B-type natriuretic peptide concentrations to guide treatment of patent ductus arteriosus

Brain natriuretic peptide and N-terminal brain natriuretic peptide for the diagnosis of haemodynamically significant patent ductus arteriosus in preterm neonates

BACKGROUND

Echocardiogram is the reference standard for the diagnosis of haemodynamically significant patent ductus arteriosus (hsPDA) in preterm infants. A simple blood assay for brain natriuretic peptide (BNP) or amino-terminal pro-B-type natriuretic peptide (NT-proBNP) may be useful in the diagnosis and management of hsPDA, but a summary of the diagnostic accuracy has not been reviewed recently.

OBJECTIVES

Primary objective: To determine the diagnostic accuracy of the cardiac biomarkers BNP and NT-proBNP for diagnosis of haemodynamically significant patent ductus arteriosus (hsPDA) in preterm neonates. Our secondary objectives were: to compare the accuracy of BNP and NT-proBNP; and to explore possible sources of heterogeneity among studies evaluating BNP and NT-proBNP, including type of commercial assay, chronological age of the infant at testing, gestational age at birth, whether used to initiate medical or surgical treatment, test threshold, and criteria of the reference standard (type of echocardiographic parameter used for diagnosis, clinical symptoms or physical signs if data were available).

SEARCH METHODS

We searched the following databases in September 2021: MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Web of Science. We also searched clinical trial registries and conference abstracts. We checked references of included studies and conducted cited reference searches of included studies. We did not apply any language or date restrictions to the electronic searches or use methodological filters, so as to maximise sensitivity.

SELECTION CRITERIA

We included prospective or retrospective, cohort or cross-sectional studies, which evaluated BNP or NT-proBNP (index tests) in preterm infants (participants) with suspected hsPDA (target condition) in comparison with echocardiogram (reference standard).

DATA COLLECTION AND ANALYSIS

Two authors independently screened title/abstracts and full-texts, resolving any inclusion disagreements through discussion or with a third reviewer. We extracted data from included studies to create 2 × 2 tables. Two independent assessors performed quality assessment using the Quality Assessment of Diagnostic-Accuracy Studies-2 (QUADAS 2) tool. We excluded studies that did not report data in sufficient detail to construct 2 × 2 tables, and where this information was not available from the primary investigators. We used bivariate and hierarchical summary receiver operating characteristic (HSROC) random-effects models for meta-analysis and generated summary receiver operating characteristic space (ROC) curves. Since both BNP and NTproBNP are continuous variables, sensitivity and specificity were reported at multiple thresholds. We dealt with the threshold effect by reporting summary ROC curves without summary points.

MAIN RESULTS

We included 34 studies: 13 evaluated BNP and 21 evaluated NT-proBNP in the diagnosis of hsPDA. Studies varied by methodological quality, type of commercial assay, thresholds, age at testing, gestational age and whether the assay was used to initiate medical or surgical therapy. We noted some variability in the definition of hsPDA among the included studies. For BNP, the summary curve is reported in the ROC space (13 studies, 768 infants, low-certainty evidence). The estimated specificities from the ROC curve at fixed values of sensitivities at median (83%), lower and upper quartiles (79% and 92%) were 93.6% (95% confidence interval (CI) 77.8 to 98.4), 95.5% (95% CI 83.6 to 98.9) and 81.1% (95% CI 50.6 to 94.7), respectively. Subgroup comparisons revealed differences by type of assay and better diagnostic accuracy at lower threshold cut-offs (< 250 pg/ml compared to ≥ 250 pg/ml), testing at gestational age < 30 weeks and chronological age at testing at one to three days. Data were insufficient for subgroup analysis of whether the BNP testing was indicated for medical or surgical management of PDA. For NT-proBNP, the summary ROC curve is reported in the ROC space (21 studies, 1459 infants, low-certainty evidence). The estimated specificities from the ROC curve at fixed values of sensitivities at median (92%), lower and upper quartiles (85% and 94%) were 83.6% (95% CI 73.3 to 90.5), 90.6% (95% CI 83.8 to 94.7) and 79.4% (95% CI 67.5 to 87.8), respectively. Subgroup analyses by threshold (< 6000 pg/ml and ≥ 6000 pg/ml) did not reveal any differences. Subgroup analysis by mean gestational age (< 30 weeks vs 30 weeks and above) showed better accuracy with < 30 weeks, and chronological age at testing (days one to three vs over three) showed testing at days one to three had better diagnostic accuracy. Data were insufficient for subgroup analysis of whether the NTproBNP testing was indicated for medical or surgical management of PDA. We performed meta-regression for BNP and NT-proBNP using the covariates: assay type, threshold, mean gestational age and chronological age; none of the covariates significantly affected summary sensitivity and specificity.

AUTHORS' CONCLUSIONS

Low-certainty evidence suggests that BNP and NT-proBNP have moderate accuracy in diagnosing hsPDA and may work best as a triage test to select infants for echocardiography. The studies evaluating the diagnostic accuracy of BNP and NT-proBNP for hsPDA varied considerably by assay characteristics (assay kit and threshold) and infant characteristics (gestational and chronological age); hence, generalisability between centres is not possible. We recommend that BNP or NT-proBNP assays be locally validated for specific populations and outcomes, to initiate therapy or follow response to therapy.

Early prediction of spontaneous Patent Ductus Arteriosus (PDA) closure and PDA-associated outcomes: a prospective cohort investigation

BACKGROUND

Patent ductus arteriosus (PDA), the most commonly diagnosed cardiovascular condition in preterm infants, is associated with increased mortality and harmful long-term outcomes (chronic lung disease, neurodevelopmental delay). Although pharmacologic and/or interventional treatments to close PDA likely benefit some infants, widespread routine treatment of all preterm infants with PDA may not improve outcomes. Most PDAs close spontaneously by 44-weeks postmenstrual age; treatment is increasingly controversial, varying markedly between institutions and providers. Because treatment detriments may outweigh benefits, especially in infants destined for early, spontaneous PDA closure, the relevant unanswered clinical question is not whether to treat all preterm infants with PDA, but whom to treat (and when). Clinicians cannot currently predict in the first month which infants are at highest risk for persistent PDA, nor which combination of clinical risk factors, echocardiographic measurements, and biomarkers best predict PDA-associated harm.

METHODS

Prospective cohort of untreated infants with PDA (n=450) will be used to predict spontaneous ductal closure timing. Clinical measures, serum (brain natriuretic peptide, N-terminal pro-brain natriuretic peptide) and urine (neutrophil gelatinase-associated lipocalin, heart-type fatty acid-binding protein) biomarkers, and echocardiographic variables collected during each of first 4 postnatal weeks will be analyzed to identify those associated with long-term impairment. Myocardial deformation imaging and tissue Doppler imaging, innovative echocardiographic techniques, will facilitate quantitative evaluation of myocardial performance. Aim1 will estimate probability of spontaneous PDA closure and predict timing of ductal closure using echocardiographic, biomarker, and clinical predictors. Aim2 will specify which echocardiographic predictors and biomarkers are associated with mortality and respiratory illness severity at 36-weeks postmenstrual age. Aim3 will identify which echocardiographic predictors and biomarkers are associated with 22 to 26-month neurodevelopmental delay. Models will be validated in a separate cohort of infants (n=225) enrolled subsequent to primary study cohort.

DISCUSSION

The current study will make significant contributions to scientific knowledge and effective PDA management. Study results will reduce unnecessary and harmful overtreatment of infants with a high probability of early spontaneous PDA closure and facilitate development of outcomes-focused trials to examine effectiveness of PDA closure in "high-risk" infants most likely to receive benefit.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03782610. Registered 20 December 2018.

Base excess and hematocrit predict response to indomethacin in very low birth weight infants with patent ductus arteriosus

Background

The treatment of patent ductus arteriosus (PDA) in very low birth weight (VLBW) infants remains a challenge. The ability to predict which infants will respond to indomethacin could spare some from the risks of unnecessary medications. Our objective was to determine if indicators of acid-base homeostasis could predict response to indomethacin treatment for ductal closure, and thus help guide treatment decisions.

Methods

We performed a retrospective analysis of medical records of VLBW (< 1500 g) neonates with hemodynamically significant PDA born at our institution between January 2009 and December 2012; all infants included in the study were treated with indomethacin for ductal closure within the first 2 weeks of life. We extracted data for a number of clinical variables including gestational age, birth weight, blood chemistries, surfactant use, hematocrit, and blood gas parameters. Our primary outcome measure was successful closure of PDA following the first round of indomethacin. Using variables that were significant on initial testing, we created multivariable regression models to determine the independent association of selected variables with indomethacin response.

Results

Of the 91 infants included in the study, 62 (68%) responded to the first course of indomethacin with successful ductal closure. Multivariable regression modeling revealed that both base excess and hematocrit were independently associated with indomethacin response; odds of PDA closure increased with increasing base excess (OR [odds ratio]: 1.81; 95% confidence interval [CI]: 1.36–2.60) and increasing hematocrit (OR: 1.21; 95% CI: 1.01–1.45). The optimal cutoff value for base excess was − 4.56, with a sensitivity of 96.8% (95% CI: 89–100) and specificity of 79.3% (95% CI: 60–92); optimal cutoff value for hematocrit was 40, with 69.4% sensitivity (95% CI: 56–80) and 65.5% specificity (95% CI: 46–82).

Conclusions

Base excess and hematocrit may be independent predictors of indomethacin response in VLBW infants with PDA. Low-cost and readily accessible, acid-base indicators such as base excess could help guide treatment decisions.

Electronic supplementary material

The online version of this article (10.1186/s13052-019-0706-y) contains supplementary material, which is available to authorized users.

N-terminal-probrain natriuretic peptide as a biomarker of moderate to severe bronchopulmonary dysplasia in preterm infants: A prospective observational study

OBJECTIVE

N-terminal-probrain natriuretic peptide (NT-proBNP) is a marker of hemodynamically significant patent ductus arteriosus (HsPDA) in preterm infants. In this study, we assessed whether NT-proBNP levels could predict the risk of moderate to severe bronchopulmonary dysplasia (BPD) and/or death.

METHODS

This was an observational prospective study of preterm infants with GA ≤32 weeks. Infants who died within the first 48 h or who had major congenital malformations or incomplete information were excluded. NT-proBNP was determined at 48-96 h of life and at 5-10 days of life. The predictive capacity of NT-proBNP for the combined outcome of BPD and/or death was evaluated using receiver operator characteristic (ROC) curves and multivariate regression.

RESULTS

Of the 125 eligible patients, 110 completed the analysis. Twenty-eight developed BPD (n = 15) and/or died (n = 13). Infants who developed BPD and/or died had higher NT-proBNP levels ​​at 48-96 h (26,848 ng/L, interquartile range [IQR] 7818-60,684 vs 3008 ng/L, IQR 1425-9876) and at 5-10 days (8849 ng/L, IQR 3796-19,526 vs 1427 ng/L, IQR 907-2889). The NT-proBNP levels at 5-10 days, but not at 48-96 h, were independently associated with BPD and/or death after adjustments for HsPDA and other confounders (OR = 3.36; 95%CI: 1.52-7.4, P = 0.006). For the prediction of this result, a cutoff of 3348 ng/L had a sensitivity and specificity of 82% and 83%, respectively (area under the curve [AUC] = 0.87; 95%CI: 0.79-0.95).

CONCLUSION

The NT-proBNP levels at 5-10 days of life may identify preterm infants with an HsPDA who are at high risk of BPD or death and may be useful for individualized preventive and therapeutic strategies.

Early NT-proBNP levels as a screening tool for the detection of hemodynamically significant patent ductus arteriosus during the first week of life in very low birth weight infants

OBJECTIVE

To assess whether early NT-ProBNP can identify the need for echocardiographic assessment of hemodynamically significant patent ductus arteriosus (HsPDA) in preterm infants.

STUDY DESIGN

Prospective observational study of infants with a gestational age ≤32 weeks. Echocardiographic assessment and NT-proBNP measurement were performed at 48-96 h. ROC curves were generated to assess optimal cutoffs to detect HsPDA and predict the need for treatment.

RESULTS

Eighty-five patients were included. HsPDA was present in 28 infants (37.6%), and 22 (25.8%) received treatment. The optimal NT-proBNP cutoff for the detection of HsPDA was 5099 pg/mL (sensitivity 94%, specificity 82%, area under the curve 0.941, P < 0.001). Only 1 child with NT-proBNP levels <5099 pg/mL was ultimately treated for PDA. NT-proBNP screening could have avoided 45 of 85 routine echocardiograms (53%).

CONCLUSION

NT-proBNP screening at 48-96 h of life may identify preterm infants at low risk for HsPDA, improving PDA management.

Individualized ibuprofen treatment using serial B-type natriuretic peptide measurement for symptomatic patent ductus arteriosus in very preterm infants

PURPOSE

Plasma level of B-type natriuretic peptide (BNP), an emerging, sensitive, and specific biomarker of hemodynamically significant patent ductus arteriosus (PDA), rapidly decreases in infants receiving cyclooxygenase inhibitors for ductal closure. We investigated the usefulness of serial BNP measurement as a guide for individual identification of early constrictive responses to ibuprofen in preterm infants with symptomatic PDA (sPDA).

METHODS

Before March 2010, the standard course of pharmacological treatment was initiated with indomethacin (or ibuprofen) and routinely followed by 2 additional doses at intervals of 24 hours. After April 2010, individualized pharmacological treatment was used, starting with the first dose of ibuprofen and withholding additional ibuprofen doses if the BNP concentration was <600 pg/mL and clinical symptoms of PDA improved.

RESULTS

The BNP-guided group received significantly fewer doses of ibuprofen than the standard group did during the first course of treatment and the entire study period. The need for further doses of cyclooxygenase inhibitors and for surgical ligation was not significantly different between the 2 groups. No significant differences were seen in clinical outcomes and/or complications related to sPDA and/or pharmacological treatment.

CONCLUSION

Individualized BNP-guided pharmacological treatment may be used clinically to avoid unnecessary doses of cyclooxygenase inhibitors without increasing the ductal closure failure and the short-term morbidity related to sPDA.

Cardiac biomarkers and haemodynamically significant patent ductus arteriosus in preterm infants

Accurately defining haemodynamically significant patent ductus arteriosus (PDA) in preterm infants who are at risk of PDA related morbidities are active areas of neonatal research. Natriuretic peptides are cardiac hormones that respond to volume and pressure loading, with elevated plasma levels found in infants with PDA. In the preterm neonatal setting, studies to date have predominantly investigated the ability of these biomarkers to discriminate between infants with and without a PDA at various postnatal ages. Their clinical utility has therefore been exclusively evaluated as a method of triaging cases of suspected hsPDA to decrease the need for echocardiograms, and to monitor treatment response. Biomarkers are yet to be robustly investigated for their ability to predict important PDA associated morbidities. In this review, we examine the most recent literature to date on the use of biomarkers in the management of PDA.

Cardiac biomarkers in pediatric heart disease: A state of art review

Every year there are more than 11000 hospitalizations related to heart failure in children resulting in significant morbidity and mortality. Over the last two decades, our understanding, diagnosis and management of pediatric heart failure is evolving but our ability to prognosticate outcomes in pediatric heart acute heart failure is extremely limited due to lack of data. In adult heart failure patients, the role of cardiac biomarkers has exponentially increased over the last two decades. Current guidelines for management of heart failure emphasize the role of cardiac biomarkers in diagnosis, management and prognostication of heart failure. It is also noteworthy that these biomarkers reflect important biological processes that also open up the possibility of therapeutic targets. There is however, a significant gap present in the pediatric population with regards to biomarkers in pediatric heart failure. Here, we seek to review available data regarding cardiac biomarkers in the pediatric population and also explore some of the emerging biomarkers from adult literature that may be pertinent to pediatric heart failure.

Circulatory Management Focusing on Preventing Intraventricular Hemorrhage and Pulmonary Hemorrhage in Preterm Infants

The goal of modern neonatal care of extremely preterm infants is to reduce mortality and long-term neurological impairments. Preterm infants frequently experience cerebral intraventricular or pulmonary hemorrhage, which usually occurs within 72 hours after birth and can lead to long-term neurological sequelae and mortality. These serious hemorrhagic complications are closely related to perinatal hemodynamic changes, including an increase in the afterload on the left ventricle of the heart after the infant is separated from the placenta, and an increased preload from a left-to-right shunt caused by a hemodynamically significant patent ductus arteriosus (PDA). The left ventricle of a preterm myocardium has limited ability to respond to such an increase in afterload and preload, and this can result in cardiac dysfunction and hemodynamic deterioration. We suggest that delayed umbilical cord clamping or umbilical cord milking to maintain optimal blood pressure and systemic blood flow (SBF), careful assessment to keep the afterload at an acceptable level, and a strategy of early targeted treatment of significant PDA to improve perfusion during this critical time period may reduce or prevent these serious complications in preterm infants.

Pediatric Pulmonary Hypertension: Guidelines From the American Heart Association and American Thoracic Society

Pulmonary hypertension is associated with diverse cardiac, pulmonary, and systemic diseases in neonates, infants, and older children and contributes to significant morbidity and mortality. However, current approaches to caring for pediatric patients with pulmonary hypertension have been limited by the lack of consensus guidelines from experts in the field. In a joint effort from the American Heart Association and American Thoracic Society, a panel of experienced clinicians and clinician-scientists was assembled to review the current literature and to make recommendations on the diagnosis, evaluation, and treatment of pediatric pulmonary hypertension. This publication presents the results of extensive literature reviews, discussions, and formal scoring of recommendations for the care of children with pulmonary hypertension.

Biomarkers in pediatric heart disease

A biomarker is a characteristic that can be used as an indicator of a biological state. A biomarker can be a clinical observation, laboratory test or an imaging parameter. In this review, we discuss the use of biomarkers in differentiating cardiac from noncardiac disease; predicting the prognosis of patients with heart failure, pulmonary hypertension and dilated cardiomyopathy; diagnosing subclinical cardiac involvement in muscular dystrophy and postchemotherapy cancer patients; detecting acute rejection following heart transplantation; diagnosing Kawasaki disease; aiding the management of postoperative cardiac patients; and managing both common (tetralogy of Fallot) and complex (single-ventricle physiology) congenital heart diseases.

B-type and N-terminal pro-B-type natriuretic peptides are equally useful in assessing patent ductus arteriosus in very preterm infants

AIM

B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NTproBNP) have been shown to correlate with the size of the patent ductus arteriosus (PDA) in preterm infants. We investigated whether BNP or NTproBNP was more closely correlated with PDA size.

METHODS

This prospective observational study included preterm infants born <32 weeks' gestation who had an echocardiogram performed within the first four days of life. Blood samples were taken simultaneously for BNP and NTproBNP measurements prior to echocardiographic examination.

RESULTS

Of the 60 infants recruited, 58 had complete data sets. The cohort's mean and standard deviation (SD) gestational age was 27(+3) (2(+2)) weeks, the mean (SD) birthweight was 1032 (315) grams, and 46 (79.3%) infants had a PDA with a mean (SD) diameter of 3.2 (0.9) mm. Median and interquartile range (IQR) BNP levels were 486.5 (219-1316) pg/mL for infants with a PDA and 190 (95.5-514.5) pg/mL for infants without a PDA. Median (IQR) NTproBNP levels were 10 858.5 (6319-42 108) pg/mL for infants with a PDA and 7488 (3363-14 227.5) pg/mL for infants without a PDA. Both BNP (R = 0.35, p = 0.0066) and NTproBNP (R = 0.31, p = 0.018) were significantly correlated with PDA size.

CONCLUSION

BNP and NTproBNP are similarly useful for assessing PDA size in preterm infants.

Diagnosing significant PDA using natriuretic peptides in preterm neonates: a systematic review

BACKGROUND AND OBJECTIVES

Echocardiogram is the gold standard for the diagnosis of hemodynamically significant patent ductus arteriosus (hsPDA) in preterm neonates. A simple blood assay for brain natriuretic peptide (BNP) or amino-terminal pro-B-type natriuretic peptide (NT-proBNP) may be useful in the diagnosis and management of hsPDA. Our objectives were to determine the diagnostic accuracy of BNP and NT-proBNP for hsPDA in preterm neonates and to explore heterogeneity by analyzing subgroups.

METHODS

The systematic review was performed as recommended by the Cochrane Diagnostic Test Accuracy Working Group. Electronic databases, conference abstracts, and cross-references were searched. We included studies that evaluated BNP or NT-proBNP (index test) in preterm neonates with suspected hsPDA (participants) in comparison with echocardiogram (reference standard). A bivariate random effects model was used for meta-analysis, and summary receiver operating characteristic curves were generated.

RESULTS

Ten BNP and 11 NT-proBNP studies were included. Studies varied by methodological quality, type of commercial assay, thresholds, age at testing, gestational age, and whether the assay was used to initiate medical or surgical therapy. Sensitivity and specificity for BNP at summary point were 88% and 92%, respectively, and for NT-proBNP they were 90% and 84%, respectively.

CONCLUSIONS

The studies evaluating the diagnostic accuracy of BNP and NT-proBNP for hsPDA varied widely by assay characteristics (assay kit and threshold) and patient characteristics (gestational and chronological age); therefore, generalizability between centers is not possible. We recommend that BNP or NT-proBNP assays be locally validated for specific patient population and outcomes, to initiate therapy or follow response to therapy.

Cerebral tissue oxygen saturation is associated with N-terminal probrain natriuretic peptide in preterm infants on their first day of life

AIM

This prospective observational study investigated if N-terminal probrain natriuretic peptide (NT-proBNP), a cardiac biomarker, correlated with cerebral tissue oxygen saturation (crSO2) in preterm infants on their first day of life.

METHODS

Using near infrared spectroscopy (NIRS), crSO2 was measured on the right forehead of preterm infants for 24 h. We also recorded arterial oxygen saturation (SpO2 ) and calculated fractional tissue oxygen extraction (cFTOE) values. At the end of the NIRS measurement, blood was taken to analyse NT-proBNP. Mean values for the 24-h period were calculated for crSO2 , cFTOE, SpO2 and these values were correlated to NT-proBNP. An echocardiography was performed in all infants during the measurement period.

RESULTS

We analysed 35 preterm neonates (33 ± 2 weeks, 1965 ± 523 g). NIRS measurements started at 3 ± 1 h and blood samples were taken at 24 ± 5 h postnatal. Echocardiography showed an open ductus arteriosus in all infants. Mean NT-proBNP was 4978 ± 3566 pg/mL, crSO2 was 76 ± 8%, and cFTOE was 0.20 ± 0.08. NT-proBNP correlated negatively with crSO2 (r = -0.75; p ≤ 0.001) and positively with cFTOE (r = 0.731; p ≤ 0.001).

CONCLUSION

These results emphasise that crSO2 is influenced by cardiac function, in addition to oxygen consumption, arterial oxygen saturation and vascular resistance, and this can be measured by NT-proBNP.

Serial N-terminal pro-brain natriuretic peptide measurement as a predictor of significant patent ductus arteriosus in preterm infants beyond the first week of life

The aim of the study was to assess the role of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration as a predictor of patent ductus arteriosus (PDA) in very low birth weight infants beyond the first week of life. This was a prospective observational study; newborns with a birth weight < 1500 g were eligible for enrolment. Enrolled infants were screened by echocardiography on day seven of life for the presence of a PDA. This was paired with a blood sample for NT-proBNP level. Echocardiography and NT-proBNP levels were repeated at weekly intervals. The primary outcome was correlation between PDA and NT-proBNP level and between measurements of PDA significance and NT-proBNP. Sixty-nine neonates were enrolled following parental consent. The mean birth weight was 1119 ± 257 g and mean gestational age was 28.6 ± 2.6 weeks. Median NT-proBNP level on day seven was 11469 ng/l in infants with a PDA vs. 898 ng/l in infants without a PDA (p < 0.0001). There was a statistically significant correlation between PDA diameter and NT-proBNP level on day seven, day 14 and day 21.

CONCLUSION

NT-proBNP concentration is significantly increased in infants with a PDA and correlates well with PDA diameter in the first three weeks of life.

The relationship between BNP, NTproBNP and echocardiographic measurements of systemic blood flow in very preterm infants

OBJECTIVE

Preterm infants are at risk of circulatory compromise following birth. Functional neonatal echocardiography including superior vena cava (SVC) flow is increasingly used in neonatal medicine, and low SVC flow has been associated with adverse outcome. However, echocardiography is not readily available in many neonatal units and B-type natriuretic peptides (BNPs) may be useful in guiding further cardiovascular assessment. This study investigated the relationship between BNP, N-terminal pro-BNP (NTproBNP) and echocardiographic measurements of systemic blood flow in very preterm infants.

STUDY DESIGN

This is a prospective observational study. Sixty preterm infants <32 weeks gestational age were included after the treating neonatologist had requested an echocardiogram for suspected cardiovascular compromise. BNP and NTproBNP were sampled just before the echocardiogram. Echocardiographic examination included fractional shortening (FS), SVC flow, left and right ventricular output (LVO and RVO). Statistical analysis included simple linear regression of BNP and NTproBNP with echocardiographic measures and multiple regression including potential confounding variables.

RESULT

Mean (s.d.) gestational age at birth was 27(5) (2(1)) weeks, median (interquartile range, IQR) birth weight was 995 (845 to 1175) grams. Neither BNP nor NTproBNP correlated with SVC flow (BNP 95% confidence interval (CI) -0.0014 to 0.013, P=0.12; NTproBNP 95% CI -0.00069 to 0.01, P=0.085); LVO (BNP 95% CI -0.00078 to 0.0072, P=0.11; NTproBNP 95% CI -0.0034 to 0.0034, P=0.99); RVO (BNP 95% CI -0.00066 to 0.0058, P=0.12; NTproBNP 95% CI -0.0012 to 0.0044, P=0.25); or FS (BNP 95% CI -0.053 to 0.051, P=0.96; NTproBNP 95% CI -0.061 to 0.019, P=0.3). Multivariate linear regression did not significantly alter results.

CONCLUSION

In this cohort of very preterm infants, BNP and NTproBNP did not correlate with echocardiographic measurements of systemic blood flow within the first 72 h of life.

Patent ductus arteriosus in preterm infants: do we have the right answers?

Patent ductus arteriosus (PDA) is a common clinical condition in preterm infants. Preterm newborns with PDA are at greater risk for several morbidities, including higher rates of bronchopulmonary dysplasia (BPD), decreased perfusion of vital organs, and mortality. Therefore, cyclooxygenase (COX) inhibitors and surgical interventions for ligation of PDA are widely used. However, these interventions were reported to be associated with side effects. In the absence of clear restricted rules for application of these interventions, different strategies are adopted by neonatologists. Three different approaches have been investigated including prophylactic treatment shortly after birth irrespective of the state of PDA, presymptomatic treatment using echocardiography at variable postnatal ages to select infants for treatment prior to the duct becoming clinically significant, and symptomatic treatment once PDA becomes clinically apparent or hemodynamically significant. Future appropriately designed randomized controlled trials (RCTs) to refine selection of patients for medical and surgical treatments should be conducted. Waiting for new evidence, it seems wise to employ available clinical and echocardiographic parameters of a hemodynamically significant (HS) PDA to select patients who are candidates for medical treatment. Surgical ligation of PDA could be used as a back-up tool for those patients who failed medical treatment and continued to have hemodynamic compromise.

Management of patent ductus arteriosus in preterm infants--where do we stand?

Patent ductus arteriosus (PDA) in preterm infants is a controversial topic in the management of preterm neonates. There are no generally accepted guidelines for diagnosis, treatment, and follow-up of PDA, and few publications have covered the whole topic or have been conclusively summarized to give a proper direction for the treating physician. Major issues remain to be clarified, both with respect to diagnosis and treatment. The definition of hemodynamic significance varies because of different use of echocardiographic criteria and uncertainty about the role of biomarkers. The detailed risks and benefits of available treatment alternatives are still under investigation. There has been a general shift in the management of PDA in preterm neonates from the "aggressive approach" to a more "conservative approach," but the effects of this strategy on morbidity in a longer time perspective are not fully known. An individualized therapeutic strategy with special emphasis on identification of hemodynamically significance seems to be the way forward. In this review we put forward the scientific background in favor of a seemingly growing body of evidence against active treatment, but we raise caution against shying away from all forms of treatment or instituting them too late. Finally, we try to integrate the current knowledge into suggestions for the management of PDA in premature infants.

NT-proBNP Levels Improve the Ability of Predicting a Hemodynamically Significant Patent Ductus Arteriosus in Very Low-Birth-Weight Infants

Purpose:

A hemodynamically significant Patent ductus arteriosus (HsPDA) in premature infants is known to be associated with significant morbidity. Recently brain natriuretic peptides and superior mesenteric artery (SMA)-resistive indices have been used to effectively diagnose HsPDA.

Objective:

To assess the sensitivity and specificity of N-terminal proBNP (NT-proBNP) in predicting an HsPDA diagnosed by clinical and echocardiographic criteria including pulsatility index (PI) of SMA.

Materials and Methods:

All preterm neonates <1500 g were evaluated with echocardiograms and NT-proBNP levels on the 3^rd to 5^th day of life and then every week until the echo showed either a closed PDA or non-HsPDA.

Results:

Sixty-nine babies with mean gestational age of 27 weeks were included in the study. NT-proBNP levels were significantly higher in the HsPDA group (n=22) with a mean±SEM of 24420±3190 compared to 3072±332 in the non-HsPDA group (n=47) (P<0.001). NT-pro BNP level of 5900 pg/ml had 96% sensitivity and 90% specificity of predicting HsPDA.

Conclusions:

With frequently changing hemodynamics in low-birth weight infants, including NT-proBNP and PI of SMA improve the ability of assessing the effects of a HsPDA and will help timing of intervention.

B-type natriuretic peptide for assessment of haemodynamically significant patent ductus arteriosus in premature infants

Aim: Haemodynamically significant patent ductus arteriosus (hsPDA) is frequently observed in premature infants. This study was conducted to explore whether the blood BNP can be a valuable biomarker to assess the necessity of treatment for hsPDA in premature infants.

Methods: Serial measurements of the blood BNP were performed during the first 5 days of life in premature infants with hsPDA (Group I) and those without hsPDA (Group N). The definition of the hsPDA was the PDA requiring treatment, such as indomethacin administration and/or surgical ligation.

Results: Forty-six subjects were enrolled. Compared with Group N, Group I showed significantly higher level of blood BNP at postnatal 24–96 h and demonstrated the peak value at postnatal 24–48 h. With the ROC curve using the data at postnatal 24–48 h in Group I, we deduced the predictive value of 250 pg/mL of blood BNP for indomethacin treatment. Similarly, with the ROC curve using the maximal value of blood BNP within the first 5 days of life, the predictive value of 2000 pg/mL for surgical ligation was deduced.

Conclusions: Blood BNP during early postnatal period can be a useful biomarker to assess the necessity of treatment for hsPDA in premature infants.

Usefulness of serum brain natriuretic peptide to predict adverse events in patients with the Eisenmenger syndrome

The aim of this study was to evaluate the prognostic value of brain natriuretic peptide (BNP) in outpatients with the Eisenmenger syndrome (ES). BNP is often elevated in patients with cyanotic congenital heart disease. The clinical utility of BNP in patients with cyanotic congenital heart disease and the ES has not been clearly delineated. Records of adults with ES who had undergone serum BNP measurement were reviewed. The primary end point was death or heart failure admission. Fifty-three patients were included, with 15 patients (28%) meeting the primary end point (death in 7, heart failure hospitalization in 8). Mean and median baseline BNP in patients meeting the primary end point were 322 ± 346 and 179 pg/ml, compared to 100 ± 157 and 41 pg/ml in those not meeting the primary end point (p = 0.0029). A Cox proportional-hazards model using baseline BNP between the 2 groups yielded a hazard ratio of 1.84 (95% confidence interval [CI] 1.19 to 2.85, p = 0.006). The relative risk for baseline BNP level >140 pg/ml was 4.62 (95% CI 1.80 to 11.3, p = 0.008). Patients who met the primary end point increased their BNP levels by 42.5 pg/ml per year (95% CI 12.09 to 72.95, p = 0.006) compared to 7.2 pg/ml per year (95% CI 2.01 to 12.47, p = 0.007) in patients who did not meet the primary end point. In conclusion, elevated BNP levels are predictive of death or heart failure admission in patients with the ES. A serum BNP level >140 pg/ml is a useful tool in identifying high-risk patients.

Use of cardiac biomarkers in neonatology

Cardiac biomarkers are used to identify cardiac disease in term and preterm infants. This review discusses the roles of natriuretic peptides and cardiac troponins. Natriuretic peptide levels are elevated during atrial strain (atrial natriuretic peptide (ANP)) or ventricular strain (B-type natriuretic peptide (BNP)). These markers correspond well with cardiac function and can be used to identify cardiac disease. Cardiac troponins are used to assess cardiomyocyte compromise. Affected cardiomyocytes release troponin into the bloodstream, resulting in elevated levels of cardiac troponin. Cardiac biomarkers are being increasingly incorporated into clinical trials as indicators of myocardial strain. Furthermore, cardiac biomarkers can possibly be used to guide therapy and improve outcome. Natriuretic peptides and cardiac troponins are potential tools in the diagnosis and treatment of neonatal disease that is complicated by circulatory compromise. However, clear reference ranges need to be set and validation needs to be carried out in a population of interest.

Managing the patent ductus arteriosus in the premature neonate: a new look at what we thought we knew

Over recent years, the clinical approach to patency of the ductus arteriosus in the premature neonate has been the subject of intensive reevaluation. What had once been considered inherently obvious is no longer to be taken for granted. In this review we will focus on some of the controversies surrounding various aspects of the pharmacologic treatment regimens for patent ductus arteriosus closure. The pros and cons of prophylactic vs therapeutic indomethacin, of early vs late therapy, of high- vs low-dose indomethacin, of single vs multiple courses of treatment, and of ibuprofen vs indomethacin will be considered. In addition, the possibility that patency of the ductus arteriosus is merely a physiological manifestation of extreme prematurity, and thus does not necessarily need to be therapeutically closed, has become a viable approach in some cases. As such, we will examine echocardiographic and biochemical criteria aimed at determining the clinical and hemodynamic significance of ductal shunting, and thereby of the need to treat. Finally, we speculate on potential therapeutic directions for the future, including individualized treatment regimens and multidrug treatment cocktails for those who fail initial monodrug therapy.

Diagnosis of the preterm patent ductus arteriosus: clinical signs, biomarkers, or ultrasound?

The current uncertainty in relation to treatment of the preterm patent ductus arteriosus reflects limitations to our understanding of the pathophysiology of ductal shunting, most particularly which ducts matter to which babies and when they matter. Doppler ultrasound offers a pragmatic tool with which to assess ductal patency and shunt significance and to allow prediction of spontaneous and therapeutic closure. Biomarkers, such as B-type natriuretic peptide, and clinical signs may have a diagnostic role where ultrasound is not available and also possibly as an adjunct to echocardiography in determining the pathophysiological impact of a ductal shunt in an individual baby.

B-type natriuretic Peptide assay for the diagnosis and prognosis of patent ductus arteriosus in preterm infants

BACKGROUND AND OBJECTIVES

Patent ductus arteriosus (PDA) is a significant cause of morbidity and mortality in preterm infants. Measurement of plasma B-type natriuretic peptide (BNP) has been reported to be a useful bedside screening tool for the presence of hemodynamically significant PDA (hsPDA) in neonates. This study was conducted to investigate the usefulness of a BNP assay as a biochemical marker for the diagnosis of hsPDA and predictive biomarker of the response to indomethacin in preterm infants.

SUBJECTS AND METHODS

Preterm infants born at <37 weeks' gestational age were prospectively enrolled within 24 hours of birth. Plasma BNP levels were measured on days 1, 4, and 7. Significant PDA was diagnosed by large ductal flow with left to right shunt on color Doppler echocardiography, along with clinical features of PDA. Following that, hsPDA was treated with indomethacin.

RESULTS

A total of 28 preterm infants were prospectively enrolled in this study. Seven infants with PDA had higher on day 4 plasma BNP values (median 654.68 pg/mL; range 428.29-1280.00) compared to the control group (median 124.52 pg/mL; range 37.21-290.49). The area under the receiver operator characteristic curve for the detection of hsPDA was high: 0.998 (95% confidence interval: 0.995-1.002). The cutoff of BNP concentration for the diagnosis of hsPDA was determined to be 412 pg/mL (sensitivity: 100%; specificity: 95%).

CONCLUSION

B-type natriuretic peptide can be a useful biomarker for the screening and diagnosis of PDA in preterm infants. Serial BNP measurements are valuable for assessing the clinical course and indomethacin responsiveness of PDA.

Urinary NT-proBNP, NGAL, and H-FABP may predict hemodynamic relevance of patent ductus arteriosus in very low birth weight infants

BACKGROUND

Hemodynamically significant patent ductus arteriosus (hsPDA) is the most common functional cardiovascular disease in preterm infants. The necessity to treat hsPDA can neither be derived solely from clinical nor from echocardiographic criteria.

OBJECTIVE

The aim of this study was to establish non-invasive parameters which can differentiate hsPDA from non-hsPDA.

METHODS

Urinary protein levels of NT-proBNP, NGAL, and H-FABP were measured and correlated with the necessity of therapy for PDA. In 37 neonates (<1,500 g), urinary protein concentrations were tested on days 0, 2, and 7 by ELISA methodology. Of 37 infants, 12 required therapeutic interventions according to current treatment standards.

RESULTS

Infants receiving an intervention for PDA showed significantly higher levels of pro-BNP, NGAL, and H-FABP at all time points except for NT-proBNP on day 0. Infants requiring a second or third course of ibuprofen had significantly higher levels of H-FABP and NGAL. In all samples, the concentration of the three proteins correlated positively with each other.

CONCLUSIONS

The present study shows that measurement of urinary proteins is a powerful and non-invasive method to quantify the effect of PDA on systemic perfusion in preterm infants. Furthermore, NGAL and H-FABP may be used to indicate the necessity of pharmacological or surgical treatment of PDA.

Early NT-proBNP is able to predict spontaneous closure of patent ductus arteriosus in preterm neonates, but not the need of its treatment

The objective of this study was to establish the potential utility of N-terminal pro-brain natriuretic peptide (NT-proBNP) in the management of patent ductus arteriosus (PDA). This was a monocentric prospective blind study that was conducted in a referral neonatal intensive care unit. The patients were very low-birth-weight/gestational-age neonates. Babies with cardiac congenital anomaly other than PDA, life-threatening congenital malformation, severe asphyxia at birth, persistent pulmonary hypertension, and death within the first week of life were excluded. Plasma NT-proBNP concentrations were determined on days 2, 4, and 7 of life. Echocardiography was performed on days 4 and 7. Results were blinded to clinicians. Only echographic results were available upon request. Thirty-one infants were included. NT-proBNP levels were significantly correlated to ductal size and to left atrial-to-aortic diameter ratio. The median NT-proBNP on both days 2 and 4 was significantly higher in neonates with later treated or persistent PDA. A level above 10.000 pg/mL at 48 h of age yielded a 100% positive and a 87% negative predictive value to exclude spontaneous ductal closure. However, no NT-proBNP threshold could predict which PDA would be judged necessary to treat. It was concluded that early low NT-proBNP values can be used as a reliable independent marker to predict spontaneous ductal closure in preterm neonates. Yet, high NT-proBNP levels should not be used to guide the decision to treat PDA, the risk being of treating many bystanding PDAs.

Patent ductus arteriosus: patho-physiology, hemodynamic effects and clinical complications

During fetal life, patent arterial duct diverts placental oxygenated blood from the pulmonary artery into the aorta by-passing lungs. After birth, decrease of prostacyclins and prostaglandins concentration usually causes arterial duct closure. This process may be delayed, or may even completely fail in preterm infants with arterial duct still remaining patent. If that happens, blood flow by-pass of the systemic circulation through the arterial duct results in pulmonary overflow and systemic hypoperfusion. When pulmonary flow is 50% higher than systemic flow, a hemodynamic "paradox" results, with an increase of left ventricular output without a subsequent increase of systemic output. Cardiac overload support neuro-humoral effects (activation of sympathetic nervous system and renin-angiotensin system) that finally promote heart failure. Moreover, increased pulmonary blood flow can cause vascular congestion and pulmonary edema. However, the most dangerous effect is cerebral under-perfusion due to diastolic reverse-flow and resulting in cerebral hypoxia. At last, blood flow decreases through the abdominal aorta, reducing perfusion of liver, gut and kidneys and may cause hepatic failure, renal insufficiency and necrotizing enterocolitis. Conclusions Large patent arterial duct may cause life-threatening multi-organ effects. In pre-term infant early diagnosis and timely effective treatment are cornerstones in the prevention of cerebral damage and long-term multi-organ failure.

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.

B-type natriuretic peptide predicts responses to indomethacin in premature neonates with patent ductus arteriosus

OBJECTIVES

To determine whether B-type natriuretic peptide (BNP) predicts indomethacin responsiveness in premature neonates with patent ductus arteriosus (PDA).

STUDY DESIGN

Premature neonates receiving indomethacin for an echocardiograhically large (diameter>1.5 mm) and clinically significant PDA were prospectively studied. All neonates underwent paired echocardiography and BNP measurements at baseline and 24 hours after each dose of indomethacin. After treatment, neonates who responded (with closed or insignificant PDA) and neonates who did not respond (with persistent significant PDA requiring surgical ligation) were compared.

RESULTS

Thirty-one premature neonates (mean gestational age, 30 weeks) underwent 119 paired echocardiography and BNP determinations. Mean BNP levels (1286+/-986 pg/mL) associated with significant PDA (n=96) were higher than those associated with closed or insignificant PDA (n=23; 118+/-124 pg/mL; P<.001). Twenty-three neonates responded and 8 neonates did not respond to indomethacin. Mean baseline BNP levels were higher in neonates who were non-responders (2234+/-991 pg/mL) than neonates who were responders (983+/-814 pg/mL; P=.001). A baseline BNP level>1805 pg/mL had a sensitivity rate of 88% and a specificity rate of 87% for predicting indomethacin non-responsiveness (P=.003).

CONCLUSIONS

High baseline BNP levels predict poor responses to indomethacin and the need for surgery in premature neonates with PDA.

Patent ductus arteriosus of the preterm infant

A persistently patent ductus arteriosus (PDA) in preterm infants can have significant clinical consequences, particularly during the recovery period from respiratory distress syndrome. With improvement of ventilation and oxygenation, the pulmonary vascular resistance decreases early and rapidly, especially in very immature infants with extremely low birth weight (<1000 g). Subsequently, the left-to-right shunt through the ductus arteriosus (DA) is augmented, thereby increasing pulmonary blood flow, which leads to pulmonary edema and overall worsening of cardiopulmonary status. Prolonged ventilation, with the potential risks of volutrauma, barotrauma, and hyperoxygenation, is strongly associated with the development and severity of bronchopulmonary dysplasia/chronic lung disease. Substantial left-to-right shunting through the ductus may also increase the risk of intraventricular hemorrhage, necrotizing enterocolitis, and death. Postnatal ductal closure is regulated by exposure to oxygen and vasodilators; the ensuing vascular responses, mediated by potassium channels, voltage-gated calcium channels, mitochondrial-derived reactive oxygen species, and endothelin 1, depend on gestational age. Platelets are recruited to the luminal aspect of the DA during closure and probably promote thrombotic sealing of the constricted DA. Currently, it is unclear whether and when a conservative, pharmacologic, or surgical approach for PDA closure may be advantageous. Furthermore, it is unknown if prophylactic and/or symptomatic PDA therapy will cause substantive improvements in outcome. In this article we review the mechanisms underlying DA closure, risk factors and comorbidities of significant DA shunting, and current clinical evidence and areas of uncertainty in the diagnosis and treatment of PDA of the preterm infant.

Early N-terminal pro-brain natriuretic peptide measurements predict clinically significant ductus arteriosus in preterm infants

We report a blinded, prospective study of the diagnostic utility of N-terminal pro-brain natriuretic peptide (NTproBNP) measurements for predicting clinically significant patent ductus arteriosus (PDA) and assessing closure.

METHODS

Plasma NTproBNP was measured during the first week in 100 preterm babies (mean gestation 28.8 +/- 2.9 weeks; mean birth weight 1224 +/- 512 g). Echocardiography was performed between days 5 and 7 by operators, blinded to NTproBNP concentration.

RESULTS

NTproBNP peaked on days 2 and 3, declined by day 7. Twenty babies, later treated for PDA, had significantly higher NTproBNP levels throughout. Areas under receiver operating characteristic (ROC) curves were 0.896, 0.897 and 0.931 on days 2, 3 and 7, respectively (p < 0.0001). A concentration > 2850 pmol/L had diagnostic sensitivity of 90% and specificity of 89% (95% CI: 68, 99; likelihood ratio 8.10). Ductal closure was associated with a fall in mean NTproBNP from 3003 to 839 pmol/L (p < 0.001).

CONCLUSION

N-terminal pro B-type brain natriuretic peptide (NTproBNP) concentrations peaked and then declined in the first week but remained higher in preterm babies whose PDA required treatment. NTproBNP on day 3 predicted whether a neonatal physician blinded to results would treat a PDA. Fall in plasma NTproBNP indicated closure.