Natriuretic Peptides in the Diagnosis and Management of Acute Heart Failure

Brain natriuretic peptide: Much more than a biomarker

Brain natriuretic peptide (BNP) modulates several biological processes by activating the natriuretic peptide receptor A (NPR-A). Atria and ventricles secrete BNP. BNP increases natriuresis, diuresis and vasodilatation, thus resulting in a decreased cardiac workload. BNP and NT-proBNP, which is the biologically inactive N-terminal portion of its pro-hormone, are fast and sensitive biomarkers for diagnosing heart failure. The plasma concentrations of both BNP and NT-proBNP also correlate with left ventricular function in patients with acute exacerbation of COPD, even without history of heart failure. Several studies have been conducted in vitro and in vivo, both in animals and in humans, in order to assess the potential role of the NPR-A activation as a novel therapeutic approach for treating obstructive pulmonary disorders. Unfortunately, these studies have yielded conflicting results. Nevertheless, further recent specific studies, performed in ex vivo models of asthma and COPD, have confirmed the bronchorelaxant effect of BNP and its protective role against bronchial hyperresponsiveness in human airways. These studies have also clarified the intimate mechanism of action of BNP, represented by an autocrine loop elicited by the activation of NPR-A, localized on bronchial epithelium, and the relaxant response of the surrounding ASM, which does not expresses NPR-A. This review explores the teleological activities and paradoxical effects of BNP with regard to chronic obstructive respiratory disorders, and provides an excursus on the main scientific findings that explain why BNP should be considered much more than a biomarker.

Diagnosis and management of pulmonary hypertension associated with left ventricular diastolic dysfunction

Pulmonary hypertension (PH) is commonly seen in patients who present with left ventricular diastolic dysfunction (LVDD) and is considered a marker of poor prognosis. While PH in this setting is thought to result from pulmonary venous congestion, there is a subset of patients in which pulmonary pressures fail to improve with appropriate management of diastolic heart failure and go on to develop a clinical picture similar to that of patients with pulmonary arterial hypertension (PAH). Despite the utility of Doppler echocardiography and exercise testing in the initial evaluation of patients with suspected PH-LVDD, the diagnosis can only be confirmed using right heart catheterization. Management of PH-LVDD centers on both optimizing fluid management and afterload reduction to reducing left ventricular diastolic pressures and also increase pulmonary venous return. To date, there is no clear evidence that addition of PH-specific drugs can improve clinical outcomes, and their use should only be considered in the setting of clinical trials. In conclusion, PH-LVDD remains a challenging clinical entity that complicates the management of left ventricular dysfunction and significantly contributes to its morbidity and mortality. Determination of the optimal diagnostic and treatment strategies for this form of PH should be the goal of future studies.

The evaluation of diagnostic role of cardiac troponin T (cTnT) in newborns with heart defects

Heart diseases are a significant cause of morbidity and mortality in newborns. Diagnostic methods are often not sufficient or, in many cases, cannot be used. There is a great advance in medical knowledge concerning biomarkers in the diagnosis of circulatory system in adult patients. Among them, cardiac troponins play the main role. In current literature, there is not enough data concerning the possibility of using them in neonatal cardiac diagnostics. Aim of the Study. To evaluate diagnostic usefulness of cTnT in correlation with other markers of circulatory failure and myocardial damage in newborns with heart defects. Patients and Methods. The study involved 83 newborns up to 46 weeks of postmenstrual age. The exclusion criteria were severe perinatal asphyxia and presence of severe noncardiac diseases. Patients were divided into 2 main groups: group I—54 patients with congenital heart defects (CHDs), and group II (control)—29 healthy neonates. All patients underwent detailed examination of circulatory system. Cardiac troponin T (cTnT) concentrations were evaluated by Roche CARDIAC T Quantitive test. Results. Performed studies revealed that cTnT levels in newborns with heart pathology were significantly higher than in healthy ones. However, cTnT concentrations in patients with CHD did not correlate with clinical symptoms of heart failure, nor with echocardiographic markers of LV function. Type of heart defect did not influence cTnT levels as well. Only hemodynamic significance evaluated by echocardiography influenced the cTnT levels with statistical significance. Conclusions. (1) Statistically significant differences in cTnT levels between newborns with heart defects and healthy subjects were shown. (2) CTnT levels in newborns with heart defects refer only to hemodynamic significance of the defect.

Epithelium integrity is crucial for the relaxant activity of brain natriuretic peptide in human isolated bronchi

BACKGROUND AND PURPOSE Brain natriuretic peptide (BNP) plays an important role in several biological functions, including bronchial relaxation. Here, we have investigated the role of BNP and its cognate receptors in human bronchial tone. EXPERIMENTAL APPROACH Effects of BNP on responses to carbachol and histamine were evaluated in non-sensitized, passively sensitized, epithelium-intact or denuded isolated bronchi and in the presence of methoctramine, N(ω) -nitro-L-arginine methyl ester (L-NAME) and aminoguanidine. Natriuretic peptide receptors (NPRs) were investigated by immunohistochemistry, RT-PCR and real-time PCR. Release of NO and acetylcholine from bronchial tissues and cultured BEAS-2B bronchial epithelial cells was also investigated. KEY RESULTS BNP reduced contractions mediated by carbachol and histamine, with decreased E(max) (carbachol: 22.7 ± 4.7%; histamine: 59.3 ± 1.8%) and increased EC(50) (carbachol: control 3.33 ± 0.88 µM, BNP 100 ± 52.9 µM; histamine: control 16.7 ± 1.7 µM, BNP 90 ± 30.6 µM); BNP was ineffective in epithelium-denuded bronchi. Among NPRs, only atrial NPR (NPR1) transcripts were detected in bronchial tissue. Bronchial NPR1 immunoreactivity was detected in epithelium and inflammatory cells but faint or absent in airway smooth muscle cells. NPR1 transcripts in bronchi increased after incubation with BNP, but not after sensitization. Methoctramine and quinine abolished BNP-induced relaxant activity. The latter was associated with increased bronchial mRNA for NO synthase and NO release, inhibited by L-NAME and aminoguanidine. In vitro, BNP increased acetylcholine release from bronchial epithelial cells, whereas NO release was unchanged. CONCLUSIONS AND IMPLICATIONS Epithelial cells mediate the BNP-induced relaxant activity in human isolated bronchi.

Bedside assessment of cardiac hemodynamics: the impact of noninvasive testing and examiner experience

BACKGROUND

Knowledge of cardiac filling pressures is critical in the diagnosis and management of patients with dyspnea or heart failure. Echocardiography and B-natriuretic peptide (BNP) testing are commonly used to estimate these pressures, but their incremental value beyond physical examination remains unknown.

METHODS

Right and left heart filling pressures were prospectively estimated as "normal" or "abnormal" by staff cardiologists and cardiovascular trainees based upon physical examination findings alone, or examination coupled with echocardiographic and BNP data in patients referred for cardiac catheterization. Net reclassification improvement was calculated to determine whether echocardiographic/BNP data had incremental value in the determination of right and left heart pressures.

RESULTS

Two hundred fifteen observations were made by 9 examiners in 116 consecutive patients. Right and left heart pressures were accurately predicted from examination alone in 71% and 60% of observations, respectively. Examination-based accuracy was greater for staff cardiologists compared with trainees for right heart (82 vs 67%, P=.03) and left heart pressures (71% vs 55%, P=.03). Exposure to echocardiographic and BNP data did not enhance accuracy beyond bedside examination alone, both for left heart pressures (net reclassification improvement=-0.004; 95% confidence interval, -0.12-0.12) and right heart pressures (net reclassification improvement=0.02, 95% confidence interval, -0.09-0.13).

CONCLUSIONS

Cardiac filling pressures can be estimated from physical examination with modest accuracy, which is enhanced with experience. While echocardiographic and BNP data predict cardiac filling pressures, they may not provide information of incremental value beyond examination alone. Rigorous teaching and practice of cardiac examination skills should continue to be emphasized during medical training.

Utilization of B-type natriuretic peptide and NT-proBNP in the diagnosis of pleural effusions due to heart failure

PURPOSE OF REVIEW

The natriuretic peptides B-type natriuretic peptide (BNP) and NT-proBNP have been incorporated into the existing clinical guidelines for the diagnostic evaluation of heart failure. Recent evidence has provided important information regarding the relative value of each of these peptides to differentiate between pleural effusions caused by heart failure and those attributable to other causes.

RECENT FINDINGS

In a meta-analysis of 10 studies, which included 1120 patients, pleural fluid levels of NT-proBNP had a pooled sensitivity and specificity of 94%, a positive likelihood ratio of 15.2, and a negative likelihood ratio of 0.06 in identifying heart failure-related effusions. Because pleural fluid and serum natriuretic peptide levels are closely correlated and display similar discriminatory properties, blood tests alone are sufficient. More than 85% of heart failure patients whose pleural fluids meet exudative criteria exhibit high pleural NT-proBNP concentrations. The diagnostic performance of pleural fluid BNP has been reported to be inferior to that of NT-proBNP.

SUMMARY

NT-proBNP is an established biomarker of heart failure-associated effusions and the most effective tool for recognizing cardiac effusions that are misclassified as exudates by Light's criteria. If clinicians choose pleural fluid specimens for natriuretic peptide testing, the lower diagnostic accuracy of BNP makes it a poor substitute for NT-proBNP measurements.

Relation of natriuretic peptides and midregional proadrenomedullin to cardiac chamber volumes by computed tomography in patients without heart failure: from the ROMICAT Trial

BACKGROUND

Stress myocyte biomarkers are used prognostically in patients with cardiovascular disease. We examined associations between amino-terminal pro-B-type natriuretic peptide (NT-proBNP), midregional pro-A-type natriuretic peptide (MR-proANP), and midregional proadrenomedullin (MR-proADM) concentrations and cardiac chamber volumes in chest pain patients without heart failure by use of computed tomography (CT).

METHODS

At the time of 64-slice CT scan, we acquired plasma and serum samples for these biomarkers from 346 patients [mean (SD) age 53 (12) years, 65% men]. Left atrial volume (LAV) and left ventricular volumes at end-diastole (LVEDV) and end-systole (LVESV) were measured and indexed to body surface area (LAVI, LVEDI, LVESI).

RESULTS

Concentrations of both natriuretic peptides were correlated with LAV and LAVI (r = 0.19-0.32, all P

CONCLUSIONS

In patients without heart failure, both NT-proBNP and MR-proANP concentrations are independently associated with LA enlargement, whereas MR-proADM concentrations are correlated with LV volumes. This may partially explain the well-recognized value of natriuretic peptides for use in risk stratification.

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MESH Headings

• Adrenomedullin/blood
• Atrial Function, Left
• Biomarkers/blood
• Cohort Studies
• Female
• Humans
• Male
• Middle Aged
• Myocardial Infarction/diagnosis
• Natriuretic Peptide, Brain/blood
• Protein Precursors/blood
• Reproducibility of Results
• Tomography, X-Ray Computed
• Ventricular Function, Left

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Grants

• T32HL076136 NHLBI NIH HHS
• R01 HL080053 NHLBI NIH HHS
• L30 HL093806-01 NHLBI NIH HHS
• L30 HL093806 NHLBI NIH HHS
• K23 HL098370 NHLBI NIH HHS
• T32 HL076136 NHLBI NIH HHS
• L30HL093896 NHLBI NIH HHS

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Affiliation(s)

Quynh A Truong Cardiac MR PET CT Program, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Emily Siegel
Mahir Karakas
James L Januzzi
Fabian Bamberg
Amir A Mahabadi
Selcuk Dasdemir
Thomas J Brady
Andreas Bergmann
Jan Kunde
John T Nagurney
Udo Hoffmann
Wolfgang Koenig

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