Ductus arteriosus ligation and alveolar growth in preterm baboons with a patent ductus arteriosus

Patent Ductus Arteriosus and Lung Magnetic Resonance Imaging Phenotype in Moderate and Severe Bronchopulmonary Dysplasia-Pulmonary Hypertension

Rationale: Hemodynamically significant patent ductus arteriosus (hsPDA) in premature infants has been associated with bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH). However, these associations remain incompletely understood. Objectives: To assess the associations between hsPDA duration and clinical outcomes, PH, and phenotypic differences on lung magnetic resonance imaging (MRI). Methods: In this retrospective cohort study, we identified all infants with BPD at <32 weeks' gestation who also underwent research lung MRI at <48 weeks' postmenstrual age (PMA) from 2014 to 2022. Clinical echocardiograms were reviewed for hsPDA and categorized as no hsPDA, hsPDA 1-60 days, and hsPDA >60 days. Outcome variables included BPD severity, PH at 36 weeks' PMA, PH after 36 weeks' PMA in the absence of shunt (PH-pulmonary vascular disease [PVD]), tracheostomy or death, and lung phenotype by MRI via modified Ochiai score, indexed total lung volume, and whole-lung hyperdensity. Logistic regression and ANOVA were used. Measurements and Main Results: In total, 133 infants born at 26.2 ± 1.9 weeks, weighing 776 ± 276 g, were reviewed (47 with no hsPDA, 44 with hsPDA 1-60 days, and 42 with hsPDA >60 d). hsPDA duration > 60 days was associated with BPD severity (P < 0.01), PH at 36 weeks' PMA (adjusted odds ratio [aOR], 9.7 [95% confidence interval (CI), 3.3-28.4]), PH-PVD (aOR, 6.5 [95% CI, 2.3-18.3]), and tracheostomy or death (aOR, 3.0 [95% CI, 1.0-8.8]). Duration of hsPDA > 60 days was associated with higher Ochiai score (P = 0.03) and indexed total lung volume (P = 0.01) but not whole-lung hyperdensity (P = 0.91). Conclusions: In infants with moderate or severe BPD, prolonged exposure to hsPDA is associated with BPD severity, PH-PVD, and increased parenchymal lung disease by MRI.

Should we "eliminate" PDA shunt in preterm infants? A narrative review

The patent ductus arteriosus frequently poses a significant morbidity in preterm infants, subjecting their immature pulmonary vascular bed to substantial volume overload. This, in turn, results in concurrent hypoperfusion to post-ductal organs, and subsequently alters cerebral blood flow. In addition, treatment has not demonstrated definitive improvements in patient outcomes. Currently, the optimal approach remains a subject of considerable debate with ongoing research controversy regarding the best approach. This article provides a comprehensive review of existing literature.

Perinatal origins of bronchopulmonary dysplasia-deciphering normal and impaired lung development cell by cell

Bronchopulmonary dysplasia (BPD) is a multifactorial disease occurring as a consequence of premature birth, as well as antenatal and postnatal injury to the developing lung. BPD morbidity and severity depend on a complex interplay between prenatal and postnatal inflammation, mechanical ventilation, and oxygen therapy as well as associated prematurity-related complications. These initial hits result in ill-explored aberrant immune and reparative response, activation of pro-fibrotic and anti-angiogenic factors, which further perpetuate the injury. Histologically, the disease presents primarily by impaired lung development and an arrest in lung microvascular maturation. Consequently, BPD leads to respiratory complications beyond the neonatal period and may result in premature aging of the lung. While the numerous prenatal and postnatal stimuli contributing to BPD pathogenesis are relatively well known, the specific cell populations driving the injury, as well as underlying mechanisms are still not well understood. Recently, an effort to gain a more detailed insight into the cellular composition of the developing lung and its progenitor populations has unfold. Here, we provide an overview of the current knowledge regarding perinatal origin of BPD and discuss underlying mechanisms, as well as novel approaches to study the perturbed lung development.

Combination pharmacotherapy for patent ductus arteriosus: Rationale and evidence

While cyclooxygenase inhibitors have been the most common medications used to facilitate earlier closure of patent ductus arteriosus in preterm infants, adverse effects and low efficacy in extremely low gestational age neonates (ELGANs) have highlighted a need for alternative options. Combination therapy with acetaminophen and ibuprofen is a novel strategy for PDA treatment in ELGANs, as it may facilitate higher ductal closure rates via additive action on two separate pathways inhibiting prostaglandin production. Initial small observational studies and pilot randomized clinical trials indicate potentially higher efficacy of the combination regime to induce ductal closure in comparison to treatment with ibuprofen alone. In this review, we examine the potential clinical impact of treatment failure in ELGANs with significant PDA, highlight the biological rationale in support of studying combination therapy, and review the randomized and non-randomized studies to date. With the rising number of ELGANs receiving neonatal intensive care, who are vulnerable to PDA-related morbidities, there is an urgent need for adequately powered clinical trials to systematically investigate the efficacy and safety of combination therapy for PDA treatment.

Clinical outcomes of different patent ductus arteriosus treatment in preterm infants born between 28 and 32 weeks in Taiwan

BACKGROUND

The patent ductus arteriosus (PDA) treatment in very preterm infants is controversial. This study focused on preterm infants born at 28-32 weeks of gestation and analyzed the association between various PDA treatments and clinical outcomes.

METHODS

We conducted a retrospective cohort study of infants born at 28-32 weeks of gestation between 2016 and 2019 at 22 hospitals in the Taiwan Premature Infant Follow-up Network. We categorized the infants into four groups according to treatment strategies: medication, primary surgery, medication plus surgery, or conservative treatment.

RESULTS

A total of 1244 infants presented with PDA, and 761 (61.1%) were treated. Medication was the predominant treatment (50.0%), followed by conservative treatment (38.9%), medication plus surgery (7.6%), and primary surgery (3.5%). The risk of mortality was not reduced in the active treatment group compared to the conservative treatment group. There was a higher prevalence of severe intraventricular hemorrhage, necrotizing enterocolitis (NEC), and any degree of bronchopulmonary dysplasia (BPD) in both the primary surgery and medication plus surgery groups than in the conservative treatment group. After adjustment, both the primary surgery and medication plus surgery groups still had higher odds ratios for the occurrence of NEC and any degree of BPD.

CONCLUSIONS

Compared with active PDA treatment, conservative treatment for PDA did not increase the risk of mortality and morbidity in very preterm infants born at 28-32 weeks of gestation. The risks and benefits of surgery (PDA ligation) in these infants must be considered cautiously.

Outcomes of and factors associated with the development of bronchopulmonary dysplasia with pulmonary hypertension in very low birth weight infants: A retrospective study in a medical center

Introduction

Bronchopulmonary dysplasia (BPD) with pulmonary hypertension (PH) leads to increased morbidity and mortality in extremely preterm infants. Recent studies have analyzed factors associated with development of PH in BPD; however, this research remains inconclusive, and controversy exists regarding the correlation between BPD and PH. This study aimed to investigate potential associated factors, clinical characteristics, and outcomes of BPD with pulmonary hypertension in very low birth weight (VLBW) preterm infants.

Methods

We conducted a retrospective study, reviewing the records of infants with gestational age (GA) <32 weeks and birth weight <1,500 g admitted to a tertiary neonatal intensive care unit between January 2020 and October 2021 who were diagnosed with moderate to severe BPD. Echocardiogram was performed at the postmenstrual age of 36 weeks or before discharge. The diagnosis of PH was based on the findings of echocardiogram. Prenatal and postnatal characteristics, demographic data, treatment details, and outcomes were collected and analyzed.

Results

A total of 139 VLBW infants with BPD were enrolled and divided into a PH group (n = 25) and a non-PH group (n = 114). The mean GA was 27.3 ± 2.3 weeks and the mean birth weight of infants with BPD was 927.3 ± 293.3 g. A multivariate logistic regression model revealed that a high positive end-expiratory pressure (PEEP) setting (OR: 2.105; 95% CI: 1.472-3.011; p < 0.001) in established BPD and surgical closure of patent ductus arteriosus (PDA; OR: 6.273; 95% CI: 1.574-24.977; p = 0.009) were associated with BPD-PH. Neonates with BPD who developed pulmonary hypertension remained hospitalized for longer (p < 0.001), received invasive mechanical ventilation support for longer (p < 0.001), had a higher incidence of retinopathy of prematurity (ROP; OR: 4.201; 95% CI: 1.561-11.304; p = 0.003), were more likely to require oxygen support at discharge (OR: 5.600; 95% CI: 2.175-14.416; p < 0.001), and were more likely to undergo tracheostomy (OR: 35.368; 95% CI: 4.03-310.43; p < 0.001).

Conclusion

PDA ligation and a higher PEEP setting were associated with BPD-PH in our cohort study. Compared with VLBW infants with BPD but without PH, infants with BPD and PH were hospitalized for longer, and also had a higher incidence of oxygen support after discharge, ROP, and tracheostomy.

Fechamento Percutâneo do Canal Arterial em Pacientes Prematuros Abaixo de 2 Kg: Experiência Inicial Brasileira

Fundamento

A incidência de ductus arteriosus patente (PCA) pode chegar a 50% em pacientes prematuros. Quando hemodinamicamente significativo, pode ser responsável por tempo de ventilação mecânica prolongado, além de importante fator de risco para o aparecimento de enterocolite necrotizante, hemorragia intraventricular e displasia broncopulmonar nessa população.

Objetivo

O objetivo deste estudo é descrever a experiência inicial do fechamento percutâneo de canal arterial em prematuros pesando menos de 2 kg.

Métodos

Trata-se de estudo prospectivo que compreendeu 14 pacientes consecutivos submetidos a fechamento percutâneo de canal arterial de março de 2020 a fevereiro de 2021 em 6 instituições no Brasil.

Resultados

A idade gestacional média ao nascimento foi de 28,45 ±3,14 semanas, a idade média no momento do procedimento foi de 38,85 ±17,35 dias e o peso médio de 1,41±0,41 kg. Dentre os prematuros, 79% necessitavam de ventilação mecânica e 79% tinham feito uso de, em média, 1,5 ciclos de anti-inflamatórios não esteroides. A maioria dos pacientes teve melhora dos parâmetros ventilatórios e o tempo médio de extubação foi de 12,6 ±7,24 dias. A taxa de sucesso foi de 100%. Não houve mortalidade relacionada ao procedimento.

Conclusão

Este estudo concluiu que o fechamento percutâneo do canal arterial em prematuros é uma realidade no Brasil, com resultados satisfatórios e baixa taxa de complicações.

A Novel Patent Ductus Arteriosus Severity Score to Predict Clinical Outcomes in Premature Neonates

Background: Patent Ductus Arteriosus (PDA) in premature neonates has been associated with comorbidities including chronic lung disease (CLD), and death. However, the treatment of PDA remains controversial. There have been several echocardiographic variables previously used to determine the hemodynamic significance of PDA but their utility in early prediction of clinical outcomes is not well studied. Objective: The objective of our study was to evaluate the use of a severity scoring system incorporating markers of systemic under perfusion, pulmonary over perfusion and left ventricular (LV) function in predicting clinical outcomes in premature neonates. Methods: It is a single center prospective observational study involving newborns < 32 weeks’ gestation. An echocardiogram was done within seven days of life to measure variables previously known to predict severity of shunting in PDA including pulmonary perfusion index (PPI). Predictors of CLD/death were identified using multivariate logistic regression. A severity score was derived and its ability to predict clinical outcomes was tested using a receiver operating characteristic curve. Results: We studied 98 infants with a mean (SD) gestation of 28.9 ± 1.91 weeks and birth weight of 1228.06 ± 318.94 g, respectively. We identified five echocardiographic variables along with gestational age that was independently associated with the outcome variable (PPI, LV output, Superior Mesenteric Artery [SMA] Velocity Time Integral [VTI], Peak diastolic flow velocity in Pulmonary Vein [PV Vd], and reversal of flow in diastole in descending aorta [DFR]). The range of severity score was 0 (low risk) to 12 (high risk). A higher score was associated with the primary outcome variable of CLD/death (7.5 [1.2] vs. 3.6 [1.5], p < 0.001). Our severity score had an area under the curve of 0.97 (95% CI 0.93−0.99, p < 0.001) for predicting CLD/death. Conclusion: Our new PDA severity score of 5.5 has a sensitivity and specificity of 94% and 93%, and positive and negative predictive values of 94% and 93%, respectively.

Functional morphometry to estimate the alveolar surface area using a premature baboon model

The main respiratory pathophysiological process following premature birth is the delayed or arrested alveolar development that translates to a smaller alveolar surface area (S_A). Histological morphometry is the gold standard method to measure the S_A but requires invasive tissue sampling or the removal of the whole organ for analysis. Alternatively, the S_A could be measured in living subjects by "functional morphometry" using Fick's first law of diffusion and noninvasive measurements of the ventilation to perfusion ratio (V̇a/Q̇). We herein aim to describe a novel functional morphometric method to measure S_A using a premature baboon model. We used both functional morphometry and postmortem histological morphometry to measure S_A in 11 premature baboons born at 135 days who received intensive care treatment for 14 days. For the calculation of the S_A by functional morphology, we measured the septal wall thickness using microscopy, the alveolar arterial oxygen gradient using concurrent measurements of arterial pressure of O₂ and CO₂, and pulmonary perfusion using echocardiography and integrated Doppler signals. The median [interquartile range (IQR)] S_A using functional morphometry was 3,100 (2,080-3,640) cm² and using histological morphometry was 1,034 (634-1,210) cm² (left lung only). The S_A measured by functional morphometry was not related to the S_A measured by histological morphometry. Following linear regression analysis, the V̇a/Q̇ significantly predicted the histologically measured S_A (R² = 0.659, P = 0.002). In conclusion, functional measurements of ventilation to perfusion ratio could be used to estimate the alveolar surface area in prematurely born baboons and the ventilation perfusion ratio was the main determinant of the alveolar surface area.NEW & NOTEWORTHY The main morphological characteristic of chronic respiratory disease in prematurely born infants is the impaired/arrested alveolar growth that corresponds to a smaller aggregated alveolar surface area (S_A). This decreased S_A might be the limiting factor later in life affecting exercise capacity and quality of life. There is paucity of sensitive, noninvasive biomarkers to monitor the evolution of neonatal respiratory disease. Our noninvasive functional morphometric S_A might help to bridge the gap between pathophysiology and clinical monitoring.

Impact of patent ductus arteriosus shunt size and duration on risk of death or severe respiratory morbidity in preterm infants born in China

The purpose of this study is to assess whether duration and size of the arterial duct were associated with severe respiratory morbidity and mortality in preterm infants. All echocardiography evaluations for patent ductus arteriosus (PDA) in a cohort of preterm infants, born at a gestational age less than 28 weeks, from birth up to 36 weeks of postconceptional age or final ductal closure were reviewed. Ductal size was measured at the pulmonary end. PDA was classified as small (E1: ductal diameter (DD) ≤ 1.5 mm), moderate (E2: 1.5 mm < DD ≤ 2.5 mm), or large (E3) (DD > 2.5 mm). The primary outcome was adverse outcome defined by the composite outcome of bronchopulmonary dysplasia (BPD) or death. Infants in whom the primary outcome occurred were classified as "high-risk" whereas patients who did not satisfy this outcome were classified as "low-risk". Intergroup comparison (high vs. low risk) was performed using univariate and multivariate analyses. A total of 135 infants, born between 2010 and 2020, were evaluated. The primary outcome was satisfied in 46 (34.1%) patients. The high-risk group was characterized by increased duration of exposure to PDA of any (E1/E2/E3) grade (44 vs. 25.5 days, p = .0004), moderate or large (E2/E3) PDA (30.5 vs. 11.5 days, p < .0001), moderate (E2) PDA (10.8 vs.6 days, p = 0.05), and large (E3) PDA (11.5 vs.0 days, p < .0001) compared with low-risk group. Lower gestational age, prolonged duration of mechanical ventilation, higher rate of inotrope use, pharmacological therapy, and PDA ligation were also associated with development of BPD or death (high-risk group). After adjusting for confounders, the rate of inotrope use [OR 2.688, 95% CI (1.011-7.142), p = 0.047], duration of large (E3) PDA [OR 1.060, 95% CI (1.005-1.118), p = 0.03], and mechanical ventilation [OR 1.130, 95% CI (1.064-1.200), p = 0.0001] were independently associated with the composite of BPD or death. Among infants who developed BPD, 27 were classified as grade I and 18 as grade II BPD, respectively. Infants with grade II BPD had prolonged MV (20.0 vs. 9.0 days, p = 0.024), prolonged exposure to PDA of any grade (55.8 vs. 36.0 days, p = 0.03), and prolonged exposure to large (E3) PDA compared with infants with grade I BPD.   Conclusion: Prolonged exposure to a large PDA was associated with severe respiratory morbidity and mortality in preterm infants. The modulator role of early intervention, in the most pathologic shunts, on severe respiratory morbidity in preterm infants should be tested in well-designed clinical trials. What is Known: • Current guidelines recommended against accelerating PDA closure of preterm infants within 2 weeks of life, with low certainty evidence indicating improved long-term outcomes. • Recent studies suggest that conservative approach regarding PDA management has detrimental effects on the respiratory outcomes in a subgroup population. What is New: • Persistent patency of significant PDA is associated with increased risk of BPD/death in extremely preterm infants. • Targeted intervention of PDA is beneficial for the at-risk preterm infants with increased PDA hemodynamic significance.

Respiratory morbidity in children with congenital heart disease

OBJECTIVE

To evaluate the respiratory outcome in children with congenital heart disease (CHD), considering recent management procedures and the CHD pathophysiology.

DESIGN AND SETTING

Clinical and functional respiratory outcome were evaluated in 8-year-old children with isolated CHD followed up from birth in the prospective population-based EPICARD cohort.

PATIENTS

Children were assigned to two groups, based on the pathophysiology of the CHD: CHDs with left-to-right shunt (n = 212) and CHDs with right outflow tract obstruction (n = 113).

RESULTS

Current wheezing episodes were observed in 15% of the children with isolated CHD and left-to-right shunt, and 11% of the children with isolated CHD and right outflow tract obstruction (not significant). Total lung capacity (TLC) was the only respiratory function parameter that significantly differed between the two groups. It was lower in children with left-to-right shunt (88.72 ± 0.65% predicted) than in those with right outflow tract obstruction (91.84 ± 0.96, p = 0.006). In multivariate analysis, CHD with left-to-right shunt (coeff. [95% CI]: -3.17 [-5.45; -0.89]) and surgery before the age of 2 months (-6.52 [-10.90; -2.15]) were identified as independent factors associated with significantly lower TLC values.

CONCLUSION

Lower TLC remains a long-term complication in CHD, particularly in cases with left-to-right shunt and in patients requiring early repair. These findings suggest that an increase in pulmonary blood flow may directly impair lung development.

Patent ductus arteriosus shunt elimination results in a reduction in adverse outcomes: a post hoc analysis of the PDA RCT cohort

OBJECTIVE

A post hoc appraisal of the PDA RCT to assess the relationship between early patent ductus arteriosus (PDA) shunt elimination and chronic lung disease or death (CLD/Death).

STUDY DESIGN

Infants <29 weeks were divided into four groups: intervention arm in whom PDA closure was achieved (n = 17); intervention arm in whom PDA closure was not achieved (n = 13); placebo arm (n = 30); low risk infants (n = 13). The main outcome measure was CLD/Death.

RESULTS

The rates of CLD/Death were lower in the Intervention Success Group (29%) when compared to the Intervention Failure Group (85%) or the Placebo Group (60%, all p < 0.05). There was no difference in CLD/Death between the Intervention Success and Low Risk Groups (8%, p > 0.05). A persistent PDA beyond Day 8 was associated with CLD/Death (aOR 6.5 [1.7-25.5]).

CONCLUSIONS

Early shunt elimination in preterm infants with a PDA may reduce respiratory morbidity when compared to infants with prolonged shunt exposure.

Early targeted patent ductus arteriosus treatment in premature neonates using a risk based severity score: study protocol for a randomised controlled trial (PDA RCT)

A patent ductus arteriosus (PDA) in preterm infants is associated with increased ventilator dependence and chronic lung disease, necrotizing enterocolitis, intraventricular haemorrhage, and poor neurodevelopmental outcome. Randomised controlled trials of early PDA treatment have not established a drop in the aforementioned morbidities. Those trials did not physiologically categorise PDA severity. Incorporating the specific physiological features of a haemodynamic significant PDA may evolve our understanding of this phenomenon, allowing accurate triaging using echocardiography and targeted treatment.  Our group has recently demonstrated that a PDA severity score (PDAsc) derived at 36-48 hours of age can accurately predict the later occurrence of chronic lung disease or death (CLD/Death). Using echocardiography, we assessed PDA characteristics, as well as left ventricular diastolic function and markers of pulmonary overcirculation, and from this formulated a PDAsc. Gestation was also incorporated into the score. We hypothesise that in preterm infants at high risk of developing CLD/Death based on a PDAsc, early treatment with Ibuprofen compared with placebo will result in a reduction in CLD/Death. This is a single centre double-blind two arm randomised controlled trial conducted in the neonatal intensive care unit in the Rotunda Hospital, Dublin. Echocardiogram is carried out in the first 36-48 hours of life to identify preterm infants with a PDAsc ≥ 5.0 and these infants are randomised to Ibuprofen or placebo. Primary outcomes are assessed at 36 weeks post menstrual age. This pilot study's purpose is to assess the feasibility of performing the trial and to obtain preliminary data to calculate a sample size for a definitive multi-centre trial of early PDA treatment using a PDAsc. We aim to recruit a total of 60 infants with a high risk PDA over three years. Trial Registration: ISRCTN ISRCTN13281214 (26/07/2016) and the European Union Drug Regulating Authorities Clinical Trials Database 2015-004526-33 (03/12/2015).

Molecular and Mechanical Mechanisms Regulating Ductus Arteriosus Closure in Preterm Infants

Failure of ductus arteriosus closure after preterm birth is associated with significant morbidities. Ductal closure requires and is regulated by a complex interplay of molecular and mechanical mechanisms with underlying genetic factors. In utero patency of the ductus is maintained by low oxygen tension, high levels of prostaglandins, nitric oxide and carbon monoxide. After birth, ductal closure occurs first by functional closure, followed by anatomical remodeling. High oxygen tension and decreased prostaglandin levels mediated by numerous factors including potassium channels, endothelin-1, isoprostanes lead to the contraction of the ductus. Bradykinin and corticosteroids also induce ductal constriction by attenuating the sensitivity of the ductus to PGE2. Smooth muscle cells of the ductus can sense oxygen through a mitochondrial network by the role of Rho-kinase pathway which ends up with increased intracellular calcium levels and contraction of myosin light chains. Anatomical closure of the ductus is also complex with various mechanisms such as migration and proliferation of smooth muscle cells, extracellular matrix production, endothelial cell proliferation which mediate cushion formation with the interaction of blood cells. Regulation of vessel walls is affected by retinoic acid, TGF-β1, notch signaling, hyaluronan, fibronectin, chondroitin sulfate, elastin, and vascular endothelial cell growth factor (VEGF). Formation of the platelet plug facilitates luminal remodeling by the obstruction of the constricted ductal lumen. Vasa vasorum are more pronounced in the term ductus but are less active in the preterm ductus. More than 100 genes are effective in the prostaglandin pathway or in vascular smooth muscle development and structure may affect the patency of ductus. Hemodynamic changes after birth including fluid load and flow characteristics as well as shear forces within the ductus also stimulate closure. Current pharmacological treatment for the closure of a patent ductus is based on the blockage of the prostaglandin pathway mainly through COX or POX inhibition, albeit with some limitations and side effects. Further research for new agents aiming ductal closure should focus on a clear understanding of vascular biology of the ductus.

Conservative Non-intervention Approach for Hemodynamically Significant Patent Ductus Arteriosus in Extremely Preterm Infants

While persistent patent ductus arteriosus (PDA) in preterm infants has been known to be associated with increased mortality and morbidities including bronchopulmonary dysplasia, and necrotizing enterocolitis, there is minimal evidence supporting their causal relationships, and most traditional medical and/or surgical treatments have failed to show improvements in these outcomes. As such, the pendulum has swung toward the conservative non-intervention approach for the management of persistent PDA during the last decade; however, the benefits and risks of this approach are unclear. In this mini review, we focused on whom, when, and how to apply the conservative non-intervention approach for persistent PDA, especially in extremely preterm infants.

Natural evolution of ductus arteriosus with noninterventional conservative management in extremely preterm infants born at 23-28 weeks of gestation

This study aimed to determine the natural course of patent ductus arteriosus (PDA) with noninterventional conservative management and whether the presence and/or prolonged duration of hemodynamically significant (HS) PDA increased the risk of mortality and morbidities in extremely preterm (EPT) infants. We retrospectively reviewed the medical records of EPT infants born at 23-28 weeks of gestation (n = 195) from January 2011 to June 2014, when PDA was managed with noninterventional conservative treatment. We stratified infants into three subgroups of 23-24, 25-26, and 27-28 weeks and analyzed the prevalence and natural evolution of HS PDA, defined as ventilator dependency and PDA size ≥2 mm. Multivariate regression analyses determined if the presence and/or prolonged duration of HS PDA increased the risk for mortality and/or morbidities. The overall incidence of HS PDA was 57% (111/195) at the end of the first postnatal week. In subgroup analyses, infants with 23-24 weeks of gestation had the highest incidence (93%, 50/54), with 64% (47/74) for 25-26 weeks and 21% (14/67) for 27-28 weeks. Six (5%) of 111 infants with HS PDA were discharged without ductus closure, 4 had spontaneous PDA closure on follow up, and device closure was performed for 2 infants. In the multivariate analyses, the presence or prolonged duration (per week) of HS PDA was not associated with the risk of mortality and/or morbidities. Spontaneous closure of HS PDA was mostly achieved, even in EPT infants, with a noninterventional conservative approach. In conclusion, our data showed the incidence and natural course of HS PDA in EPT infants and suggested that the presence or prolonged duration of HS PDA might not increase the rate of mortality or morbidities.

Patent ductus arteriosus, its treatments, and the risks of pulmonary morbidity

A persistent left-to-right shunt through a patent ductus arteriosus (PDA) increases the rate of hydrostatic fluid filtration into the lung's interstitium, impairs pulmonary mechanics, and prolongs the need for mechanical ventilation. In preclinical trials, pharmacologic PDA closure leads to improved alveolarization and minimizes the impaired postnatal alveolar development that is the pathologic hallmark of bronchopulmonary dysplasia (BPD). Although routine prophylactic treatment of a PDA on the day of birth does not appear to offer any more protection against BPD than delaying treatment for 2-3 days, recent evidence from quality improvement trials suggests that early pharmacologic treatment decreases the incidence of BPD compared with a treatment approach that exposes infants to a moderate-to-large PDA shunt for the first 7-10 days after birth. After the first week, routine pharmacologic treatment (compared with continued PDA exposure) no longer appears to alter the course of BPD development. Evidence from epidemiologic, preclinical, and randomized controlled trials demonstrate that early ductus ligation is an independent risk factor for the development of BPD.

Post-ligation cardiac syndrome is associated with increased morbidity in preterm infants

OBJECTIVE

The influence of post-ligation cardiac syndrome (PLCS), a complication of patent ductus arteriosus (PDA) ligations, on neonatal outcomes is unknown. The purpose of this study was to determine the risks of PLCS on severe pulmonary morbidity and severe retinopathy of prematurity (ROP).

STUDY DESIGN

Retrospective cohort study of infants who underwent a PDA ligation between 2006 and 2015. Data were collected on patients with and without PLCS. The primary outcome was the difference in severe bronchopulmonary dysplasia (BPD) between groups. Secondary outcomes included discharge with home oxygen and severe ROP.

RESULT

A total of 100 infants that underwent PDA ligation during the study period were included in the study; 31 (31%) neonates developed PLCS. In adjusted analysis, PLCS was associated with increased risk for severe BPD (RR 1.67, 95% CI: 1.15-2.42) and home oxygen therapy (RR: 1.47, 95% CI: 1.09-1.99) only. No association with severe ROP was seen (RR: 1.48; 95% CI: 0.87-2.52).

CONCLUSION

PLCS is associated with severe neonatal pulmonary morbidity, but not with severe ROP. Further investigation is warranted to validate these results.

Patent Ductus Arteriosus closure in preterms less than 2kg: Surgery versus transcatheter

BACKGROUND

As new devices come into the market, percutaneous techniques improve and interventionalists become more experienced; percutaneous closure gets more common in preterms. In this study we aimed to compare efficacy and safety of Patent Ductus Arteriosus closure surgically versus transcatheter method in preterms <2kg. Best of our knowledge this study is the first one that compares outcomes of surgery and percutaneous Patent Ductus Arteriosus closure in preterms.

METHODS & RESULTS

Between the dates July 1997 to October 2014 in our center Patent Ductus Arteriosus of 26 patients <2kg were closed percutaneously (Group A) and 31 less than 2kg operated (Group B). Weight of patients in percutaneous Patent Ductus Arteriosus closure group was significantly more than the surgery group. Mean gestational age of the patients in Group A was 30±1.8weeks, in group B was 28.6±3.5weeks. In group A; all cases were closed successfully except 4 cases: device embolization in 2, cardiac tamponade and iatrogenic aortic coarctation were seen. Pneumomediastinum and chylothorax were the major complications of the surgery group. There was no statistically significance between complication and success rates between two groups.

CONCLUSION

Percutaneous Patent Ductus Arteriosus closure is the candidate for taking the place of surgery in preterms. However, it is not applied routinely; can only be done in fully equipped large centers by experienced interventionalists.

Prophylactic Indomethacin Compared with Delayed Conservative Management of the Patent Ductus Arteriosus in Extremely Preterm Infants: Effects on Neonatal Outcomes

OBJECTIVE

To determine whether prophylactic indomethacin (PINDO) has more or less morbidity than delayed conservative management of the moderate-to-large patent ductus arteriosus (PDA).

STUDY DESIGN

We performed a prospective double cohort controlled study of infants delivered at ≤27^6/7 weeks gestation (n = 397). From January 2005 through April 2011, all infants were treated with PINDO (n = 247). From May 2011 through August 2016, no infant was treated with indomethacin until at least 8 postnatal days (conservative epoch, n = 150). Echocardiograms were performed on day 7 and at planned intervals until the PDA was small or closed. A single neonatologist prospectively collected all data.

RESULTS

The incidence of moderate-to-large PDA on day 7 and duration of exposure to moderate-to-large PDA were significantly less in the PINDO epoch (incidence = 10%, median = 2 days) than the conservative epoch (incidence = 67%, median = 14 days). Ligation rates were low in both epochs (PINDO = 14%, conservative = 5%). In multivariate analyses, PINDO infants had a significantly lower incidence of bronchopulmonary dysplasia (BPD) (risk ratio = 0.68, CI: 0.46-0.89) and BPD or death (risk ratio= 0.78, CI: 0.62-0.95) than conservative infants. There were no differences between the epochs in death, intraventricular hemorrhage grades 3 and 4, necrotizing enterocolitis, or retinopathy of prematurity receiving treatment. The effects of PINDO on BPD and BPD or death were no longer significant when analyses were adjusted for presence of a moderate-to-large PDA on day 7. The significant effects of PINDO were independent of whether or not a ligation was performed.

CONCLUSIONS

PINDO decreases BPD and BPD or death compared with delayed conservative PDA management. These effects are mediated by closure of the PDA.

Prophylactic versus Early Rescue Surfactant Treatment in Preterm Infants Born at Less than 30 Weeks Gestation or with Birth Weight Less than or Equal 1,250 Grams

Prophylactic surfactant is known to be effective to reduce chronic lung disease in preterm infants compared with rescue surfactant treatment. In Korea, early prophylactic surfactant therapy was introduced in 2011. However, recently, the increased utilization of antenatal steroids and early stabilization through continuous positive airway pressure (CPAP) in the delivery room may have changed the risks and benefits of prophylactic surfactant therapy of infants at high risk of respiratory distress syndrome (RDS). We compared the effects and safety of prophylactic surfactant therapy (within 30 minutes after birth) and early selective surfactant therapy (within 3 hours after birth) in preterm infants born at < 30 weeks gestation or with birth weight ≤ 1,250 g. The clinical data of 193 infants in period 1 (from 2008 to 2010, early selective surfactant therapy group) were collected retrospectively; those of 191 infants in period 2 (from 2012 to 2014, prophylactic surfactant therapy group) were collected prospectively. Compared to period 1, the rate of intubation and surfactant use were significantly increased in period 2. The use of multiple doses of surfactant in period 2 was significantly increased compared with period 1. Despite more invasive and aggressive management in period 2, there was no difference in the duration of mechanical ventilation, the incidence of bronchopulmonary dysplasia (BPD) or death, and the risk of other adverse neonatal outcomes between the 2 groups. In conclusion, the benefit of prophylactic surfactant therapy in infants treated under current practices is no longer clear compared to early selective surfactant therapy.

Lung function in very low birth weight infants after pharmacological and surgical treatment of patent ductus arteriosus - a retrospective analysis

BACKGROUND

The indications and strategies for treatment of patent ductus arteriosus (PDA) are controversial, and the safety and long-term benefits of surgical PDA closure remain uncertain. The aim of this study was to compare the lung function of very low birth weight (VLBW) infants after successful PDA treatment with a cyclooxygenase inhibitor or secondary surgical ligation.

METHODS

A total of 114 VLBW infants (birth weight < 1500 g), including 94 infants (82%) with a birth weight < 1000 g, who received treatment for hemodynamically significant PDA (hsPDA), were examined at a median postmenstrual age of 48 weeks. All infants were initially given pharmacological treatment, and 40 infants (35%) required PDA ligation. Lung function testing (LFT) included tidal breathing measurements, measurement of respiratory mechanics assessed by the occlusion test, whole-body plethysmography, SF₆ multiple breath washout, forced expiratory flow (V'max_FRC) by the rapid thoracoabdominal compression technique, exhaled NO (FeNO), and arterialized capillary blood gas analysis.

RESULTS

On the day of the LFT, the 2 groups had similar postconceptional age and body weight. However, the PDA ligation group was more immature at birth (p < 0.001) and had reduced respiratory compliance (p < 0.001), lower V'max_FRC (p = 0.006), increased airway resistance (R_aw) (p < 0.001), and impaired blood gases (p < 0.001). Multivariate analysis showed that PDA surgery was an independent risk factor for increased R_aw.

CONCLUSION

PDA ligation after failed pharmacological treatment is associated with impaired lung function as compared to successful pharmacological closure in infants at a postmenstrual age of 48 weeks. However, only Raw was independently affected by PDA ligation, while all other differences were merely explained by patient characteristics.

Mandatory Closure Versus Nonintervention for Patent Ductus Arteriosus in Very Preterm Infants

OBJECTIVE

To determine whether a nonintervention approach for treating hemodynamically significant patent ductus arteriosus (PDA) is associated with decreased mortality and/or morbidity compared with a mandatory closure approach in extremely low birth weight infants.

STUDY DESIGN

We reviewed the medical records of 178 infants of 23-26 weeks' gestational age with PDA, requiring ventilator treatment, and with hemodynamically significant PDA ≥2 mm in size. Mandatory closure was used during period I (July 2009 to December 2011, n = 81), and nonintervention was used during period II (January 2012 to June 2014, n = 97).

RESULTS

During period I, 64% of infants were first treated with indomethacin, and 82% were ultimately ligated surgically. During period II, no infant was treated with indomethacin and/or ligation. The average postnatal day of PDA closure was day 13 and day 44 during periods I and II, respectively. There was significantly more use of diuretics and fluid restriction during period II compared with period I. There was no difference in mortality or morbidities such as necrotizing enterocolitis or intraventricular hemorrhage. The incidence of bronchopulmonary dysplasia (BPD) and the propensity score adjusted OR of BPD were significantly lower during period II compared with period I.

CONCLUSIONS

Despite longer PDA exposure, nonintervention was associated with significantly less BPD compared with mandatory closure. Additional study is warranted to determine the benefits and risks of non-intervention for the hemodynamically significant PDA in extremely low birth weight infants.

Transcatheter closure of PDA in premature babies less than 2 kg

Objective:

Our hypothesis was that percutaneous PDA closure in babies less than 2 kg was a safe and effective method. The aim of this study is to share our experience in transcatheter PDA closure in infants whose body weight is less than 2 kg in order to support our hypothesis.

Methods:

Between July 1997 and October 2014, 382 percutaneous PDA closures were done in our center. Nineteen patients who weighed less than 2 kg were included in this retrospectively study. The other inclusion criteria were 1) being symptomatic and PDA was thought as a possible contributor of medical state and 2) persistence of PDA after medical closure treatment. Patients who had sepsis and bleeding diathesis were excluded. According to size and shape of PDA, different types of devices were used such as detachable coils and Amplatzer duct occluders. Data was expressed as mean (SD) or median (minimum–maximum). Comparisons of means and medians were performed with Student’s t-test and with Mann–Whitney U test, respectively.

Results:

The median patient age and weight were 32 days and 1603 g (range 910–2000 g) respectively. Mean PDA diameter was 3.2±1.3 mm. Morphology of PDA was type A in 7 patients, type C in 10, type E in 1, and type B in 1 patient. There were no reported major complications. Stenosis of left pulmonary artery was detected in four patients, all of which resolved in 6 months follow-up.

Conclusion:

Percutaneous PDA closure in babies less than 2 kg is a safe and effective method that can be an alternative to surgery. Main distinguishing feature of this study is that it includes the largest cohort of patients less than 2 kg whose PDA closed percutaneously.

A Patent Ductus Arteriosus Severity Score Predicts Chronic Lung Disease or Death before Discharge

OBJECTIVES

To test the hypothesis that a patent ductus arteriosus (PDA) severity score (PDAsc) incorporating markers of pulmonary overcirculation and left ventricular (LV) diastolic function can predict chronic lung disease or death before discharge (CLD/death).

STUDY DESIGN

A multicenter prospective observational study was conducted for infants <29 weeks gestation. An echocardiogram was carried out on day 2 to measure PDA diameter and maximum flow velocity, LV output, diastolic flow in the descending aorta and celiac trunk, and variables of LV function using tissue Doppler imaging. Predictors of CLD/death were identified using logistic regression methods. A PDAsc was created and a receiver operating characteristic curve was constructed to assess its ability to predict CLD/death.

RESULTS

We studied 141 infants at a mean (SD) gestation and birthweight of 26 (1.4) weeks and 952 (235) g, respectively. Five variables were identified that were independently associated with CLD/death (gestation at birth, PDA diameter, maximum flow velocity, LV output, and LV a' wave). The PDAsc had a range from 0 (low risk) to 13 (high risk). Infants who developed CLD/death had a higher score than those who did not (7.3 [1.8] vs 3.8 [2.0], P < .001). PDAsc had an area under the curve of 0.92 (95% CI 0.86-0.97, P < .001) for the ability to predict CLD/death. A PDAsc cut-off of 5 has sensitivity and specificity of 92% and 87%, and positive and negative predictive values of 92% and 82%, respectively.

CONCLUSIONS

A PDAsc on day 2 can predict the later occurrence of CLD/death further highlighting the association between PDA significance and morbidity.

Animal models of bronchopulmonary dysplasia. The preterm baboon models

Much of the progress in improved neonatal care, particularly management of underdeveloped preterm lungs, has been aided by investigations of multiple animal models, including the neonatal baboon (Papio species). In this article we highlight how the preterm baboon model at both 140 and 125 days gestation (term equivalent 185 days) has advanced our understanding and management of the immature human infant with neonatal lung disease. Not only is the 125-day baboon model extremely relevant to the condition of bronchopulmonary dysplasia but there are also critical neurodevelopmental and other end-organ pathological features associated with this model not fully discussed in this limited forum. We also describe efforts to incorporate perinatal infection into these preterm models, both fetal and neonatal, and particularly associated with Ureaplasma/Mycoplasma organisms. Efforts to rekindle the preterm primate model for future evaluations of therapies such as stem cell replacement, early lung recruitment interventions coupled with noninvasive surfactant and high-frequency nasal ventilation, and surfactant therapy coupled with antioxidant or anti-inflammatory medications, to name a few, should be undertaken.

Managing the patent ductus arteriosus: current treatment options

Optimal management of the patent ductus arteriosus (PDA) in the premature infant remains controversial. Despite considerable historical and physiological data indicating that a persistent PDA may be harmful, robust evidence of long-term benefits or harms from treatment is lacking. This has been equated to a lack of benefit but is also a reflection of the fact that most clinical trials were designed to assess the effects of short-term (2-8 days) rather than prolonged exposure to a PDA. No clinical trials have been designed to assess the effects of prolonged exposure of persistent PDA on morbidity and mortality of very premature infants in the era of antenatal corticosteroids, surfactant and non-invasive respiratory support. Further research is required, but new insights and novel therapies are evolving, which will allow greater individual patient assessment, understanding of risk and optimisation of treatment. In this paper, we review the current literature, evidence for treatment options, including a non-interventional approach, and research directions for infants <28 weeks' gestational age.

Patent ductus arteriosus ligation and adverse outcomes: causality or bias?

Observational studies have associated patent ductus arteriosus (PDA) ligation in preterm infants with increased chronic lung disease (CLD), retinopathy of prematurity, and neurodevelopmental impairment at long-term follow-up. Although the biological rationale for this association is incompletely understood, there is an emerging secular trend toward a permissive approach to the PDA. However, insufficient adjustment for postnatal, pre-ligation confounders, such as intraventricular hemorrhage and the duration and intensity of mechanical ventilation, suggests the presence of residual bias due to confounding by indication, and obliges caution in interpreting the ligation-morbidity relationship. A period of conservative management after failure of medical PDA closure may be considered to reduce the number of infants treated with surgery. Increased mortality and CLD in infants with persistent symptomatic PDA suggests that surgical ligation remains an important treatment modality for preterm infants.

PDA ligation and health outcomes: a meta-analysis

BACKGROUND AND OBJECTIVE

Patent ductus arteriosus (PDA) ligation has been variably associated with neonatal morbidities and neurodevelopmental impairment (NDI). The objective was to systematically review and meta-analyze the impact of PDA ligation in preterm infants at <32 weeks' gestation on the risk of mortality, severe neonatal morbidities, and NDI in early childhood.

METHODS

Medline, Embase, Cochrane Central Register of Controlled Trials, Education Resources Information Centre (ERIC), Cumulative Index to Nursing and Allied Health (CINAHL), PsycINFO, and the Dissertation database were searched (1947 through August 2013). Risk of bias was assessed by using the Newcastle-Ottawa Scale and the Cochrane Risk of Bias tool. Meta-analyses were performed by using a random-effects model. Unadjusted and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were pooled when appropriate.

RESULTS

Thirty-nine cohort studies and 1 randomized controlled trial were included. Nearly all cohort studies had at least moderate risk of bias mainly due to failure to adjust for survival bias and important postnatal preligation confounders such as ventilator dependence, intraventricular hemorrhage, and sepsis. Compared with medical treatment, surgical ligation was associated with increases in NDI (aOR: 1.54; 95% CI: 1.01-2.33), chronic lung disease (aOR: 2.51; 95% CI: 1.98-3.18), and severe retinopathy of prematurity (aOR: 2.23; 95% CI: 1.62-3.08) but with a reduction in mortality (aOR: 0.54; 95% CI: 0.38-0.77). There was no difference in the composite outcome of death or NDI in early childhood (aOR: 0.95; 95% CI: 0.58-1.57).

CONCLUSIONS

Surgical ligation of PDA is associated with reduced mortality, but surviving infants are at increased risk of NDI. However, there is a lack of studies addressing survival bias and confounding by indication.

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.

Morbidity and mortality in preterm neonates with patent ductus arteriosus on day 3

OBJECTIVE

To assess the association between a patent ductus arteriosus (PDA) on day 3 of life and severe morbidity and mortality.

DESIGN

Cohort study.

SETTING

Neonatal Intensive Care Unit, Aarhus University Hospital, Denmark.

PATIENTS

All neonates with a gestational age less than 32 weeks admitted from 2010 to 2012.

INTERVENTIONS

All neonates (n=183) were routinely screened with echocardiography for PDA on day 3 of life. Information on baseline characteristics and outcome was collected by structured coding sheets and medical records.

MAIN OUTCOME MEASURES

The association among PDA diameter and pulmonary haemorrhage, intraventricular haemorrhage (IVH), necrotising enterocolitis, bronchopulmonary dysplasia (BPD), death, and the composite outcome of death or severe morbidity was assessed.

RESULTS

In neonates, born prior to 28 gestational weeks, a PDA on day 3 of life was associated with a threefold increase in odds of death or severe morbidity compared with neonates without PDA (OR=3.4; CI 1.1 to 11). The odds were highest in neonates with a large PDA (diameter ≥1.5 mm). Neonates with a large PDA were also found to have increased odds of IVH (OR 4.2; CI 1.3 to 14) and BPD (OR 3.7; CI 1.0 to 14) compared with neonates with no PDA.

CONCLUSIONS

In neonates born with a gestational age below 28 weeks the presence of a PDA on day 3 of life was associated with adverse outcome; this association was even more pronounced with a large PDA. Thus, early echocardiography may facilitate the identification of neonates suitable for a targeted approach to intervention in future randomised controlled trials.

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.

Pulmonary outcome and its correlates in school-aged children born with a gestational age ≤ 32 weeks

BACKGROUND

There is limited data regarding factors influencing the respiratory outcome at school age of ex-preterms born since the introduction of antenatal steroids, surfactant replacement together with less aggressive ventilation.

OBJECTIVES

To establish the main antenatal, neonatal and early childhood respiratory correlates of respiratory status in school-aged children born at ≤ 32 weeks of gestation.

METHODS

Ex-preterm children born at ≤ 32 weeks of gestation between 1997 and 2001 at Bordeaux University Hospital were evaluated at school age, using a respiratory questionnaire and lung function tests (spirometry, plethysmography, exercise challenge test and CO lung diffusing capacity DLCO measurements). Factors associated with lung function were investigated using polynomial regression analyses.

RESULTS

Of the 151 included children [mean age: 8.6 ± 0.8 years; mean gestational age, 30.1 ± 1.7 weeks; mean birth weight = 1310 ± 380 g; 68.2% ventilated at birth; 46.4% treated with surfactant; 36.4% with prior bronchopulmonary dysplasia (BPD)], 47% presented obstructive lung abnormalities, 11% restrictive or mixed lung abnormalities, 41% exercise-induced bronchoconstriction, and 15.5% reduced DLCO. Surfactant therapy was independently associated with a lower risk of lung abnormalities (p < 0.05). The association between BPD and lung abnormalities at school age was not significant, but prior BPD increased the risk of restrictive or mixed abnormalities (odds ratio: 6.11, confidence interval [1.1; 33.99]). Early childhood respiratory events were not associated with the occurrence of lung abnormalities.

CONCLUSION

Children born at ≤ 32 weeks of gestation remain at risk for impaired lung function at school age in particular when they did not receive surfactant. Restrictive or mixed lung defects are mainly associated with prior BPD.

The role of patent ductus arteriosus and its treatments in the development of bronchopulmonary dysplasia

A persistent left-to-right shunt through a patent ductus arteriosus (PDA) increases the rate of hydrostatic fluid filtration into the lung's interstitium, impairs pulmonary mechanics, and prolongs the need for mechanical ventilation. In preclinical trials, pharmacologic PDA closure leads to improved alveolarization and minimizes the impaired postnatal alveolar development that is the pathologic hallmark of the "new bronchopulmonary dysplasia (BPD)". Although early pharmacologic closure of the PDA decreases the incidence of pulmonary hemorrhage, intraventricular hemorrhage, and the need for PDA ligation, there is little evidence from controlled, clinical trials to support or refute a causal role for the PDA in the development of BPD. However, evidence from epidemiologic, preclinical, and randomized controlled clinical trials demonstrate that early ductus ligation is an independent risk factor for the development of BPD and may directly contribute to the neonatal morbidities it is trying to prevent.

Pros and cons of patent ductus arteriosus ligation: hemodynamic changes and other morbidities after patent ductus arteriosus ligation

Although surgical ligation of a persistent patent ductus arteriosus resolves the adverse hemodynamic consequences of the systemic-to-pulmonary shunt and may confer some long-term benefits, it is also associated with both immediate and long-term negative effects. The population that benefits from or is harmed by the procedure is not clearly defined. Although indiscriminate ligation of the patent ductus arteriosus in all patients is not supported by the available information, the recent suggestion declaring the ductus harmless is not supported either. As we await the results of appropriately designed randomized control studies to define the indications for ligation, we must use clinical and echocardiographic indicators of a hemodynamically significant ductus arteriosus and thoughtful assessment of each individual patient to help guide us in addressing this complex problem.

Patent ductus arteriosus: are current neonatal treatment options better or worse than no treatment at all?

Although a moderate-sized patent ductus arteriosus (PDA) needs to be closed by the time a child is 1-2 years old, there is great uncertainty about whether it needs to be closed during the neonatal period. Although 95% of neonatologists believe that a moderate-sized PDA should be closed if it persists in infants (born before 28 weeks) who still require mechanical ventilation, the number of neonatologists who treat a PDA when it occurs in infants who do not require mechanical ventilation varies widely. Both the high likelihood of spontaneous ductus closure and the absence of randomized controlled trials, specifically addressing the risks and benefits of neonatal ductus closure, add to the current uncertainty. New information suggests that early pharmacologic treatment has several important short-term benefits for the preterm newborn. By contrast, ductus ligation, while eliminating the detrimental effects of a PDA on lung development, may create its own set of morbidities that counteract many of the benefits derived from ductus closure.

Relationship between circulating platelet counts and ductus arteriosus patency after indomethacin treatment

OBJECTIVE

To determine whether low platelet counts are related to the incidence of patent ductus arteriosus (PDA) after indomethacin treatment in preterm human infants.

STUDY DESIGN

Multivariable logistic regression modeling was used for a cohort of 497 infants, who received indomethacin (within 15 hours of birth).

RESULTS

Platelet counts were not related to the incidence of permanent closure after indomethacin constriction. There was a relationship between platelet counts and the initial degree of constriction; however, this relationship appeared to be primarily influenced by the high end of the platelet distribution curve. PDA incidence was similar in infants with platelet counts < 50 × 10⁹/L and those with platelet counts above this range. Only when platelet counts were consistently >230 ×10⁹/L was there a decrease in PDA incidence.

CONCLUSION

In contrast to the evidence in mice, low circulating platelet counts do not affect permanent ductus closure (or ductus reopening) in human preterm infants.

Patent ductus arteriosus ligation alters pulmonary gene expression in preterm baboons

Ibuprofen-induced ductus closure improves pulmonary mechanics and increases alveolar surface area in premature baboons compared with baboons with a persistent patent ductus arteriosus (PDA). Ibuprofen-treatment has no effect on the expression of genes that regulate pulmonary inflammation but does increase the expression of alpha-ENaC (the transepithelial sodium channel that is critical for alveolar water clearance). Although ligation eliminates the PDA, it does not improve pulmonary mechanics or increase alveolar surface area. We used preterm baboons (delivered at 67% of term gestation and ventilated for 14 d) to study whether the lack of beneficial effects, after PDA ligation, might be due to alterations in pulmonary gene expression. We found no differences in ventilation or oxygenation indices between animals that were ligated (n = 7) on day of life 6 and those that had a persistent PDA (n = 12) during the entire 14 d study. In contrast with no intervention, PDA ligation produced a significant increase in the expression of genes involved with pulmonary inflammation (COX-2, TNF-α, and CD14) and a significant decrease in alpha-ENaC sodium channel expression. We speculate that these changes may decrease the rate of alveolar fluid clearance and contribute to the lack of improvement in pulmonary mechanics after PDA ligation.

Interatrial defect and patent ductus arteriosus

We greatly appreciated the letter to the Editor by Rana Olgunturk and Serdar Kula. We can say that his interpretation coincides with our interpretation and with the knowledge about patent ductus arteriosus (PDA) and secundum atrial septal defects. Although functional closure of PDA usually occurs in the first few hours of life in healthy infants born at term (about 15 h of life in healthy infants born at term), true anatomic closure, in which the ductus loses the ability to reopen, may take several weeks. Persistent, patency for up to 10 days after birth is encountered in premature infants. The male Italian newborn infant of the cited case report was referred at the age of 2 days to the Cardiology Unit for a cardiovascular check-up (in the text: "in a 3-day-old newborn infant" must be comprehended as "in a 2-day-old newborn infant") and was mature. Interatrial septal shunts in newborns are frequently encountered. Since there are no definitive diagnostic criteria for both patent foramen ovale and secundum atrial septal defects, it is difficult to differentiate these two lesions by echocardiography, particularly in the early newborn period. Some authors, called these two lesions as "interatrial septal openings". The diagnosis, in the case report cited, was made not only on the basis of the first observation but also on the basis of the persistence of abnormalities during the long-term follow-up and therefore the infant was referred to a pediatric heart surgical unit were the abnormalities were confirmed.

Patent ductus arteriosus in the preterm infant: to treat or not to treat?

Pharmacological and/or surgical closure of a hemodynamically significant patent ductus arteriosus (PDA) in the very preterm infant has been the standard of care over the past few decades. However, the rationale for closure of PDA has recently been challenged. In this article, the factors that have fueled the controversy of the approach to the management of PDA and the gap in our knowledge are reviewed in detail. In addition, the pros and cons of the different treatment strategies applied in clinical care are evaluated with a focus on discussing the available evidence in the literature.

Early surgical ligation versus a conservative approach for management of patent ductus arteriosus that fails to close after indomethacin treatment

OBJECTIVE

To examine whether a more conservative approach to treating patent ductus arteriosus (PDA) is associated with an increase or decrease in morbidity compared with an approach involving early PDA ligation.

STUDY DESIGN

In January 2005, we changed our approach to infants born at age

RESULTS

The 2 periods had similar rates of perinatal/neonatal risk factors and indomethacin failure (24%), as well as ventilator management and feeding advance protocols. The conservative approach (period 2) was associated with decreased rates of duct ligation (72% vs 100%; P<.05). Even though infants subjected to this approach were exposed to larger PDA shunts for longer durations, the rates of bronchopulmonary dysplasia, sepsis, retinopathy of prematurity, neurologic injury, and death were similar to those in period 1. The overall rate of necrotizing enterocolitis was significantly lower in period 2 compared with period 1.

CONCLUSIONS

These findings support the need for new controlled, randomized trials to reexamine the benefits and risks of different approaches to PDA treatment.

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Key Words

• surgery
• ductus ligation
• indomethacin
• patent ductus arteriosus

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MESH Headings

• Ductus Arteriosus, Patent/drug therapy
• Ductus Arteriosus, Patent/surgery
• Female
• Humans
• Indomethacin/therapeutic use
• Infant, Newborn
• Ligation
• Male
• Prospective Studies
• Time Factors
• Treatment Failure

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Grants

• R01 HL046691 NHLBI NIH HHS
• R01 HL046691-16 NHLBI NIH HHS
• UL1 RR024131 NCRR NIH HHS
• HL46691 NHLBI NIH HHS

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Affiliation(s)

Nami Jhaveri Department of Pediatrics, University of California, San Francisco, CA 94143-0544, USA
Anita Moon-Grady
Ronald I Clyman

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The role of patent ductus arteriosus ligation in bronchopulmonary dysplasia: reexamining a randomized controlled trial

OBJECTIVE

To reexamine data from a randomized controlled trial of prophylactic ductus ligation to determine whether ligation contributes directly to the development of bronchopulmonary dysplasia (BPD) in extremely low birth weight infants.

STUDY DESIGN

The control group underwent ligation only if they had development of a symptomatic patent ductus arteriosus (PDA). The Prophylactic Ligation group underwent ligation within 24 hours of birth regardless of the presence or absence of symptoms of a PDA. We hypothesized that the incidence of BPD would be higher in the prophylactic ligation group because more ligations were performed than in the control group.

RESULTS

Prophylactic ligation significantly increased the incidence of BPD (defined as a supplemental oxygen requirement at 36 weeks postmenstrual age) and the incidence of mechanical ventilation at 36 weeks. The groups were statistically similar in gestation, sex, race, fluid administration, intraventricular hemorrhage, pulmonary air leaks, and survival to 36 weeks. The lower incidence of BPD in the control group occurred despite the fact that the incidence of necrotizing enterocolitis (a known risk factor for BPD) was significantly elevated in the control group. Only infants who had previously undergone a PDA ligation had development of BPD in the control group.

CONCLUSION

Prophylactic ligation, while eliminating the PDA, increases the risk for BPD.