperglycemia (SH) is unknown.

METHODS

Hospitalized patients with congestive heart failure (CHF) exacerbation (receiving IV or subcutaneous insulin) or SH requiring insulin infusion were compared to outpatients referred for retrospective CGM.

RESULTS

Forty-three patients with CHF, 15 patients with SH, and 88 outpatients yielded 470, 164, and 2150 meter-sensor pairs, respectively. Admission glucose differed (188 versus 509 mg/dl in CHF and SH, p < .001) but not the first sensor glucose (p = .35). In continuous glucose error grid analysis, 67-78% of pairs during hypoglycemia were in zones A+B (p = .63), compared with 98-100% in euglycemia (p < .001) and 98%, 92%, and 99% (p = .001) during hyperglycemia for the CHF, SH, and outpatient groups, respectively. Mean absolute relative difference (MARD) was lower in the CHF versus the SH group in glucose strata above 100 mg/dl, but there was no difference between the CHF and outpatient groups. Linear regression models showed that CHF versus outpatient, SH versus CHF, and coefficient of variation were significant predictors of higher MARD. Among subjects with CHF, MARD was not associated with brain natriuretic peptide or change in plasma volume, but it was significantly higher in subjects randomized to IV insulin (p = .04).

CONCLUSIONS

The results suggest that SH and glycemic variability are more important determinants of CGM accuracy than known CHF status alone in hospitalized patients.

Determinants and Consequences of Renal Function Variations With Aldosterone Blocker Therapy in Heart Failure Patients After Myocardial Infarction

Background—

We evaluated the effect of the selective mineralocorticoid receptor antagonist eplerenone on renal function and the interaction between changes in renal function and subsequent cardiovascular outcomes in patients with heart failure and left ventricular systolic dysfunction after an acute myocardial infarction in the Eplerenone Post–Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS).

Methods and Results—

Serial changes in estimated glomerular filtration rate (eGFR) were available in 5792 patients during a 24-month follow-up. Patients assigned to eplerenone had a decline in eGFR with an adjusted mean difference of −1.4±0.3 mL · min −1 · 1.73 m −2 compared with placebo ( P <0.0001), an effect that appeared within the first month (−1.3±0.4 mL · min −1 · 1.73 m −2 ) and persisted throughout the study. Overall, 914 patients experienced a decline in eGFR >20% in the first month, 16.9% and 14.7% in the eplerenone and placebo groups, respectively (odds ratio, 1.15; 95% confidence interval, 1.02–1.30; P =0.017). In multivariate analyses, determinants of this early decline in eGFR were female sex, age ≥65 years, smoking, left ventricular ejection fraction <35%, and use of eplerenone and loop diuretic. An early decline in eGFR by >20% was associated with worse cardiovascular outcomes independently of baseline eGFR and of the use of eplerenone, which retained its prognostic benefits even under these circumstances.

Conclusions—

In patients with heart failure after acute myocardial infarction and receiving standard medical care, an early decline in eGFR is not uncommon and is associated with poor long-term outcome. Eplerenone induced a moderately more frequent early decline in eGFR, which did not affect its clinical benefit on cardiovascular outcomes.

Eplerenone survival benefits in heart failure patients post-myocardial infarction are independent from its diuretic and potassium-sparing effects. Insights from an EPHESUS (Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study) substudy

OBJECTIVES

The purpose of this study was to determine whether a diuretic effect may be detectable in patients treated with eplerenone, a mineralocorticoid receptor antagonist, as compared with placebo during the first month of EPHESUS (Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival study) (n = 6,080) and whether this was associated with eplerenone's beneficial effects on cardiovascular outcomes.

BACKGROUND

The mechanism of the survival benefit of eplerenone in patients with heart failure post-myocardial infarction remains uncertain.

METHODS

A diuretic effect was indirectly estimated by changes at 1 month that was superior to the median changes in the placebo group in body weight (-0.05 kg) and in the estimated plasma volume reduction (+1.4%). A potassium-sparing effect was defined as a serum potassium increase greater than the median change in the placebo group: +0.11 mmol/l.

RESULTS

In the eplerenone group, body weight (p < 0.0001) and plasma volume (p = 0.047) decreased, whereas blood protein and serum potassium increased (both, p < 0.0001), as compared with the placebo group, suggesting a diuretic effect induced by eplerenone, associated with a potassium-sparing effect. A diuretic effect, as defined by an estimated plasma volume reduction, was independently associated with 11% to 19% better outcomes (lower all-cause death, cardiovascular death or cardiovascular hospitalization, all-cause death or hospitalization, hospitalization for heart failure). Potassium sparing was also independently associated with 12% to 34% better outcomes. There was no statistically significant interaction between the observed beneficial effects of eplerenone (9% to 17%) on cardiovascular outcomes and potassium-sparing or diuretic effects.

CONCLUSIONS

Eplerenone's beneficial effects on long-term survival and cardiovascular outcomes are independent from early potassium-sparing or diuretic effects, suggesting that mineralocorticoid receptor antagonism provides cardiovascular protection beyond its diuretic and potassium-sparing properties.

Measurement of plasma volume using fluorescent silica-based nanoparticles

Plasma volume (PV) is an important determinant of cardiovascular function and organ perfusion, and it is the target of infusion and diuretic therapies in daily clinical practice. Despite its fundamental importance PV is not commonly measured because available methods of tracer dilution are reliant on dye substances that suffer from numerous drawbacks including binding plasma proteins, spectral changes, and clearance kinetics that complicate analysis and interpretation. To address these issues, we have tested the utility of fluorescent nanoparticles comprised of a dye-rich silica core and polyethylene glycol-coated shell. Photophysical and visual analysis showed discrete size-gradated nanoparticle populations could be synthesized within a distribution tolerance of ±4 nm, which were optically unaffected in the presence of plasma/albumin. In normal mice, the cutoff for renal filtration of nanoparticles from blood into urine was ≤11 nm. A linear relationship between body weight and PV was readily determined in mice administered far red fluorescent nanoparticles sized either 20 or 30 nm. PV measurements using nanoparticles were correlated to values obtained with Evans blue dye. Induced expansion or contraction of PV was demonstrated with albumin or furosemide administration, respectively, in mice. Longitudinal experiments >30 min required matched untreated control mice to correct for nanoparticle loss (≈30%) putatively to the reticuloendothelial/phagocyte system. Collectively, the findings support a nanotechnology-based solution to methodological problems in measure of PV, notably in clinical settings where information on hemodynamic changes may improve treatment of injury and disease.

Detection of preclinical body fluid retention in established heart failure patients during follow-up by a digital weight scale incorporating a bioelectrical impedance analyzer

This study examined the characteristics of asymptomatic worsening heart failure (HF) events and validated the role of a novel HF monitoring method (measuring body weight [BW] and percent body fat [BF%]) to identify such worsening HF events. A clinician determined worsening HF status by evaluating symptoms, physical signs, and pleural effusion on ultrasonography. A criterion of significant fluid weight gain was defined as BW gain ≥1.5 kg with a concomitant decrease in BF%. A total of 74 HF patients were included. During a mean follow-up of 20.8 months, 1588 visits were evaluated. A total of 79 worsening HF events occurred in 50 patients, in which worsening was symptomatic in 46 events (58%) and asymptomatic in 33 events (42%). Novel method eliminated 42 of 73 (58%) false-positive indications of worsening HF events based only on the BW criterion (≥1.5 kg) without excluding true worsening HF events. The test characteristics of this method in the diagnosis of overall HF events were sensitivity 65.8% (95% confidence interval [CI], 54.3-76.1), specificity 97.9% (95%, CI 97.1-98.6), positive predictive value 62.7% (95% CI, 51.3-73.0), and negative predictive value 98.2% (95% CI, 97.4-98.8). Preclinical fluid retention occurs frequently in established HF patients, and novel monitoring method can specifically identify preclinical worsening HF.

Treatment with iron of patients with heart failure with and without anemia

Iron deficiency is a common cause of anemia in otherwise healthy individuals and plays an important role in the development of anemia within the heart failure patient population. Iron-deficient heart failure patients experience worse symptoms and are less exercise tolerant than those without iron deficiency. These symptoms may occur even before clinical anemia is evident. This article reviews studies of the benefits of the use of intravenous iron to treat iron deficiency in anemic and nonanemic heart failure patients and an overview of the physiology and pathophysiology of iron metabolism in chronic heart failure.

Treatment of anemia in heart failure: potential risks and benefits of intravenous iron therapy in cardiovascular disease

Iron-deficiency anemia is common in patients with heart failure (HF), but the optimum diagnostic tests to detect iron deficiency and the treatment options to replete iron have not been fully characterized. Recent studies in patients with HF indicate that intravenous iron can rapidly replenish iron stores in patients having iron-deficiency anemia, with resultant increased hemoglobin levels and improved functional capacity. Preliminary data from a subgroup analysis also suggest that supplemental intravenous iron therapy can improve functional capacity even in those subjects without anemia. The mechanisms responsible for this observation are not fully characterized, but may be related to beneficial effects of iron supplementation on mitochondrial respiration in skeletal muscle. The long-term safety of using intravenous iron supplementation in HF populations is not known. Iron is a known pro-oxidant factor that can inhibit nitric oxide signaling and irreversibly injury cells. Increased iron stores are associated with vascular endothelial dysfunction and increased risk of coronary heart disease events. Additional clinical trials are needed to more fully characterize the therapeutic potential and safety of intravenous iron in HF patients.

Cardiac output and systemic transit time dispersion as determinants of circulatory mixing time: a simulation study

A new approach to characterize the kinetics of intravascular mixing process is presented. The mixing time, defined as the time required for achieving 95% homogeneity, is calculated by numerical simulations using a circulatory model applied to the intravascular marker indocyanine green (ICG). The results suggest that the mixing time is determined by cardiac output and the relative dispersion of transit time distribution across the systemic circulation, whereby the rate of mixing increases with increasing cardiac output and decreasing transit time dispersion, and vice versa. The estimation of plasma volume from simulated ICG dilution data using the backextrapolation method shows that slow mixing is accompanied by an overestimation of blood volume. This error may be negligible for mixing times of less than approximately 3 min but high in disease states characterized by low cardiac output and/or high transit time dispersion. In view of the role of transit time dispersion as determinant of intravascular mixing, it would be interesting to know more about the effect of disease states on systemic transit time dispersion.

Emergency department stabilization of heart failure

Optimizing heart failure management begins in the emergency department. Prompt recognition and treatment of underlying pathophysiology can improve patient outcomes. A review of therapeutic options is provided, with the goal of providing best practices in patient care.

Measuring impedance in congestive heart failure: current options and clinical applications

Measurement of impedance is becoming increasingly available in the clinical setting as a tool for assessing hemodynamics and volume status in patients with heart failure. The 2 major categories of impedance assessment are the band electrode method and the implanted device lead method. The exact sources of the impedance signal are complex and can be influenced by physiologic effects such as blood volume, fluid, and positioning. This article provides a critical review of our current understanding and promises of impedance measurements, the techniques that have evolved, as well as the evidence and limitations regarding their clinical applications in the setting of heart failure management.

Intravascular kinetics of C-reactive protein and their relationships with features of the metabolic syndrome

OBJECTIVE

The objective of the study was to describe, for the first time, the intravascular kinetics of C-reactive protein (CRP), using stable isotopes, and its relationship with features of the metabolic syndrome.

METHODS

Sixteen men and 16 women [aged 49 +/- 9 years, body mass index (BMI) 28.7 +/- 4.5 kg/m(2)] underwent a 12-h primed-constant infusion of 5,5,5-(2)H(3)-l-leucine. CRP was purified from the plasma fraction rho greater than 1.25 g/ml by affinity chromatography, and isotopic enrichment over time was determined by gas chromatography/mass spectrometry.

RESULTS

The CRP fractional catabolic rate was 60% higher in men than women (0.49 +/- 1.83 vs. 0.30 +/- 1.80 pool/d, P = 0.03), but this difference was no longer significant in a multivariate model that included several features associated with the metabolic syndrome. The CRP production rate (PR) and pool size were not statistically different between sexes. Plasma CRP concentrations were more strongly correlated with the PR (r = 0.80, P < 0.0001) than with the fractional catabolic rate of CRP (r = 0.39, P < 0.05). The PR of CRP was positively correlated with waist girth (r = 0.53, P < 0.01), plasma low-density lipoprotein apolipoprotein B-100 (r = 0.42, P = 0.07), triglyceride (r = 0.41, P = 0.06), and IL-6 concentrations (r = 0.61, P = 0.0008) and inversely correlated with high-density lipoprotein-cholesterol (r = -0.47, P = 0.03) and adiponectin (r = -0.63, P < 0.0005) after adjustment for sex. Blood pressure and low-density lipoprotein-cholesterol showed no association with CRP kinetics.

CONCLUSION

The PR of CRP appeared as the main determinant of CRP concentrations and showed significant associations with features of the metabolic syndrome as well as with adipose tissue-derived cytokines such as IL-6 and adiponectin.

Heart failure and anemia: mechanisms and pathophysiology

Anemia is a common comorbidity in patients with heart failure and affects up to 50% of patients, depending on the definition of anemia used and on the population studied. Presence of anemia and lower hemoglobin (Hgb) concentrations are powerful independent predictors of adverse outcomes in heart failure. Even small reductions in Hgb are associated with worse outcomes. Correction of anemia may be useful in improving heart failure outcomes. However, the causes of anemia in heart failure are not entirely clear. Specific causes of anemia such as hematinic abnormalities are seen only in a minority of subjects. Renal dysfunction and neurohormonal and proinflammatory cytokine activation appear to contribute to anemia of chronic disease in the majority of the patients, resulting in inappropriate erythropoietin production and defective iron utilization. Under normal conditions, reduced tissue oxygenation due to chronic anemia results in non-hemodynamic and hemodynamic compensatory responses to enhance oxygen carrying capacity. Erythropoiesis is the predominant non-hemodynamic response to hypoxia, but because erythropoiesis is defective in heart failure, hemodynamic mechanisms predominate. Hemodynamic responses are complex and involve a vasodilation-mediated high-output state with neurohormonal activation. The high-output state initially helps to increase oxygen transport. However, the hemodynamic and neurohormonal alterations could potentially have deleterious long-term consequences and could contribute to anemia's role as an independent risk factor for adverse outcomes.

Effects of Body Mass Index and Age on N-Terminal Pro–Brain Natriuretic Peptide Are Associated with Glomerular Filtration Rate in Chronic Heart Failure Patients

Background: Obesity is a state characterized by glomerular hyperfiltration and age-related decreases in glomerular filtration rate (GFR). Body mass index (BMI), age, and GFR are associated with plasma concentrations of N-terminal pro-brain natriuretic peptide (NT-proBNP) in chronic heart failure (CHF) patients. We hypothesized that the effects of BMI and age on plasma concentrations of NT-proBNP are associated with GFR.

Methods: We obtained clinical data and laboratory test results from 345 CHF patients at the baseline visit in our heart failure clinic and examined the hypothesis using multiple linear regression models.

Results: Age (P = 0.0184), BMI (P = 0.0098), hemoglobin (P = 0.0043), heart rhythm (P &lt;0.0001), and left ventricular ejection fraction (P &lt;0.0001) were associated with log(NT-proBNP). After adjustment for GFR estimated by the Cockcroft and Gault equation, the parameter estimates for BMI (P = 0.3807) and age (P = 0.7238) changed markedly and became insignificant. In another model, after adjustment for GFR estimated by the 4-component Modification of Diet in Renal Disease formula (eGFRMDRD), the parameter estimates for age (P = 0.0674) changed markedly and became insignificant, but BMI (P = 0.0067) remained significant and unchanged. The eGFRMDRD is adjusted for body surface area, which may explain the difference.

Conclusions: In CHF patients, the effect of age on NT-proBNP is associated with estimates for GFR derived from serum creatinine, and the significance of the effects of BMI on NT-proBNP depends on the method by which GFR is estimated.

Arterial remodeling and plasma volume expansion in caveolin-1-deficient mice

Caveolin-1 (Cav-1) is essential for the morphology of membrane caveolae and exerts a negative influence on a number of signaling systems, including nitric oxide (NO) production and activity of the MAP kinase cascade. In the vascular system, ablation of caveolin-1 may thus be expected to cause arterial dilatation and increased vessel wall mass (remodeling). This was tested in Cav-1 knockout (KO) mice by a detailed morphometric and functional analysis of mesenteric resistance arteries, shown to lack caveolae. Quantitative morphometry revealed increased media thickness and media-to-lumen ratio in KO. Pressure-induced myogenic tone and flow-induced dilatation were decreased in KO arteries, but both were increased toward wild-type (WT) levels following NO synthase (NOS) inhibition. Isometric force recordings following NOS inhibition showed rightward shifts of passive and active length-force relationships in KO, and the force response to alpha(1)-adrenergic stimulation was increased. In contrast, media thickness and force response of the aorta were unaltered in KO vs. WT, whereas lumen diameter was increased. Mean arterial blood pressure during isoflurane anesthesia was not different in KO vs. WT, but greater fluctuation in blood pressure over time was noted. Following NOS inhibition, fluctuations disappeared and pressure increased twice as much in KO (38 +/- 6%) compared with WT (17 +/- 3%). Tracer-dilution experiments showed increased plasma volume in KO. We conclude that NO affects blood pressure more in Cav-1 KO than in WT mice and that restructuring of resistance vessels and an increased responsiveness to adrenergic stimulation compensate for a decreased tone in Cav-1 KO mice.

Blood Volume Assessment in the Diagnosis and Treatment of Chronic Heart Failure

Symptoms of intravascular volume overload and increased cardiac filling pressures in the systemic and pulmonary venous circulations are among the most common complaints in patients with chronic heart failure (CHF). The clinical utility of physical examination for estimation of intravascular volume status in patients with CHF is limited due to poor specificity and sensitivity of most signs of congestion. Direct measurement of blood volume with radioisotope techniques is FDA-approved and has been shown to be closely associated with invasive measurements of cardiac filling pressures in patients with CHF. Unrecognized volume overload is common in CHF patients and is associated with adverse clinical outcomes. Additional work is needed to determine the clinical utility of serial blood volume measurements in the management of patients with CHF.

Unexplained week-to-week variation in BNP and NT-proBNP is low in chronic heart failure patients during steady state

BACKGROUND

The usefulness of brain-natriuretic-peptide (BNP) and N-terminal-pro-brain-natriuretic-peptide (NT-proBNP) for monitoring of chronic heart failure (CHF) patients has been questioned because of high levels of unexplained variation.

AIMS

Week-to-week total variance (CV(T)), unexplained variation (CV(I)), reference change values (RCV), index of individualities (IOI) and number of samples (N) with week-to-week intervals needed to estimate the underlying homeostatic set point (+/-15%) for BNP and NT-proBNP were calculated in pre-specified stable CHF patients.

METHODS AND RESULTS

We measured plasma concentrations of BNP and NT-proBNP, clinical and laboratory variables in 20 CHF patients with a 7-days interval. Only patients considered to be in steady state were included. The CV(I) was 15% (BNP) and 8% (NT-proBNP). CV(T) was 16% (BNP) and 8% (NT-proBNP) and RCV was 43% (BNP) and 23% (NT-proBNP). IOI was 0.14 for BNP and 0.03 for NT-proBNP and N was 1 for BNP and 1 for NT-proBNP.

CONCLUSIONS

Our data demonstrate that unexplained variation of BNP and NT-proBNP is low in CHF patients during steady state, which is a prerequisite for the use of these peptides for monitoring of the disease.

Body composition and echocardiographic abnormalities associated to anemia and volume overload in heart failure patients

BACKGROUND

Heart failure (HF) patients with hemodilutional anemia had a worse prognosis than those with true anemia. Volume overload (VO) in anemic patients must be identified in order to select the best treatment.

METHOD

We assessed the prevalence of anemia and VO in systolic and diastolic HF patients, and its effects on clinical status, body composition, and quality of life (QOL). Anemia was defined according to the OMS criteria and VO was assessed by bioelectrical impedance analysis (BIA). Echocardiography variables were also obtained.

RESULTS

We studied 132 HF patients, 59.1% with systolic and 40.9% with diastolic HF. Anemia was present in 29.5% patients with systolic and 24.1% with diastolic HF (P=0.7). Anemic patients in the systolic HF group tend to be worse functional class than the non-anemic subjects; moreover, in both groups of cardiac dysfunction, the anemic patients had less grip strength, lower body mass index (BMI) and waist and hip circumferences, and a higher percentage of extracellular water (ECW), a higher proportion of patients with total serum cholesterol concentration below the 25th percentile, and a lower serum albumin. When patients were divided in 4 subgroups according to the presence of anemia and/or VO, we observed that VO affected the body composition not only through lower BMI, and waist and hip circumferences but also through a lower phase angle. Systolic HF patients with anemia and VO had the highest dimension of left atrium and pulmonary artery pressure (PAP) levels.

CONCLUSION

Anemia is common in HF and its prevalence is similar in systolic and diastolic HF patients. Anemia was associated to VO, less grip strength and body composition abnormalities; however, VO was related to more severe body composition and echocardiographic abnormalities, as well as to an impairment of QOL. So that, it is important to differentiate between those who have anemia associated to VO and those who have true anemia.

Blood volume and brain natriuretic peptide in congestive heart failure: a pilot study

BACKGROUND

Brain natriuretic peptide (BNP) levels rise in response to stretch of ventricular myocytes or increases in wall tension, as in congestive heart failure (CHF). Brain natriuretic peptide can be released in bursts, but nonetheless, BNP levels may lag behind clinical changes. We postulated that concomitant measurement of blood volume (BV), BNP, and hemodynamics during treatment of CHF may elucidate interrelationships among changes in these parameters.

METHODS

We studied 10 male patients, aged 60 +/- 8 years, who were admitted for pulmonary catheter-guided treatment of CHF. Hemodynamics, venous BNP, and blood and plasma volumes were measured at baseline before treatment and again on the following morning after 12 to 24 hours of acute treatment for CHF.

RESULTS

At baseline, all 10 patients exhibited marked expansion of BV at 29% +/- 19%. At baseline, increased systolic pulmonary artery pressure correlated with BV (r = 0.615) and diastolic pulmonary artery pressure (PAD) with BV (r = 0.609). After treatment, there was an inverse correlation between change (decline) in expanded BV and change (improvement) in mixed venous oxygenation (r = -0.775) and a positive correlation with central venous pressure (CVP) (r = 0.710). Poor correlation was found between BNP and any hemodynamic parameter. Little correlation was found between absolute BNP and BV before or after treatment (r = -0.127 and -0.126, respectively).

CONCLUSION

In this pilot study, changes in BV with treatment correlate better with hemodynamics than do changes in BNP, likely reflecting the lag in BNP response to treatment and its tendency to reflect long-term rather than instantaneous volume status. These preliminary data suggest that BV may be a more accurate guide in optimizing CHF treatment than BNP.

Blood haemoglobin is an independent predictor of B-type natriuretic peptide (BNP)

BNP (B-type natriuretic peptide) and anaemia are both associated with adverse outcome in patients with chronic heart failure. Whether low haemoglobin levels are independently predictive of elevated BNP levels in subjects without heart failure is unknown. In the present study, we examined the relationship between haemoglobin and BNP levels in 234 patients with suspected coronary heart disease without a history of chronic heart failure, adjusting for known predictors of BNP levels. By univariate analysis, haemoglobin levels were inversely related to logarithmically transformed BNP values (r=−0.30, P<0.0001). After adjustment for patient age, gender, body mass index, history of myocardial infarction, use of diuretics, angiotensin-converting enzyme inhibitors and β-blockers, estimated creatinine clearance rate, extent of coronary disease, left ventricular ejection fraction and left ventricular end-diastolic pressure, blood haemoglobin remained an independent predictor of plasma BNP (standardized β-coefficient=−0.253, P<0.0001). A similar relationship was observed between haematocrit and BNP (standardized β-coefficient −0.215, P<0.0001). We conclude that haemoglobin levels are independently predictive of plasma BNP levels in patients with suspected coronary heart disease without heart failure. Anaemia may contribute to elevated BNP levels in the absence of heart failure, and may represent an important confounder of the relationship between BNP, cardiac function and prognosis.

Predictors of Elevated B-Type Natriuretic Peptide Concentrations in Dyspneic Patients Without Heart Failure: An Analysis From the Breathing Not Properly Multinational Study

STUDY OBJECTIVE

B-type natriuretic peptide (BNP) is an established tool for the diagnosis of acute congestive heart failure in patients presenting with dyspnea. Some patients have moderately elevated BNP levels (ie, 100 to 500 pg/mL) in the absence of acute congestive heart failure. The objective of the current study was to identify independent predictors of elevated BNP concentrations in the absence of congestive heart failure.

METHODS

We studied 781 patients without acute congestive heart failure and BNP levels 0 to 500 pg/mL drawn from a cohort of 1,586 patients with acute dyspnea who had BNP levels measured on emergency department arrival. Two cardiologists blinded to BNP results reviewed all clinical data and categorized patients according to whether they had acute congestive heart failure or not.

RESULTS

Independent predictors of elevated BNP levels (ie, >100 pg/mL) were a medical history of atrial fibrillation, radiographic cardiomegaly, decreased blood hemoglobin concentration, decreased body mass index, and increased age.

CONCLUSION

Knowledge of these commonly obtained variables should aid clinicians in the interpretation of moderately elevated BNP results in patients presenting with acute dyspnea in the emergency department.

Therapeutic hypertension: principles and methods

The aspects of cardiovascular physiology important for the safe and effective implementation and titration of hypertensive therapy among neurosurgical patients with neurological or neurosurgical illness/injury are reviewed. Therapeutic hypertension may be an appropriate treatment for some neurological or neurosurgical conditions, e.g., vasospasm or support of cerebral perfusion pressure. Initiation and maintenance of hypertension should be done safely to avoid complications and/or undesired side effects. Accurate measurement of the arterial and central vascular pressures, the limitations of those methods, and alternative estimates of intravascular volume are reviewed. Hypertensive therapy is accomplished by modifying cardiac output and systemic vascular resistance, the principal physiological determinants of blood pressure. The goals of hypertensive therapy can be achieved by proper evaluation and manipulation of the four components of cardiac output, preload, afterload, heart rate and contractility. Measurement or calculation of estimates of these parameters is important in the selection of proper medications or supplemental fluid administration.

Anemia in chronic heart failure: pathogenetic mechanisms

Anemia can be the cause of heart failure, but also its consequence. The pathogenesis of anemia in chronic heart failure (CHF) has yet to be fully elucidated, but is likely to be complex. Epidemiologic studies suggest that kidney dysfunction (by reducing the erythropoietic response to anemia), inflammation (by inducing erythropoietin resistance), decreased body mass index, old age, female gender, and poor clinical status may be important factors in the development of anemia in CHF. Intestinal malabsorption, chronic aspirin use, and proteinuria predisposes to iron deficiency. Proinflammatory cytokines are likely to play a significant role in anemia in CHF by generating the "anemia of chronic illness" that is a hallmark of inflammatory conditions. Few studies have investigated the mechanisms of anemia in CHF. There is a need for such studies.

Anemia Management in Heart Failure: A Thick Review of Thin Data

Heart failure is defined as the inability of the heart to pump blood at an amount sufficient to meet the metabolic needs of the body. In heart failure, the inability to meet the body's metabolic needs is based on hemodynamic derangement and suboptimal oxygen-carrying capacity of the blood itself. Current pharmacologic therapy attempts to improve survival and reduce symptomatology by optimizing hemodynamics to increase oxygen delivery, but does not address oxygen-carrying capacity. Unfortunately, there is a high prevalence of anemia in patients with heart failure, which compromises oxygen-carrying capacity, is an independent predictor of mortality, and may be caused in part by pharmacologic agents that confer morbidity and mortality benefits in this population. Recombinant human erythropoietin supplementation improves the functional capacity of the failing myocardium, reverses and antagonizes the detrimental remodeling induced by autoimmune activity, and may reduce mortality and morbidity among patients receiving maximal pharmacologic therapy for heart failure. However, limited clinical data prohibit widespread recommendations for its use in patients with heart failure.

Relation of unrecognized hypervolemia in chronic heart failure to clinical status, hemodynamics, and patient outcomes

Clinically unrecognized intravascular volume overload may contribute to worsening symptoms and disease progression in patients with chronic heart failure (CHF). The present study was undertaken to prospectively compare measured blood volume status (determined by radiolabeled albumin technique) with clinical and hemodynamic characteristics and patient outcomes in 43 nonedematous ambulatory patients with CHF. Blood volume analysis demonstrated that 2 subjects (5%) were hypovolemic (mean deviation from normal values -20 +/- 6%), 13 subjects (30%) were normovolemic (mean deviation from normal values -1 +/- 1%), and 28 subjects (65%) were hypervolemic (mean deviation from normal values +30 +/- 3%). Physical findings of congestion were infrequent and not associated with blood volume status. Increased blood volume was associated with increased pulmonary capillary wedge pressure (p = 0.01) and greatly increased risk of death or urgent cardiac transplantation during a median follow-up of 719 days (1-year event rate 39% vs 0%, p <0.01 by log-rank test). Systolic blood pressure was significantly lower in hypervolemic patients than in those with normovolemia or hypovolemia (107 +/- 2 vs 119 +/- 2 mm Hg, p = 0.008), and hypotension was independently associated with increased risk of hypervolemia in multivariate analysis (odds ratio 2.64 for a 10-mm Hg decrease in systolic blood pressure, 95% confidence interval 1.13 to 6.19, p = 0.025). These findings demonstrate that clinically unrecognized hypervolemia is frequently present in nonedematous patients with CHF and is associated with increased cardiac filling pressures and worse patient outcomes.