Physiological, pathological, pharmacological, biochemical and hematological factors affecting BNP and NT-proBNP

Prognostic role of haemodynamics at follow-up in patients with pulmonary arterial hypertension: a challenge to current European Society of Cardiology/European Respiratory Society risk tools

Background

Haemodynamic variables like right atrial pressure (RAP), cardiac index (CI), stroke volume index (SVI) and mixed venous oxygen saturation (S vO2 ) predict survival in patients with pulmonary arterial hypertension (PAH). However, there is the need to identify further prognostic haemodynamic parameters as well as to redefine their role in PAH risk stratification compared to current risk tools and non-invasive parameters.

Methods

This cohort study includes treatment-naïve patients assessed at baseline and after first-line PAH therapy with clinical, functional, exercise, laboratory and haemodynamic evaluations. Using a stepwise multivariate Cox regression analysis, independent prognostic haemodynamic parameters were identified and stratified according to cut-offs already defined in the European Society of Cardiology (ESC)/European Respiratory Society (ERS) risk table or defined based on the highest Chi-squared of the log-rank test. Their discriminatory power was tested for all-cause death and a combined end-point of death, hospitalisation and need of treatment escalation.

Results

794 patients with PAH were enrolled. At first follow-up, RAP and pulmonary artery elastance were independently associated with death. Because of high correlations between haemodynamic parameters, different multivariable analyses were done identifying six other variables (pulmonary arterial compliance, cardiac efficiency, pulmonary vascular resistance, S vO2 , CI and SVI). Haemodynamic parameters were of no added prognostic value compared to ESC/ERS risk tools for the all-cause death end-point but they showed additional value to non-invasive parameters for the combined end-point and, when taken alone, had a discriminatory capacity comparable to ESC/ERS risk tools.

Conclusion

Haemodynamics' discriminative ability for clinical worsening is comparable to current ESC/ERS risk tools and is of added value to non-invasive parameters.

Association between N-terminal pro-B-type natriuretic peptide and clinical outcomes in bedridden patients with stroke: a cross-sectional study

OBJECTIVES

Patients with stroke often remain bedridden despite rehabilitation. Serum N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) levels increase after stroke. Our study aimed to investigate the difference in NT-pro-BNP levels between bedridden and non-bedridden patients with stroke and to explore the factors influencing NT-pro-BNP levels in bedridden patients.

DESIGN

A single-centre, cross-sectional study.

SETTING

This study was conducted in a hospital, Shenzhen, China.

PARTICIPANTS

Between January 2019 and December 2022, 465 participants were included in this study.

OUTCOME MEASURES

The collected data included basic information, laboratory data and echocardiographic parameters. Binary logistic regression analysis and receiver operating characteristic curves were used to identify factors associated with high NT-pro-BNP levels.

RESULTS

Bedridden patients with stroke had higher levels of NT-pro-BNP, D-dimer, high-sensitivity C reactive protein (hs-CRP) and lower levels of creatinine, high-density lipoprotein cholesterol, albumin and haemoglobin, as well as lower left ventricular ejection fraction, fractional shortening and the ratio between the peak velocities of early and late diastolic filling than non-bedridden patients. In bedridden patients, age ≥75 years, high levels of hs-CRP and creatinine, and low levels of albumin were associated with high NT-pro-BNP levels. In non-bedridden patients, age ≥75 years and high creatinine levels were associated with high NT-pro-BNP levels. In bedridden patients with stroke, the area under the curve (AUC) of hs-CRP was 0.700 (p<0.001, 95% CI 0.638 to 0.762) with a cut-off value of 5.12 mg/L. The AUC of albumin was 0.671 (p<0.001, 95% CI 0.606 to 0.736) with a cut-off value of 37.15 g/L.

CONCLUSIONS

NT-pro-BNP levels were higher in bedridden patients with stroke than in non-bedridden patients. Decreased albumin and elevated hs-CRP levels were associated with high levels of NT-pro-BNP in bedridden patients. Further studies are needed to explore the risk stratification and potential treatments for elevated NT-pro-BNP in bedridden patients with stroke.

N-terminal brain natriuretic peptide, cardiac troponin-I, and point-of-care ultrasound in dogs with cardiac and noncardiac causes of nonhemorrhagic ascites

BACKGROUND

Nonhemorrhagic ascites (NHA) can be caused by cardiac diseases (cNHA) and noncardiac diseases (ncNHA). N-terminal brain natriuretic peptide (NT-proBNP), cardiac troponin-I (cTnI), and point-of-care ultrasound (POCUS) may differentiate between cNHA and ncNHA.

HYPOTHESIS/OBJECTIVES

We compared NT-proBNP and cTnI concentrations as well as POCUS findings in dogs presented with cNHA and ncNHA.

ANIMALS

Dogs (n = 60) were enrolled based on identification of NHA with an effusion packed cell volume < 10%.

METHODS

Blood samples were collected and POCUS was performed on all dogs. Dogs were diagnosed with cNHA (n = 28) or ncNHA (n = 32) based on echocardiography. The cNHA group was subdivided into cardiac non-pericardial disease (n = 17) and pericardial disease (n = 11).

RESULTS

The NT-proBNP concentration (median; range pmol/L) was significantly higher in the cNHA group (4510; 250-10 000) compared to the ncNHA group (739.5; 250-10 000; P = .01), with a sensitivity of 53.8% and specificity of 85.7% using a cut-off of 4092 pmol/L. The NT-proBNP concentrations were significantly higher in the cardiac non-pericardial disease group (8339; 282-10 000) compared with the pericardial disease group (692.5; 250-4928; P = .002). A significant difference in cTnI concentration (median; range ng/L) between the cNHA group (300; 23-112 612) and ncNHA group (181; 17-37 549) was not detected (P = .41). A significantly higher number of dogs had hepatic venous and caudal vena cava distension in the cNHA group compared to the ncNHA group, respectively (18/28 vs 3/29, P < .0001 and 13/27 vs 2/29, P < .001). Gall bladder wall edema was not significantly different between groups (4/28 vs 3/29, P = .74).

CONCLUSIONS AND CLINICAL IMPORTANCE

NT-proBNP concentration and POCUS help distinguish between cNHA and ncNHA.

Effect of thyroid dysfunction on N-terminal pro-B-type natriuretic peptide levels: A systematic review and meta-analysis

Purpose

Thyroid hormones (THs) significantly affect the cardiovascular system. N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a useful biomarker for diagnosing, evaluating, and predicting outcomes in heart failure (HF). This comprehensive review and meta-analysis aimed to investigate the effects of thyroid dysfunction (hypothyroidism and hyperthyroidism) on NT-proBNP levels.

Methods

Two investigators independently searched PubMed, Embase, Cochrane Library, and Web of Science databases for studies published from inception to July 31, 2022, without any restrictions on language.

Results

21 studies were included. In participants without HF, NT-proBNP levels may be elevated in those with overt hyperthyroidism (standardized mean difference [SMD] 2.38, 95% confidence interval [CI]:1.0-3.76). Notably, among patients with preexisting HF, significantly higher NT-proBNP levels were found in patients with overt hyperthyroidism, overt hypothyroidism, or subclinical hypothyroidism than in euthyroid subjects (SMD [95%CI] = 0.31[0.01, 0.62], 0.32[0.08, 0.56], and 0.33[0.21, 0.46], respectively). Seven trials compared NT-proBNP levels in patients with thyroid dysfunction before and after therapy, and significant drops in NT-proBNP levels were observed in patients with hyperthyroidism (SMD [95%CI] = -1.53[-2.50, -0.55]) upon achieving a euthyroid state. In contrast, increased NT-proBNP levels were observed in hypothyroid patients after treatment (SMD [95%CI] = 1.07[0.28, 1.85]).

Conclusion

Thyroid dysfunction can significantly affect NT-proBNP levels, which may change upon achieving a euthyroid state. Notably, the effect of thyroid dysfunction on cardiac function may depend on the underlying cardiac status. Thus, timely recognition and effective treatment of cardiac symptoms in patients with thyroid dysfunction are mandatory because the prognosis of HF may be improved with appropriate treatment of thyroid dysfunction.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42022353700.

Association of circulating B-type natriuretic peptide with osteoporosis in a Chinese type 2 diabetic population

Background

Altered circulating levels and genetic variation of B-type natriuretic peptide (BNP), has been associated with lower bone mineral density (BMD) values and incidence of osteoporosis in peritoneal dialysis patients, renal transplant recipients, and postmenopausal women. The potential relationship of circulating BNP with osteoporosis in patients with type 2 diabetes mellitus (T2DM), however, has not yet been studied.

Methods

Circulating BNP levels were measured in 314 patients with T2DM, and participants were divided into normal BMD group (n = 73), osteopenia group (n = 120), and osteoporosis group (n = 121). The association of circulating BNP with diabetic osteoporosis and other parameters was analyzed.

Results

Circulating BNP was significantly higher in diabetic osteoporosis subjects than normal and osteopenia groups (P < 0.01 or P < 0.05). Circulating BNP levels correlated significantly and positively with neutrophil to lymphocyte ratio, systolic blood pressure, urinary albumin-to-creatinine ratio, and prevalence of hypertension, peripheral arterial disease, diabetic retinopathy, peripheral neuropathy, and nephropathy, and negatively with triglyceride, fasting blood glucose, lymphocyte count, hemoglobin, estimated glomerular filtration rate, bilirubin, osteoporosis self-assessment tool for Asians, BMD at different skeletal sites and corresponding T scores (P < 0.01 or P < 0.05). After multivariate adjustment, circulating BNP remained independently significantly associated with the presence of osteoporosis (odds ratio, 2.710; 95% confidence interval, 1.690–4.344; P < 0.01). BMD at the femoral neck and total hip and corresponding T scores were progressively decreased, whereas the prevalence of osteoporosis was progressively increased with increasing BNP quartiles (P for trend< 0.01). Moreover, receiver-operating characteristic analysis revealed that the optimal cutoff point of circulating BNP to indicate diabetic osteoporosis was 16.35 pg/ml.

Conclusions

Circulating BNP level may be associated with the development of osteoporosis, and may be a potential biomarker for diabetic osteoporosis.

The relationship between body mass index and N-terminal pro-B-type natriuretic peptide in community-acquired pneumonia

BACKGROUND

The relationship between body mass index (BMI) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) has not been fully investigated in patients with community-acquired pneumonia (CAP).

METHODS

This prospective observational study examined 510 consecutive patients hospitalized for CAP. NT-proBNP, BMI, and the pneumonia severity index (PSI) were determined for all participants. The moderating effects of BMI on the relationship between NT-proBNP and CAP mortality were examined using interaction terms in a multivariable regression model. The ability of NT-proBNP to predict mortality was evaluated using the area under the curve (AUC).

RESULTS

A significant inverse relationship was observed between BMI and NT-proBNP. After multivariable adjustment including BMI, NT-proBNP remained a significant predictor of CAP mortality. The AUC of the fully adjusted (including BMI) NT-proBNP model was significantly higher than that excluding BMI (p = 0.021) and that of PSI (p = 0.038), respectively. The predictive performance of NT-proBNP for mortality significantly differed by BMI group, with the NT-proBNP of the overweight and obesity group having a significantly higher AUC than that of the underweight and normal-weight group. The AUC of NT-proBNP was significantly higher and tended to be higher than that of PSI in the overweight group (p = 0.013) and the obesity group (p = 0.113), respectively.

CONCLUSIONS

BMI significantly strengthens the prognostic performance of NT-proBNP in CAP patients. The BMI-NT-proBNP interaction is significantly associated with CAP mortality, but as a prognostic determinant for CAP, NT-proBNP seems to be more useful for overweight and obese patients than for underweight and normal-weight patients.

N-Terminal pro-B-type natriuretic peptide and coronary microvascular dysfunction in women with preserved ejection fraction: A report from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study

BACKGROUND

Women with symptoms and signs of ischemia, preserved left ventricular ejection fraction (LVEF), and no obstructive coronary artery disease (CAD), often have coronary microvascular dysfunction (CMD), and are at risk of future heart failure with preserved ejection fraction (HFpEF). N-terminal pro-B-type natriuretic peptide (NT-proBNP) is used to evaluate HF and myocardial ischemia. Relationships between NT-proBNP and CMD are not well defined in this population.

METHODS

We evaluated resting NT-proBNP levels in 208 women with symptoms and signs of ischemic heart disease, preserved LVEF and no obstructive CAD undergoing clinically indicated invasive coronary flow reserve (CFR) as a measure of CMD-related ischemia and resting left ventricular end-diastolic pressure (LVEDP). Chi-square testing was used for categorical variables and ANOVA or Kruskal-Wallis tests were used for continuous variables.

RESULTS

Overall, 79% had an elevated resting LVEDP, and mean NT-proBNP was 115 ± 158 pg/mL. NT-proBNP levels correlated directly with age (r = 0.28, p = <0.0001), and indirectly with body mass index (r = -0.21, p = 0.0006), but did not independently associate with CFR. When stratified by NT-proBNP thresholds, higher NT-proBNP was initially associated with lower CFR, which did not persist with adjustment for multiple testing (p = 0.01 and 0.36, respectively).

CONCLUSION

Among women with symptoms and signs of ischemia, preserved LVEF, no obstructive CAD, and undergoing clinically indicated functional coronary angiography (FCA) for suspected CMD, while a majority had elevated resting LVEDP, we failed to find an independent association between CFR and NT-proBNP, although stratified clinical thresholds may relate to lower CFR. Further work is needed to investigate if these findings support the hypothesis that CMD-related ischemia may be a precursor to HFpEF.

The minimal informative monitoring interval of N-terminal pro-B-type natriuretic peptide in patients with stable heart failure

Background

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a potential biomarker for monitoring the status of heart failure. However, the optimal monitoring interval of NT-proBNP is unknown. This study sought to investigate the minimal informative monitoring interval of NT-proBNP in patients with stable chronic heart failure.

Methods

This retrospective cohort study included patients who were admitted due to heart failure and subsequently followed with serial NT-proBNP measurements in a tertiary hospital. We analyzed NT-proBNP measured between six months after discharge and the earliest timepoint of: an alteration of medication regimen, readmission due to worsening of heart failure, or all-cause death. To distinguish progression of the disease from biological variability and measurement error, the signal-to-noise ratio method was applied with a random-effects model.

Results

In the 368 patients included, NT-proBNP was measured for a median 6 times. In the random-effects model, signal (progression of disease) exceeded noise (biological variability and measurement error) at 7.9 months (95% confidence interval [CI]: 5.1–9.6), while noise corresponded to a 61% increase from baseline. In stratified analysis using the AHEAD risk score, the minimal informative monitoring interval shortened as the risk score increased (0–1 point: 12.2 months [95%CI: 10.3–14.4]; 2–3 points: 8.0 months [95%CI: 6.8–9.7]; 4–5 points: 3.3 months [95%CI: 3.0–3.8]).

Conclusions

In patients with stable chronic heart failure, the minimal informative monitoring interval of NT-proBNP measurement was 7.9 months in the current population, which varied with underlying risks. The optimal monitoring interval could be lengthened for patients at lower risks.

Circular RNA Expression Profiles in Plasma from Patients with Heart Failure Related to Platelet Activity

Heart failure (HF) is a deadly disease that is difficult to accurately diagnose. Circular RNAs (circRNAs) are a novel class of noncoding RNAs that might play important roles in many cardiovascular diseases. However, their role in HF remains unclear. CircRNA microarrays were performed on plasma samples obtained from three patients with HF and three healthy controls. The profiling results were validated by quantitative reverse transcription polymerase chain reaction. The diagnostic value of circRNAs for HF was evaluated by receiver operating characteristic (ROC) curves. The expression profiles indicated that 477 circRNAs were upregulated and 219 were downregulated in the plasma of patients with HF compared with healthy controls. Among the dysregulated circRNAs, hsa_circ_0112085 (p = 0.0032), hsa_circ_0062960 (p = 0.0006), hsa_circ_0053919 (p = 0.0074) and hsa_circ_0014010 (p = 0.025) showed significantly higher expression in patients with HF compared with healthy controls. The area under the ROC curve for hsa_circ_0062960 for HF diagnosis was 0.838 (p < 0.0001). Correlation analysis showed that the expression of hsa_circ_0062960 was highly correlated with B-type natriuretic peptide (BNP) serum levels. Some differential circRNAs were found to be related to platelet activity by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The landscape of circRNA expression profiles may play a role in HF pathogenesis and improve our understanding of platelet function in HF. Moreover, hsa_circ_0062960 has potential as a novel diagnostic biomarker for HF.

Biomarkers in diagnosing and treatment of acute heart failure

Acute heart failure (AHF) is a complex disorder involving different pathophysiological pathways. In recent years, there is an increased focus on biomarkers that help with diagnosis, risk stratification and disease monitoring of AHF. Finding a reliable set of biomarkers not only improves morbidity and mortality but it can also potentially reveal the new targets of therapy. In this paper, we have reviewed the biomarkers found useful for the diagnosis as well as for risk stratification and prognostication in patients with AHF. We have discussed the established biomarkers for AHF including cardiac troponins and natriuretic peptides and emerging biomarkers including adiponectin, mi-RNA, sST2, Gal-3, MR-proADM, OPG, CT-proAVP and H-FABP for the purposes of making diagnosis, their use as a guide of therapy or for determination of prognosis.

Mathematical model to predict B-type natriuretic peptide levels in haemodialysis patients

AIM

Clinical interpretation of B-type natriuretic peptide (BNP) levels in haemodialysis (HD) patients for fluid management remains elusive.

METHODS

We conducted a retrospective observational monocentric study. We built a mathematical model to predict BNP levels, using multiple linear regressions. Fifteen clinical/biological characteristics associated with BNP variation were selected. A first cohort of 150 prevalent HD (from September 2015 to March 2016) was used to build several models. The best model proposed was internally validated in an independent cohort of 75 incidents HD (from March 2016 to December 2017).

RESULTS

In cohort 1, mean BNP level was 630 ± 717 ng/mL. Cardiac disease (CD - stable coronary artery disease and/or atrial fibrillation) was present in 45% of patients. The final model includes age, systolic blood pressure, albumin, CD, normo-hydrated weight (NHW) and the fluid overload (FO) assessed by bio-impedancemetry. The correlation between the measured and the predicted log-BNP was 0.567 and 0.543 in cohorts 1 and 2, respectively. Age (β = 3.175e^-2 , P < 0.001), CD (β = 5.243e^-1 , P < 0.001) and FO (β = 1.227e^-1 , P < 0.001) contribute most significantly to the BNP level, respectively, but within a certain range. We observed a logistic relationship between BNP and age between 30 and 60 years, after which this relationship was lost. BNP level was inversely correlated with NHW independently of CD. Finally, our model allows us to predict the BNP level according to the FO.

CONCLUSION

We developed a mathematical model capable of predicting the BNP level in HD. Our results show the complex contribution of age, CD and FO on BNP level.

Biomarkers, myocardial fibrosis and co-morbidities in heart failure with preserved ejection fraction: an overview

The prevalence of heart failure with preserved ejection fraction (HFpEF) is steadily increasing. Its diagnosis remains difficult and controversial and relies mostly on non-invasive echocardiographic detection of left ventricular diastolic dysfunction and elevated filling pressures. The large phenotypic heterogeneity of HFpEF from pathophysiologic al underpinnings to clinical manifestations presents a major obstacle to the development of new therapies targeted towards specific HF phenotypes. Recent studies suggest that natriuretic peptides have the potential to improve the diagnosis of early HFpEF, but they still have significant limitations, and the cut-off points for diagnosis and prognosis in HFpEF remain open to debate. The purpose of this review is to present potential targets of intervention in patients with HFpEF, starting with myocardial fibrosis and methods of its detection. In addition, co-morbidities are discussed as a means to treat HFpEF according to cut-points of biomarkers that are different from usual. Biomarkers and approaches to co-morbidities may be able to tailor therapies according to patients' pathophysiological needs. Recently, soluble source of tumorigenicity 2 (sST2), growth differentiation factor 15 (GDF-15), galectin-3, and other cardiac markers have emerged, but evidence from large cohorts is still lacking. Furthermore, the field of miRNA is a very promising area of research, and further exploration of miRNA may offer diagnostic and prognostic applications and insight into the pathology, pointing to new phenotype-specific therapeutic targets.

Prognostic and diagnostic significance of mid-regional pro-atrial natriuretic peptide in acute exacerbation of chronic obstructive pulmonary disease and acute heart failure: data from the ACE 2 Study

PURPOSE

To compare the diagnostic and prognostic value of mid-regional pro-ANP (MR-proANP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with acute dyspnea.

METHODS

MR-proANP and NT-proBNP were measured with commercial immunoassays at hospital admission (n = 313), on day 2 (n = 234), and before discharge (n = 91) and compared for diagnosing acute heart failure (HF; n = 143) and to predict mortality among patients with acute HF and acute exacerbation of chronic obstructive pulmonary disease (AECOPD; n = 84) separately.

RESULTS

The correlation coefficient between MR-proANP and NT-proBNP was 0.89 (p < 0.001) and the receiver-operating area under the curve (AUC) was 0.85 (95% CI 0.81-0.89) for MR-proANP and 0.86 (0.82-0.90) for NT-proBNP to diagnose acute HF. During a median follow-up of 816 days, mortality rates were 46% in acute HF patients and 42% in AECOPD patients. After adjustment for other risk variables by multivariate Cox regression analysis, MR-proANP and NT-proBNP concentrations were associated with mortality in patients with acute HF, but only MR-proANP were associated with mortality among patients with AECOPD: hazard ratio (_lnMR-proANP) 1.98 (95% CI 1.17-3.34).

CONCLUSION

MR-proANP and NT-proBNP concentrations provide similar diagnostic and prognostic information in patients with acute HF. In contrast to NT-proBNP, MR-proANP measurements also provided independent prognostic information in AECOPD patients.

Hemodynamic Determinants of the Biologic Variation of N-Terminal Pro-B-Type Natriuretic Peptide in Patients With Stable Systolic Chronic Heart Failure

BACKGROUND CONTEXT

Biologic variation of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in chronic heart failure (CHF) may affect blood levels and risk stratification. The sources of NT-proBNP variation are unknown.

METHODS AND RESULTS

We performed NT-proBNP measurements and clinical and hemodynamic assessments in 50 patients with heart failure with reduced ejection fraction (HFrEF) who met criteria for clinical stability over 2 time intervals. Hemodynamic variables were measured with the use of inert gas rebreathing and impedance cardiography. Heart rhythm was monitored with the use of external electrocardiographic event recorders throughout the study. Determinants of NT-proBNP-levels and both absolute (ΔNT-proBNP_abs) and relative (ΔNT-proBNP_%) changes at 1-week and 2-week intervals were identified with the use of univariable and multivariable linear mixed-effects models and linear regression analyses, respectively. Clinical and hemodynamic variables did not significantly change between study visits. The individual variation of NT-proBNP at 2 weeks was 9.2% (range 3.9%-18.6%). Weight and glomerular filtration rate were independently associated with baseline NT-proBNP concentrations (P = .01 and P = .005, respectively). There was no relationship between absolute and relative changes of NT-proBNP at 1-week intervals and changes in clinical and hemodynamic variables. Absolute change of NT-proBNP at 2-week intervals was associated with absolute change in left cardiac work index (P = .008), and relative change in NT-proBNP at 2-week intervals was determined by relative change of thoracic fluid content index (P = .008) and diastolic blood pressure (P = .01). The coefficients of determination (R²) for the multivariable models with Δ_1wkNT-proBNP_abs, Δ_2-weeksNT-proBNP_abs, Δ_1wkNT-proBNP_%, and Δ_2wksNT-proBNP_% as dependent variables were 0.21, 0.19, 0.10, and 0.32, respectively.

CONCLUSIONS

In patients with stable HFrEF, changes in clinical and hemodynamic variables only marginally contribute to the variation of NT-proBNP.

Effect of Breed on Plasma Endothelin-1 Concentration, Plasma Renin Activity, and Serum Cortisol Concentration in Healthy Dogs

BACKGROUND

There are breed differences in several blood variables in healthy dogs.

OBJECTIVE

Investigate breed variation in plasma endothelin-1 (ET-1) concentration, plasma renin activity, and serum cortisol concentration.

ANIMALS

Five-hundred and thirty-one healthy dogs of 9 breeds examined at 5 centers (2-4 breeds/center).

METHODS

Prospective observational study. Circulating concentrations of ET-1 and cortisol, and renin activity, were measured using commercially available assays. Absence of organ-related or systemic disease was ensured by thorough clinical investigations, including blood pressure measurement, echocardiography, ECG, blood and urine analysis.

RESULTS

Median ET-1 concentration was 1.29 (interquartile range [IQR], 0.97-1.82) pg/mL, median cortisol concentration 46.0 (IQR, 29.0-80.8) nmol/L, and median renin activity 0.73 (IQR, 0.48-1.10) ng/mL/h in all dogs. Overall, breed differences were found in ET-1 and cortisol concentrations, and renin activity (P < .0001 for all). Pair-wise comparisons between breeds differed in 67% of comparisons for ET-1, 22% for cortisol, and 19% for renin activity, respectively. Within centers, breed differences were found at 5/5 centers for ET-1, 4/5 centers for cortisol, and 2/5 centers for renin activity. Newfoundlands had highest median ET-1 concentration, 3 times higher than Cavalier King Charles Spaniels, Doberman Pinschers, and Dachshunds. Median renin activity was highest in Dachshunds, twice the median value in Newfoundlands and Boxers. Median cortisol concentration was highest in Finnish Lapphunds, almost 3 times higher than in Boxers.

CONCLUSIONS AND CLINICAL IMPORTANCE

Breed variation might be important to take into consideration when interpreting test results in clinical studies.

Left atrial minimum volume is more strongly associated with N-terminal pro-B-type natriuretic peptide than the left atrial maximum volume in a community-based sample

Previous data have demonstrated that left atrial (LA) minimum volume indexed for body surface area (LAVImin) is more strongly associated with the Doppler echocardiographic E/e′ ratio than LA maximum volume index (LAVImax). We sought to explore if LAVImin was more closely related to serum levels of NT-proBNP than LAVImax and E/e′ in the community. A community-based sample of 730 subjects underwent echocardiographic examinations and NT-proBNP measurements. The mean age of the participants was 66.3 years (range 38–86) and 72 % were men. Age (Spearman correlation [rho] 0.533), LAVImin (rho 0.460), LAVImax (rho 0.360), estimated glomerular filtration rate (rho −0.349), and E/e′ (rho 0.301; all P < 0.001) were strongly correlated with log-NT-proBNP. In a multiple linear regression model with log-NT-proBNP as dependent variable and LAVImin, LAVImax, E/e′ ratio, and potential confounders as predictors, an adjusted R² of 44.9 % was obtained. When excluding either of LAVImin (R² 42.6 %, P < 0.001) or E/e′ (R² 44.6 %, P = 0.019) the model fit was significantly reduced. In contrast, when LAVImax was excluded the model fit was preserved (R² 45.0 %, P = 0.69). To detect an NT-proBNP level of >125 ng/L, LAVImin yielded a significantly larger area under the receiver operating characteristic curve (AUC) of 0.749 than LAVImax (AUC 0.701; P < 0.001) and E/e′ (AUC 0.661; P < 0.001). In our community-based sample, LAVImin was more strongly associated with NT-proBNP than LAVImax. Moreover, the discriminatory power to detect an elevated NT-proBNP level was stronger in LAVImin than in LAVImax and E/e′. Our findings support previous data that LAVImin may be more closely related to LV filling function than LAVImax.

Falsely high B-type natriuretic peptide concentration in patients without heart failure attributed to AxSYM assay: case series of eight subjects

We report a case series of eight subjects complaining of non‐specific chest pain without heart failure, but with apparent high concentrations of plasma B‐type natriuretic peptide (BNP). No positive clinical characteristics were identified in physical examinations, cardiac imaging, laboratory findings, or pulmonary function tests. However, we observed unusually high BNP values when analysing blood samples of the patients using the AxSYM assay, and this was not supported by readings from Triage® or ADVIA Centaur® assays on the same samples, which showed BNP within the normal range. We believe that the possibility for false readings for high BNP levels in healthy individuals measured by AxSYM assay should be taken into account by physicians in clinical practice to avoid medical errors.

A clinical review of the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats

OBJECTIVE

To review the current literature in reference to the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats.

ETIOLOGY

Pyothorax, also known as thoracic empyema, is characterized by the accumulation of septic purulent fluid within the pleural space. While the actual route of pleural infection often remains unknown, the oral cavity and upper respiratory tract appear to be the most common source of microorganisms causing pyothorax in dogs and cats. In human medicine, pyothorax is a common clinical entity associated with bacterial pneumonia and progressive parapneumonic effusion.

DIAGNOSIS

Thoracic imaging can be used to support a diagnosis of pleural effusion, but cytologic examination or bacterial culture of pleural fluid are necessary for a definitive diagnosis of pyothorax.

THERAPY

The approach to treatment for pyothorax varies greatly in both human and veterinary medicine and remains controversial. Treatment of pyothorax has classically been divided into medical or surgical therapy and may include administration of antimicrobials, intermittent or continuous thoracic drainage, thoracic lavage, intrapleural fibrinolytic therapy, video-assisted thoracic surgery, and traditional thoracostomy. Despite all of the available options, the optimal treatment to ensure successful short- and long-term outcome, including the avoidance of recurrence, remains unknown.

PROGNOSIS

The prognosis for canine and feline pyothorax is variable but can be good with appropriate treatment. A review of the current veterinary literature revealed an overall reported survival rate of 83% in dogs and 62% in cats. As the clinical presentation of pyothorax in small animals is often delayed and nonspecific, rapid diagnosis and treatment are required to ensure successful outcome.

Breed differences in natriuretic peptides in healthy dogs

BACKGROUND

Measurement of plasma concentration of natriuretic peptides (NPs) is suggested to be of value in diagnosis of cardiac disease in dogs, but many factors other than cardiac status may influence their concentrations. Dog breed potentially is 1 such factor.

OBJECTIVE

To investigate breed variation in plasma concentrations of pro-atrial natriuretic peptide 31-67 (proANP 31-67) and N-terminal B-type natriuretic peptide (NT-proBNP) in healthy dogs.

ANIMALS

535 healthy, privately owned dogs of 9 breeds were examined at 5 centers as part of the European Union (EU) LUPA project.

METHODS

Absence of cardiovascular disease or other clinically relevant organ-related or systemic disease was ensured by thorough clinical investigation. Plasma concentrations of proANP 31-67 and NT-proBNP were measured by commercially available ELISA assays.

RESULTS

Overall significant breed differences were found in proANP 31-67 (P < .0001) and NT-proBNP (P < .0001) concentrations. Pair-wise comparisons between breeds differed in approximately 50% of comparisons for proANP 31-67 as well as NT-proBNP concentrations, both when including all centers and within each center. Interquartile range was large for many breeds, especially for NT-proBNP. Among included breeds, Labrador Retrievers and Newfoundlands had highest median NT-proBNP concentrations with concentrations 3 times as high as those of Dachshunds. German Shepherds and Cavalier King Charles Spaniels had the highest median proANP 31-67 concentrations, twice the median concentration in Doberman Pinschers.

CONCLUSIONS AND CLINICAL IMPORTANCE

Considerable interbreed variation in plasma NP concentrations was found in healthy dogs. Intrabreed variation was large in several breeds, especially for NT-proBNP. Additional studies are needed to establish breed-specific reference ranges.

Changes in Hypothalamus–Pituitary–Adrenal Axis Following Transient Ischemic Attack

Acute brain ischemia caused by transient ischemic attack initiates a complex sequence of events in the central nervous system and hypothalamic–pituitary–adrenal (HPA) axis which may ultimately culminate in neuronal and cell damage. The brain is highly susceptible to ischemia and in response to stress shows changes in morphology and chemistry that are largely reversible. These responses are known to modify the function of the HPA axis, but their mechanisms are not yet clear. Duration and size of the HPA axis activation are regulated by corticotropin-releasing hormone, vasopressin (AVP), and glucocorticoids, including cortisol. Numerous studies suggest that activation of these hormones following brain ischemia can result in neurohormonal dysfunction that can exacerbate long-term prognosis following stroke. These studies represent evidence that changes in the HPA axis play an important role in brain ischemia.

[Correlations between B-type natriuretic peptide levels and non-geometric echocardiographic parameters in pediatric cardiomyopathies]

INTRODUCTION

B-type natriuretic peptide is a conventional cardiac biomarker in adult cardiology, however, it is not commonly used in pediatric cases.

AIMS

After introducing B-type natriuretic peptide measurements in pediatric patients for the evaluation of systemic right ventricular function, the authors wanted to evaluate the value of plasma B-type natriuretic peptide and compare the results with systolic and diastolic myocardial parameters obtained with conventional echocardiography and tissue Doppler imaging in children with cardiomyopathy.

METHODS

Between 2007 and 2010, 58 plasma B-type natriuretic peptide measurements were performed in 32 children (dilated cardiomyopathy in 20, hypertrophic cardiomyopathy in 10 and non-compacted cardiomyopathy in 2 cases). The age of the patients was 7.9±6.6 years (mean±SD). Plasma B-type natriuretic peptide was measured using an electrochemiluminescent assay within one day from echocardiographic evaluation.

RESULTS

As compared to normal values, children with the 3 types of cardiomyopathies showed significant differences in plasma B-type natriutretic peptide levels (dilated cardiomyopathy vs normal, p<0.001; hypertrophic cardiomyopathy vs. normal, p<0.01; non-compacted cardiomyopathy vs. normal, p<0.001). There was a significant negative correlation (r = -0,63; p<0,01) between B-type natriuretic peptide levels (range, 12-7002 ng/L; mean±SD, 1531±1750 ng/L) and linEF values (range, 4-50%; mean±SD, 22.5±13%). For B-type natriuteric peptide, a cut-off point of 1000 ng/L proved to differentiate significantly decreased linEF values (<17%). B-type natriuretic peptide levels significantly correlated with left ventricular end-diastolic diameter (r = 0.899; p<0.001), with left ventricular anular S wave parameters (r = 0.689; p<0.001) and with E/e ratio (r = 0.43; p<0.05).

CONCLUSIONS

B-type natriuretic peptide measurements are recommended in all types of cardiomyopathies.

Plasma N-terminal pro-brain natriuretic peptide levels are positively correlated with pulmonary arterial pressure in atrial septal defect patients

N-terminal pro-brain natriuretic peptide (NT-proBNP), a pro-hormone secreted by the myocardium in response to various stimuli, was found to be correlated with several hemodynamic parameters in pulmonary hypertension associated with systemic sclerosis. We investigated plasma NT-proBNP levels and the relationships between NT-proBNP and several hemodynamic parameters in atrial septal defect (ASD) patients with or without pulmonary arterial hypertension (PAH). We found that plasma NT-proBNP level was significantly higher in PAH group compared with the control group (5495.4±388.4 pg/ml vs 4005.1±260.5 pg/ml, P<0.05). In a multiple regression model analysis, only mean pulmonary arterial pressure was an independent predictor of NT-proBNP (standardized coefficient=0.663, P=0.002). In the PAH group, only right atrial systolic pressure was found to be positively correlated with NT-proBNP, whereas other parameters were not found to be correlated with NT-proBNP. Our data suggests that NT-proBNP might also be a predictor of the severity of pulmonary hypertension in the ASD patients.

Plasma B-type natriuretic peptide level in patients with acute cerebral infarction according to infarction subtype and infarction volume

BACKGROUND

Plasma B-type natriuretic peptide (BNP) is used as a diagnostic marker of cardiovascular diseases. BNP is secreted mainly from the myocardium and has been detected by immunoreactivity in brain and cerebral arteries. The aim of our study was to investigate plasma BNP in patients with acute cerebral infarction according to infarction subtype and infarction volume.

METHODS

We studied 141 patients with acute cerebral infarction, classified as large artery atherosclerosis (LAA), cardioembolism (CE), or small vessel disease (SA) according to the Trial of Org 10172 in Acute Stroke Treatment classification. Plasma BNP level was measured in patients and 61 healthy controls. We analyzed various clinical and laboratory variables of patients according to plasma BNP level.

RESULTS

Compared to controls, the patients had higher plasma BNP (11.9 ± 11.7 pg/mL versus 124.6 ± 228.8 pg/mL, p <0.01). The highest quartile BNP group was associated with advanced age, female gender, current non-smoker, atrial fibrillation, heart failure, CE group, increased white blood cell counts, increased high sensitivity C-reactive protein, increased left atrium size, decreased left ventricular ejection fraction, increased initial National Institute of Health Stroke Scale, and increased infarction volume. According to multiple regression analysis, CE group, female gender, and infarction volume were independently associated with plasma BNP. Plasma BNP level showed statistically significant differences among LAA (n = 71), CE (n = 50), and SA (n = 20) groups (p <0.001), and the expression decreased in order of CE (253.8 ± 337.1 pg/mL), LAA (61.6 ± 78.8 pg/mL), and SA (25.3 ± 24.8 pg/mL). Increased plasma BNP correlated with increased infarction volume (r = 0.42, p <0.001).

CONCLUSIONS

Plasma BNP may be helpful for prediction of etiologic classification of acute cerebral infarction and infarction volume.

Increased serum N-terminal pro-B-type natriuretic peptide and left ventricle diastolic dysfunction in patients with hepatitis C virus infection

Prior studies demonstrated that patients with hepatitis C virus (HCV) infection had higher plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, which may indicate the presence of a subclinical cardiac dysfunction. However, there are few data regarding the echocardiographic assessment in HCV-infected patients. The objectives of this study were to investigate changes in the left ventricle (LV) with echocardiography and to identify echocardiographic correlates of serum NT-proBNP levels in HCV-infected patients. Ninety HCV-infected patients and 90 age and gender-matched healthy controls were included. The level of serum NT-proBNP was higher in the patient group (P < 0.001). The proportion of patients whose serum NT-proBNP levels were higher than 125 pg/mL was greater than that of controls (15.56%vs 3.33%, P = 0.011). Echocardiography did not show any significant difference of cardiac structural abnormalities between groups. In the patient group, E, E' and E/A were lower, and E/E' was higher. The proportion of patients (13, 14.44%) with impaired diastolic filling (E/A ≤ 0.75; 0.75 < E/A < 1.5 and E/E' ≥ 10) was greater than that of the control group (3, 3.33%; P = 0.018). Simple regression analysis demonstrated a statistically significant linear correlation between NT-proBNP levels and left ventricular diastolic diameter (LVDd) (r = 0.178, P = 0.013), left ventricular posterior wall diastolic thickness (LVPWd) (r = 0.147, P = 0.023) and mitral E/E' (r = 0.414, P = 0.027). Independent correlates of NT-proBNP levels (R(2) = 0.34) were older age (β' = 0.034, P = 0.011) and E/E' ratio (β' = 0.026, P = 0.018). In conclusion, the combined analysis of NT-proBNP and echocardiography showed a possible subclinical left ventricular diastolic dysfunction as evidence of a pathogenic link between HCV and CVD.

Practical use of natriuretic peptide measurement: questionnaire results from general practitioners and cardiologists

AIMS

To elucidate the knowledge regarding B-type natriuretic peptide (BNP)/N-terminal proBNP (NT-proBNP) measurement among doctors using this biomarker.

MATERIALS & METHODS

We performed a questionnaire-based study on the use of BNP/NT-proBNP measurement among doctors; 21 general practitioners and 23 randomly chosen doctors at cardiology departments were interviewed.

RESULTS

12 general practitioners (57%) answered 'yes', eight (38%) answered 'no' and one (5%) was 'undecided' for use of BNP/NT-proBNP measurement to exclude a diagnosis of heart failure. Among cardiologists, 11 (48%) answered 'yes', ten (43%) answered 'no' and two (9%) were 'undecided' (no difference between groups, p = 0.56). The majority of doctors were familiar with BNP/NT-proBNP being affected by age but were unaware of the impact of gender and obesity.

CONCLUSION

We propose that BNP/NT-proBNP measurement results should be supplied with age- and gender-related cut-off values, along with a notion of the negative predictive value and other parameters affecting the concentration in plasma.

NT-proBNP, NT-proANP and cTnI concentrations in dogs with pre-capillary pulmonary hypertension

OBJECTIVES

To compare [NT-proBNP], [NT-proANP] and [cTnI] between control dogs with respiratory disease without pulmonary hypertension (PH) and dogs with pre-capillary PH, and to assess the accuracy of [NT-proBNP], [NT-proANP], [cTnI] to predict Doppler-derived peak tricuspid regurgitation (TR) gradient.

ANIMALS

20 dogs. 8 control dogs with respiratory disease with no PH and 12 with pre-capillary PH.

METHODS

[NT-proBNP], [NT-proANP] and [cTnI] were compared between the 2 groups and simple linear regression analysis was used to predict peak TR gradients from various blood biomarkers.

RESULTS

Median [NT-proBNP] was higher in the dogs with PH (2011 pmol/L, 274-7713 pmol/L) compared to control dogs (744 pmol/L; 531-2710 pmol/L) (p = 0.0339). [NT-proBNP] was associated with peak TR gradient (R(2) = 0.7851, p = 0.0001). Median [NT-proANP] did not differ between dogs with PH (1747 fmol/L; 894-2884 fmol/L) and control dogs (1209 fmol/L; 976-1389 fmol/L (p = 0.058). [NT-proANP] was not associated with peak TR gradient (R(2) = 0.2780, p = 0.0781). Median [cTnI] did not differ between dogs with PH (0.2850 ng/mL; 0.19-1.13 ng/mL) and control dogs (0.2 ng/mL; 0.19-0.82 ng/mL, p = 0.3051). Median [TnI] was not associated with peak TR gradient (R(2) = 0.024, p = 0.6307).

CONCLUSIONS

[NT-proBNP] concentration is significantly higher in dogs with pre-capillary PH when compared to dogs with respiratory disease without PH, and [NT-proBNP] may be useful to predict the severity of estimated PH. Elevations in [NT-proBNP] due to pre-capillary PH may complicate the interpretation of [NT-proBNP] elevations in patients presenting with cardiorespiratory abnormalities. [NT-proANP] and [cTnI] were not elevated in dogs with pre-capillary PH.

Cardiovascular and renal surrogate markers in the clinical management of hypertension

INTRODUCTION

Surrogate markers represent a significant contribution to early diagnosis, longitudinal prognoses, and outcome prediction in cases of hypertension. They often enable detection of disease and disease potential when the disease is still subclinical and are useful noninvasive tools for designing and evaluating therapeutic programs. Surrogate markers are increasingly employed as predictive endpoints for treatment.

METHODS

Key studies supporting the importance of surrogate markers as diagnostic and prognostic predictors of cardiovascular and renal clinical outcomes in hypertension, as well as what is known about the effects of renin-angiotensin-aldosterone system-blocking agents on these biomarkers were reviewed.

RESULTS

Clinical data supporting the use of surrogate markers for heart failure, such as brain natriuretic peptide (BNP) and N-terminal prohormone BNP; markers for renal function, such as urinary albumin to creatinine ratio (UACR), urinary albumin excretion rates (UAER), and creatinine, reflecting glomerular filtration; and markers of cardiac remodeling, such as left ventricular hypertrophy and calculations of left ventricular mass index (LVMI), were reviewed for their utility in improving prognosis and treatment efficacy. Finally, hypertension treatment with angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and potentially direct renin inhibitors can significantly improve outcomes predicted by surrogate markers.

CONCLUSIONS

BNP, UACR, UAER, and LVMI, among others, have been increasingly established as valid surrogate markers with significant value for hypertension prognosis and therapy. The benefits of using surrogate markers to gauge the effectiveness of hypertension therapy in reducing renal and cardiac complications can be seen in improved morbidity and mortality.

BNP at discharge in acute heart failure patients: is it all about volemia? A study using impedance cardiography to assess fluid and hemodynamic status

BACKGROUND

Besides hemodynamic parameters, several other variables have been associated to B-type natriuretic peptide (BNP) levels. Limited knowledge on BNP determinants in acute heart failure (HF) can undermine the interpretation of BNP levels.

METHODS AND RESULTS

To identify predictors of BNP levels, we evaluated 163 hospitalized acute HF patients. Thoracic fluid content (TFC) and hemodynamic parameters were measured by impedance cardiography at discharge. Patients were followed-up for 60 days for the occurrence of death/hospital admission. Median discharge BNP levels were 659.3 pg/ml. In multivariable linear regression analysis, TFC (β=0.043, 95% CI 0.024-0.062 per U/kΩ, p<0.001) was a powerful predictor of BNP levels, independently of known markers of HF severity like severe systolic dysfunction and discharge New York Heart Association class. Other independent predictors were: new onset HF, albumin, and body mass index. Sex, left cardiac work index, stroke index, hemoglobin, renal failure and discharge furosemide and lisinopril doses were associated to BNP only in univariate analysis. During follow-up, 45 (27.6%) patients were hospitalized or died. TFC (HR=1.047 (1.016-1.080) per U/kΩ increase, p=0.003) and BNP (HR=1.003 (1.001-1.004) per 10 pg/ml increase, p<0.001) were univariate predictors of the outcome, but in multivariate Cox regression analysis, only BNP was independently associated with prognosis.

CONCLUSION

Discharge BNP levels in acute HF patients reflected volemia and disease severity. Persistently high BNP levels during hospitalization should raise the possibility of remaining congestion, which could negatively influence prognosis. The utility of BNP as prognostic marker in HF may reside on its ability to reflect multiple underlying pathophysiological disturbances.

Serial changes in adiponectin and BNP in ACS patients: paradoxical associations with each other and with prognosis

Plasma adiponectin is inversely associated with the risk of coronary heart disease in healthy people. However, adiponectin and BNP (B-type natriuretic peptide) are both known to be positively associated with a risk of poor outcome, and with each other, in ACS (acute coronary syndrome) patients. Serial changes in plasma adiponectin and BNP following ACS have not been assessed previously, and may clarify these apparently paradoxical associations. In the present study, adiponectin, BNP, classical risk markers and clinical parameters were measured in plasma from 442 consecutive ACS patients in an urban teaching hospital, with repeat measures at 7 weeks (n=338). Patients were followed-up for 10 months. Poor outcome was defined as mortality or readmission for ACS or congestive heart failure (n=90). In unadjusted analysis, the change in adiponectin (but not baseline or 7-week adiponectin) was significantly associated with the risk of an adverse outcome {odds ratio (OR), 5.42 [95% CI (confidence interval), 2.78-10.55]}. This association persisted after adjusting for classical risk factors and clinical markers, but was fully attenuated by adjusting for the 7-week BNP measurement [OR, 1.13 (95% CI, 0.27-4.92)], which itself remained associated with risk [OR, 5.86 (95% CI, 1.04-32.94)]. Adiponectin and BNP positively correlated at baseline and 7 weeks, and the change in both parameters over 7 weeks also correlated (r=0.39, P<0.001). In conclusion, increases in plasma adiponectin (rather than absolute levels) after ACS are related to the risk of an adverse outcome, but this relationship is not independent of BNP levels. The results of the present study allude to a potential direct or indirect relationship between adiponectin and BNP post-ACS which requires further investigation.

Weekly variability of plasma and serum NT-proBNP measurements in normal dogs

OBJECTIVES

To determine the weekly variability of serum and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations in healthy dogs.

ANIMALS, MATERIALS AND METHODS

Fifty-three normal dogs were examined prospectively. Serum (n=25) or plasma (n=28) samples were obtained for NT-proBNP assay at one week interval for 3 consecutive weeks.

RESULTS

Median serum or plasma NT-proBNP concentration did not change over 3 consecutive weeks. Twenty-two of 53 dogs (42%) had at least one NT-proBNP value >500 pmol/L, including 14 dogs with at least one serum NT-proBNP concentration >500 pmol/L and 8 dogs with at least one plasma NT-proBNP concentration >500 pmol/L during the 3-week sampling period. The difference between the maximum and minimum NT-proBNP value obtained over the 3-week sampling period was <100 pmol/L in 40% of dogs, between 100 and 200 pmol/L in 40% of dogs, and >200 pmol/L in 20% of dogs. Of the 19 dogs with a value >500 pmol/L on either week 1 or 2, 11 dogs (58%) had a subsequent NT-proBNP value <500 pmol/L on either week 2 or 3.

CONCLUSIONS

There is a high degree of variability in weekly serum and plasma NT-proBNP values in healthy dogs. Individual variability should be considered when interpreting NT-proBNP results in dogs.

Plasma NT-proBNP increases in response to LPS administration in healthy men

Circulating levels of B-type natriuretic peptide (BNP) and NH2-terminal-proBNP (NT-proBNP) increase in response to volume overload and help in the differential diagnosis of acute heart failure. Elevated plasma BNP levels are observed also in sepsis and do not always correspond to left ventricular dysfunction. Here, we investigated plasma NT-proBNP fluctuations in response to human bacterial endotoxinemia, an experimental model of systemic infection and inflammation. Escherichia coli endotoxin (LPS) (2 ng/kg) was administered to 10 healthy volunteers in a randomized, placebo-controlled, cross-over design. Plasma NT-proBNP, C-reactive protein (CRP), COOH terminal pro-endothelin-1 (CT-proET-1), and midregional-pro-adrenomedullin (MR-proADM) were measured at hourly intervals for 6 h. LPS administration induced a continuous increase in plasma NT-proBNP that reached peak values after 6 h (40.7 ± 7.9 vs. 16.1 ± 3.2 pg/ml in placebo days, mean ± SE; P = 0.023). The profile of changes in NT-proBNP correlated to changes in body temperature ( P < 0.001), heart rate ( P = 0.005), CRP ( P < 0.001), and CT-proET-1 ( P = 0.008), but not to blood pressure values. Our results demonstrate that plasma NT-proBNP increases in a model of systemic infection/inflammation in healthy men with normal heart function. This finding emphasizes the necessity to consider concomitant infections when interpreting elevated circulating NT-proBNP concentrations.

B-type natriuretic peptide and wall stress in dilated human heart

Background Although B-type natriuretic peptide (BNP) is used as complimentary diagnostic tool in patients with unknown thoracic disorders, many other factors appear to trigger its release. In particular, it remains unresolved to what extent cellular stretch or wall stress of the whole heart contributes to enhanced serum BNP concentration. Wall stress cannot be determined directly, but has to be calculated from wall volume, cavity volume and intraventricular pressure of the heart. The hypothesis was, therefore, addressed that wall stress as determined by cardiac magnetic resonance imaging (CMR) is the major determinant of serum BNP in patients with a varying degree of left ventricular dilatation or dysfunction (LVD). Methods A thick-walled sphere model based on volumetric analysis of the LV using CMR was compared with an echocardiography-based approach to calculate LV wall stress in 39 patients with LVD and 21 controls. Serum BNP was used as in vivo marker of a putatively raised wall stress. Nomograms of isostress lines were established to assess the extent of load reduction that is necessary to restore normal wall stress and related biochemical events. Results Both enddiastolic and endsystolic LV wall stress were correlated with the enddiastolic LV volume (r = 0.54, P < 0.001; r = 0.81, P < 0.001). LV enddiastolic wall stress was related to pulmonary pressure (capillary: r = 0.69, P < 0.001; artery: r = 0.67, P < 0.001). Although LV growth was correlated with the enddiastolic and endsystolic volume (r = 0.73, P < 0.001; r = 0.70, P < 0.001), patients with LVD exhibited increased LV wall stress indicating an inadequately enhanced LV growth. Both enddiastolic (P < 0.05) and endsystolic (P < 0.01) wall stress were increased in patients with increased BNP. In turn, BNP concentration was elevated in individuals with increased enddiastolic wall stress (>8 kPa: 587 +/- 648 pg/ml, P < 0.05; >12 kPa: 715 +/- 661 pg/ml, P < 0.001; normal < or =4 kPa: 124 +/- 203 pg/ml). Analysis of variance revealed LV enddiastolic wall stress as the only independent hemodynamic parameter influencing BNP (P < 0.01). Using nomograms with "isostress" curves, the extent of load reduction required for restoring normal LV wall stress was assessed. Compared with the CMR-based volumetric analysis for wall stress calculation, the echocardiography based approach underestimated LV wall stress particularly of dilated hearts. Conclusions In patients with LVD, serum BNP was increased over the whole range of stress values which were the only hemodynamic predictors. Cellular stretch appears to be a major trigger for BNP release. Biochemical mechanisms need to be explored which appear to operate over this wide range of wall stress values. It is concluded that the diagnostic use of BNP should primarily be directed to assess ventricular wall stress rather than the extent of functional ventricular impairment in LVD.