Ventricular expression of brain natriuretic peptide gene following orthotopic cardiac transplantation in children--a three year follow up

Estimating filling pressures in paediatric heart transplant recipients using echocardiographic parameters and B-type natriuretic peptide

BACKGROUND

Longitudinal evaluation of allograft diastolic function in paediatric heart transplant recipients is important for early detection of acute rejection, cardiac allograft vasculopathy, and graft dysfunction. Mean diastolic right atrial and pulmonary capillary wedge pressures obtained at catheterisation are the reference standards for assessment. Echocardiography is non-invasive and more suitable for serial surveillance, but individual parameters have lacked accuracy. This study aimed to identify covariates of post-transplant mean right atrial and pulmonary capillary wedge pressures, including B-type natriuretic peptide and certain echocardiographic parameters.

METHODS

A retrospective review of 143 scheduled cardiac catheterisations and echocardiograms from 56 paediatric recipients transplanted from 2007 to 2011 was performed. Samples with rejection were excluded. Univariate and multivariate linear regression models using backward selection were applied to a database consisting of B-type natriuretic peptide, haemodynamic, and echocardiographic data.

RESULTS

Ln B-type natriuretic peptide, heart rate z-score, left ventricular end-diastolic dimension z-score, mitral E/e', and percent interventricular septal thickening in systole were independently associated with mean right atrial pressure. Ln B-type natriuretic peptide, heart rate z-score, left ventricular end-diastolic dimension z-score, left ventricular mass (observed/predicted), and mitral E/e' were independently associated with mean pulmonary capillary wedge pressure. Covariates of B-type natriuretic peptide included mean pulmonary artery and pulmonary capillary wedge pressures, height, haemoglobin, fractional shortening, percent interventricular septal thickening in systole, and pulmonary vascular resistance index.

CONCLUSIONS

B-type natriuretic peptide and echocardiographic indices of diastolic function were independently related to post-transplant mean right atrial and pulmonary capillary wedge pressures in paediatric heart transplant recipients without rejection.

Brain natriuretic peptide and right heart dysfunction after heart transplantation

Heart transplantation (HT) should normalize cardiac endocrine function, but brain natriuretic peptide (BNP) levels remain elevated after HT, even in the absence of left ventricular hemodynamic disturbance or allograft rejection. Right ventricle (RV) abnormalities are common in HT recipients (HTx), as a result of engraftment process, tricuspid insufficiency, and/or repeated inflammation due to iterative endomyocardial biopsies. RV function follow-up is vital for patient management as RV dysfunction is a recognized cause of in-hospital death and is responsible for a worse prognosis. Interestingly, few and controversial data are available concerning the relationship between plasma BNP levels and RV functional impairment in HTx. This suggests that infra-clinical modifications, such as subtle immune system disorders or hypoxic conditions, might influence BNP expression. Nevertheless, due to other altered circulating molecular forms of BNP, a lack of specificity of BNP assays is described in heart failure patients. This phenomenon could exist in HT population and could explain elevated BNP plasmatic levels despite a normal RV function. In clinical practice, intra-individual change in BNP over time, rather than absolute BNP values, might be more helpful in detecting right cardiac dysfunction in HTx.

BNP in children with congenital cardiac disease: is there now sufficient evidence for its routine use?

Interest in brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) in the management of children with CHD has increased. There are, however, no current guidelines for their routine use. The aim of this review article is to provide an update on the data regarding the use of BNP/NT-proBNP in the evaluation and surgical treatment of children with CHD. BNP/NT-proBNP levels in children with CHD vary substantially according to age, laboratory assay methods, and the specific haemodynamics associated with the individual congenital heart lesion. The accuracy of BNP/NT-proBNP as supplemental markers in the integrated screening, diagnosis, management, and follow-up of CHD has been established. In particular, the use of BNP/NT-proBNP as a prognostic indicator in paediatric cardiac surgery has been widely demonstrated, as well as its role in the subsequent follow-up of surgical patients. Most of the data, however, are derived from single-centre retrospective studies using multivariable analysis; prospective, randomised clinical trials designed to evaluate the clinical utility and cost-effectiveness of routine BNP/NT-proBNP use in CHD are lacking. The results of well-designed, prospective clinical trials should assist in formulating guidelines and expert consensus recommendations for its use in patients with CHD. Finally, the use of new point-of-care testing methods that use less invasive sampling techniques - capillary blood specimens - may contribute to a more widespread use of the BNP assay, especially in neonates and infants, as well as contribute to the development of screening programmes for CHD using this biomarker.

Beta-adrenergic adaptation in paediatric idiopathic dilated cardiomyopathy

BACKGROUND

Although the pathophysiology and treatment of adult heart failure (HF) are well studied, HF in children remains poorly understood. In adults, adrenergic receptor (AR)-mediated adaptation plays a central role in cardiac abnormalities in HF, and these patients respond well to β-blocker (BB) therapy. However, in children with HF, there is a growing body of literature suggesting a lack of efficacy of adult HF therapies. Due to these unanticipated differences in response to therapy and the paucity of data regarding the molecular adaptation of the paediatric heart, we investigated the molecular characteristics of HF in children.

METHODS AND RESULTS

Explanted hearts from adults and children with idiopathic dilated cardiomyopathy and non-failing controls were used in the study. Our results show that the molecular characteristics of paediatric HF are strikingly different from their adult counterparts. These differences include: (i) down-regulation of β1- and β2-AR in children, whereas β2-AR expression is maintained in adults; (ii) up-regulation of connexin43 in children, whereas down-regulation is observed in adults; (iii) no differences in phosphatase expression, whereas up-regulation is observed in adults; (iv) no decrease in the phosphorylation of phospholamban at the Ser16 or Thr17 sites in children, which are known characteristics of adult HF.

CONCLUSION

There is a different adaptation of β-AR and adrenergic signalling pathways in children with HF compared with adults. Our results begin to address the disparities in cardiovascular research specific to children and suggest that age-related differences in adaptation could influence the response to therapy. These findings could lead to a paradigm shift in the contemporary management of children with HF.

Diagnostic, prognostic and therapeutic relevance of B-type natriuretic hormone and related peptides in children with congenital heart diseases

The aim of this article is to review the diagnostic and prognostic relevance of measurement of brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) in pediatric patients with congenital cardiac diseases (CHD). A computerized literature search in the National Library of Medicine using the keywords "BNP assay" and "NT-proBNP assay"+neonate/s and newborn/s was performed. Next, we refined the analysis to include only the studies specifically designed to evaluate the clinical usefulness of BNP and NT-proBNP measurements in children with CHD. Several authors suggested that BNP/NT-proBNP is clinically helpful as a diagnostic and prognostic marker for children with suspected CHD. BNP values are age dependent, even in paediatric populations. Unfortunately, accurate reference values for BNP and NT-proBNP for neonatal ages have only recently become available. As a result, the lack of homogenous and accurate decisional levels in the neonatal period greatly limits the clinical impact of the BNP assay, and also contributed to the production of conflicting results. Regardless of age, there is great variability in BNP/NT-proBNP values among CHD characterized by different hemodynamic and clinical conditions. In particular, cardiac defects characterized by left ventricular volume and pressure overload usually show a higher BNP response than CHD which is characterized by right ventricular volume or pressure overload. BNP and NT-proBNP may be considered helpful markers in the integral clinical approach for patients with CHD. Measurement of BNP cannot replace cardiac imaging (including echocardiography, angiography and magnetic resonance), but provide independent, low cost and complementary information for the evaluation of cardiac function and clinical status.

Screening for rejection in symptomatic pediatric heart transplant recipients: the sensitivity of BNP

As the pediatric OHT population expands, there is increasing demand for convenient, yet sensitive screening techniques to identify children with acute rejection when they present to acute care facilities. In children, symptoms of acute rejection or other causes of graft dysfunction are often non-specific and can mimic other childhood illnesses. The aim of this study was to assess the utility of BNP as a biomarker to assist providers in clinical decision-making when evaluating symptomatic pediatric heart transplant patients. One hundred twenty-two urgent care and emergency room visits from 53 symptomatic pediatric OHT patients were retrospectively reviewed to evaluate the relationship between BNP levels, symptoms, and clinical diagnosis at these visits. An ROC curve was generated to determine the accuracy of BNP as a screening tool for acute rejection in this patient population. In this group of patients, a BNP value of >700 pg/mL was 100% sensitive and 92% specific for detecting allograft acute rejection (NPV of 100%). We concluded that BNP is a highly sensitive screening test for acute rejection in symptomatic pediatric heart transplant patients.

Clinical relevance of measurement of brain natriuretic peptide and N-terminal pro-brain natriuretic peptide in pediatric cardiology

BACKGROUND

The aim of this review is to understand the clinical usefulness of Brain Natriuretic Peptide (BNP) and N-terminal pro-Brain Natriuretic Peptide (NT-proBNP) in pediatric cardiology.

METHODS

A computerized literature search on National Library of Medicine using the keywords "BNP assay" and "NT-proBNP assay" was performed. Then, we refined the analysis to include only the studies specifically designed to evaluate the clinical usefulness of BNP and NT-proBNP assays in patients with congenital heart disease.

RESULTS

BNP and NT-proBNP are useful marker for diagnosis of heart failure, for the assessment of clinical severity and for the follow-up of congenital and pediatric heart diseases. However, results from different studies are often partial and not always univocal. Moreover, reference intervals in pediatric population have not yet been extensively evaluated.

CONCLUSIONS

BNP and NT-proBNP may be considered helpful markers for the integrated diagnosis and management of pediatric patients, though further studies are needed to support their routine use.

Prognostic value of B-type natriuretic peptide in surgical palliation of children with single-ventricle congenital heart disease

The objective of this prospective study was to assess the prognostic role of perioperative B-type natriuretic peptide (BNP) levels in infants and children with single-ventricle congenital heart disease undergoing Norwood, bidirectional cavopulmonary anastomosis (BCPA), or Fontan operation. BNP levels were measured at baseline, after cardiopulmonary bypass, 6 to 12 hours after surgery, and then daily until indwelling vascular catheters were removed. Outcome measures included length of mechanical ventilation, inotropic support, and hospital stay. Twenty subjects underwent 23 surgical procedures (13 Norwood, 5 BCPA, and 5 Fontan). BNP levels were significantly higher in patients undergoing a Norwood procedure compared with a BCPA or Fontan procedure (p < 0.01). BNP levels measured 6 to 12 hours after surgery were predictive of duration of hospitalization (p = 0.005) and inotropic support (p = 0.01). An increase in BNP level within 48 hours of extubation was observed in 92% of patients undergoing a Norwood procedure. Early postoperative BNP levels correlate significantly with the ensuing duration of inotropic support and length of hospitalization. An increase in BNP after extubation may be reflective of the degree of underlying cardiopulmonary instability. Further investigation is necessary to define this important relation.

Neuroendocrine profiling of humans receiving cardiac allografts

BACKGROUND

Several studies have investigated changes in circulating hormones and markers of cardiac status after heart transplantation in humans. As a result, plasma levels of various hormones and autocoids have been associated with cardiac allograft rejection status. However, no clear associations can be defined given the highly contradictory nature of the available literature.

METHODS

In this study of 69 consecutive heart transplant patients followed for >2 years we examine the relationship between neurohumors potentially related to allograft rejection and endomyocardial biopsy grade of rejection (according to the ISHLT) and hemodynamic status. Markers assessed include brain natriuretic peptide (BNP), amino-terminal pro-BNP (N-BNP), atrial natriuretic factor (ANF), adrenomedullin, interleukin-1beta, interleukin-6, tumor necrosis factor-alpha, troponin C and C-reactive protein.

RESULTS

The highest plasma levels for most neurohumors were found shortly after surgery and showed a trend towards normalization with time. BNP and N-BNP were the only significantly elevated plasma analytes for patients with Grade 3 rejection as compared with other ISHLT grades. ANF plasma levels correlated with BNP and N-BNP in Grades 0 to 2, but not in Grade 3, suggesting that in this rejection grade the usual coordinated changes observed in BNP and ANF secretion no longer exist. Cardiac filling pressures were correlated with plasma BNP, N-BNP and ANF levels only for Grades 0 and 1.

CONCLUSIONS

The timing of blood sampling after transplantation influences the level of the neurohumors measured, which may help explain the conflicting literature reports on the association between neurohumor levels and rejection grade. The significant increase in circulating levels of BNP and N-BNP observed in most cases of Grade 3 rejection occurred with no apparent relationship to post-transplantation time, which suggests a specific influence of acute rejection on BNP gene expression.

Brain natriuretic peptide levels do not correlate with acute cellular rejection in De Novo orthotopic heart transplant recipients

BACKGROUND

The changes in brain natriuretic peptide (BNP) levels after orthotopic heart transplantation have not been previously described. The use of brain natriuretic peptide levels as a surrogate marker for cellular rejection remains controversial, with conflicting data.

METHODS

We prospectively evaluated the potential utility of BNP levels in the first 6 months after transplantation and sought correlation with histologic grade of rejection and hemodynamic status.

RESULTS

Thirty-five patients and 265 biopsy samples were included in the study. BNP levels did not correlate with histologic grade of rejection. They showed good correlation with central venous pressure and pulmonary capillary wedge pressure. BNP levels were elevated after transplant and showed a steep time-dependent decline. BNP levels correlated with echocardiographically derived indices of diastolic dysfunction.

CONCLUSIONS

BNP levels are not a surrogate marker for rejection in the first 2 months after orthotopic heart transplantation and do not obviate the necessity for endomyocardial biopsy. Whether BNP levels have long-term prognostic significance is unclear and remains the subject of ongoing prospective study.

B-type natriuretic peptide in children after cardiac transplantation

BACKGROUND

The normal B-type natriuretic peptide (BNP) concentration and the significance of increased BNP concentration in children after orthotopic heart transplant (OHT) remain unknown. We sought to determine plasma BNP concentrations in relation to post-transplant time and to explore factors associated with increased BNP in pediatric OHT recipients.

METHODS

We obtained plasma BNP concentrations in 44 pediatric patients at 1 to 171 months after OHT. All patients underwent endomyocardial biopsies and echocardiography. We analyzed the association between BNP and post-transplant time, as well as the association between BNP concentration and left ventricular end-diastolic dimension (LVEDD) after transplantation.

RESULTS

The age of study patients ranged from 0.9 to 21.2 years (mean, 11.4 +/- 6.2 years; median, 10.5 years). We evaluated BNP concentrations immediately after transplantation. The mean BNP concentration decreased exponentially to 100 pg/ml by 14 weeks after OHT. Although BNP concentration relative to time after OHT varied among individuals, all patients with multiple measurements showed predictable rates of decrease. This decrease in BNP concentration was not associated with changes in LVEDD.

CONCLUSIONS

Plasma BNP concentration was elevated in children after OHT and decreased exponentially in time to 100 pg/ml by 14 weeks after OHT. The decrease in BNP concentration was unrelated to left ventricular dimension.

BNP Consensus Panel 2004: A Clinical Approach for the Diagnostic, Prognostic, Screening, Treatment Monitoring, and Therapeutic Roles of Natriuretic Peptides in Cardiovascular Diseases

Among the most exciting developments in the field of heart failure in recent times has been the rediscovery of the natriuretic peptide system and its pleuripotent effects on cardiac structure and function. This is particularly true of its natriuretic and hemodynamic effects. There has been an explosion of the knowledge base seeking to understand the wide range of homeostatic, regulatory, and counter-regulatory functions in which the natriuretic peptide system participates. Additional interest has been stimulated by advances in technology such as point-of-care and core laboratory BNP assays and the use of the recombinant B-type natriuretic peptide nesiritide as a treatment option. Despite this recent interest, the available literature lacks a comprehensive expert review of the current science and roles of natriuretic peptides for diagnostic, prognostic, screening, treatment monitoring, and therapeutic purposes. More importantly, a summary updating and guiding the clinician on most of these advances was lacking. An expert Consensus Panel with basic, methodological, and clinical expertise was convened to summarize current knowledge in these areas and the findings and consensus statements are contained herein.

Usefulness of an elevated B-type natriuretic peptide to predict allograft failure, cardiac allograft vasculopathy, and survival after heart transplantation

B-type natriuretic peptide (BNP) has emerged as an important marker of ventricular wall stress and is predictive of hemodynamic abnormalities in heart transplantation despite "preserved" systolic function. We evaluated the capacity of BNP to predict deaths due to allograft failure in 62 patients long after heart transplantation (mean 5 +/- 2.5 years). Based on the median tendency of measurement of BNP in the absence of rejection during stable surveillance, 2 distinct patient groups were identified as having low BNP (n = 39, < 250 pg/ml; median BNP 70 pg/ml) and high BNP (n = 23, > or =250 pg/ml; median BNP 592 pg/ml). No differences between the 2 BNP groups were noted with regard to age, gender, race, time after transplantation, diabetes mellitus, hypertension, and hyperlipidemia with measurement of BNP. Multivariable analysis showed that decreased left ventricular ejection fraction, angiographic coronary artery disease, and increased serum creatinine were independent predictors of elevated BNP. Cardiac deaths were significantly greater in those with high BNP levels (35%) than in those with low BNP (2.5%, p = 0.01). Absence of significant angiographic coronary artery disease coupled with a BNP of < 250 pg/ml was associated with the lowest event rate (0%), whereas patients with coronary artery disease and BNP > or =250 pg/ml exhibited a 50% cardiac death rate (p <0.01 for trend). Cox's model confirmed that increased BNP and decreased left ventricular ejection fraction are independent predictors of poor survival. Survival analysis associated lower BNP levels with an excellent long-term survival rate (95%) and higher BNP levels with a markedly decreased survival rate (60%, p = 0.002). Higher BNP levels in patients long after heart transplantation are associated with allograft dysfunction and cardiac allograft vasculopathy and are strongly and independently predictive of cardiovascular death.

Predictive value of brain natriuretic peptide in the diagnosis of heart transplant rejection

AIM

To evaluate the pattern of brain natriuretic peptide (BNP) concentration in heart transplant (HT) recipients and its relation to the degree of graft rejection determined by endomyocardial biopsy specimen.

METHODS

We studied 71 consecutive HT recipients (62 men, 53 +/- 11 years). The patients underwent 383 biopsies. Creatinine and BNP concentrations and hemodynamic parameters were determined along with the degree of graft rejection using endomyocardial biopsy specimens. We considered treatable rejection as International Society for Heart and Lung Transplantation Grade >or=2 in the first 90 days and >or=3A thereafter. We included a control group of 36 healthy individuals.

RESULTS

Brain natriuretic peptide concentration was significantly greater among HT recipients (264 +/- 318 pg/ml) than in controls (17 +/- 16 pg/ml). In the first 90 days, BNP concentration was significantly greater among the patients with graft rejection (510 +/- 470, n = 84, vs 278 +/- 255, n = 87; p < 0.0001), although the corresponding discriminatory capacity was small. After the first 90 days, BNP values were similar in patients with and without graft rejection (170 +/- 297, n = 17, vs 142 +/- 203, n = 195; p = not significant). Creatinine concentration increased with time after transplantation and did not correlate with BNP concentration. We observed significant positive correlation between BNP concentration and hemodynamic parameters.

CONCLUSIONS

Brain natriuretic peptide concentration remains increased after HT, with stabilization after the 4th month. Brain natriuretic peptide concentrations are slightly greater among patients with treatable rejection, particularly in the first 90 days, although BNP concentration lacks discriminatory capacity to serve as a guide to performing biopsy.

Usefulness of B-type natriuretic peptide as a noninvasive screening tool for cardiac allograft pathology in pediatric heart transplant recipients

We examined the utility of B-type natriuretic peptide (BNP) in the evaluation of pediatric orthotopic heart transplant recipients for allograft pathology by measuring the serum BNP levels at the time of either screening echocardiography and biopsy, or at the time of clinical rejection. There was a significant difference (p <0.0001) in the BNP levels in 37 patients in the group with evidence of pathology compared with those without evidence. There was also 100% sensitivity and 100% negative predictive value of BNP levels >100 pg/ml for identifying graft pathology.

B-type natriuretic peptide in heart transplantation: an important marker of allograft performance

The successful management of a cardiac allograft recipient centers around detection of allograft dysfunction early and preferably in a noninvasive manner. Up to this point, echocardiography or right heart catherization with endomyocardial biopsy are the only definitive methods available to diagnose allograft dysfunction. However, these methods do not reflect early structural changes and neurohormonal aberrations involved in allograft dysfunction. B-type natriuretic peptide (BNP) reflects ventricular wall stress and pressure and early studies have intimated potential usefulness of this marker in heart transplantation. Recent studies utilizing point-of-care BNP assay in heart transplant recipients have demonstrated elevated BNP levels at baseline compared with controls. Furthermore, the two most significant correlates of BNP levels are central hemodynamic perturbations despite preserved systolic function and presence of right sided cardiac dysfunction. Initial investigations have demonstrated BNP levels to serve as prognostic marker for cardiac related events and to track responses to therapeutic interventions. Further studies are needed to further assess the utility of BNP as surrogate marker for cardiac function and adaptation.

Plasma concentrations of aminoterminal pro atrial natriuretic peptide and aminoterminal pro brain natriuretic peptide in healthy neonates: marked and rapid increase after birth

OBJECTIVE

The purpose of the study was to examine the possible age dependency of plasma N-terminal pro atrial natriuretic peptide (N-ANP) and N-terminal pro brain natriuretic peptide (N-BNP) levels in healthy term neonates to establish normal ranges for the neonatal period.

METHODS

N-ANP and N-BNP plasma concentrations were measured in peripheral venous (n = 116) and umbilical cord blood (n = 37) in 153 healthy term neonates (mean: 5.1; range: 0-30 days) using an enzyme immunoassay. The neonates were classified into 8 groups according to their age (day of delivery and 1, 2, 3, 4, 5-7, 8-14, and 14-30 days of age).

RESULTS

The plasma N-ANP and N-BNP concentration were the highest at the first day of age (96 700; 6912-436 000 and 641; 254-1272 fmol/mL) and were found significantly higher compared with the day of delivery (5680; 1005-16 900 and 221; 58-478 fmol/mL; P < 0,0001). After this marked increase, N-ANP and N-BNP levels decreased steadily and became stable at the fifth (5232; 2691-7353 fmol/mL) and third (246; 110-430 fmol/mL) day of life, respectively.

CONCLUSIONS

The N-ANP and N-BNP plasma concentrations in healthy neonates showed a marked increase during the first days of age, suggesting that ANP and BNP have physiologic roles in the perinatal circulatory change from fetus to neonate.

Radioimmunometric assay of B-type natriuretic peptide (BNP) in heart transplantation: correlation between BNP determinations and biopsy grading of rejection

The aim of this study was to determine whether elevated brain natriuretic peptide (BNP) levels after heart transplantation are correlated with the severity of rejection by using endomyocardial biopsy (EMB) and echocardiographic parameters indicative of ventricular function of the transplanted heart. This was an observational study of 80 orthotopic heart transplant recipients (11 women and 69 men; mean age 53+/-11 years). BNP determinations were performed within 48 h of endomyocardial biopsy. The echocardiographic study and BNP determination were also performed in a group of healthy volunteers. We found significantly higher BNP mean levels in heart transplant patients than in healthy volunteers (volunteers, 16.7+/-16.2 pg.ml-1; transplant, 213.4+/-268.6 pg.ml-1; P<0.001). Transplant recipients with rejection grades 2, 3 and 4 on EMB had significantly higher BNP levels than those with rejection grades 0 and 1 (higher rejection grade, 162.5+/-168.4 pg.ml-1; lower rejection grade, 292+/-361.8 pg.ml-1; P<0.01). BNP values of patients with good left ventricular function (LVF) were significantly lower than in patients with mildly and moderately impaired LVF and patients with severely impaired LVF (good function, 199.76+/-233.6 pg.ml-1; mildly/moderately impaired LVF, 937+/-644.5 pg.ml-1; severely impaired LVF, 1038+/-491.2 pg.ml-1; P<0.001). It is concluded that BNP plasma levels are elevated in heart transplant patients compared to the normal population. The distribution of BNP levels in heart transplanted patients show a wide range. BNP elevation is greater in patients with higher rejection grades on EMB and greater impairment of left ventricular function.

Major increase in brain natriuretic peptide indicates right ventricular systolic dysfunction in patients with heart failure

This study sought to investigate whether the presence of right ventricular systolic dysfunction with pre-existing left ventricular systolic dysfunction is associated with higher plasma brain natriuretic peptide (BNP) levels, compared with patients with isolated left ventricular dysfunction. Eighty-five patients referred for evaluation of isotopic ventricular function were prospectively included in the study. Left (LVEF) and right (RVEF) ventricular ejection fractions were evaluated by gated blood pool scintigraphy and compared with plasma BNP levels. BNP correlated negatively with LVEF, except in patients with ischaemic heart disease (P=0.09) and in patients with LVEF<40% (P=0.11). In contrast, BNP levels correlated negatively with RVEF for all subgroups. Among patients with RVEF<40%, no significant BNP difference was found between patients with or without additional left ventricular systolic dysfunction (P=0.51). Among patients with LVEF<40%, plasma BNP levels were significantly higher in patients with RVEF<40% than in patients with RVEF>/=40% (P=0.004) whereas age, renal function, clinical findings, ventricular volumes, LVEF or medication were not significantly different. In conclusion, an important increase in BNP levels in patients with left ventricular systolic dysfunction should be considered by cardiologists as an indication of high risk of right ventricular dysfunction and should justify further investigation.

Plasma concentrations of N-terminal pro-brain natriuretic peptide in control children from the neonatal to adolescent period and in children with congestive heart failure

OBJECTIVE

To determine plasma levels of N-terminal pro-brain natriuretic peptide (N-BNP) in control children to establish a normal age-dependent range from the neonatal period to adulthood. In addition, plasma concentrations of N-BNP were measured in children with congestive heart failure (CHF) and correlated with ejection fraction and clinical symptoms of heart failure.

METHODS

For establishing a normal age-dependent range of plasma N-BNP, venous blood samples were taken in 133 control patients from the neonatal period to adulthood (10 days-32 years) and in 31 children with CHF. Plasma N-BNP levels were determined by an enzyme immunoassay. In children (1 month-14 years) with CHF, plasma N-BNP levels were correlated to ejection fraction measured by echocardiography and clinical symptoms of heart failure using the Ross Score.

RESULTS

N-BNP levels in control children, adolescents, and adults did not show a significant age-related difference. In control children, the normal range was established between 150 (10th percentile) and 430 fmol/mL (90th percentile). Mean plasma N-BNP in control children was 311 fmol/mL (range: 74-654 fmol/mL). In 31 children with CHF, the plasma N-BNP levels were significantly higher (mean: 846; range: 219-2718) than in control children. N-BNP levels showed a negative correlation with the ejection fraction (r = -0.53) and a positive correlation with the clinical heart failure score (r = 0.74).

CONCLUSIONS

Plasma N-BNP levels reflect the severity of symptoms of heart failure and the impairment of cardiac function in children with CHF. In the future, determination of plasma N-BNP levels may be used as a helpful adjunct to monitor the effect of various treatments for CHF in children.

Measurement of brain natriuretic peptide in plasma samples and cardiac tissue extracts by means of an immunoradiometric assay method

We evaluated the analytical characteristics and clinical usefulness of a commercial immunoradiometric assay (IRMA) kit for brain natriuretic peptide (BNP). Mean (+/-SD) plasma BNP concentrations measured in 129 normal subjects were 2.9+/-2.7 pmol/l (median 2.2 pmol/l; range 0.1-12.4 pmol/l). The mean (+/- SD) value observed in healthy men (2.1 +/- 2.0 pmol/l, n = 49) was significantly (p=0.0009) different to that found in women (3.4 +/- 2.9 pmol/l, n=80). A positive relationship (R=0.214, p=0.0174) was found between BNP values and age. In 65 patients with cardiac diseases, BNP levels increased with the progression of clinical severity of disease; patients with more severe disease [NYHA functional class III-IV, mean (+/- SD) BNP +/- 254 +/- 408 pmol/l, n=22] showed significantly (p<0.0001) increased values compared to patients with mild symptoms of disease (NYHA functional class I-II, mean (+/- SD) BNP=19.6 +/- 17.2 pmol/l, n=43). Furthermore, in 32 patients with chronic renal failure, greatly increased (p<0.0001) BNP values were found both before (mean +/- SD=88. 1+/- 111.1 pmol/l) and after haemodialysis (mean +/- SD=65.6 +/- 76.7 pmol/l), with a significant reduction after haemodialysis (p=0.0004) compared to pre-haemodialysis. The mean (+/- SD) BNP value found in atrial extracts collected during aorto-coronary bypass operations in 15 patients was 14.5 +/- 51.9 pmol/g of cardiac tissue. Moreover, the mean (+/- SD) tissue levels of BNP in 7 heart transplant recipients were 128.4 +/- 117.2 pmol/g of cardiac tissue in atrium, 68.4 +/- 76.7 pmol/g in ventricle, and 10.9 +/- 8.5 pmol/g in interventricular septum. Finally, BNP values found in cardiac tissues of two subjects collected at autopsy were considerably lower (on average 1/1000) than those observed in cardiac tissues of patients with cardiac diseases. The IRMA method for BNP determination evaluated in this study showed a good degree of sensitivity, precision and practicability. Therefore, this method should be a reliable tool for the measurement of plasma BNP levels for both experimental studies and routine assay.

Significance of raised natriuretic peptides after bicaval and standard cardiac transplantation

BACKGROUND

High levels of plasma atrial natriuretic peptide (ANP) and ventricular natriuretic peptide (BNP) have been identified after standard orthotopic cardiac transplantation. It has been postulated that the high ANP levels are a result of persistent secretion from the large residual atrial mass after transplantation. This study was undertaken to investigate the significance of raised ANP and BNP levels after standard and bicaval orthotopic heart transplantation.

METHODS

Plasma ANP and BNP levels were measured in 40 ambulatory, randomly selected cardiac transplant patients (group A, n = 20 had bicaval transplantation; group B, n = 20 had standard transplantation) and 10 healthy volunteers (group C). Cardiac transplant patients underwent endomyocardial biopsy and hemodynamic evaluation.

RESULTS

Plasma levels of ANP and BNP were elevated in the transplant recipients in comparison with normal volunteers (p = 0.0001 and p < 0.0001, respectively). There was no significant difference in the ANP levels between group A and group B, whereas BNP levels were higher in group B compared with group A (p = 0.03). Linear regression analysis showed that a faster heart rate, high mean pulmonary artery pressure, high pulmonary capillary wedge pressure, and high transpulmonary gradient were associated with higher levels of BNP (p < 0.05). Lower mean systemic pressure was associated with higher levels of ANP (p < 0.05).

CONCLUSIONS

High levels of ANP and BNP are synthesized and secreted by the transplanted denervated human heart regardless of the surgical technique. The level of BNP correlates with ventricular performance and afterload. The bicaval technique seems to be associated with better left ventricular and right ventricular diastolic performance.