Patent ductus arteriosus in the preterm infant: new insights into pathogenesis and clinical management

Serial Doppler velocimetry of mesenteric and portal flow in very-low-birth-weight preterm neonates with and without patent ductus arteriosus

BACKGROUND

Very-low-birth-weight (VLBW) preterm neonates are vulnerable to patent ductus arteriosus (PDA), which might be related to high-resistance flow in the superior mesenteric artery (SMA), with decreased diastolic flow in situations of marked intestinal hypoperfusion. No previous studies have evaluated the portal vein and superior mesenteric vein (SMV) parameters to assess the PDA hemodynamic repercussions.

OBJECTIVE

To assess mesenteric and portal flow in VLBW preterm neonates with or without PDA using serial Doppler ultrasonography (US).

MATERIALS AND METHODS

We conducted a prospective longitudinal study on 61 VLBW preterm neonates submitted to 161 Doppler US exams, from 2 days to 20 days of age.

RESULTS

All infants exhibited a progressive daily increase in the mean of the SMA diameter and systolic velocity, the portal vein diameter, the peak velocity, the mean velocity and the flow volume and of SMV diameter (P<0.05). The incidence of PDA was 37.7% (n=23) and infants with the disease revealed a smaller diameter, greater systolic velocity, lower diastolic velocity, and higher resistivity and pulsatility indices on SMA compared to those without PDA (P<0.05). Additionally, 47.8% (n=11) of infants with PDA exhibited absent or reversed end-diastolic flow in the SMA, and its resolution was seen among 54.5% (n=6) of these. Infants with PDA also exhibited lower values of portal vein diameter and flow volume and of SMV diameter (P<0.01).

CONCLUSION

Doppler US enhances the understanding of mesenteric and portal flow, including the effects of PDA. The study of SMV and portal vein flow is proposed as a new parameter in PDA evaluation.

The dark side of ibuprofen in the treatment of patent ductus arteriosus: could paracetamol be the solution?

INTRODUCTION

Patent ductus arteriosus (PDA) persistence is associated, in prematures, to several complications. The optimal PDA management is still under debate, especially regarding the best therapeutic approach and the time to treat. The available drugs are not exempt from contraindications and side effects; ibuprofen itself, although representing the first-choice therapy, can show nephrotoxicity and other complications. Paracetamol seems a valid alternative to classic nonsteroidal anti-inflammatory Drugs, with a lower toxicity. Areas covered: Through an analysis of the published literature on ibuprofen and paracetamol effects in preterm neonates, this review compares the available treatments for PDA, analyzing the mechanisms underlining ibuprofen-associated nephrotoxicity and the eventual paracetamol-induced hepatic damage, also providing an update of what has been yet demonstrated and a clear description of the still open issues. Expert Opinion: Paracetamol is an acceptable alternative in case of contraindication to ibuprofen; its toxicity, in this setting, is very low. Lower doses may be effective, with even fewer risks. In the future, paracetamol could represent an efficacious first-line therapy, although its safety, optimal dosage, and global impact have to be fully clarified through long-term trials, also in the perspective of an individualized and person-based therapy taking into account the extraordinary individual variability.

Paracetamol in Patent Ductus Arteriosus Treatment: Efficacious and Safe?

In preterm infants, failure or delay in spontaneous closure of Ductus Arteriosus (DA), resulting in the condition of Patent Ductus Arteriosus (PDA), represents a significant issue. A prolonged situation of PDA can be associated with several short- and long-term complications. Despite years of researches and clinical experience on PDA management, unresolved questions about the treatment and heterogeneity of clinical practices in different centers still remain, in particular regarding timing and modality of intervention. Nowadays, the most reasonable strategy seems to be reserving the treatment only to hemodynamically significant PDA. The first-line therapy is medical, and ibuprofen, related to several side effects especially in terms of nephrotoxicity, is the drug of choice. Administration of oral or intravenous paracetamol (acetaminophen) recently gained attention, appearing effective as traditional nonsteroidal anti-inflammatory drugs (NSAIDs) in PDA closure, with lower toxicity. The results of the studies analyzed in this review mostly support paracetamol efficacy in ductal closure, with inconstant low and transient elevation of liver enzymes as reported side effect. However, more studies are needed to confirm if this therapy shows a real safety profile and to evaluate its long-term outcomes, before considering paracetamol as first-choice drug in PDA treatment.

Development of a Diagnostic Clinical Score for Hemodynamically Significant Patent Ductus Arteriosus

There is no consensus about the hemodynamic significance and, therefore, the need to treat a persistent ductus arteriosus in preterm newborns. Since the diagnosis of a hemodynamically significant persistent ductus arteriosus (hsPDA) is made by a summary of non-uniform echo-criteria in combination with the clinical deterioration of the preterm neonate, standardized clinical and ultrasound scoring systems are needed. The objective of this study was the development of a clinical score for the detection and follow-up of hsPDA. In this observational cohort study of 154 preterm neonates (mean gestational age 28.1 weeks), clinical signs for the development of hsPDA were recorded in a standardized score and compared to echocardiography. Analyzing the significance of single score parameters compared to the diagnosis by echocardiography, we developed a short clinical score (calculated sensitivity 84% and specificity 80%). In conclusion, this clinical diagnostic PDA score is non-invasive and quickly to implement. The continuous assessment of defined clinical parameters allows for a more precise diagnosis of hemodynamic significance of PDA and, therefore, should help to detect preterm neonates needing PDA-treatment. The score, therefore, allows a more targeted use of echocardiography in these very fragile preterm neonates.

Recent Advances in the Treatment of Preterm Newborn Infants with Patent Ductus Arteriosus

A patent ductus arteriosus (PDA) is associated with several adverse clinical conditions. Several strategies for PDA treatment exist, although data regarding the benefits of PDA treatment on outcomes are sparse. Moreover, the optimal treatment strategy for preterm neonates with PDA remains subject to debate. It is still unknown whether and when PDA treatment should be initiated and which approach (conservative, pharmacologic, or surgical) is best for individual patients (tailored therapies). This article reviews the current strategies for PDA treatment with a special focus on recent developments such as oral ibuprofen, high-dose regimens, and the use of paracetamol (oral, intravenous).

Metabolomics in Newborns

Metabolomics is the quantitative analysis of a large number of low molecular weight metabolites that are intermediate or final products of all the metabolic pathways in a living organism. Any metabolic profiles detectable in a human biological fluid are caused by the interaction between gene expression and the environment. The metabolomics approach offers the possibility to identify variations in metabolite profile that can be used to discriminate disease. This is particularly important for neonatal and pediatric studies especially for severe ill patient diagnosis and early identification. This property is of a great clinical importance in view of the newer definitions of health and disease. This review emphasizes the workflow of a typical metabolomics study and summarizes the latest results obtained in neonatal studies with particular interest in prematurity, intrauterine growth retardation, inborn errors of metabolism, perinatal asphyxia, sepsis, necrotizing enterocolitis, kidney disease, bronchopulmonary dysplasia, and cardiac malformation and dysfunction.

The timing of surgical ligation for patent ductus arteriosus is associated with neonatal morbidity in extremely preterm infants born at 23-25 weeks of gestation

The purpose of this study was to evaluate prognostic factors associated with surgical ligation for patent ductus arteriosus (PDA) in extremely preterm infants born at the limits of viability. Ninety infants who were born at 23-25 weeks of gestation and who received surgical ligation were included and their cases were retrospectively reviewed. Infants were classified into two different groups: survivors with no major morbidity (N), and non-survivors or survivors with any major morbidity (M). Clinical characteristics were compared between the groups. Possible prognostic factors were derived from this comparison and further tested by logistic regression analysis. The mean gestational age and the mean birth weight of M were significantly lower than those of N. Notably, the mean postnatal age at time of ligation in N was significantly later than that of the other group (17 ± 12 vs 11 ± 8 days in N and M, respectively). An adjusted analysis showed that delayed ligation (>2 weeks) was uniquely associated with a significantly decreased risk for mortality or composite morbidity after surgical ligation (OR, 0.105; 95% CI, 0.012-0.928). In conclusion, delayed surgical ligation for PDA (>2 weeks) is associated with decreased mortality or morbidities in extremely preterm infants born at 23-25 weeks of gestation.

High prevalence of interatrial septal aneurysm in young adults who were born preterm

BACKGROUND

The cardiovascular vulnerability of young adults who were born preterm was first acknowledged over a decade ago.

AIMS

(1) To examine the echocardiographic characteristics of a group of young adults born preterm with an extremely low birthweight (<1000 g; ex-ELBW) in comparison with healthy controls born at term (C); (2) to identify a correlation between the potential echocardiographic abnormalities detected in ex-ELBW and their anthropometric parameters, age, presence of respiratory distress, patency of ductus arteriosus, length of stay in Neonatal Intensive Care Unit.

METHODS

Thirty-seven ex-ELBW (11 males, 26 females; mean age: 22.2 ± 1.8 years) were compared with 37 C (11 males, 26 females). Both groups underwent standard mono- and bi-dimensional transthoracic echocardiogram with color Doppler.

RESULTS

No statistically significant differences were detected between the two groups regarding mono-dimensional echocardiography or Doppler measurements (p = ns). Conversely, a statistically significant difference was observed between the prevalence of interatrial septal aneurysm (ASA) in ex-ELBW compared to C (p = 0.0016). A significant association was likewise observed between ASA and the presence of both respiratory distress at birth (p < 0.05) and patency of the ductus arteriosus (p < 0.05).

CONCLUSIONS

A significant prevalence of ASA was detected in ex-ELBW subjects compared to C, underlining a probable correlation with respiratory distress and patent ductus arteriosus. In view of the association between ASA and stroke in young adults devoid of other cerebrovascular risk factors, this unexpected observation suggests that all ex-preterm subjects should undergo transthoracic or transesophageal echocardiographic examination with the aim of detecting this potentially emboligenic cardiac abnormality.

Preservation of the metabolic rate of oxygen in preterm infants during indomethacin therapy for closure of the ductus arteriosus

BACKGROUND

The aim of this study was to assess and quantify the effects of indomethacin on cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2) in preterm infants undergoing treatment for a patent ductus arteriosus (PDA).

METHODS

CBF and CMRO2 were measured before and after the first dose of a 3-d course of indomethacin to close hemodynamically significant PDA in preterm neonates. Indocyanine-green (ICG) concentration curves were acquired before and after indomethacin injection to quantify CBF and CMRO2.

RESULTS

Eight preterm neonates (gestational age, 27.6 ± 0.5 wk; birth weight, 992 ± 109 g; 6 males:2 females) were treated at a median age of 4.5 d (range, 4-21 d). Indomethacin resulted in an average CBF decrease of 18% (pre- and post-CBF = 12.9 ± 1.3 and 10.6 ± 0.8 ml/100 g/min, respectively) and an OEF increase of 11% (pre- and post-OEF = 0.38 ± 0.02 and 0.42 ± 0.02, respectively) but no significant change in CMRO2 (pre- and post-CMRO2 = 0.83 ± 0.07 and 0.76 ± 0.07 ml O2/100 g/min, respectively). Corresponding mean blood pressure (BP), arterial oxygen saturation (SaO2), heart rate, and end-tidal carbon dioxide tension levels remained unchanged.

CONCLUSION

Indomethacin resulted in significant reduction in CBF but did not alter CMRO2 because of a compensatory increase in OEF.

The importance of biomarkers in neonatology

Despite a 35% decline in the mortality rate for infants aged <5 years over the past two decades, every year nearly 40% of all deaths in this age group occur in the neonatal period, defined as the first 28 days of life. New knowledge on molecular and biochemical pathways in neonatal diseases will lead to the discovery of new candidate biomarkers potentially useful in clinical practice. In the era of personalized medicine, biomarkers may play a strategic role in accelerating the decline in neonatal mortality by assessing the risk of developing neonatal diseases, by implementing tailored therapeutic treatment, and by predicting the clinical outcome. However, there is an urgent need to reduce the gap in translating newly acquired knowledge from bench to bedside. Traditional and candidate biomarkers for neonatal sepsis and necrotizing enterocolitis will be discussed in this review, such as C-reactive protein (CRP), procalcitonin (PCT), serum amyloid A (SAA), soluble form of CD14 subtype presepsin (sCD14-ST), lipolysaccharide binding protein (LBP), angiopoietins (Ang)-1 and -2, soluble form of triggering receptor expressed on myeloid cells (sTREM-1), soluble form of urokinase-type plasminogen activator receptor (suPAR), platelet-activating factor (PAF) and calprotectin. New frontiers in managing critically ill newborns may be opened by metabolomics, a diagnostic tool based on the recognition of metabolites contained in biological fluids. Metabolomics represents the passage from a descriptive science to a predictive science, having the potential to translate benchtop research to real clinical benefits.

Prolonged persistent patent ductus arteriosus: potential perdurable anomalies in premature infants

OBJECTIVE

Patent ductus arteriosus (PDA) is a common condition among preterm infants. Controversy exists regarding the risk-benefit ratio of early closure of PDAs by either medical or surgical treatments. On the other hand, potential morbidities associated with no or delayed closure has not been well studied. The objective of the study was to determine if there is an association of prolonged persistent PDA (PP-PDA) with various morbidities in infants ≤28 weeks or 1250 g.

STUDY DESIGN

This matched case-control analysis includes preterm infants with a diagnosis of PDA over a period of 28 months in a single level III center in the USA. The predictive variable was the presence of a PP-PDA (PDA>3 weeks). Cases were infants with PP-PDA and controls were those with PDA but not PP-PDA (two controls for each case). Outcome variables included days on mechanical ventilation and with oxygen treatment, length of hospital stay, bronchopulmonary dysplasia (BPD), retinopathy of prematurity stage III-V (ROP) necrotizing enterocolitis grade II or more (NEC), delayed growth, direct hyperbilirubinemia >4 mg dl(-1) and osteopenia of prematurity. Data was obtained from database collected prospectively and from the review of clinical records when necessary. Statistics included ANOVA, Kaplan-Meier curves and χ (2). Significance was set at P<0.05.

RESULT

PP-PDA was associated with a significant increase in the number of days of mechanical ventilation, oxygen treatment and length of hospital stay, and in the rates of BPD (60% vs 4.5%), NEC (29% vs 5%), ROP (43% vs 5%), direct hyperbilirubinemia (41% vs 3%), osteopenia (44% vs 6%), parenteral nutrition for >40 days (70% vs 21%), tracheostomy during the hospitalization (15% vs 0%) and delayed growth (70% vs 21%), were also significantly higher in babies with PP-PDA.

CONCLUSION

A prolonged exposure to PDA does not seem to be inconsequential for some infants and is associated with an increase prevalence of severe morbidities with potential long lasting effects.

Cardiovascular phenotype in extremely low birth weight infants: long-term consequences

Low birth weight, a possible consequence of prematurity at birth or intrauterine growth restriction, has been recently recognized as an emerging risk factor to develop cardiovascular (CV) future adverse events. Our aim was to perform a short review about the studies conducted in order to evaluate the CV risk profile of a specific subpopulation of infants suffering from low birth weight, that is those having a birth weight less than 1,000 g, called extremely low birth weight.

Should we definitively abandon prophylaxis for patent ductus arteriosus in preterm new-borns?

Although the prophylactic administration of indomethacin in extremely low-birth weight infants reduces the frequency of patent ductus arteriosus and severe intraventricular hemorrhage, it does not appear to provide any long-term benefit in terms of survival without neurosensory and cognitive outcomes. Considering the increased drug-induced reduction in renal, intestinal, and cerebral blood flow, the use of prophylaxis cannot be routinely recommended in preterm neonates. However, a better understanding of the genetic background of each infant may allow for individualized prophylaxis using NSAIDs and metabolomics.