Evaluation of the association between patent ductus arteriosus approach and neurodevelopment in extremely preterm infants

OBJECTIVE

Assess if unit-level PDA management correlates with neurodevelopmental impairment (NDI) at 18-24 months corrected postnatal age (CPA) in extremely preterm infants.

STUDY DESIGN

Retrospective analysis of infants born at <29 weeks (2014-2017) across two units having distinct PDA strategies. Site 1 utilized an echocardiography-based treatment strategy aiming for accelerated closure (control). Site 2 followed a conservative approach.

PRIMARY ENDPOINT

NDI, characterized by cerebral palsy, any Bayley-III composite score <85, sensorineural/mixed hearing loss, or at least unilateral visual impairment.

RESULTS

377 infants were evaluated. PDA treatment rates remained unchanged in Site 1 but eventually reached 0% in Site 2. Comparable rates of any/significant NDI were seen across both sites (any NDI: 38% vs 36%; significant NDI: 13% vs 10% for Site 1 and 2, respectively). After adjustments, NDI rates remained similar.

CONCLUSION

PDA management strategies in extremely preterm newborns showed no significant impact on neurodevelopment outcomes at 18-24 months CPA.

Pulmonary Hypertension in Developmental Lung Diseases

Diverse genetic developmental lung diseases can present in the neonatal period with hypoxemic respiratory failure, often associated with with pulmonary hypertension. Intractable hypoxemia and lack of sustained response to medical management should increase the suspicion of a developmental lung disorder. Genetic diagnosis and lung biopsy are helpful in establishing the diagnosis. Early diagnosis can result in optimizing management and redirecting care if needed. This article reviews normal lung development, various developmental lung disorders that can result from genetic abnormalities at each stage of lung development, their clinical presentation, management, prognosis, and differential diagnoses.

Multilamellated Basement Membranes in the Capillary Network of Alveolar Capillary Dysplasia

A minimal diffusion barrier is key to the pulmonary gas exchange. In alveolar capillary dysplasia (ACD), a rare genetically driven disease of early infancy, this crucial fibrovascular interface is compromised while the underlying pathophysiology is insufficiently understood. Recent in-depth analyses of vascular alterations in adult lung disease encouraged researchers to extend these studies to ACD and compare the changes of the microvasculature. Lung tissue samples of children with ACD (n = 12), adults with non-specific interstitial pneumonia (n = 12), and controls (n = 20) were studied using transmission electron microscopy, single-gene sequencing, immunostaining, exome sequencing, and broad transcriptome profiling. In ACD, pulmonary capillary basement membranes were hypertrophied, thickened, and multilamellated. Transcriptome profiling revealed increased CDH5, COL4A1, COL15A1, PTK2B, and FN1 and decreased VIT expression, confirmed by immunohistochemistry. In contrast, non-specific interstitial pneumonia samples showed a regular basement membrane architecture with preserved VIT expression but also increased COL15A1+ vessels. This study provides insight into the ultrastructure and pathophysiology of ACD. The lack of normally developed lung capillaries appeared to cause a replacement by COL15A1+ vessels, a mechanism recently described in interstitial lung disease. The VIT loss and FN1 overexpression might contribute to the unique appearance of basement membranes in ACD. Future studies are needed to explore the therapeutic potential of down-regulating the expression of FN1 and balancing VIT deficiency.

From 6-wk Lungs to 6 y: Increasing the Donor Pool for Pediatric Lung Transplantation

BACKGROUND

Lung transplantation in the pediatric population is a challenge. With the donor pool being so small and lungs from young donors rare and precious, every organ available needs to be utilized to its best potential.

CASE

Here, we describe the case of a 6-wk-old donor of double lungs to a 5-mo-old baby girl diagnosed with alveolar capillary dysplasia with misalignment of the pulmonary veins. The recipient is doing very well, 6 y after the transplant, now following normal growth.

DISCUSSION

The challenges facing pediatric cardiothoracic transplantation in terms of organ supply and demand are enormous.

CONCLUSIONS

In this article, we discuss some of the issues around the shortage of organs and alternatives to increase the organ donor pool.

Early neurodevelopmental outcomes of extreme preterm infants exposed to paracetamol: a retrospective cohort study

BACKGROUND

Paracetamol is commonly used for analgesia and patent ductus arteriosus (PDA) treatment in preterm infants. We aimed to evaluate early neurodevelopmental outcomes of extreme preterm infants exposed to paracetamol during their neonatal admission.

METHODS

This retrospective cohort study included surviving infants born at <29 weeks gestation, or with a birth weight of <1000 grams. Neurodevelopmental outcomes studied were early cerebral palsy (CP) or high risk of CP diagnosis, Hammersmith Infant Neurological Examination (HINE) score and Prechtl General Movement Assessment (GMA) at 3-4 months corrected age.

RESULTS

Two hundred and forty-two infants were included, of which 123 were exposed to paracetamol. After adjusting for birth weight, sex and chronic lung disease, there were no significant associations between paracetamol exposure and early CP or high risk of CP diagnosis (aOR 1.46, 95% CI 0.61, 3.5), abnormal or absent GMA (aOR 0.82, 95% CI 0.37, 1.79) or HINE score (adjusted β -0.19, 95% CI -2.39, 2.01). Subgroup analysis stratifying paracetamol exposure into <180 mg/kg or ≥180 mg/kg cumulative dose found that neither had significant effects on outcomes.

CONCLUSIONS

In this cohort of extreme preterm infants, no significant association was found between exposure to paracetamol during the neonatal admission and adverse early neurodevelopment.

IMPACT

Paracetamol is commonly used in the neonatal period for analgesia and patent ductus arteriosus treatment in preterm infants, although prenatal paracetamol use has been associated with adverse neurodevelopmental outcomes. Exposure to paracetamol during the neonatal admission was not associated with adverse early neurodevelopment at 3-4 months corrected age in this cohort of extreme preterm infants. The findings from this observational study is consistent with the small body of literature supporting the lack of association between neonatal paracetamol exposure and adverse neurodevelopmental outcomes in preterm infants.

[Treatment of patent ductus arteriosus in very preterm infants in China]

Objective: To describe the current status and trends in the treatment of patent ductus arteriosus (PDA) among very preterm infants (VPI) admitted to the neonatal intensive care units (NICU) of the Chinese Neonatal Network (CHNN) from 2019 to 2021, and to compare the differences in PDA treatment among these units. Methods: This was a cross-sectional study based on the CHNN VPI cohort, all of 22 525 VPI (gestational age<32 weeks) admitted to 79 tertiary NICU within 3 days of age from 2019 to 2021 were included. The overall PDA treatment rates were calculated, as well as the rates of infants with different gestational ages (≤26, 27-28, 29-31 weeks), and pharmacological and surgical treatments were described. PDA was defined as those diagnosed by echocardiography during hospitalization. The PDA treatment rate was defined as the number of VPI who had received medication treatment and (or) surgical ligation of PDA divided by the number of all VPI. Logistic regression was used to investigate the changes in PDA treatment rates over the 3 years and the differences between gestational age groups. A multivariate Logistic regression model was constructed to compute the standardized ratio (SR) of PDA treatment across different units, to compare the rates after adjusting for population characteristics. Results: A total of 22 525 VPI were included in the study, with a gestational age of 30.0 (28.6, 31.0) weeks and birth weight of 1 310 (1 100, 1 540) g; 56.0% (12 615) of them were male. PDA was diagnosed by echocardiography in 49.7% (11 186/22 525) of all VPI, and the overall PDA treatment rate was 16.8% (3 795/22 525). Of 3 762 VPI who received medication treatment, the main first-line medication used was ibuprofen (93.4% (3 515/3 762)) and the postnatal day of first medication treatment was 6 (4, 10) days of age; 59.3% (2 231/3 762) of the VPI had been weaned from invasive respiratory support during the first medication treatment, and 82.2% (3 092/3 762) of the infants received only one course of medication treatment. A total of 143 VPI underwent surgery, which was conducted on 32 (22, 46) days of age. Over the 3 years from 2019 to 2021, there was no significant change in the PDA treatment rate in these VPI (P=0.650). The PDA treatment rate decreased with increasing gestational age (P<0.001). The PDA treatment rates for VPI with gestational age ≤26, 27-28, and 29-31 weeks were 39.6% (688/1 737), 25.9% (1 319/5 098), and 11.4% (1 788/15 690), respectively. There were 61 units having a total number of VPI≥100 cases, and their rates of PDA treatment were 0 (0/116)-47.4% (376/793). After adjusting for population characteristics, the range of standardized ratios for PDA treatment in the 61 units was 0 (95%CI 0-0.3) to 3.4 (95%CI 3.1-3.8). Conclusions: From 2019 to 2021, compared to the peers in developed countries, VPI in CHNN NICU had a different PDA treatment rate; specifically, the VPI with small birth gestational age had a lower treatment rate, while the VPI with large birth gestational age had a higher rate. There are significant differences in PDA treatment rates among different units.

Effect of Endotracheal Suctioning on Infants Born through Meconium-Stained Amniotic Fluid: A Meta-analysis

OBJECTIVE

Meconium is a common finding in amniotic fluid and placental specimens, particularly in term and post-term pregnancies. The objective of this paper was to perform a meta-analysis to examine the impact of endotracheal suctioning on the occurrence of meconium aspiration syndrome (MAS), mortality, and complications.

STUDY DESIGN

PubMed, EMBASE, and the Cochrane library were systematically searched for comparative studies. Odds ratios (ORs), weighted mean differences (WMDs), and corresponding 95% confidence intervals (CIs) were used to compare the outcomes.

RESULTS

Twelve studies were included in the meta-analysis. There were no significant impacts of endotracheal suctioning on the occurrence of MAS (OR = 3.05, 95% CI: 0.48-19.56), mortality (OR = 1.25, 95% CI: 0.35-4.44), the need for mechanical ventilation (OR = 4.20, 95% CI: 0.32-54.72), the occurrence of pneumothorax (OR = 0.99, 95% CI: 0.34-2.85), persistent pulmonary hypertension of the newborn (PPHN), (OR = 1.31, 95% CI: 0.58-2.98), hypoxic-ischemic encephalopathy (HIE) (OR = 0.82, 95% CI: 0.52-1.30), and length of stay (WMD = -0.11, 95% CI: -0.99-0.77).

CONCLUSION

Routine endotracheal suctioning at birth is not useful in preventing MAS, mortality, mechanical ventilation, PPHN, HIE, and prolonged length of stay in neonates born through MSAF.

KEY POINTS

· Routine suctioning is not recommended for newborns.. · Endotracheal aspiration is not beneficial for MAS.. · Future research may focus on selected neonates..

FOXF1 Regulates Alveolar Epithelial Morphogenesis through Transcriptional Activation of Mesenchymal WNT5A

Mutations in the FOXF1 (forkhead box F1) gene, encoding the mesenchymal FOX (forkhead box) transcription factor, are linked to alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV), a severe congenital disorder associated with the loss of alveolar capillaries and lung hypoplasia. Although proangiogenic functions of FOXF1 have been extensively studied, the role of FOXF1 in mesenchymal-epithelial signaling during lung development remains uncharacterized. Herein, we used murine lung organoids to demonstrate that the S52F FOXF1 mutation (found in patients with ACDMPV) stimulates canonical WNT/β-catenin signaling in type 2 alveolar epithelial cells (AEC2s), leading to increased proliferation of AEC2s and decreased differentiation of AEC2s into type 1 alveolar epithelial cells (AEC1s). Alveolar organoids containing Foxf1WT/S52F lung fibroblasts and wild-type epithelial cells grew faster on Matrigel and exhibited AEC2 hyperplasia. AEC2 hyperplasia and loss of AEC1s were found in the lungs of Foxf1WT/S52F embryos, a mouse model of ACDMPV. Activation of canonical WNT/β-catenin signaling in AEC2s of lung organoids and Foxf1WT/S52F mice was associated with decreased expression of noncanonical WNT5A (Wnt family member 5A) ligand in lung fibroblasts. Mechanistically, FOXF1 directly activates the Wnt5a gene transcription through an evolutionarily conserved +6320/+6326 region located in the first intron of the Wnt5a gene. Site-directed mutagenesis of the +6320/+6326 region prevented the transcriptional activation of the Wnt5a enhancer by FOXF1. Treatment with exogenous WNT5A ligand inhibited the effects of the S52F FOXF1 mutation on canonical WNT/β-catenin signaling in alveolar organoids, preventing aberrant AEC2 expansion and restoring differentiation of AEC1s. Activation of either FOXF1 or WNT5A may provide an attractive strategy to improve lung function in patients with ACDMPV.

Clinical and echocardiographic characteristics associated with evolution of patent ductus arteriosus in preterm neonates: A prospective cohort study

BACKGROUND

In preterm infants, persistence of ductus arteriosus is an important medical condition. Functional echocardiography for patent ductus arteriosus (PDA) may guide clinical decision-making regarding treatment requirement strategies. Objectives of the study were to assess the trends of clinical and functional echocardiographic parameters with evolution of ductus arteriosus in babies≤1250 gm of birth weight and to evaluate whether there is any association of these parameters with persistence of ductus.

METHODS

In this prospective observational study, recruited babies were assessed serially for clinical events and functional echocardiography. Babies were classified into three groups: without PDA, with PDA but PDA spontaneously closed (within 7 days) and persistent PDA.

RESULT

We included 143 infants (Birth weight 1017±179 g, gestational age 30.8±2.7 weeks). Out of 60 babies with PDA, PDA failed to close spontaneously in first week in 32 (53.4 %) infants. PDA Doppler flow pattern on day 3 was found to be one of the most significant markers for future ductus. The highest frequency of growing pattern (37.5%) and pulsatile pattern (59.4%) was seen in persistence ductus group. PDA diameter and LA/Ao ratio were found strongly correlated with all other variables except E/A ratio.

CONCLUSION

We noticed persistence of ductus in preterm infants had significant clinical and echocardiographic association. PDA doppler flow pattern on day 3 was found to be a significant marker for future behaviour of ductus. Significant correlation was found among individual functional echocardiographic parameters in babies with PDA. This would guide judicious treatment of PDA in preterm neonates.

Nebulized Magnesium Sulfate for Treatment of Persistent Pulmonary Hypertension of Newborn: A Pilot Randomized Controlled Trial

OBJECTIVES

To investigate the effectiveness of nebulized magnesium sulfate in treating persistent pulmonary hypertension of newborn (PPHN).

METHODS

Twenty-eight mechanically ventilated term neonates with severe PPHN were randomized into two groups: NebMag group (n = 14), who receiving nebulized isotonic magnesium (1024 mg/h), and IVMag group (n = 14), who received intravenous magnesium (200 mg/kg over 30 min, followed by 50 mg/kg/h). The study time frame was 24 h. Outcome measures were the changes in oxygenation index (OI), mean arterial blood pressure (MABP), vasoactive inotropic score (VIS), and serum magnesium level.

RESULTS

Baseline demographic, ventilatory, and hemodynamic characteristics were comparable between the two groups. At the end of the study, the OI decreased by 44.3% in the NebMag group compared with 35.3% in the IVMag group (mean difference -3.14; 95%CI -5.08, -1.19; p 0.003). The NebMag group had a higher MABP (mean difference 2.29 mmHg; 95% CI 1.80, 2.77; p 0.000) and lower VIS (mean difference -14.64; 95% CI -16.52, -12.77; p 0.000) at the 24-h study time point. The increase in serum magnesium level, measured at 12-h study time point, was lower in the NebMag group (mean difference -2.26 mmol/L; 95% CI -2.58, -1.96; p 0.000).

CONCLUSION

Nebulized magnesium sulfate may be an effective therapeutic modality for neonates with severe PPHN on mechanical ventilation, but this should be confirmed by larger studies. Retrospectively registered at www.clinicaltrials.gov (identifier: NCT04328636).

PPHN and oxidative stress: a review of literature

Persistent pulmonary hypertension of the neonate is a multifactorial condition characterized by maladaptive pulmonary vascular remodeling and abnormal contractile reactivity. This review evaluates the role of oxidative stress and antioxidant treatment on the persistent pulmonary hypertension of the neonate.

Genotype-phenotype correlation in two Polish neonates with alveolar capillary dysplasia

BACKGROUND

Alveolar capillary dysplasia (ACD) is a rare cause of severe pulmonary hypertension and respiratory failure in neonates. The onset of ACD is usually preceded by a short asymptomatic period. The condition is refractory to all available therapies as it irreversibly affects development of the capillary bed in the lungs. The diagnosis of ACD is based on histopathological evaluation of lung biopsy or autopsy tissue or genetic testing of FOXF1 on chromosome 16q24.1. Here, we describe the first two Polish patients with ACD confirmed by histopathological and genetic examination.

CASE PRESENTATION

The patients were term neonates with high Apgar scores in the first minutes of life. They both were diagnosed prenatally with heart defects. Additionally, the first patient presented with omphalocele. The neonate slightly deteriorated around 12th hour of life, but underwent surgical repair of omphalocele followed by mechanical ventilation. Due to further deterioration, therapy included inhaled nitric oxide (iNO), inotropes and surfactant administration. The second patient was treated with prostaglandin E1 since birth due to suspicion of aortic coarctation (CoA). After ruling out CoA in the 3rd day of life, infusion of prostaglandin E1 was discountinued and immediately patient's condition worsened. Subsequent treatment included re-administration of prostaglandin E1, iNO and mechanical ventilation. Both patients presented with transient improvement after application of iNO, but died despite maximized therapy. They were histopathologically diagnosed post-mortem with ACD. Array comparative genomic hybridization in patient one and patient two revealed copy-number variant (CNV) deletions, respectively, ~ 1.45 Mb in size involving FOXF1 and an ~ 0.7 Mb in size involving FOXF1 enhancer and leaving FOXF1 intact.

CONCLUSIONS

Both patients presented with a distinct course of ACD, extra-pulmonary manifestations and response to medications. Surgery and ceasing of prostaglandin E1 infusion should be considered as potential causes of this variability. We further highlight the necessity of thorough genetic testing and histopathological examination and propose immunostaining for CD31 and CD34 to facilitate the diagnostic process for better management of infants with ACD.

Sepiapterin improves angiogenesis of pulmonary artery endothelial cells with in utero pulmonary hypertension by recoupling endothelial nitric oxide synthase

Persistent pulmonary hypertension of the newborn (PPHN) is associated with decreased blood vessel density that contributes to increased pulmonary vascular resistance. Previous studies showed that uncoupled endothelial nitric oxide (NO) synthase (eNOS) activity and increased NADPH oxidase activity resulted in marked decreases in NO bioavailability and impaired angiogenesis in PPHN. In the present study, we hypothesize that loss of tetrahydrobiopterin (BH4), a critical cofactor for eNOS, induces uncoupled eNOS activity and impairs angiogenesis in PPHN. Pulmonary artery endothelial cells (PAEC) isolated from fetal lambs with PPHN (HTFL-PAEC) or control lambs (NFL-PAEC) were used to investigate the cellular mechanisms impairing angiogenesis in PPHN. Cellular mechanisms were examined with respect to BH4 levels, GTP-cyclohydrolase-1 (GCH-1) expression, eNOS dimer formation, and eNOS-heat shock protein 90 (hsp90) interactions under basal conditions and after sepiapterin (Sep) supplementation. Cellular levels of BH4, GCH-1 expression, and eNOS dimer formation were decreased in HTFL-PAEC compared with NFL-PAEC. Sep supplementation decreased apoptosis and increased in vitro angiogenesis in HTFL-PAEC and ex vivo pulmonary artery sprouting angiogenesis. Sep also increased cellular BH4 content, NO production, eNOS dimer formation, and eNOS-hsp90 association and decreased the superoxide formation in HTFL-PAEC. These data demonstrate that Sep improves NO production and angiogenic potential of HTFL-PAEC by recoupling eNOS activity. Increasing BH4 levels via Sep supplementation may be an important therapy for improving eNOS function and restoring angiogenesis in PPHN.

Duration of persistent abnormal ductus venosus flow and its impact on perinatal outcome in fetal growth restriction

OBJECTIVE

To study if the duration of individual Doppler abnormalities is an independent predictor of adverse outcome in fetal growth restriction (FGR) caused by placental dysfunction.

METHODS

This was a secondary analysis of patients with FGR (abdominal circumference < 5(th) percentile and umbilical artery (UA) pulsatility index (PI) elevation) who had at least three examinations before delivery. Days of duration of absent/reversed UA end-diastolic velocity (UA-AREDV), low middle cerebral artery PI (brain sparing), ductus venosus (DV) and umbilical vein Doppler abnormalities were related to stillbirth, major neonatal morbidity and intact survival.

RESULTS

One hundred and seventy-seven study participants underwent a total of 1069 examinations. The duration of an absent/reversed a-wave in the DV (DV-RAV) was significantly higher in stillbirths (median, 6 days) compared with intact survivors and those with major morbidity (median, 0 days for both; P = 0.006 and P = 0.001, respectively). Duration of brain sparing was also longer in stillbirth cases compared with intact survivors (median, 19 days vs. 9 days, P = 0.02). Stepwise multinomial logistic regression showed that gestational age at delivery was a significant codeterminant of outcome for all arterial Doppler abnormalities when the DV a-wave was antegrade. However, when present, the duration of DV-RAV was the only contributor to stillbirth (probability of stillbirth = 1/(1 + exp - (interval to delivery × 1.03 - 2.28)), r2 = 0.73). Receiver-operating characteristics curve statistics showed that a DV-RAV for > 7 days predicted stillbirth (100% sensitivity, 80% specificity, likelihood ratio = 5.0, P < 0.0001). In contrast, neither neonatal death nor neonatal morbidity was predicted by the days of persistent DV-RAV.

CONCLUSIONS

The duration of absent or reversed flow during atrial systole in the DV is a strong predictor of stillbirth that is independent of gestational age. While prematurity remains the strongest predictor of neonatal risks it is unlikely that pregnancy can be prolonged by more than 1 week in this setting.

[Recommendations for inhaled nitric oxide treatment in the newborn]

The recommendations in this document describe the current indications for inhaled nitric oxide (iNO) treatment in the newborn and clearly distinguish between those supported by scientific evidence and those for which evidence is still lacking, such as its use in preterm infants. The methodology for iNO administration, its dosage and the main secondary effects are discussed, and the reasons for lack of response to this treatment are analyzed.

Maternal, neonatal, and placental features associated with diffuse chorioamniotic hemosiderosis, with special reference to neonatal morbidity and mortality

OBJECTIVE

Our purpose was to examine the significance of diffuse chorioamniotic hemosiderosis (DCH) on neonatal morbidity and mortality.

METHODS

Using data from a retrospective case-control study, we analyzed 46 singleton placentas with DCH from infants who were delivered and/or admitted to the neonatal intensive care unit of Kanagawa Children's Medical Center during 1987-2001 and 92 control placentas without DCH from infants of comparable gestational age, birth weight, and duration.

RESULTS

Mean and standard deviation of gestational age and infants' birth weight at delivery from the DCH group were 27 +/- 3 weeks and 939 +/- 342 g, respectively. Macroscopically, the placentas with DCH were more likely to show old peripheral blood clots (46% in the DCH group vs 8% in control group), subchorionic hematoma (20% vs 1%), and circumvallation (13% vs 1%). Histologically, amniotic necrosis was significantly more frequent in the DCH group (63% vs 24%). Of the obstetric factors, incidence of recurrent episodes of vaginal bleeding (70% vs 11%), oligohydramnios (59% vs 8%), and chronic abruption-oligohydramnios sequence (57% vs 5%) were significantly higher in the DCH group. Of the neonatal factors, persistent pulmonary hypertension of the newborn (29% vs 8%) and dry lung and/or pulmonary hypoplasia (20% vs 4%) were more common. However, respiratory distress syndrome was rare (15% vs 45%) in the DCH group. Neonatal death including stillbirth was increased in the DCH group but was not significant (24% vs 15%). Of infants who survived beyond day 28, chronic lung disease (CLD) was more frequent in the DCH group (51% vs 22%). The association of DCH, especially accompanied by amniotic necrosis, with CLD was still evident using likelihood ratio test.

CONCLUSION

DCH is closely associated with preterm delivery, pulmonary hypertension of the newborn, and dry lung syndrome and is a significant risk factor for CLD.

Pulmonary hypertension caused by medial hypertrophy associated with aortic stenosis and preductal coarctation

A 7-month-old female infant with aortic stenosis, preductal coarctation, and pulmonary hypertension underwent operation. Intraoperative lung biopsy revealed marked medial hypertrophy of the pulmonary arterioles. This histopathology is compatible with persistent pulmonary hypertension in the newborn. She is alive about 5 years after the operation, but pulmonary hypertension remains. The pathogenesis is discussed.

Pulmonary hypertension in childhood

In the presence of pulmonary hypertension, the pulmonary vasculature fails to remodel after birth. Secondary changes then develop, and do so more rapidly than in the adult lung because the cells are exposed to the insult whilst still relatively undifferentiated. The commonest causes of pulmonary hypertension in newborn and young infants are alveolar hypoxia, and congenital heart disease causing a left-to-right shunt and increased pulmonary blood flow. The initial response of an increase in pulmonary arterial muscularity is common to both, but intimal proliferation can develop rapidly in those with complex congenital heart disease. The structural abnormalities are accompanied by abnormalities in the control of pulmonary vascular reactivity, a problem which is the focus of much current research activity.

Patent ductus arteriosus in the neonate

Recently there has been a significant reappraisal of the role of PDA in the context of neonatal cardiopulmonary disease. This article reviews surgical intervention, pharmacologic treatment, and assessment of ductal patency in the neonate.