Efficacy and safety of oral sildenafil in children with Down syndrome and pulmonary hypertension

BMPR-II, caspase-3, HIF-1α, and VE-cadherin profile in Down syndrome children with and without congenital heart disease and pulmonary hypertension

Several cellular markers have been identified as effective in detecting vascular remodeling recently. The reduced activity of bone morphogenetic protein receptor type-II (BMPR-II), commonly observed in Down syndrome, results in insufficient production of vascular endothelial cadherin (VE-cadherin). This, in turn, increases hypoxia-inducible factor-1α (HIF-1α) levels and leads to excessive production of caspase-3. The aim of this study was to compare the plasma levels of BMPR-II, VE-cadherin, HIF-1α, and caspase-3 between pediatric Down syndrome with and without congenital heart disease (CHD) and pulmonary hypertension (PH). This was to investigate the role of these biomarkers in the pathogenesis of PH associated or not associated with CHD. A cross-sectional study was conducted on Down syndrome children aged two months to five years at a tertiary hospital between January and December 2023. The children were classified into four groups: CHD with PH, CHD without PH, non-CHD with PH and normal heart. Plasma levels of BMPR-II, caspase-3, HIF-1α, and VE-cadherin were measured using ELISA and compared based on the presence or absence of CHD and PH using Kruskal-Wallis followed by post hoc Bonferroni tests. Elevated plasma HIF-1α levels were observed in all patients with PH, with significantly higher levels in those with CHD-PH. Elevated levels of caspase-3 were also observed among children with PH groups, with the highest levels observed in the non-CHD PH group. Plasma levels of BMPR-II and VE-cadherin were elevated in PH, with significantly higher levels in the non-CHD PH group compared to other groups.

Sildenafil Attenuates Persistent Pulmonary Hypertension of the Newborn via Inhibiting the Growth and Migration of Pulmonary Artery Smooth Muscle Cells

INTRODUCTION

Sildenafil, a selective phosphodiesterase 5 inhibitor, modulates vascular dysfunction, with hypoxia-induced pulmonary artery smooth muscle cells (PASMCs) proliferation, migration, and invasion closely implicated in vascular remodeling in persistent pulmonary hypertension of the newborn (PPHN). This study aimed to assess sildenafil's protective effects against PPHN and elucidate underlying molecular pathways.

METHODS

Cell Counting Kit-8, wound healing, and Transwell assays evaluated rat PASMC proliferation, migration, and invasion under hypoxia. A rat PPHN model assessed sildenafil's impact on right ventricular systolic pressure (RVSP), right ventricular hypertrophy (RVH), and vascular remodeling. JAK2/STAT3 signaling was analyzed via Western blotting.

RESULTS

Sildenafil significantly inhibited hypoxia-induced PASMC proliferation, migration, and invasion. In addition, sildenafil reduced RVSP, RVH, and vascular remodeling in PPHN. Further, sildenafil decreased JAK2 and STAT3 phosphorylation in hypoxia-exposed PASMCs and the PPHN rat model. The JAK2/STAT3 pathway agonist colivelin reversed sildenafil's suppressive effects on PASMC proliferation, migration, invasion, as well as RVSP, RVH, and vascular remodeling in PPHN.

CONCLUSIONS

Sildenafil protects against PPHN by inhibiting PASMC proliferation, migration, and invasion via suppression of JAK2/STAT3 signaling, indicating its potential as a therapeutic target for PPHN and contributing to a more comprehensive understanding of PPHN pathogenesis.

Knowledge, Attitude, and Practice of Physiotherapists about Cardiac Rehabilitation Program Adherence among Patients Discharged from the Hospital after Cardiac Surgery in India

Background

In most settings, patients receive phase 1 cardiac rehabilitation in CTVS ICU at the hospital, but there are several barriers to follow-up after patients are discharged from the hospital. Physiotherapists play an important role in the enrolment and continuation of cardiac rehabilitation. Thus, we aim to study the knowledge, attitude, and practice of physiotherapists about CR program adherence among patients discharged from the hospital after cardiac surgery.

Objectives

(i) To study the knowledge of physiotherapists about the importance of cardiac rehabilitation after discharge; (ii) to know the attitude of physiotherapists towards cardiac surgery patients after discharge; and (iii) to know what approach various centres are applying for patients after discharge to ensure adherence to cardiac rehabilitation.

Methods

A questionnaire was developed with reference to the objectives of the study, which was answered by a total of 127 physiotherapists.

Results

The overall response rate was 42.3%; nearly 35.4% of the participants indicated that they knew a lot about CR, while 5.5% said they knew very little. Regarding the program's content, 36.2% of participants reported having a medium degree of awareness of the diverse CR components, while 8.6% reported having very little knowledge of them. Only about one-third, 35.7% stated that CR in India is effective and 95% believed that CR will have an added value for the country. Approximately 80% of respondents thought that it would be challenging for a physiotherapist to recommend patients to a CR in the nation. Nearly 35% of respondents believed that they, "themselves as physios," needed to commence CR, and slightly less than 70% thought that doctors were required to choose and refer the patients when asked who should take the initiative to start this kind of programme in the country. A little over 40% of respondents said that insurance firms are also involved in starting a CR programme.

Conclusion

Physiotherapists have good knowledge of cardiac rehabilitation. However, their attitude and practice towards adherence to exercise protocols are confounded by various clinician- and patient-level factors.

Tailoring of Bilosomal Nanogel for Augmenting the Off-Label Use of Sildenafil Citrate in Pediatric Pulmonary Hypertension

Pediatric pulmonary hypertension is a serious syndrome with significant morbidity and mortality. Sildenafil is widely used off-label in pediatric patients with pulmonary arterial hypertension. In this study, bile salt-stabilized nanovesicles (bilosomes) were screened for their efficacy to enhance the transdermal delivery of the phosphodiesterase type 5 inhibitor, sildenafil citrate, in an attempt to augment its therapeutic efficacy in pediatric pulmonary hypertension. A response surface methodology was implemented for fabricating and optimizing a bilosomal formulation of sildenafil (SDF-BS). The optimized SDF-BS formulation was characterized in terms of its entrapment efficiency (EE), zeta potential, vesicle size, and in vitro release profile. The optimized formula was then loaded onto hydroxypropyl methyl cellulose (HPMC) hydrogel and assessed for skin permeation, in vivo pharmacokinetics, and pharmacodynamic studies. The optimized SDF-BS showed the following characteristic features; EE of 88.7 ± 1.1%, vesicle size of 185.0 + 9.2 nm, zeta potential of -20.4 ± 1.1 mV, and efficiently sustained SDF release for 12 h. Skin permeation study revealed a remarkable improvement in SDF penetration from bilosomal gel compared to plain SDF gel. In addition, pharmacokinetic results revealed that encapsulating SDF within bilosomal vesicles significantly enhanced its systemic bioavailability (∼3 folds), compared to SDF oral suspension. In addition, pharmacodynamic investigation revealed that, compared to plain SDF gel or oral drug suspension, SDF-BS gel applied topically triggered a significant elevation (p < 0.05) in cGMP serum levels, underscoring the superior therapeutic efficacy of SDF-BS gel. Conclusively, bilosomes can be viewed as a promising nanocarrier for transdermal delivery of SDF that would grant higher therapeutic efficiency while alleviating the limitations encountered with SDF oral administration.

Development of pulmonary hypertension remains a major hurdle to corrective surgery in Down syndrome

Down syndrome is the most common chromosomal abnormality encountered in clinical practice with 50% of them having associated congenital heart disease (CHD). Shunt lesions account for around 75% of all CHDs in Down syndrome. Down syndrome patients, especially with large shunts are particularly predisposed to early development of severe pulmonary hypertension (PH) compared with shunt lesions in general population. This necessitates timely surgical correction which remains the only viable option to prevent long term morbidity and mortality. However, despite clear recommendations, there is wide gap between actual practice and fear of underlying PH which often leads to surgical refusals in Down syndrome even when the shunt is reversible. Another peculiarity is that Down syndrome patients can develop PH even after successful correction of shunt. It is not uncommon to come across Down syndrome patients with uncorrected shunts in adulthood with irreversible PH at which stage intracardiac repair is contraindicated and the only option available is a combined heart-lung transplant. However, despite the guidelines laid by authorities, the rates of cardiac transplant in adult Down syndrome remain dismal largely attributable to the high prevalence of intellectual disability in them. The index case presents a real-world scenario highlighting the impact of severe PH on treatment strategies and discrimination driven by the fear of worse outcomes in these patients.

Recent Advances in Pediatric Pulmonary Hypertension: Implications for Diagnosis and Treatment

PURPOSE

Pediatric pulmonary hypertension (PH) is a condition characterized by elevated pulmonary arterial pressure, which has the potential to be life-limiting. The etiology of pediatric PH varies. When compared with adult cohorts, the etiology is often multifactorial, with contributions from prenatal, genetic, and developmental factors. This review aims to provide an up-to-date overview of the causes and classification of pediatric PH, describe current therapeutics in pediatric PH, and discuss upcoming and necessary research in pediatric PH.

METHODS

PubMed was searched for articles relating to pediatric pulmonary hypertension, with a particular focus on articles published within the past 10 years. Literature was reviewed for pertinent areas related to this topic.

FINDINGS

The evaluation and approach to pediatric PH are unique when compared with that of adults, in large part because of the different, often multifactorial, causes of the disease in children. Collaborative registry studies have found that the most common disease causes include developmental lung disease and subsets of pulmonary arterial hypertension, which includes genetic variants and PH associated with congenital heart disease. Treatment with PH-targeted therapies in pediatrics is often guided by extrapolation of adult data, small clinical studies in pediatrics, and/or expert consensus opinion. We review diagnostic considerations and treatment in some of the more common pediatric subpopulations of patients with PH, including developmental lung diseases, congenital heart disease, and trisomy 21.

IMPLICATIONS

The care of pediatric patients with PH requires consideration of unique pediatric-specific factors. With significant variability in disease etiology, ongoing efforts are needed to optimize treatment strategies based on disease phenotype and guide evidence-based practices.

Advances in targeted therapy for pulmonary arterial hypertension in children

Pulmonary arterial hypertension (PAH) is a rare and devastating disease of the pulmonary vasculature with a high morbidity and mortality rate in infants and children. Currently, treatment approaches are mostly based on adult guidelines and pediatrician clinical experience, focusing on specific pulmonary antihypertensive therapy and conventional supportive care. The advent of targeted drugs has led to significant advances in the treatment of PAH in children, including endothelin receptor antagonists, phosphodiesterase type 5 inhibitors, and prostacyclins, which have been studied and proven to improve hemodynamics and functional class in children PAH. A new targeted drug, riociguat, is assessing its safety and efficacy in clinical trials. However, more randomized controlled studies are needed to evaluate the combination of drugs, treatment strategies, and clinical endpoints of targeted therapy in children PAH. In this review, we summarize the research advances of PAH-targeted therapy in children over the last decade in order to provide a theoretical basis for future studies.

CONCLUSION

Pulmonary arterial hypertension (PAH) is a rare and devastating pulmonary vascular disease that is associated with a variety of diseases of any age in childhood onset.

WHAT IS KNOWN

• Therapeutic strategies for targeted drugs for PAH in children are based almost exclusively on data from adult studies and clinical experience of pediatric specialists. • Due to the complex etiology of PAH in children and the relative lack of clinical trial data, the selection of appropriate targeted drug therapy remains difficult.

WHAT IS NEW

• We redefine the definition of pulmonary arterial hypertension in children and summarize the progress of targeted therapy of pulmonary arterial hypertension in children in the past ten years. • The dosage and adverse reactions were summarized, and the mechanism of action was drawn according to the available targeted drugs. It can provide theoretical support for the development of guidelines and treatment strategies for the diagnosis and treatment of pulmonary arterial hypertension in children.

Cardiovascular Complications of Down Syndrome: Scoping Review and Expert Consensus

Cardiovascular disease is a leading cause of morbidity and mortality in individuals with Down syndrome. Congenital heart disease is the most common cardiovascular condition in this group, present in up to 50% of people with Down syndrome and contributing to poor outcomes. Additional factors contributing to cardiovascular outcomes include pulmonary hypertension; coexistent pulmonary, endocrine, and metabolic diseases; and risk factors for atherosclerotic disease. Moreover, disparities in the cardiovascular care of people with Down syndrome compared with the general population, which vary across different geographies and health care systems, further contribute to cardiovascular mortality; this issue is often overlooked by the wider medical community. This review focuses on the diagnosis, prevalence, and management of cardiovascular disease encountered in people with Down syndrome and summarizes available evidence in 10 key areas relating to Down syndrome and cardiac disease, from prenatal diagnosis to disparities in care in areas of differing resource availability. All specialists and nonspecialist clinicians providing care for people with Down syndrome should be aware of best clinical practice in all aspects of care of this distinct population.

Hemodynamic Characteristics After Fontan Procedure in Patients with Down's Syndrome

Patients with Down's syndrome (DS) are generally regarded as not being good candidates for the Fontan procedure. However, detailed hemodynamic changes over time are not fully clarified. A retrospective chart review of all patients with DS who underwent the Fontan procedure and 5 times that number of Fontan patients without DS performed in Fukuoka Children's Hospital and Kyushu University Hospital. Seven Fontan patients with DS were identified, and 35 Fontan patients without DS were recruited. During the mean observational periods of 14.7 years and 15.0 years (DS and non-DS, respectively) after the Fontan procedure, only one DS patient died. Central venous pressure (CVP) and transpulmonary pressure gradient significantly increased, and arterial oxygen saturation significantly decreased over time in DS patients after the Fontan procedure compared with those without DS. CVP in DS patients after the Fontan procedure increased over time compared with non-DS patients. Better management including the efficacy of Pulmonary arterial hypertension-specific therapy should be clarified in further studies.

Pulmonary Hypertension in the Population with Down Syndrome

Persons with Down syndrome (DS) have an increased reported incidence of pulmonary hypertension (PH). A majority of those with PH have associations with congenital heart disease (CHD) or persistent pulmonary hypertension of the newborn (PPHN); however, there are likely multifactorial contributions that include respiratory comorbidities. PH appears to be most commonly identified early in life, although respiratory challenges may contribute to a later diagnosis or even a recurrence of previously resolved PH in this population. Currently there are few large-scale, prospective, lifetime cohort studies detailing the impact PH has on the population with DS. This review will attempt to summarize the epidemiology and characteristics of PH in this population. This article will additionally review current known and probable risk factors for developing PH, review pathophysiologic mechanisms of disease in the population with DS, and evaluate current screening and management recommendations while suggesting areas for additional or ongoing clinical, translational, and basic science research.

Clinical Efficacy and Safety of Different Doses of Sildenafil in the Treatment of Persistent Pulmonary Hypertension of the Newborn: A Network Meta-analysis

Objective: To evaluate the efficacy and safety of different doses of sildenafil for persistent pulmonary hypertension of the newborn (PPHN) with Bayesian random effects network meta-analysis.

Methods: We searched Chinese and English databases for randomized controlled trials (RCTs) concerning sildenafil in newborns with persistent pulmonary hypertension from 1998 to December 2020.

Results: Twenty-two RCTs including over 2131 patients were included. Sildenafil was administered by nasal feeding at 0.3–2 mg/kg every 4–6 h. The network meta-analysis revealed that 1.5 mg/kg of sildenafil led to a significant decrease in pulmonary artery systolic pressure (PASP) compared with 0.3 and 0.6 mg/kg (p < 0.05); 1.5 mg/kg was better than 0.3, 0.5, and 1.0 mg/kg at increasing the partial pressure of oxygen (PaO₂) (p < 0.05); 1.5 mg/kg was better than 0.5, 0.6 and 1.0 mg/kg at reducing the partial pressure of carbon dioxide (PaCO₂) (p < 0.05); and 1.2 mg/kg was better than 0.3, 0.5 and 1.0 mg/kg at increasing the arterial oxygen saturation (SaO₂) (p < 0.05). The surface under the cumulative ranking analysis (SUCRA) results showed that 1.5 mg/kg had the best effect in reducing PASP (SUCRA = 92.0%, moderate certainty evidence) and PaCO₂ (91.1%) and increasing PaO₂ (SUCRA = 79.3%, moderate certainty evidence), 2.0 mg/kg had the best effect in increasing SaO₂ (SUCRA = 88.6%, moderate certainty evidence) and total effective rate (SUCRA = 93.5%, low certainty of evidence)). No severe adverse effects were observed with the different doses of sildenafil.

Conclusion: Different doses of sildenafil can significantly improve PPHN, and 1.5 mg/kg of sildenafil has better clinical efficacy and does not increase the probability of adverse reactions.

Down syndrome and congenital heart disease: perioperative planning and management

Approximately 50% of newborns with Down syndrome have congenital heart disease. Non-cardiac comorbidities may also be present. Many of the principles and strategies of perioperative evaluation and management for patients with congenital heart disease apply to those with Down syndrome. Nevertheless, careful planning for cardiac surgery is required, evaluating for both cardiac and noncardiac disease, with careful consideration of the risk for pulmonary hypertension. In this manuscript, for children with Down syndrome and hemodynamically significant congenital heart disease, we will summarize the epidemiology of heart defects that warrant intervention. We will review perioperative planning for this unique population, including anesthetic considerations, common postoperative issues, nutritional strategies, and discharge planning. Special considerations for single ventricle palliation and heart transplantation evaluation will also be discussed. Overall, the risk of mortality with cardiac surgery in pediatric patients with Down syndrome is no more than the general population, except for those with functional single ventricle heart defects. Underlying comorbidities may contribute to postoperative complications and increased length of stay. A strong understanding of cardiac and non-cardiac considerations in children with Down syndrome will help clinicians optimize perioperative care and long-term outcomes.

Efficacy and safety of pulmonary vasodilators in the patients with Eisenmenger syndrome: a meta-analysis of randomized controlled trials

Few meta-analyses evaluated the efficacy and safety of pulmonary vasodilators in patients with Eisenmenger syndrome. Recently, some studies have reported conflicting results regarding improvements in exercise capacity. This study evaluated the efficacy and safety of pulmonary vasodilators in patients with Eisenmenger syndrome. Relevant studies were identified by searching major databases. Pooled outcomes were used to assess the efficacy and safety of pulmonary vasodilators. In total, five studies with 508 patients were included. Meta-analysis indicated that the pulmonary vasodilators reduced the mortality (odd risk (OR) = 0.35; 95% CI, 0.13 to 0.95; P = 0.04), slashed the mean pulmonary artery pressure (mean difference (MD) = -4.35 mmHg; 95% CI, -7.19 to -1.50; P = 0.003), decreased pulmonary vascular resistance index (MD = -480.08 dyn · s · cm-5 · m2; 95% CI, -753.51 to -206.64; P = 0.0006), increased the 6-min walk distance (MD = 28.38 m; 95% CI, 2.99 to 53.77; P = 0.03), and elevated the systemic oxygen saturation at rest (MD = 1.00%; 95% CI, 0.12 to 1.88; P = 0.03). Four studies reported side effects, but only two studies reported serious adverse effects which were mostly rare and curable. The present meta-analysis indicated that pulmonary vasodilators decrease mortality and improve hemodynamics and exercise capacity in patients with Eisenmenger syndrome. Overall, pulmonary vasodilators are well tolerated.

Long-Term Survival and Causes of Death in Children with Trisomy 21 After Congenital Heart Surgery

OBJECTIVE

To evaluate long-term transplant-free survival and causes of death in the trisomy 21 (T21) population after surgery for congenital heart disease (CHD) in comparison with patients who are euploidic.

STUDY DESIGN

This is a retrospective cohort study from the Pediatric Cardiac Care Consortium, enriched with prospectively collected data from the National Death Index and the Organ Procurement and Transplantation Network for patients with sufficient direct identifiers. Kaplan-Meier survival plots were generated and multivariable Cox proportional hazards models were used to examine risk factors for mortality between patients with T21 and 1:1 matched patients with comparable CHD who are euploidic.

RESULTS

A long-term survival analysis was completed for 3376 patients with T21 (75 155 person-years) who met inclusion criteria. The 30-year survival rate for patients with T21 ranged from 92.1% for ventricular septal defect to 65.3% for complex common atrioventricular canal. Of these, 2185 patients with T21 were successfully matched with a patient who was euploidic. After a median follow-up of 22.86 years (IQR, 19.45-27.14 years), 213 deaths occurred in the T21 group (9.7%) compared with 123 (5.6%) in the euploidic comparators. After adjustment for age, sex, era, CHD complexity, and initial palliation, the hazard ratio of CHD-related mortality was 1.34 times higher in patients with T21 (95% CI, 0.92-1.97; P = .127).

CONCLUSIONS

CHD-related mortality for patients with T21 after cardiac surgical intervention is comparable with euploidic comparators. Children with T21 require lifelong surveillance for co-occurring conditions associated with their chromosomal abnormality.

Pulmonary hypertension in children with Down syndrome

Individuals with Down syndrome (DS) have an increased risk of developing pulmonary hypertension (PH). In this review, we explore the epidemiology and clinical characteristics of PH in the population with DS and examine genetic, molecular and clinical contributions to the condition. The presence of an additional copy of chromosome 21 (trisomy 21) increases the risk of developing PH in children with DS through many mechanisms, including increased hemodynamic stress in those with congenital heart disease, hypoxemia through impaired ventilation to perfusion matching secondary to developmental lung abnormalities, pulmonary hypoplasia from pulmonary vascular endothelial dysfunction, and an increase in pulmonary vascular resistance often related to pulmonary comorbidities. We review recent studies looking at novel biomarkers that may help diagnose, predict or monitor PH in the population with DS and examine current cardiopulmonary guidelines for monitoring children with DS. Finally, we review therapeutic interventions specific to PH in individuals with DS. Contemporary work has identified exciting mechanistic pathways including the upregulation of antiangiogenic factors and interferon activity, which may lead to additional biomarkers or therapeutic opportunities. Throughout the manuscript, we identify gaps in our knowledge of the condition as it relates to the population with DS and offer suggestions for future clinical, translational, and basic science research.

Novel Insights Regarding Nitric Oxide and Cardiovascular Diseases

Nitric oxide (NO) is a powerful mediator with biological activities such as vasodilation and prevention of vascular smooth muscle cell proliferation as well as functional regulation of cardiac cells. Thus, impaired production or reduced bioavailability of NO predisposes to the onset of different cardiovascular (CV) diseases. Alterations in the redox balance associated with excitation-contraction coupling have been identified in heart failure (HF), thus contributing to contractile abnormalities and arrhythmias. For its ability to influence cell proliferation and angiogenesis, NO may be considered a therapeutic option for the management of several CV diseases. Several clinical studies and trials investigated therapeutic NO strategies for systemic hypertension, atherosclerosis, and/or prevention of in stent restenosis, coronary heart disease (CHD), pulmonary arterial hypertension (PAH), and HF, although with mixed results in long-term treatment and effective dose administered in selected groups of patients. Tadalafil, sildenafil, and cinaguat were evaluated for the treatment of PAH, whereas vericiguat was investigated in the treatment of HF patients with reduced ejection fraction. Furthermore, supplementation with hydrogen sulfide, tetrahydrobiopterin, and nitrite/nitrate has shown beneficial effects at the vascular level.

Genetics and Genomics of Pediatric Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease with high mortality despite recent therapeutic advances. The disease is caused by both genetic and environmental factors and likely gene-environment interactions. While PAH can manifest across the lifespan, pediatric-onset disease is particularly challenging because it is frequently associated with a more severe clinical course and comorbidities including lung/heart developmental anomalies. In light of these differences, it is perhaps not surprising that emerging data from genetic studies of pediatric-onset PAH indicate that the genetic basis is different than that of adults. There is a greater genetic burden in children, with rare genetic factors contributing to ~42% of pediatric-onset PAH compared to ~12.5% of adult-onset PAH. De novo variants are frequently associated with PAH in children and contribute to at least 15% of all pediatric cases. The standard of medical care for pediatric PAH patients is based on extrapolations from adult data. However, increased etiologic heterogeneity, poorer prognosis, and increased genetic burden for pediatric-onset PAH calls for a dedicated pediatric research agenda to improve molecular diagnosis and clinical management. A genomics-first approach will improve the understanding of pediatric PAH and how it is related to other rare pediatric genetic disorders.

Genetics and Other Omics in Pediatric Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease with high mortality despite therapeutic advances. Clinical management of children with PAH is particularly challenging because of increased complexity of disease etiology and clinical presentation, and the lack of data from pediatric-specific clinical trials. In children, PAH often develops in association with congenital heart disease and other developmental disorders. Emerging data from genetic studies of pediatric-onset PAH indicate that the genetic basis is different than that of adults. There is a greater genetic burden in children, with rare genetic factors contributing to at least 35% of pediatric-onset idiopathic PAH (IPAH) compared with approximately 11% of adult-onset IPAH. De novo variants are the most frequent monogenetic cause of PAH in children, likely contributing to approximately 15% of all cases. Rare deleterious variants in BMPR2 contribute to pediatric-onset IPAH and familial PAH with similar frequency as adult-onset disease but rarely explain cases of PAH associated with other diseases. Rare deleterious variants in developmental genes-including TBX4, SOX17, and other genes requiring confirmation in larger cohorts-are emerging as important contributors to pediatric-onset disease. Because each causal gene contributes to only a small number of cases, large cohorts of pediatric-onset PAH are needed to further identify the unique etiologic differences of PAH in children. We propose a genetics-first approach followed by focused phenotyping of pediatric patients grouped by genetic diagnosis to define endophenotypes that can be used to improve risk stratification and treatment.

Elevated Nucleated Red Blood Cells in Neonates with Down Syndrome and Pulmonary Hypertension

We report an association between higher absolute nucleated red blood cells and mean corpuscular volume and idiopathic persistent pulmonary hypertension of the newborn in neonates with Down syndrome. Elevation of these blood indicies should prompt echocardiographic studies to monitor pulmonary arterial pressures.

Treatment of pediatric pulmonary arterial hypertension: A focus on the NO-sGC-cGMP pathway

OBJECTIVE

While pulmonary arterial hypertension (PAH) is rare in infants and children, it results in substantial morbidity and mortality. In recent years, prognosis has improved, coinciding with the introduction of new PAH-targeted therapies, although much of their use in children is off-label. Evidence to guide the treatment of children with PAH is less extensive than for adults. The goal of this review is to discuss the treatment recommendations for children with PAH, as well as the evidence supporting the use of prostanoids, endothelin receptor antagonists (ERAs), and phosphodiesterase type 5 inhibitors (PDE5i) in this setting.

DATA SOURCES

Nonsystematic PubMed literature search and authors' expertise.

STUDY SELECTION

Articles were selected concentrating on the nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway in PAH. The methodology of an ongoing study evaluating the sGC stimulator riociguat in children with PAH is also described.

RESULTS

Despite recent medical advances, improved therapeutic strategies for pediatric PAH are needed. The efficacy and tolerability of riociguat in adults with PAH have been well trialed.

CONCLUSION

The pooling of data across trials, supplemented by registry data, will help to confirm the safety and tolerability of prostanoids, ERAs, and PDE5i in children. Ongoing studies will clarify the place of sGC stimulators in the treatment strategy for pediatric PAH.

Postoperative and long-term outcomes in children with Trisomy 21 and single ventricle palliation

OBJECTIVE

Patients with Trisomy 21 (T21) and single ventricle (SV) physiology present unique challenges compared to euploidic counterparts. This study reports postoperative and long-term outcomes in patients with T21 and SV palliation.

DESIGN

This retrospective cohort study from the Pediatric Cardiac Care Consortium (PCCC) included patients with T21 (<21 years old) that underwent surgical palliation for SV between 1982 and 2008 and control patients without known genetic anomaly following Fontan palliation for similar diagnoses. Kaplan-Meier survival plots were created based on death events obtained from the PCCC and by linkage with the National Death Index (NDI) and the Organ Procurement and Transplantation Network (OPTN) through 2014 for patients with adequate identifiers.

RESULTS

We identified 118 children with T21 who underwent initial surgical SV palliation. Among 90 (75.6%) patients surviving their first surgery, 66 (73.3%) underwent Glenn anastomosis and 25 (27.8%) completed Fontan palliation with in-hospital survival of 80.3% and 76.0%, respectively. Fifty-three patients had sufficient identifiers for PCCC-NDI-OPTN linkage. Ten-year survival, conditioned on discharge alive after the Fontan procedure, was 66.7% compared to 92.2% for 51 controls without genetic anomaly (P = .001). Median age at death for T21 patients following initial surgical SV palliation was 2.69 years (IQR 1.34-7.12) with most deaths (89.2%) attributed to the underlying congenital heart disease (CHD).

CONCLUSIONS

Children with T21 and SV are at high risk for procedural and long-term mortality related to their genetic condition and underlying CHD. Nevertheless, a select group of patients can successfully complete Glenn or Fontan palliation, reaching satisfactory long-term survival.

Safety of enteral sildenafil in hemodynamically unstable children

BACKGROUND

Enteral sildenafil may be used in the intensive care unit for treatment of pulmonary arterial hypertension. We aimed to determine if initial enteral sildenafil dosing is safe in children receiving concurrent vasoactive infusions.

METHODS

We performed a single-centre retrospective chart review that included patients less than 2 years of age in paediatric and cardiovascular intensive care units at an academic medical centre from 1 January, 2010 to 30 November, 2016. Included patients received concomitant enteral sildenafil and a continuously infused vasoactive agent. Exclusion criteria consisted of mechanical circulatory support, any form of dialysis, or a suspicion of septic shock at the time of sildenafil initiation. We sought to identify patients who developed worsening hemodynamic instability after initiation of enteral sildenafil defined as one or more of the following observations within 24 hours of sildenafil initiation: sildenafil discontinuation, total fluid bolus receipt &gt;10 ml/kg, increased vasoactive support, epinephrine intravenous push administration, and/or the initiation of mechanical circulatory support.

RESULTS

Worsening hemodynamic instability was identified in 35% of the 130-patient cohort. Patients younger than 4 months were at increased risk of further hemodynamic instability compared with older patients (56% versus 44%, p = 0.0003) despite receiving lower median doses (1.28 mg/kg/day versus 1.78 mg/kg/day, p = 0.01).

CONCLUSIONS

Critically ill children receiving vasoactive infusions may be at increased risk for further hemodynamic instability after initiation of enteral sildenafil, particularly in younger patients. This population may benefit from lower starting enteral sildenafil doses of 0.25 mg/kg/dose or less every 8 hours to avoid further hemodynamic compromise.

Pulmonary vascular resistance index: Getting the units right and why it matters

Pulmonary vascular resistance (PVR) and PVR index (PVRI) are key variables in a broad range of contexts, including prediction of outcomes in heart and liver transplantation, determining candidacy for closure of atrial or ventricular septal defects, and guiding treatment of pulmonary hypertension. Significant variability exists among the units used to report PVRI in current literature, making the interpretation of data and translation into clinical practice difficult. Here, we will review the measurement and derivation of PVR and PVRI and demonstrate the extent of confusion in the literature. We conducted a literature search of all published articles in PubMed using the term “PVRI.” This yielded 218 sources with defined units for PVRI, including 33 unique variants. Among all reviewed literature, 45.4% of sources reported PVRI with units ending in m² (meters squared), which we defined as correct, whereas 54.6% reported PVRI with units not ending in m², which we defined as incorrect. This lack of uniformity has led to considerable confusion among researchers and clinicians, with potentially life‐altering consequences.

Sildenafil Use in Children with Pulmonary Hypertension

OBJECTIVE

To assess the demographics, treatment algorithm, and outcomes in a large cohort of children treated with sildenafil.

STUDY DESIGN

A retrospective cohort study of children with pulmonary hypertension (PH) treated with sildenafil at a single institution between 2004 and 2015. Baseline and follow-up data collected by chart review.

RESULTS

There were 269 children included in this study: 47 with idiopathic pulmonary arterial hypertension, 53 with congenital heart disease, 135 with bronchopulmonary dysplasia, 24 with congenital diaphragmatic hernia, and 7 with other causes. Sildenafil was initial monotherapy in 84.8% and add-on therapy in 15.2%. Median follow-up time was 3.1 years (2  weeks-12.4 years). On follow-up, 99 (37%) remained on sildenafil or transitioned to tadalafil, 93 (35%) stopped sildenafil for improvement in PH, 54 (20%) died, and 20 (7%) were lost to follow-up. PH was most likely to improve in those with bronchopulmonary dysplasia, allowing for the discontinuation of sildenafil in 45%. Eighteen deaths were related to PH and 36 from other systemic causes. Two patients stopped sildenafil owing to airway spasm with desaturation. Overall survival was significantly lower in World Health Organization group 3 PH (bronchopulmonary dysplasia and congenital diaphragmatic hernia) vs group 1 (idiopathic pulmonary arterial hypertension and congenital heart disease), P = .02.

CONCLUSIONS

In this retrospective experience in children with mainly World Health Organization groups 1 and 3 PH, low-dose sildenafil was well-tolerated, safe, and had an acceptable side effect profile. Although patients with group 3 PH have high mortality, survivors have a high likelihood of PH improving.

Management dilemmas in pulmonary arterial hypertension associated with congenital heart disease

There are few randomised controlled data to guide management of patients with pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD). In this clinical review, common areas of uncertainty in the management of PAH-CHD are identified, the literature is summarised and discussed and a suggested approach offered for each clinical dilemma.

Efficacy and tolerability of pharmacological interventions for pulmonary arterial hypertension: A network meta-analysis

PURPOSE

This network meta-analysis (NMA) is designed to compare the efficacy and tolerability of various therapies and combinations for pulmonary arterial hypertension (PAH).

METHOD

We conducted a systematic search in databases PubMed, Embase, and Cochrane Library. Treatment efficacy and tolerability were compared by synthesizing direct and indirect evidence. The surface under the curve ranking area was utilized to rank multiple interventions.

RESULT

A total of 43 randomized clinical trials were included in our NMA. With regard to efficacy outcomes, including 6 min walking distance (6MWD), functional class amelioration (FCA), death, clinical worsening (CW), pulmonary vascular resistance (PVR), mean pulmonary artery pressure (mPAP), cardiac index (CI), and mean right atrial pressure (mRAP), endothelin receptor antagonists (ERA), phosphodiesterase 5 inhibitor (PDE-5Is), ERA combined with PDE-5Is (EAP), and prostacyclin analogs (PGI) combined with ERA (PAE) performed better than others. Meanwhile PAP and PGE demonstrated better than others in tolerability. Overall, EAP and PAE showed good efficacy and were well-tolerated among all therapies.

CONCLUSION

Overall, we recommend EAP as the optimal choice for patients with PAH in clinical practice and PAE as suboptimal in view of their desirable performance in efficacy. Most of the combination therapies performed better than monotherapies.