Persistent pulmonary hypertension of the newborn: pathogenesis, etiology, and management

Defining the Typical Course of Persistent Pulmonary Hypertension of the Newborn: When to Think Beyond Reversible Causes

OBJECTIVES

To describe the typical clinical course of reversible persistent pulmonary hypertension of the newborn (PPHN) from perinatal etiologies and compare that with the clinical course of PPHN due to underlying fetal developmental etiologies.

STUDY DESIGN

This was a single-center, retrospective cohort study of liveborn newborns either born or transferred to our facility for higher level of care between 2015 and 2020 with gestational age ≥35 weeks and a clinical diagnosis of PPHN in the electronic health record. Newborns with complex congenital heart disease and congenital diaphragmatic hernia were excluded. Using all data available at time of collection, newborns were stratified into 2 groups by PPHN etiology - perinatal and fetal developmental causes. Primary outcomes were age at initiation, discontinuation, and total duration of extracorporeal life support, mechanical ventilation, supplemental oxygen, inhaled nitric oxide, inotropic support, and prostaglandin E1. Our secondary outcome was age at echocardiographic resolution of pulmonary hypertension. Groups were compared by t-test. Time-to-event Kaplan Meier curves described and compared (log-rank test) discontinuation of each therapy.

RESULTS

Sixty-four (72%) newborns had perinatal etiologies whereas 24 (28%) had fetal developmental etiologies. The resolution of perinatal PPHN was more rapid compared with fetal developmental PPHN. By 10 days of age, more neonates were off inotropes (98% vs 29%, P < .01), decannulated from extracorporeal life support (100% vs 0%, P < .01), extubated (75% vs 37%, P < .01), and had echocardiographic resolution of PH (35% vs 7%, P = .02).

CONCLUSIONS

An atypical PPHN course, characterized by persistent targeted therapies in the second week of life, warrants further work-up for fetal developmental causes.

Serum pentraxin 3 levels in term neonates with persistent pulmonary hypertension

BACKGROUND

Persistent pulmonary hypertension of the neonate (PPHN) is a serious disorder. The long pentraxin 3 (PTX3) plays an important role in angiogenesis, cell proliferation, tissue repair and cell regulation. The present study aims to assess the diagnostic and clinical value of PTX3 in PPHN.

METHODS

The present case-control 60 full-term neonates diagnosed with PPHN by echocardiography within 72 hours of birth. In addition, there were 30 age and sex-matched healthy neonates who served as controls. All participants were subjected to careful history taking and complete clinical examination, Laboratory investigations included complete blood count, C-reactive protein (CRP), blood culture and PTX3 level. Radiological investigations included plain X- ray and two-dimensional transthoracic echocardiography (TTE).

RESULTS

Comparison between patients and controls revealed that patients had significantly higher CRP (6.12±2.18 versus 3.69±1.25 mg/dl, p < 0.001) and PTX3 levels (2.07±0.67 versus 0.96±0.21, p < 0.001) when compared with controls. Patients with associated PDA had significantly higher PTX3 levels when compared with patients without (2.58±0.5 versus 2.02±0.51 ng/ml, p = 0.002). Also, patients with associated PFO had significantly higher PTX3 levels when compared with patients without (2.12±1.05 versus 2.05±0.46, p = 0.002). ROC curve analysis identified good performance of CRP and PTX3 levels in diagnosis of PPHN with PTX3 showing better performance.

CONCLUSIONS

There is a significant association between serum PTX3 levels and PPHN particularly those with associated PDA or PFO.

Evidence-Based Guidelines for Acute Stabilization and Management of Neonates with Persistent Pulmonary Hypertension of the Newborn

Persistent pulmonary hypertension of the newborn, or PPHN, represents a challenging condition associated with high morbidity and mortality. Management is complicated by complex pathophysiology and limited neonatal specific evidence-based literature, leading to a lack of universal contemporary clinical guidelines for the care of these patients. To address this need and to provide consistent high-quality clinical care for this challenging population in our neonatal intensive care unit, we sought to develop a comprehensive clinical guideline for the acute stabilization and management of neonates with PPHN. Utilizing cross-disciplinary expertise and incorporating an extensive literature search to guide best practice, we present an approachable, pragmatic, and clinically relevant guide for the bedside management of acute PPHN. KEY POINTS: · PPHN is associated with several unique diagnoses; the associated pathophysiology is different for each unique diagnosis.. · PPHN is a challenging, dynamic, and labile process for which optimal care requires frequent reassessment.. · Key management goals are adequate tissue oxygen delivery, avoiding harm..

Consensus Panel Recommendations for the Pharmacological Management of Pregnant Women with Depressive Disorders

INTRODUCTION

The initiative of a consensus on the topic of antidepressant and anxiolytic drug use in pregnancy is developing in an area of clinical uncertainty. Although many studies have been published in recent years, there is still a paucity of authoritative evidence-based indications useful for guiding the prescription of these drugs during pregnancy, and the data from the literature are complex and require expert judgment to draw clear conclusions.

METHODS

For the elaboration of the consensus, we have involved the scientific societies of the sector, namely, the Italian Society of Toxicology, the Italian Society of Neuropsychopharmacology, the Italian Society of Psychiatry, the Italian Society of Obstetrics and Gynecology, the Italian Society of Drug Addiction and the Italian Society of Addiction Pathology. An interdisciplinary team of experts from different medical specialties (toxicologists, pharmacologists, psychiatrists, gynecologists, neonatologists) was first established to identify the needs underlying the consensus. The team, in its definitive structure, includes all the representatives of the aforementioned scientific societies; the task of the team was the evaluation of the most accredited international literature as well as using the methodology of the "Nominal Group Technique" with the help of a systematic review of the literature and with various discussion meetings, to arrive at the drafting and final approval of the document.

RESULTS

The following five areas of investigation were identified: (1) The importance of management of anxiety and depressive disorders in pregnancy, identifying the risks associated with untreated maternal depression in pregnancy. (2) The assessment of the overall risk of malformations with the antidepressant and anxiolytic drugs used in pregnancy. (3) The evaluation of neonatal adaptation disorders in the offspring of pregnant antidepressant/anxiolytic-treated women. (4) The long-term outcome of infants' cognitive development or behavior after in utero exposure to antidepressant/anxiolytic medicines. (5) The evaluation of pharmacological treatment of opioid-abusing pregnant women with depressive disorders.

CONCLUSIONS

Considering the state of the art, it is therefore necessary in the first instance to frame the issue of pharmacological choices in pregnant women who need treatment with antidepressant and anxiolytic drugs on the basis of data currently available in the literature. Particular attention must be paid to the evaluation of the risk/benefit ratio, understood both in terms of therapeutic benefit with respect to the potential risks of the treatment on the pregnancy and on the fetal outcome, and of the comparative risk between the treatment and the absence of treatment; in the choice prescription, the specialist needs to be aware of both the potential risks of pharmacological treatment and the equally important risks of an untreated or undertreated disorder.

Sildenafil for pulmonary hypertension in neonates: An updated systematic review and meta-analysis

OBJECTIVES

To provide an updated review and meta-analysis on the efficacy and safety of sildenafil for treating persistent pulmonary hypertension in neonates (PPHN).

METHODS

PubMed/Medline, SCOPUS, Cochrane Central Register of Controlled Trials, and Web of Science were searched from the inception of publication to January 2021. The principal outcomes include oxygenation parameters, hemodynamic metrics and echocardiographic measurements, as well as adverse outcomes.

RESULTS

A total of eight studies were included with 216 term and premature neonates with PPHN. Compelling evidence showed the use of sildenafil could improve the prognosis of PPHN neonates, compared with baseline or placebo in neonates with PPHN, and a time-dependent pattern of the improvements can be observed. After 24 h of treatment, the Oxygenation index suggested a steady decrease (SD: -1.80, 95% confidence interval [CI]: -2.92, -0.67) and sildenafil exerted peak effects after 72 h of treatment (SD: -4.02, 95% CI: -5.45, -2.59). No clinically significant side effects were identified. Egger's test and funnel plots of the major outcomes were performed, and the publication bias was not significant.

CONCLUSION

Improvements were shown in oxygenation index, pulmonary arterial pressure, and adverse outcomes after using sildenafil for PPHN in neonates. However, future research with robust longitudinal or randomized controlled design is still needed.

Oral drugs used to treat persistent pulmonary hypertension of the newborn

Introduction:Persistent Pulmonary Hypertension of the Newborn (PPHN) is a life-threatening neonatal condition, mostly treated with inhaled nitric oxide (iNO), intravenous prostaglandins, oral bosentan, sildenafil and tadalafil. However, the utility of non-oral agents is limited in PPHN for their side effects and inconvenient deliveries. Therefore, oral agents such as bosentan, sildenafil and tadalafil are becoming appealing for their satisfactory efficacy, easy mode of administration and acceptable side effects. Areas covered: We conducted a comprehensive search on Pubmed, Scopus, Web of Sciences concerning the use of bosentan, sildenafil and tadalafil to treat PPHN and summarized their efficacy, safety and pharmacokinetics. Expert opinion: Current randomized controlled trials (RCTs) have demonstrated the favorable responses and tolerable side effects of bosentan and sildenafil. Nevertheless, those RCTs are small and only one study has described the pharmacokinetics of sildenafil in neonates. Accordingly, bosentan, sildenafil and tadalafil remain off-label in clinical use. More well-designed RCTs with large samples and long-term follow-up and pharmacometrics studies are needed to demonstrate the efficacy, safety and pharmacokinetics of bosentan, sildenafil and tadalafil in PPHN.

Pentraxin 3: A Potential Novel Predictor for Neonatal Pulmonary Hypertension

BACKGROUND:

Persistent pulmonary hypertension of the newborn (PPHN) is a serious neonatal problem which has a high mortality rate even with advanced modes of mechanical ventilation. Pentraxin 3 is one of the long pentraxins, which plays an essential role in regulation of cell proliferation and angiogenesis.

AIM:

This study aims to assess serum pentraxin 3 levels in neonates with pulmonary arterial hypertension and compare them in those who have other congenital heart diseases and healthy neonates. Also, we intended to evaluate serum levels of CRP as a mediator of inflammation in the studied groups.

METHODS:

The study is a case-control study. Cases were recruited from El Galaa Teaching Hospital, classified into three groups; each group had thirty cases. The first one: cases with pulmonary hypertension (PHT), the second one: cases with congenital heart diseases (CHD) without pulmonary hypertension and the third group included healthy neonates. All participants were subjected to full history taking and full clinical examination. Diagnosis of congenital heart disease and pulmonary hypertension was made according to echocardiographic findings by pediatric cardiologist using echocardiography machine. Laboratory investigations included measurement of serum pentraxin 3, Routine CBC, CRP.

RESULTS:

This study found that the mean serum pentraxin 3 in PHT neonates was significantly higher than that of the control and CHD neonates (p ≤ 0.001, p = 0.02 respectively). Also, the mean Pentraxin3 of the CHD neonates was significantly higher than that of the control (p = 0.06). Also, the mean CRP of the PHT neonates was significantly higher than that of the control (p = 0.01). Regression analysis showed that Pentraxin3 was the main predictor of PAP (P = 0.01).

CONCLUSION:

Serum pentraxin 3 is significantly elevated in neonates with pulmonary hypertension, so measurement of pentraxin 3 levels in neonates may be valuable as a predictor for pulmonary hypertension in neonates.

Lung Ultrasound to Assess the Etiology of Persistent Pulmonary Hypertension of the Newborn (LUPPHYN Study): A Pilot Study

INTRODUCTION

Persistent pulmonary hypertension of the newborn (PPHN) is a neonatal syndrome associated with significant morbidity and mortality that is caused by the failure of postnatal drop in pulmonary vascular resistance. In extreme cases, patients may require extracorporeal membrane oxygenation therapy (ECMO). The aim of this study was to explore lung ultrasound (LUS) patterns in newborns with PPHN requiring ECMO.

PATIENTS AND METHODS

From January 2014 to January 2018, LUS was performed on patients with PPHN admitted for ECMO treatment. PPHN diagnosis was based on clinical and echocardiographic findings. LUS was performed before patients underwent ECMO cannulation. An underlying diagnosis was made taking into account the patient's complete medical history, excluding LUS information. A blinded physician, unaware of the patient's clinical condition, analyzed the stored ultrasound images. Results were then compared with chest x-ray (CXR) diagnoses.

RESULTS

Seventeen patients were recruited; 12 were male (70.6%). The median gestational age was 38.7 weeks, with 13 term newborns (76.5%). Twelve were cannulated for VA ECMO, with a median ECMO run of 111.2 h. Six patients (35%) survived. Patients with alveolar capillary dysplasia with misaligned pulmonary veins, fetal ductus arteriosus constriction, or sepsis had normal LUS patterns (A-lines with lung sliding). LUS showed a better sensitivity (88.9%) and specificity (85%) than CXR (55.6 and 77.5%, respectively) in identifying patients with nonparenchymal lung disease.

CONCLUSIONS

LUS can provide essential information to help diagnose the underlying cause of PPHN in an earlier and more effective way than CXR. LUS is suitable for routine utilization in the intensive care unit.

Echocardiographic Evaluation of Transitional Circulation for the Neonatologists

The hemodynamic changes during the first few breaths after birth are probably the most significant and drastic adaptation in the human life. These changes are critical for a smooth transition of fetal to neonatal circulation. With the cord clamping, lungs take over as the source of oxygenation from placenta. A smooth transition of circulation is a complex mechanism and primarily depends upon the drop in pulmonary vascular resistance (PVR) and increase in systemic vascular resistance (SVR). Understanding the normal transition physiology and the adverse adaptation is of utmost importance to the clinicians looking after neonates. It may have a significant influence on the presentation of congenital heart defects (CHDs) in infants. Bedside echocardiography may help in understanding the transition physiology, especially the hemodynamic changes and shunting across ductus arteriosus and foramen ovale, and it may play an important role in making judicious clinical decisions based upon the altered physiology.

Maternal use of selective serotonin-reuptake inhibitors and risk of persistent pulmonary hypertension of the newborn

Use of selective serotonin reuptake inhibitors (SSRIs) in late pregnancy has been associated with persistent pulmonary hypertension of the newborn (PPHN), a rare condition with substantial infant mortality and morbidity. Although the increase in absolute risk is small on a population level, it may be of concern to many patients. It remains unclear the extent to which the increased risks reported for PPHN are explained by the underlying maternal illness rather than the use of SSRIs.

A role for actin polymerization in persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is defined as the failure of normal pulmonary vascular relaxation at birth. Hypoxia is known to impede postnatal disassembly of the actin cytoskeleton in pulmonary arterial myocytes, resulting in elevation of smooth muscle α-actin and γ-actin content in elastic and resistance pulmonary arteries in PPHN compared with age-matched controls. This review examines the original histological characterization of PPHN with attention to cytoskeletal structural remodeling and actin isoform abundance, reviews the existing evidence for understanding the biophysical and biochemical forces at play during neonatal circulatory transition, and specifically addresses the role of the cortical actin architecture, primarily identified as γ-actin, in the transduction of mechanical force in the hypoxic PPHN pulmonary circuit.

Thromboxane-induced actin polymerization in hypoxic neonatal pulmonary arterial myocytes involves Cdc42 signaling

In hypoxic pulmonary arterial (PA) myocytes, challenge with thromboxane mimetic U46619 induces marked actin polymerization and contraction, phenotypic features of persistent pulmonary hypertension of the newborn (PPHN). Rho GTPases regulate the actin cytoskeleton. We previously reported that U46619-induced actin polymerization in hypoxic PA myocytes occurs independently of the RhoA pathway and hypothesized involvement of the Cdc42 pathway. PA myocytes grown in normoxia or hypoxia for 72 h were stimulated with U46619, then analyzed for Rac/Cdc42 activation by affinity precipitation, phosphatidylinositide-3-kinase (PI3K) activity by phospho-Akt, phospho-p21-activated kinase (PAK) by immunoblot, and association of Cdc42 with neuronal Wiskott Aldrich Syndrome protein (N-WASp) by immunoprecipitation. The effect of Rac or PAK inhibition on filamentous actin was quantified by laser-scanning cytometry and by cytoskeletal fractionation; effects of actin-modifying agents were measured by isometric myography. Basal Cdc42 activity increased in hypoxia, whereas Rac activity decreased. U46619 challenge increased Cdc42 and Rac activity in hypoxic cells, independently of PI3K. Hypoxia increased phospho-PAK, unaltered by U46619. Association of Cdc42 with N-WASp decreased in hypoxia but increased after U46619 exposure. Hypoxia doubled filamentous-to-globular ratios of α- and γ-actin isoforms. Jasplakinolide stabilized γ-filaments, increasing force; cytochalasin D depolymerized all actin isoforms, decreasing force. Rac and PAK inhibition decreased filamentous actin in tissues although without decrease in force. Rho inhibition decreased myosin phosphorylation and force. Hypoxia induces actin polymerization in PA myocytes, particularly increasing filamentous α- and γ-actin, contributing to U46619-induced contraction. Hypoxic PA myocytes challenged with a thromboxane mimetic polymerize actin via the Cdc42 pathway, reflecting increased Cdc42 association with N-WASp. Mechanisms regulating thromboxane-mediated actin polymerization are potential targets for future PPHN pharmacotherapy.

Oral sildenafil and inhaled iloprost in the treatment of pulmonary hypertension of the newborn

OBJECTIVE

This study was performed to examine the effectiveness and safety of oral sildenafil and inhaled iloprost in term newborns with persistent pulmonary hypertension of the newborn (PPHN).

PATIENTS AND METHODS

Oral sildenafil and inhaled iloprost were administered to 27 and 20 neonates, respectively, for treatment of persistent pulmonary hypertension. All patients were term infants at 37 gestational weeks or older. In the sildenafil group, 14 patients had meconium aspiration syndrome, 8 had asphyxia (hypoxic ischemic encephalopathy stages II and III), 3 had congenital pneumonia, 1 had transient tachypnea, and 1 had idiopathic PPHN. In the iloprost group, 9 patients had meconium aspiration syndrome, 7 had asphyxia (hypoxic ischemic encephalopathy stages II and III), 3 had congenital pneumonia, and 1 had transient tachypnea. Sildenafil citrate was administered via an oral feeding tube. Iloprost was administered endotracheally to patients on mechanical ventilation using a jet nebulizer.

RESULTS

Iloprost appeared to be more effective than sildenafil in the treatment of PPHN with regard to time to adequate clinical response, ventilatory parameters, duration of drug administration, duration of mechanical ventilation, duration of return to normal values of respiratory failure indices, use of MgSO4 as a second vasodilator and requirement for support with inotropic agents. We observed no side effects on blood pressure or homeostasis in any of the patients in the iloprost group. Systemic hypotension was significantly elevated in the sildenafil group. Four and three infants died of PPHN in the sildenafil and iloprost groups, respectively. Pulmonary systolic arterial pressure decreased to normal levels in the remaining 40 patients, and they were discharged from hospital.

CONCLUSION

We suggested that inhaled iloprost may be a safe and effective treatment choice in newborn infants with persistent pulmonary hypertension. In cases where treatment with inhaled iloprost, ECMO or INO is not possible, oral sildenafil can be an alternative therapy option in the treatment of PPHN.

Risk factors and outcomes of persistent pulmonary hypertension of the newborn in neonatal intensive care unit of Al-minya university hospital in egypt

Background:

Persistent pulmonary hypertension of the newborn (PPHN) result from the failure of the normal fetal-to-neonatal circulatory transition is associated with substantial infant mortality and morbidity.

Objective:

To estimate the possible risk factors and assess the outcome of these cases.

Materials and Methods:

Prospective study was performed enrolling all full-term and post-term newborn admitted to the NICU from January 2009 to April 2012, All neonates were subjected to complete history and physical examination, laboratory data including a complete blood count, arterial blood gases, blood glucose, serum electrolytes, and blood culture to exclude sepsis. Cases with PPHN had a continuous pulse oximeter, blood pressure and electrocardiography monitoring. Chest X-ray and echocardiogarphy were carried out to verify shunt and exclude structural congenital heart disease.

Results:

Out of the studied 640 infants, 32 infants (5%) developed PPHN, Meconium aspiration, birth asphyxia, hyaline membrane diseases, neonatal septicemia, post-term birth being large for gestational age, cesarean section, maternal overweight, and diabetes mellitus were associated with an elevated risk for PPHN. All neonates treated with O₂, 10 neonates with Mg sulphate, 16 with oral sildenafil and 12 with mechanical ventilation. After 6 months follow-up, 12 (37.54%) improved and followed-up without sequelae, 4 (12.5%) developed some neurodevelopmental impairment, 8 (25%) died, 3 (9.3%) developed chronic lungs diseases, 2 (6.2%) developed hearing defects and another 3 (9.3%) missed follow-up.

Conclusion:

PPHN was found in 5% of the studied population. Meconium aspiration, birth asphyxia, neonatal septicemia, post-term were associated with an elevated risk for PPHN. As this is a unit based study, a comprehensive countrywide survey on PPHN in Egypt is recommended to determine any regional differences in disease incidence.

Pathophysiology, management, and outcome of persistent pulmonary hypertension of the newborn: a clinical review

Persistent Pulmonary Hypertension of the Newborn (PPHN) results from the failure of relaxation of the pulmonary vasculature at birth, leading to shunting of non-oxygenated blood from the pulmonary to the systemic circulation. More often, full term and near-term infants are affected, however it is not uncommon to see PPHN in preterm infants who have respiratory distress syndrome. In some infants pulmonary vascular remodeling is present at birth, pointing toward the prenatal onset of the disease process. Regardless of the etiology, PPHN should be diagnosed and treated as soon as possible to avoid hypoxia related short term and long-term morbidities. The mainstay therapy is the treatment of the underlying condition along with several promising therapeutic modalities such as oxygen supplementation, mechanical ventilation, nitric oxide, phosphodiesterase inhibitors, prostaglandins analogs, endothelin receptor antagonists, and extracorporeal membrane oxygenation. The optimal approach to the management of PPHN remains controversial. After discharge from the NICU, infants with PPHN warrant long-term follow up since they are at risk for neurodevelopmental disabilities and chronic health conditions.

Hydralazine in infants with persistent hypoxemic respiratory failure

BACKGROUND

Most deaths of infants with chronic lung disease (CLD) are caused by respiratory failure, unremitting pulmonary artery hypertension (PAH) with cor pulmonale, or infection. Although the exact prevalence of PAH in infants with CLD is unknown, infants with CLD and severe PAH have a high mortality rate. Except for oxygen supplementation, no specific interventions have been established as effective in the treatment for PAH in premature infants with CLD. Little has been proven regarding the clinical efficacy of vasodilators and concerns remain regarding adverse effects.

OBJECTIVES

To review current evidence for the benefits and harms of hydralazine therapy to infants with persistent hypoxemic respiratory failure.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE via PubMed and EMBASE, and other clinical trials registries through November 2011 using the standard search strategy of the Cochrane Neonatal Review Group. We searched these databases using a strategy combining a variation of the Cochrane highly sensitive search strategy for identifying randomised trials in MEDLINE; sensitivity-maximising version with selected MeSH and free-text terms: hydralazine, vasodilator agent, antihypertensive agent, heart diseases, lung diseases, respiratory tract diseases, infant, and randomised controlled trial.

SELECTION CRITERIA

We considered only randomised controlled trials and quasi-randomised trials for inclusion. We included low birth weight (LBW) infants with persistent hypoxemic respiratory failure who were treated with any type of hydralazine therapy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality according to pre-specified criteria.

MAIN RESULTS

We found no studies meeting the criteria for inclusion in this review.

AUTHORS' CONCLUSIONS

There was insufficient evidence to determine the safety and efficacy of hydralazine in LBW infants with persistent hypoxemic respiratory failure. Since hydralazine is inexpensive and potentially beneficial, randomised controlled trials are recommended. Such trials are particularly needed in settings where other medications such as sildenafil, inhaled nitric oxide (iNO), or extracorporeal membrane oxygenation (ECMO) are not available.

Classification of pulmonary hypertension

Pulmonary hypertension (PH) can develop in association with many different diseases and risk factors, and its presence is nearly always associated with reduced survival. The prognosis and management of PH is largely dependent upon its underlying etiology and severity of disease. The combination of clinical and hemodynamic classifications of PH provides a framework for the diagnostic evaluation of PH to establish a final clinical diagnosis that guides therapy. As our understanding of the different pathologic mechanisms that underlie the syndrome of PH evolves, so too will the classification and treatment of PH.

A randomized, double-blind, placebo-controlled, prospective study of bosentan for the treatment of persistent pulmonary hypertension of the newborn

OBJECTIVE

To assess the efficacy and safety of bosentan as an adjuvant therapy of persistent pulmonary hypertension of the newborn (PPHN).

STUDY DESIGN

Forty-seven neonates with PPHN were randomly assigned to receive either bosentan (n=24) or placebo (n=23). Efficacy was evaluated with a favorable outcome defined as fulfilling all the following criteria (for example, oxygenation index <15, normal pulmonary artery pressure (<20 mm Hg) and no premature discontinuation of the drug because of drug-related toxicity or lack of efficacy). Evaluation of safety was done by monitoring drug-related adverse events.

RESULT

Bosentan treatment was superior to placebo with a favorable response in 87.5% of patients treated with bosentan as compared with 20% of those who received placebo (P<0.0001). None of patients in the bosentan group had drug-related clinical or laboratory adverse events.

CONCLUSION

Bosentan may be a useful adjuvant therapy of PPHN.

Molecular mechanisms regulating the vascular prostacyclin pathways and their adaptation during pregnancy and in the newborn

Prostacyclin (PGI(2)) is a member of the prostanoid group of eicosanoids that regulate homeostasis, hemostasis, smooth muscle function and inflammation. Prostanoids are derived from arachidonic acid by the sequential actions of phospholipase A(2), cyclooxygenase (COX), and specific prostaglandin (PG) synthases. There are two major COX enzymes, COX1 and COX2, that differ in structure, tissue distribution, subcellular localization, and function. COX1 is largely constitutively expressed, whereas COX2 is induced at sites of inflammation and vascular injury. PGI(2) is produced by endothelial cells and influences many cardiovascular processes. PGI(2) acts mainly on the prostacyclin (IP) receptor, but because of receptor homology, PGI(2) analogs such as iloprost may act on other prostanoid receptors with variable affinities. PGI(2)/IP interaction stimulates G protein-coupled increase in cAMP and protein kinase A, resulting in decreased [Ca(2+)](i), and could also cause inhibition of Rho kinase, leading to vascular smooth muscle relaxation. In addition, PGI(2) intracrine signaling may target nuclear peroxisome proliferator-activated receptors and regulate gene transcription. PGI(2) counteracts the vasoconstrictor and platelet aggregation effects of thromboxane A(2) (TXA(2)), and both prostanoids create an important balance in cardiovascular homeostasis. The PGI(2)/TXA(2) balance is particularly critical in the regulation of maternal and fetal vascular function during pregnancy and in the newborn. A decrease in PGI(2)/TXA(2) ratio in the maternal, fetal, and neonatal circulation may contribute to preeclampsia, intrauterine growth restriction, and persistent pulmonary hypertension of the newborn (PPHN), respectively. On the other hand, increased PGI(2) activity may contribute to patent ductus arteriosus (PDA) and intraventricular hemorrhage in premature newborns. These observations have raised interest in the use of COX inhibitors and PGI(2) analogs in the management of pregnancy-associated and neonatal vascular disorders. The use of aspirin to decrease TXA(2) synthesis has shown little benefit in preeclampsia, whereas indomethacin and ibuprofen are used effectively to close PDA in the premature newborn. PGI(2) analogs have been used effectively in primary pulmonary hypertension in adults and have shown promise in PPHN. Careful examination of PGI(2) metabolism and the complex interplay with other prostanoids will help design specific modulators of the PGI(2)-dependent pathways for the management of pregnancy-related and neonatal vascular disorders.

Persistent pulmonary hypertension results in reduced tetralinoleoyl-cardiolipin and mitochondrial complex II + III during the development of right ventricular hypertrophy in the neonatal pig heart

Persistent pulmonary hypertension of the newborn (PPHN) results in right ventricular (RV) hypertrophy followed by right heart failure and an associated mitochondrial dysfunction. The phospholipid cardiolipin plays a key role in maintaining mitochondrial respiratory and cardiac function via modulation of the activities of enzymes involved in oxidative phosphorylation. In this study, changes in cardiolipin and cardiolipin metabolism were investigated during the development of right heart failure. Newborn piglets (<24 h old) were exposed to a hypoxic (10% O(2)) environment for 3 days, resulting in the induction of PPHN. Two sets of control piglets were used: 1) newborn or 2) exposed to a normoxic (21% O(2)) environment for 3 days. Cardiolipin biosynthetic and remodeling enzymes, mitochondrial complex II + III activity, incorporation of [1-(14)C]linoleoyl-CoA into cardiolipin precursors, and the tetralinoleoyl-cardiolipin pool size were determined in both the RV and left ventricle (LV). PPHN resulted in an increased heart-to-body weight ratio, RV-to-LV plus septum weight ratio, and expression of brain naturetic peptide in RV. In addition, PPHN reduced cardiolipin biosynthesis and remodeling in the RV and LV, which resulted in decreased tetralinoleoyl-cardiolipin levels and reduced complex II + III activity and protein levels of mitochondrial complexes II, III, and IV in the RV. This is the first study to examine the pattern of cardiolipin metabolism during the early development of both the RV and LV of the newborn piglet and to demonstrate that PPHN-induced alterations in cardiolipin biosynthetic and remodeling enzymes contribute to reduced tetralinoleoyl-cardiolipin and mitochondrial respiratory chain function during the development of RV hypertrophy. These defects in cardiolipin may play an important role in the rapid development of RV dysfunction and right heart failure in PPHN.

Pentoxifylline in preterm neonates: a systematic review

Sepsis, necrotizing enterocolitis (NEC), and chronic lung disease (CLD) in preterm neonates are associated with significant mortality and morbidity, including long-term neurodevelopmental impairment and socioeconomic burden. Safe and effective drugs for the prevention and treatment of these conditions are urgently needed. Pentoxifylline, a synthetic theobromine derivative, is a non-steroidal immunomodulating agent with unique hemorrheologic effects which has been used in a range of infectious, vascular, and inflammatory conditions in adults and children. The unique properties of pentoxifylline explain its potential benefits in preterm neonates with sepsis, NEC, and CLD, conditions characterized by activation of the inflammatory cytokine cascade, free radical toxicity, and impaired microcirculation. Pentoxifylline has anti-inflammatory properties resulting from inhibition of erythrocyte phosphodiesterase. It lowers blood viscosity and improves microcirculation and tissue perfusion. As a phosphodiesterase inhibitor, pentoxifylline downregulates pro-inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-6, and interferon-gamma. Methylxanthines, including caffeine, theophylline, and theobromine are relatively non-toxic drugs; of these, theobromine is the least toxic. Pentoxifylline-related significant adverse events are thus very rare. Unlike other methylxanthines, pentoxifylline does not have significant cardiac and bronchodilating effects at therapeutic doses. Although it is contraindicated in adults with recent cerebral hemorrhage due to its effect on platelets, red blood cells, and plasma fibrinogen levels, no significant adverse effects including thrombocytopenia and bleeding have been reported in critically ill preterm neonates with sepsis or NEC after treatment with pentoxifylline. Based on data from pilot randomized trials and observational studies, our systematic review suggests that pentoxifylline may reduce mortality and/or morbidity in preterm neonates with sepsis, NEC, and CLD. Results of experimental studies also indicate that pentoxifylline may potentially be beneficial in meconium aspiration syndrome and hypoxic ischemic encephalopathy. Given the substantial burden of sepsis, NEC, and CLD in high-risk preterm neonates, and the findings of this systematic review, pentoxifylline needs to be evaluated urgently as a preventative and therapeutic agent for these conditions in randomized controlled trials that can detect minimal clinically significant effect sizes. Further clinical and experimental studies are also necessary to evaluate whether pentoxifylline is safe and effective in meconium aspiration syndrome and hypoxic ischemic encephalopathy.

A 20-year experience on neonatal extracorporeal membrane oxygenation in a referral center

OBJECTIVE

Advances in treatment of neonatal respiratory failure are responsible for a decline in the number of newborns treated with extracorporeal membrane oxygenation (ECMO). The aim of this study are to determine demographic changes, focusing on time of referral, diagnosis, and respiratory parameters in neonates put on ECMO.

DESIGN

Retrospective review.

SETTING

Tertiary ECMO center.

PATIENTS

A total of 321 neonates were treated with ECMO from January 1987 to December 2006.

RESULTS

Overall number of patients increased with every 5-year period, whereby congenital diaphragmatic hernia (CDH) was the most common diagnosis (53%), followed by meconium aspiration syndrome (MAS) (21%), sepsis and/or pneumonia (13%), and others such as persistent pulmonary hypertension of the newborn (PPHN), respiratory distress syndrome (RDS), or hypoplasia of the lung (13%). Worsening severity of illness as measured by ECMO duration and days on ventilator has to be stated for all diagnoses. Nevertheless, survival rate remained stable; both overall and diagnosis-specific mortality rates did not change significantly. Of all children, 67% survived to discharge or transfer, while best rates were seen for MAS (94%), followed by sepsis and/or pneumonia (69%), CDH (62%), and other diagnoses (43%). Concerning survival rate, no difference between inborn and outborn children occurred. However, between early- and late-referred children, a referral to the ECMO center during the first 24 h of life was associated with a significantly higher rate of survival (77% versus 54%, p = 0.0004), predominantly seen for CDH (67% versus 35%, p = 0.02).

CONCLUSION

We strongly recommend timely transfer to an ECMO center in patients with CDH who are at risk of circulatory failure.

Expression of HIF-1 alpha, VEGF and EPO in peripheral blood from patients with two cardiac abnormalities associated with hypoxia

OBJECTIVES

HIF-1 alpha (hypoxia-inducible factor-1 alpha) mediates the responses of mammalian cells to hypoxia/ischemia by inducing the expression of adaptive gene products (e.g., vascular endothelial growth factor (VEGF) and erythropoietin (EPO)). Persistent pulmonary hypertension of the newborn (PPHN) and cyanotic congenital heart disease (CCHD) are common neonatal diseases considered as paradigms of hypoxemia. Since the expression HIF-1 alpha, VEGF and EPO in newborns diagnosed with these diseases has yet to be studied, we set out to define the expression of these genes in peripheral blood from newborn infants diagnosed with PPHN and CCHD.

DESIGN AND METHODS

The mRNA transcripts encoding HIF-1 alpha, VEGF and EPO were measured by RT-PCR in healthy newborn infants and infants diagnosed with PPHN and CCHD.

RESULTS

An important increase in HIF-1 alpha expression was observed in both pathological conditions, accompanied by significant increases in VEGF and EPO expression when compared to healthy infants.

CONCLUSIONS

HIF-1 alpha mRNA expression increases in newborn infants with PPHN or CCHD, as does the expression of its target genes VEGF and EPO.

Use of the myocardial performance index to assess right ventricular function in infants with pulmonary hypertension

BACKGROUND

This study aimed to measure and compare right ventricular (RV) function in normal infants and those with pulmonary hypertension (PHT) using the myocardial performance index (RVMPI) and to investigate the relationship between RV function and pulmonary artery pressure.

METHODS

A case-control study measured RVMPI in 16 infants with PHT (9 of whom had congenital diaphragmatic hernia) and 28 normal control infants. For the PHT infants, 43 paired measures of RVMPI and pulmonary artery pressure (estimated from tricuspid regurgitation jet velocity) were taken to allow investigation of the relationship between RVMPI and pulmonary artery pressure.

RESULTS

The mean RVMPI for the control infants was 0.24+/-0.09. The RVMPI was significantly elevated in the PHT group (0.55+/-0.17; p<0.0001), including a subgroup of infants with PHT secondary to congenital diaphragmatic hernia (0.58+/-0.18; p<0.0001). The correlation between RVMPI and pulmonary artery pressure in the infants with PHT (R2=0.05; p=0.17) was poor.

CONCLUSIONS

In infants, RVMPI allows quantification of right ventricular function and detection of RV dysfunction in PHT. No linear relationship exists between RVMPI pulmonary artery pressure. Use of RVMPI in the clinical setting must take into account the global and load-dependent nature of this measure.

Prenatal prediction of neonatal morbidity in survivors with congenital diaphragmatic hernia: a multicenter study

OBJECTIVES

To investigate the value of the observed to expected fetal lung area to head circumference ratio (o/e LHR) and liver position in the prediction of neonatal morbidity in survivors with congenital diaphragmatic hernia (CDH).

METHODS

Neonatal morbidity was recorded in 100 consecutive cases with isolated CDH diagnosed in fetal medicine units, which were expectantly managed in the prenatal period, were delivered after 30 weeks and survived until discharge from hospital. Regression analysis was used to identify the significant predictors of morbidity, including prenatal and immediate neonatal findings.

RESULTS

The o/e LHR provided significant prediction of the need for prosthetic patch repair, duration of assisted ventilation, need for supplemental oxygen at 28 days, and incidence of feeding problems. An additional independent prenatal predictor of the need for patch repair was the presence of fetal liver in the chest.

CONCLUSIONS

In isolated CDH the prenatally assessed size of the contralateral lung is a significant predictor of the need for prosthetic patch repair, the functional consequences of impaired lung development and occurrence of feeding problems.

Nitric oxide and cardiac function

Nitric oxide (NO) participates in the control of contractility and heart rate, limits cardiac remodeling after an infarction and contributes to the protective effect of ischemic pre- and postconditioning. Low concentrations of NO, with production of small amounts of cGMP, inhibit phosphodiesterase III, thus preventing the hydrolysis of cAMP. The subsequent activation of a protein-kinase A causes the opening of sarcolemmal voltage-operated and sarcoplasmic ryanodin receptor Ca(2+) channels, thus increasing myocardial contractility. High concentrations of NO induce the production of larger amounts of cGMP which are responsible for a cardiodepression in response to an activation of protein kinase G (PKG) with blockade of sarcolemmal Ca(2+) channels. NO is also involved in reduced contractile response to adrenergic stimulation in heart failure. A reduction of heart rate is an evident effect of NO-synthase (NOS) inhibition. It is noteworthy that the direct effect of NOS inhibition can be altered if baroreceptors are stimulated by increases in blood pressure. Finally, NO can limit the deleterious effects of cardiac remodeling after myocardial infarction possibly via the cGMP pathway. The protective effect of NO is mainly mediated by the guanylyl cyclase-cGMP pathway resulting in activation of PKG with opening of mitochondrial ATP-sensitive potassium channels and inhibition of the mitochondrial permeability transition pores. NO acting on heart is produced by vascular and endocardial endothelial NOS, as well as neuronal and inducible synthases. In particular, while in the basal control of contractility, endothelial synthase has a predominant role, the inducible isoform is mainly responsible for the cardiodepression in septic shock.