Characterisation of Pediatric Pulmonary Hypertensive Vascular Disease from the PPHNet Registry

Invasive haemodynamics predict outcomes in paediatric pulmonary artery hypertension

BACKGROUND

Invasive haemodynamics are often performed for initiating and guiding pulmonary artery hypertension therapy. Little is known about the predictive value of invasive haemodynamic indices for long-term outcomes in children with pulmonary artery hypertension. We aimed to evaluate invasive haemodynamic data to help predict outcomes in paediatric pulmonary artery hypertension.

METHODS

Patients with pulmonary artery hypertension who underwent cardiac catheterisation (2006-2019) at a single centre were included. Invasive haemodynamic data from the first cardiac catheterisation and clinical outcomes were reviewed. The combined adverse outcome was defined as pericardial effusion (due to right ventricle failure), creation of a shunt for pulmonary artery hypertension (atrial septal defect or reverse Pott's shunt), lung transplant, or death.

RESULTS

Among 46 patients with a median [interquartile range (IQR)] age of 13.2 [4.1-44.7] months, 76% had CHD. Median mean pulmonary artery pressure was 37 [28-52] mmHg and indexed pulmonary vascular resistance was 6.2 [3.6-10] Woods units × m2. Median pulmonary artery pulsatility index was 4.0 [3.0-4.7] and right ventricular stroke work index was 915 [715-1734] mmHg mL/m2. After a median follow-up of 2.4 years, nine patients had a combined adverse outcome (two had a pericardial effusion, one underwent atrial level shunt, one underwent reverse Pott's shunt, and six died). Patients with an adverse outcome had higher systolic and mean pulmonary artery pressures, higher diastolic and transpulmonary pressure gradients, higher indexed pulmonary vascular resistance, higher pulmonary artery elastance, and higher right ventricular stroke work index (p < 0.05 each).

CONCLUSION

Invasive haemodynamics (especially mean pulmonary artery pressure and diastolic pressure gradient) obtained at first cardiac catheterisation in children with pulmonary artery hypertension predicts outcomes.

Long-term pulmonary outcomes in BPD throughout the life-course

Respiratory disease is one of the most common complications of preterm birth. Survivors of prematurity have increased risks of morbidities and mortalities independent of prematurity, and frequently require multiple medications, home respiratory support, and subspecialty care to maintain health. Although advances in neonatal and pulmonary care have improved overall survival, earlier gestational age, lower birth weight, chorioamnionitis and late onset sepsis continue to be major factors in the development of bronchopulmonary dysplasia. These early life events associated with prematurity can have respiratory consequences that persist into adulthood. Furthermore, after initial hospital discharge, air pollution, respiratory tract infections and socioeconomic status may modify lung growth trajectories and influence respiratory outcomes in later life. Given that the incidence of respiratory disease associated with prematurity remains stable or increased, there is a need for pediatric and adult providers to be familiar with the natural history, manifestations, and common complications of disease.

A single institution anesthetic experience with catheterization of pediatric pulmonary hypertension patients

Cardiac catheterization remains the gold standard for the diagnosis and management of pediatric pulmonary hypertension (PH). There is lack of consensus regarding optimal anesthetic and airway regimen. This retrospective study describes the anesthetic/airway experience of our single center cohort of pediatric PH patients undergoing catheterization, in which obtaining hemodynamic data during spontaneous breathing is preferential. A total of 448 catheterizations were performed in 232 patients. Of the 379 cases that began with a natural airway, 274 (72%) completed the procedure without an invasive airway, 90 (24%) received a planned invasive airway, and 15 (4%) required an unplanned invasive airway. Median age was 3.4 years (interquartile range [IQR] 0.7-9.7); the majority were either Nice Classification Group 1 (48%) or Group 3 (42%). Vasoactive medications and cardiopulmonary resuscitation were required in 14 (3.7%) and eight (2.1%) cases, respectively; there was one death. Characteristics associated with use of an invasive airway included age <1 year, Group 3, congenital heart disease, trisomy 21, prematurity, bronchopulmonary dysplasia, WHO functional class III/IV, no PH therapy at time of case, preoperative respiratory support, and having had an intervention (p < 0.05). A composite predictor of age <1 year, Group 3, prematurity, and any preoperative respiratory support was significantly associated with unplanned airway escalation (26.7% vs. 6.9%, odds ratio: 4.9, confidence interval: 1.4-17.0). This approach appears safe, with serious adverse event rates similar to previous reports despite the predominant use of natural airways. However, research is needed to further investigate the optimal anesthetic regimen and respiratory support for pediatric PH patients undergoing cardiac catheterization.

Pulmonary Hypertension in Established Bronchopulmonary Dysplasia: Physiologic Approaches to Clinical Care

Preterm infants with bronchopulmonary dysplasia (BPD) are prone to develop pulmonary hypertension (PH). Strong laboratory and clinical data suggest that antenatal factors, such as preeclampsia, chorioamnionitis, oligohydramnios, and placental dysfunction leading to fetal growth restriction, increase susceptibility for BPD-PH after premature birth. Echocardiogram metrics and serial assessments of NT-proBNP provide useful tools to diagnose and monitor clinical course during the management of BPD-PH, as well as monitoring for such complicating conditions as left ventricular diastolic dysfunction, shunt lesions, and pulmonary vein stenosis. Therapeutic strategies should include careful assessment and management of underlying airways and lung disease, cardiac performance, and systemic hemodynamics, prior to initiation of PH-targeted drug therapies.

[Diagnosis of pulmonary hypertension associated with congenital heart disease based on statistical features of the second heart sound]

Aiming at the problems of obscure clinical auscultation features of pulmonary hypertension associated with congenital heart disease and the complexity of existing machine-aided diagnostic algorithms, an algorithm based on the statistical characteristics of the high-frequency components of the second heart sound signal is proposed. Firstly, an endpoint detection adaptive segmentation method is employed to extract the second heart sounds. Subsequently, the high-frequency component of the heart sound is decomposed using the discrete wavelet transform. Statistical features including the Hurst exponent, Lempel-Ziv information and sample entropy are extracted from this component. Finally, the extracted features are utilized to train an extreme gradient boosting algorithm (XGBoost) classifier, which achieves an accuracy of 80.45% in triple classification. Notably, this method eliminates the need for a noise reduction algorithm, allows for swift feature extraction, and achieves effective multi-classification using only three features. It is promising for early screening of pulmonary hypertension associated with congenital heart disease.

Cumulus: A federated EHR-based learning system powered by FHIR and AI

Objective

To address challenges in large-scale electronic health record (EHR) data exchange, we sought to develop, deploy, and test an open source, cloud-hosted app 'listener' that accesses standardized data across the SMART/HL7 Bulk FHIR Access application programming interface (API).

Methods

We advance a model for scalable, federated, data sharing and learning. Cumulus software is designed to address key technology and policy desiderata including local utility, control, and administrative simplicity as well as privacy preservation during robust data sharing, and AI for processing unstructured text.

Results

Cumulus relies on containerized, cloud-hosted software, installed within a healthcare organization's security envelope. Cumulus accesses EHR data via the Bulk FHIR interface and streamlines automated processing and sharing. The modular design enables use of the latest AI and natural language processing tools and supports provider autonomy and administrative simplicity. In an initial test, Cumulus was deployed across five healthcare systems each partnered with public health. Cumulus output is patient counts which were aggregated into a table stratifying variables of interest to enable population health studies. All code is available open source. A policy stipulating that only aggregate data leave the institution greatly facilitated data sharing agreements.

Discussion and Conclusion

Cumulus addresses barriers to data sharing based on (1) federally required support for standard APIs (2), increasing use of cloud computing, and (3) advances in AI. There is potential for scalability to support learning across myriad network configurations and use cases.

Multi-dose enteral L-citrulline administration in premature infants at risk of developing pulmonary hypertension associated with bronchopulmonary dysplasia

OBJECTIVE

Information is needed to guide the design of randomized controlled trials (RCTs) evaluating L-citrulline therapy for premature infants with pulmonary hypertension associated with bronchopulmonary dysplasia (BPD-PH). Based on our single-dose pharmacokinetic study, we evaluated the ability of a multi-dose enteral L-citrulline strategy to achieve a target trough steady-state L-citrulline plasma concentration and its tolerability in premature infants.

STUDY DESIGN

Plasma L-citrulline concentrations were measured in six premature infants receiving 60 mg/kg L-citrulline every 6 h for 72 h before the first and last L-citrulline doses. L-citrulline concentrations were compared to concentration-time profiles from our previous study.

RESULTS

Target trough plasma L-citrulline concentrations were achieved in 2/6 subjects. No serious adverse events occurred.

CONCLUSIONS

Multi-dose L-citrulline was well tolerated. These results will assist in the design of phase II RCTs evaluating L-citrulline dosage strategies to achieve target plasma L-citrulline concentrations in infants at risk for BPD-PH.

CLINICAL TRIALS

gov ID: NCT03542812.

Pulmonary hypertension

Pulmonary hypertension encompasses a range of conditions directly or indirectly leading to elevated pressures within the pulmonary arteries. Five main groups of pulmonary hypertension are recognized, all defined by a mean pulmonary artery pressure of >20 mmHg: pulmonary arterial hypertension (rare), pulmonary hypertension associated with left-sided heart disease (very common), pulmonary hypertension associated with lung disease (common), pulmonary hypertension associated with pulmonary artery obstructions, usually related to thromboembolic disease (rare), and pulmonary hypertension with unclear and/or multifactorial mechanisms (rare). At least 1% of the world's population is affected, with a greater burden more likely in low-income and middle-income countries. Across all its forms, pulmonary hypertension is associated with adverse vascular remodelling with obstruction, stiffening and vasoconstriction of the pulmonary vasculature. Without proactive management this leads to hypertrophy and ultimately failure of the right ventricle, the main cause of death. In older individuals, dyspnoea is the most common symptom. Stepwise investigation precedes definitive diagnosis with right heart catheterization. Medical and surgical treatments are approved for pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. There are emerging treatments for other forms of pulmonary hypertension; but current therapy primarily targets the underlying cause. There are still major gaps in basic, clinical and translational knowledge; thus, further research, with a focus on vulnerable populations, is needed to better characterize, detect and effectively treat all forms of pulmonary hypertension.

Actigraphy methodology in the Kids Mod PAH trial: Physical activity as a functional endpoint in pediatric clinical trials

Pulmonary vasodilator treatment can improve hemodynamics, right ventricular function, symptoms, and survival in pediatric pulmonary hypertension (PH). However, clinical trial data are lacking due to many constraints. One major limitation is the lack of relevant trial endpoints reflective of hemodynamics or functional status in patients in whom standard exercise testing is impractical, unreliable, or not reproducible. The Kids Mod PAH trial (Mono- vs. Duo Therapy for Pediatric Pulmonary Arterial Hypertension) is an ongoing multicenter, Phase III, randomized, open-label, pragmatic trial to compare the safety and efficacy of first-line combination therapy (sildenafil and bosentan) to first-line monotherapy (sildenafil alone) in 100 pediatric patients with PH across North America. Investigators will measure participants' physical activity with a research-grade, wrist-worn actigraphy device at multiple time points as an exploratory secondary outcome. Vector magnitude counts per minute and activity intensity will be compared between the treatment arms. By directly and noninvasively measuring physical activity in the ambulatory setting, we aim to identify a novel, simple, inexpensive, and highly reproducible approach for quantitative assessment of exercise tolerance in pediatric PH. These data will increase the field's understanding of the effect of pulmonary vasodilator treatment on daily activity - a quantitative measure of functional status and wellbeing in pediatric PH and a potential primary outcome for future clinical trials in children with cardiopulmonary disorders.

[New aspects in pediatric pulmonary hypertension - Commented 2022ERS/ESC-PH guidelines]

Pulmonary hypertension (PH) in childhood differs from that of adulthood particularly in the specific pathophysiology of congenital heart disease-associated pulmonary arterial hypertension, the presence of developmental lung disease, and the frequent association with chromosomal, genetic, and syndromal abnormalities. Treatment of children with PH requires a modified diagnostic algorithm tailored to childhood, as well as pathophysiologically oriented therapeutic strategies. In the current 2022 ERS/ESC-PH guidelines, the specific features of PH in children are highlighted in its own chapter and commented on by the authorship group in this article.

Kids Mod PAH trial: A multicenter trial comparing mono- versus duo-therapy for initial treatment of pediatric pulmonary hypertension

Pulmonary hypertension (PH) is a significant health problem that contributes to high morbidity and mortality in diverse cardiac, pulmonary, and systemic diseases in children. Evidence-based advances in PH care have been challenged by a paucity of quality endpoints for assessing clinical course and the lack of robust clinical trial data to guide pharmacologic therapies in children. While the landmark adult AMBITION trial demonstrated the benefit of up-front combination PH therapy with ambrisentan and tadalafil, it remains unknown whether upfront combination therapy leads to more rapid and sustained clinical benefits in children with various categories of PH. In this article, we describe the inception of the Kids Mod PAH Trial, a multicenter Phase III trial, to address whether upfront combination therapy (sildenafil and bosentan vs. sildenafil alone) improves PH outcomes in children, recognizing that marked differences between the etiology and therapeutic response between adults and children exist. The primary endpoint of this study is WHO functional class (FC) 12 months after initiation of study drug therapy. In addition to the primary outcome, secondary endpoints are being assessed, including a composite measure of time to clinical worsening, WHO FC at 24 months, echocardiographic assessment of PH and quantitative assessment of right ventricular function, 6-min walk distance, and NT-proBNP levels. Exploratory endpoints include selected biomarkers, actigraphy, and assessments of quality of life. This study is designed to pave the way for additional clinical trials by establishing a robust infrastructure through the development of a PPHNet Clinical Trials Network.

Real-world evidence to advance knowledge in pulmonary hypertension: Status, challenges, and opportunities. A consensus statement from the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative's Real-world Evidence Working Group

This manuscript on real-world evidence (RWE) in pulmonary hypertension (PH) incorporates the broad experience of members of the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative Real-World Evidence Working Group. We aim to strengthen the research community's understanding of RWE in PH to facilitate clinical research advances and ultimately improve patient care. Herein, we review real-world data (RWD) sources, discuss challenges and opportunities when using RWD sources to study PH populations, and identify resources needed to support the generation of meaningful RWE for the global PH community.

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.

Multi-dose enteral L-citrulline administration in premature infants at risk of developing pulmonary hypertension associated with bronchopulmonary dysplasia

Objective

Information is needed to guide the design of randomized controlled trials (RCTs) evaluating L-citrulline as a therapy for premature infants with pulmonary hypertension associated with bronchopulmonary dysplasia (BPD-PH). Our goal was to evaluate the tolerability and ability to achieve a target steady-state L-citrulline plasma concentration in prematures treated enterally with a multi-dose L-citrulline strategy based on our single-dose pharmacokinetic study.

Study Design

Six prematures received 60 mg/kg of L-citrulline every 6 hours for 72 hours. Plasma L-citrulline concentrations were measured before the first and last L-citrulline doses. L-citrulline concentrations were compared to concentration-time profiles from our previous study.

Results

Plasma L-citrulline concentrations agreed with the simulated concentration-time profiles. No serious adverse events occurred.

Conclusions

Simulations based on single-doses can be used to predict target multi-dose plasma L-citrulline concentrations. These results assist the design of RCTs evaluating the safety and effectiveness of L-citrulline therapy for BPD-PH. Clinical trials.gov ID: NCT03542812.

Characteristics, Long-term Survival, and Risk Assessment of Pediatric Pulmonary Arterial Hypertension in China: Insights From a National Multicenter Prospective Registry

BACKGROUND

Registry-based studies of pediatric pulmonary arterial hypertension (PPAH) are scarce in developing countries, including China. The PPAH risk assessment tool needs further evaluation and improvement.

RESEARCH QUESTION

What are the characteristics and long-term survival of PPAH in China and what is the performance of the PPAH risk model in Chinese patients?

STUDY DESIGN AND METHODS

Patients with PAH were enrolled in the national prospective multicenter registry from August 2009 through December 2019. Children 3 months to 18 years of age at the time of PAH diagnosis were analyzed.

RESULTS

A total of 247 children with PAH were enrolled. The median patient age was 14.8 years, and 58.3% of patients were female. Most patients had a diagnosis of PAH associated with congenital heart disease (CHD; 61.5%) and idiopathic or heritable PAH (37.7%). The median time from symptom onset to PAH diagnosis was 24 months. The mean pulmonary artery pressure and pulmonary vascular resistance index were 70.78 ± 19.80 mm Hg and 21.82 ± 11.18 Wood Units·m2, respectively. Patients with CHD-associated PAH experienced a longer diagnostic delay and demonstrated higher pulmonary artery pressure, but better cardiac performance, than those with idiopathic or heritable PAH. An increased number of patients received targeted therapy at the last follow-up compared with baseline. The 5- and 10-year survival rates of the entire cohort were 74.9% and 55.7%, respectively, with better survival in patients with CHD-associated PAH than in those with idiopathic or heritable PAH. Patients with low risk had better survival than those with high risk according to the simplified noninvasive risk score model with weight, function class, and echocardiographic right ventricular size, both at baseline and follow-up.

INTERPRETATION

Patients with PPAH in China showed severely compromised hemodynamics with marked diagnostic delay. The long-term survival of PPAH is poor despite the increased usefulness of targeted drugs. The simplified noninvasive risk model demonstrated good performance for predicting survival in Chinese children with PAH.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01417338; URL: www.

CLINICALTRIALS

gov.

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.

Pharmacotherapy for Pulmonary Hypertension in Infants with Bronchopulmonary Dysplasia: Past, Present, and Future

Approximately 8-42% of premature infants with chronic lung disease of prematurity, bronchopulmonary dysplasia (BPD), develop pulmonary hypertension (PH). Infants with BPD-PH carry alarmingly high mortality rates of up to 47%. Effective PH-targeted pharmacotherapies are desperately needed for these infants. Although many PH-targeted pharmacotherapies are commonly used to treat BPD-PH, all current use is off-label. Moreover, all current recommendations for the use of any PH-targeted therapy in infants with BPD-PH are based on expert opinion and consensus statements. Randomized Control Trials (RCTs) are needed to determine the efficacy of PH-targeted treatments in premature infants with or at risk of BPD-PH. Prior to performing efficacy RCTs, studies need to be conducted to obtain pharmacokinetic, pharmacodynamic, and safety data for any pharmacotherapy used in this understudied and fragile patient population. This review will discuss current and needed treatment strategies, identify knowledge deficits, and delineate both challenges to be overcome and approaches to be taken to develop effective PH-targeted pharmacotherapies that will improve outcomes for premature infants with or at risk of developing BPD-PH.

Idiopathic Pulmonary Arterial Hypertension in Paediatrics Represents Still a Serious Challenge: A Case Series Study

Introduction: Paediatric pulmonary hypertension (PH) represents a heterogeneous illness that is responsible for high morbidity and mortality if left without treatment. Idiopathic pulmonary arterial hypertension (IPAH) is a subtype of PAH rarely seen in paediatrics. Limited long-term data are available. Methods: Over a period of 20 years, 10 paediatric patients were enrolled at two tertiary centres. Their clinical, echocardiographic, and right heart catheterisation (RHC) features and outcome were evaluated. Results: The mean age at first diagnosis was 5.7 ± 5.7 years. The age at the last follow-up was 12.4 ± 6.1 years. The average follow-up was 6.6 ± 0.8 years. There was a female prevalence of 60% (p < 0.05) in this case series. Regarding the NYHA functional class, 80% of IPAH subjects were in class III or IV. The mean saturation was 91 ± 5%. In this regard, 70% of the patients were on a combination of three drugs, with sildenafil (90%) included. On echocardiography, longitudinal right ventricular contractility (TAPSE) was slightly reduced (13.4 ± 2.6 mm), whilst RVSP was severely elevated (101 ± 19 mmHg). The RHC data showed that mPAP was 61.8 ± 23.1 mmHg (p = 0.0017 with RVSP on echocardiography), mRAP was 10.7 ± 3.8 mmHg, CI was 2.6 ± 1 L·min−1·m−2, PVRi was 16.8 ± 12.6 WU·m2, and SVO2 was 63.6 ± 14.8%. Regarding the outcome, two male IPAH patients (20%) died, and 50% underwent lung transplant or were on transplant assessment or already on the waiting list for lung transplantation. One patient underwent a ductus arteriosus stenting (reverse Potts shunt) and another underwent atrial septostomy and stenting. Conclusions: Notwithstanding the progress in medical therapy, IPAH continues to represent a serious challenge, particularly in the paediatric population, with the need for lung transplantation and significant mortality.

IoT-Enabled Classification of Echocardiogram Images for Cardiovascular Disease Risk Prediction with Pre-Trained Recurrent Convolutional Neural Networks

Cardiovascular diseases currently present a key health concern, contributing to an increase in death rates worldwide. In this phase of increasing mortality rates, healthcare represents a major field of research, and the knowledge acquired from this analysis of health information will assist in the early identification of disease. The retrieval of medical information is becoming increasingly important to make an early diagnosis and provide timely treatment. Medical image segmentation and classification is an emerging field of research in medical image processing. In this research, the data collected from an Internet of Things (IoT)-based device, the health records of patients, and echocardiogram images are considered. The images are pre-processed and segmented, and then further processed using deep learning techniques for classification as well as forecasting the risk of heart disease. Segmentation is attained via fuzzy C-means clustering (FCM) and classification using a pretrained recurrent neural network (PRCNN). Based on the findings, the proposed approach achieves 99.5% accuracy, which is higher than the current state-of-the-art techniques.

Pulmonary Hypertension in Children with Down Syndrome: Results from the Pediatric Pulmonary Hypertension Network Registry

OBJECTIVE

To characterize distinct comorbidities, outcomes, and treatment patterns in children with Down syndrome and pulmonary hypertension in a large, multicenter pediatric pulmonary hypertension registry.

STUDY DESIGN

We analyzed data from the Pediatric Pulmonary Hypertension Network (PPHNet) Registry, comparing demographic and clinical characteristics of children with Down syndrome and children without Down syndrome. We examined factors associated with pulmonary hypertension resolution and a composite outcome of pulmonary hypertension severity in the cohort with Down syndrome.

RESULTS

Of 1475 pediatric patients with pulmonary hypertension, 158 (11%) had Down syndrome. The median age at diagnosis of pulmonary hypertension in patients with Down syndrome was 0.49 year (IQR, 0.21-1.77 years), similar to that in patients without Down syndrome. There was no difference in rates of cardiac catheterization and prescribed pulmonary hypertension medications in children with Down syndrome and those without Down syndrome. Comorbidities in Down syndrome included congenital heart disease (95%; repaired in 68%), sleep apnea (56%), prematurity (49%), recurrent respiratory exacerbations (35%), gastroesophageal reflux (38%), and aspiration (31%). Pulmonary hypertension resolved in 43% after 3 years, associated with a diagnosis of pulmonary hypertension at age <6 months (54% vs 29%; P = .002) and a pretricuspid shunt (65% vs 38%; P = .02). Five-year transplantation-free survival was 88% (95% CI, 80%-97%). Tracheostomy (hazard ratio [HR], 3.29; 95% CI, 1.61-6.69) and reflux medication use (HR, 2.08; 95% CI, 1.11-3.90) were independently associated with a composite outcome of severe pulmonary hypertension.

CONCLUSIONS

Despite high rates of cardiac and respiratory comorbidities that influence the severity of pulmonary hypertension, children with Down syndrome-associated pulmonary hypertension generally have a survival rate similar to that of children with non-Down syndrome-associated pulmonary hypertension. Resolution of pulmonary hypertension is common but reduced in children with complicated respiratory comorbidities.

Pharmacokinetics of L-Citrulline in Neonates at Risk of Developing Bronchopulmonary Dysplasia-Associated Pulmonary Hypertension

BACKGROUND

Options to treat pulmonary hypertension (PH) in neonates with bronchopulmonary dysplasia (BPD) are few and largely ineffective. Improving the bioavailability of nitric oxide (NO) might be an efficacious treatment for BPD-PH. When administered orally, the NO-L-arginine precursor, L-citrulline, increases NO production in children and adults, however, pharmacokinetic (PK) studies of oral L-citrulline have not been performed in infants and children.

OBJECTIVES

This study characterized the PK of enterally administered L-citrulline in neonates at risk of developing BPD-PH to devise a model-informed dosing strategy.

METHODS AND RESULTS

Ten premature neonates (≤ 28 weeks gestation) were administered a single dose of 150 mg/kg (powder form solubilized in sterile water) oral L-citrulline at 32 ± 1 weeks postmenstrual age. Due to the need to limit blood draws, time windows were used to maximize the sampling over the dosing interval by assigning neonates to one of two groups (ii) samples collected pre-dose and at 1- and 2.5-h post-dose, and (ii) pre-dose and 0.25- and 3-h post-dose. The L-arginine concentrations (µmol/L) and the L-citrulline (µmol/L) plasma concentration-time data were evaluated using non-compartmental analysis (Phoenix WinNonlin version 8.1). Optimal dosage strategies were derived using a simulation-based methodology. Simulated doses of 51.5 mg or 37.5 mg/kg given four times a day produced steady-state concentrations close to a target of 50 µmol/L. The volume of distribution (V/F) and clearance (CL/F) were 302.89 ml and 774.96 ml/h, respectively, with the drug exhibiting a half-life of 16 minutes. The AUC from the time of dosing to the time of last concentration was 1473.3 h*μmol/L, with Cmax and Tmax of 799 μmol/L and 1.55 h, respectively.

CONCLUSION

This is the first PK study in neonates presenting data that can be used to inform dosing strategies in future randomized controlled trials evaluating enteral L-citrulline as a potential treatment to reduce PH associated with BPD in premature neonates.

REGISTRATION

Clinical trials.gov Identifier: NCT03542812.

Case report: High-dose epoprostenol therapy in pediatric patients with pulmonary hypertension and developmental lung disease

Pulmonary hypertension (PH) with developmental lung disease is a life-threatening disease and accounts for 10%-12% of pediatric PH patients. Administration of specific pulmonary vasodilators to pediatric PH patients has brought about improvement of their long-term prognosis. Intravenous epoprostenol therapy is a gold standard therapy for severe idiopathic pulmonary arterial hypertension (IPAH), but there are few reports demonstrating the efficacy of epoprostenol for pediatric PH patients with developmental lung disease, especially when treating with high doses of epoprostenol. Two cases of pediatric PH patients with alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) and congenital diaphragmatic hernia (CDH) with bronchopulmonary dysplasia (BPD), respectively, treated with epoprostenol above 100 ng/kg/min are presented. In these two cases, severe PH was improved significantly by an aggressive increase of the epoprostenol infusion rate with administration of oral pulmonary vasodilators and appropriate respiratory management, without any significant adverse effects. High-dose epoprostenol therapy may be one of the therapeutic options in pediatric PH patients with developmental lung disease.

Genes in pediatric pulmonary arterial hypertension and the most promising BMPR2 gene therapy

Pulmonary arterial hypertension (PAH) is a rare but progressive and lethal vascular disease of diverse etiologies, mainly caused by proliferation of endothelial cells, smooth muscle cells in the pulmonary artery, and fibroblasts, which ultimately leads to right-heart hypertrophy and cardiac failure. Recent genetic studies of childhood-onset PAH report that there is a greater genetic burden in children than in adults. Since the first-identified pathogenic gene of PAH, BMPR2, which encodes bone morphogenetic protein receptor 2, a receptor in the transforming growth factor-β superfamily, was discovered, novel causal genes have been identified and substantially sharpened our insights into the molecular genetics of childhood-onset PAH. Currently, some newly identified deleterious genetic variants in additional genes implicated in childhood-onset PAH, such as potassium channels (KCNK3) and transcription factors (TBX4 and SOX17), have been reported and have greatly updated our understanding of the disease mechanism. In this review, we summarized and discussed the advances of genetic variants underlying childhood-onset PAH susceptibility and potential mechanism, and the most promising BMPR2 gene therapy and gene delivery approaches to treat childhood-onset PAH in the future.

Twenty-Year Experience and Outcomes in a National Pediatric Pulmonary Hypertension Service

Rationale: Pediatric pulmonary hypertension is an important cause of childhood morbidity and mortality, but there are limited data on the range of associated diseases, contributions of different pulmonary hypertension subtypes, therapeutic strategies, and clinical outcomes in children. Objectives: To report the 20-year experience of a large UK National Pediatric Pulmonary Hypertension Service focusing on epidemiology and clinical outcomes. Methods: Consecutive patients presenting between 2001 and 2021 were included, and survival analysis was performed for incident patients. Measurements and Main Results: Of 1,353 patients assessed, a pulmonary hypertension diagnosis was made in 1,101 (81.4%) patients (51% female, median age, 2.6 [interquartile range, 0.8-8.2] years). The most common form was pulmonary arterial hypertension in 48%, followed by 32.3% with pulmonary hypertension due to lung disease. Multiple contributory causes of pulmonary hypertension were common, with 16.9% displaying features of more than one diagnostic group. The annual incidence of childhood pulmonary hypertension was 3.5 (95% confidence interval [CI], 3.3-3.8) per 1 million children, and the prevalence was 18.1 (95% CI, 15.8-20.4) per 1 million. The incidence was highest for pulmonary hypertension due to lung disease in infancy (15.0 [95% CI, 12.7-17.2] per 1 million per year). Overall, 82.4% patients received pulmonary arterial hypertension therapy, and escalation to triple therapy during follow-up was required in 13.1%. In 970 (88.1%) incident patients, transplant-free survival was 86.7% (95% CI, 84.5-89%) at 1 and 68.6% (95% CI, 64.7-72.6%) at 10 years. Pulmonary hypertension due to left heart disease had the lowest survival (hazard ratio, 2.0; 95% CI, 1.36-2.94; P < 0.001). Conclusions: Clinical phenotypes of pediatric pulmonary hypertension are heterogeneous and overlapping, with clinical phenotypes that evolve throughout childhood. Despite widespread use of pulmonary arterial hypertension therapy, the prognosis remains poor.

Clinical Implications of the Genetic Background in Pediatric Pulmonary Arterial Hypertension: Data from the Spanish REHIPED Registry

Background: Pulmonary arterial hypertension (PAH) is a severe and rare disease with an important genetic background. The influence of genetic testing in the clinical classification of pediatric PAH is not well known and genetics could influence management and prognosis. Objectives: The aim of this work was to identify the molecular fingerprint of PH children in the REgistro de pacientes con HIpertensión Pulmonar PEDiátrica (REHIPED), and to investigate if genetics could have an impact in clinical reclassification and prognosis. Methods: We included pediatric patients with a genetic analysis from REHIPED. From 2011 onward, successive genetic techniques have been carried out. Before genetic diagnosis, patients were classified according to their clinical and hemodynamic data in five groups. After genetic analysis, the patients were reclassified. The impact of genetics in survival free of lung transplantation was estimated by Kaplan–Meier curves. Results: Ninety-eight patients were included for the analysis. Before the genetic diagnoses, there were idiopathic PAH forms in 53.1%, PAH associated with congenital heart disease in 30.6%, pulmonary veno-occlusive disease—PVOD—in 6.1%, familial PAH in 5.1%, and associated forms with multisystemic disorders—MSD—in 5.1% of the patients. Pathogenic or likely pathogenic variants were found in 44 patients (44.9%). After a genetic analysis, 28.6% of the cohort was “reclassified”, with the groups of heritable PAH, heritable PVOD, TBX4, and MSD increasing up to 18.4%, 8.2%, 4.1%, and 12.2%, respectively. The MSD forms had the worst survival rates, followed by PVOD. Conclusions: Genetic testing changed the clinical classification of a significant proportion of patients. This reclassification showed relevant prognostic implications.

Outcomes for Children With Pulmonary Hypertension Undergoing Tracheostomy Placement: A Multi-Institutional Analysis

OBJECTIVES

To describe epidemiology, interventions, outcomes, and the health services experience for a cohort of children with pulmonary hypertension (PH) who underwent tracheostomy placement and to identify risk factors for inhospital mortality and 30-day readmissions.

DESIGN

Retrospective cohort study of the Pediatric Health Information System database.

SETTING

Thirty-seven freestanding U.S. children's hospitals.

PATIENTS

Patients 31 days to 21 years old who were discharged from the hospital between January 1, 2009, and December 31, 2017, with a diagnosis of primary or secondary PH, and who underwent tracheostomy placement. Outcomes were examined over a 2-year period from the time of discharge from the index encounter.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 793 patients with PH who underwent tracheostomy placement. The overall inhospital mortality rate was 23.7%. Secondary PH due to congenital heart disease (CHD) was significantly associated with overall inhospital mortality (adjusted odds ratio [OR], 2.36; 95% CI, 1.38-4.04). The rate of 30-day readmissions for patients over the 2-year follow-up period was 33.3%. Tracheostomy during the index encounter and the diagnosis of secondary PH due to CHD were significantly associated with lower rates of 30-day readmissions (adjusted OR, 0.34; 95% CI, 0.19-0.61; and adjusted OR, 0.43; 95% CI, 0.24-0.77, respectively).

CONCLUSIONS

In the context of expanding utilization of tracheostomy and long-term ventilation, children with PH are among the highest risk cohorts for extended and repeated hospitalization and death. Tracheostomy placement during the index encounter was associated with fewer 30-day readmissions over the 2-year follow-up period. Further understanding of which subgroups may benefit from earlier intervention and which subgroups are at highest risk may offer important clinical insight when considering optimal timing of tracheostomy and may enhance informed decision-making for all stakeholders.

Imaging in neonatal respiratory disease

The purpose of this review is to describe the current state of the art in clinical imaging for NICU patients, divided into major areas that correspond to likely phenotypes of neonatal respiratory disease: airway abnormalities, parenchymal disease, and pulmonary vascular disease. All common imaging modalities (ultrasound, X-ray, CT, and MRI) are discussed, with an emphasis on modalities that are most relevant to the individual underlying aspects of disease. Some promising aspects of dynamic and functional imaging are included, where there may be future clinical applicability.

Factors associated with discontinuation of pulmonary vasodilator therapy in children with bronchopulmonary dysplasia-associated pulmonary hypertension

OBJECTIVE

To evaluate factors associated with discontinuation of pulmonary vasodilator therapy in bronchopulmonary dysplasia-related pulmonary hypertension (BPD-PH).

STUDY DESIGN

Retrospective study of neonatal, echocardiographic, and cardiac catheterization data in 121 infants with BPD-PH discharged on pulmonary vasodilator therapy from 2009-2020 and followed into childhood.

RESULT

After median 4.4 years, medications were discontinued in 58%. Those in whom medications were discontinued had fewer days of invasive support, less severe BPD, lower incidence of PDA closure or cardiac catheterization, and higher incidence of fundoplication or tracheostomy decannulation (p < 0.05). On multivariable analysis, likelihood of medication discontinuation was lower with longer period of invasive respiratory support [HR 0.95 (CI:0.91-0.99), p = 0.01] and worse RV dilation on pre-discharge echocardiogram [HR 0.13 (CI:0.03-0.70), p = 0.017]. In those with tracheostomy, likelihood of medication discontinuation was higher with decannulation [HR 10.78 (CI:1.98-58.59), p < 0.001].

CONCLUSION

In BPD-PH, childhood discontinuation of pulmonary vasodilator therapy is associated with markers of disease severity.

Diagnosis and management of pulmonary hypertension in infants with bronchopulmonary dysplasia

Chronic pulmonary hypertension of infancy (cPHi) is a heterogeneous disease process that contributes to morbidity and mortality in preterm infants. cPHi is most commonly associated with chronic lung disease of prematurity and represents a unique phenotype of bronchopulmonary dysplasia. It is characterized by persistently elevated or newly rising pulmonary vascular resistance and pulmonary artery pressure beyond the first weeks of age. The high-pressure afterload on the right ventricle may or may not be tolerated, depending upon additional cardiovascular shunting and co-morbidities. A comprehensive clinical evaluation combined with advanced hemodynamic assessment by echocardiography and other cardiac imaging modalities help decipher the etiopathologies of disease, identify cardiopulmonary compromise earlier and guide individualized therapeutic intervention tailored by the phenotype. This review summarizes the underlying etiologies, risk factors for development, hemodynamic assessment, management, and follow-up of cPHi in preterm infants. We offer an algorithm for early detection of cPHi and outline research priorities.

Factors Determining Change in Treatment for Ambulatory Children With Pulmonary Arterial Hypertension: Implications for Monitoring

While care models adapt to the COVID‐19 pandemic with virtual and hybrid visits, clinical factors associated with treatment changes among ambulatory pediatric pulmonary arterial hypertension (PAH) patients are not well characterized. To understand which data critically altered treatment recommendations, we conducted a retrospective review among ambulatory children with Group 1 PAH to determine optimal visit and diagnostic strategies. Changes in management included: unplanned new treatments, dose modifications of vasodilators or diuretics, unscheduled hospitalizations, or changes to activity recommendations, catheterization schedule, or other testing. Factors prompting management changes were classified as symptoms, exam findings, or diagnostic tests. Across 398 ambulatory visits by 48 patients, 38 patients (79%) at 88 visits (22%) required change in management, most commonly in targeted PH medication. Changes were driven by symptoms alone (15%), diagnostic testing alone (47%), exam only (2%), symptoms and exam (2%), combination of testing and symptoms or testing and exam (25%), and other reasons (9%). Patients with World Health Organization functional Class IV (odds ratio [OR] 9.04 vs. Class I, p = 0.014) or Class III (OR 2.08 vs. Class I, p = 0.050) were more likely to undergo change in management. However, among Class I patients, 18% of visits generated changes in management because of test findings. While multiple factors affect management in ambulatory pediatric PH, neither symptoms nor exam was sufficient for identifying patients warranting clinical change in management. Testing accounted for most changes. Thus, in‐person or hybrid surveillance including history, exam, and diagnostic testing remains essential for optimal management of pediatric PAH.

A Measurement-Based Protocol Improves Inter-Rater Agreement And Accuracy of Right Ventricular Systolic Pressure Assessment by Echocardiography in Children: A Call for Quality Improvement

BACKGROUND

Echocardiographic measurements carry the promise of improving inter-rater agreement (IR) over subjective assessment. In this study we assess the effect of implementing a measurement-based protocol on the IR agreement and accuracy in reporting of right ventricular (RV) systolic pressure in children. We also evaluate the effect of this reporting protocol on the IR agreement in reporting RV dilation, hypertrophy and systolic function.

METHODS

Five echocardiography readers reported their assessment of the RV systolic pressure, dilation, hypertrophy and systolic function on 40 deidentified echocardiograms using their individual accustomed methods and then using an agreed-upon protocol based solely on RV measurements. The IR agreement was assessed using kappa statistics. Accuracy of the RV systolic pressure ratings was assessed using McNemar's test in comparison to hemodynamic data obtained by cardiac catheterization. The reliability of the RV measurements was assessed using intraclass correlation coefficient (ICC) and coefficient of variation (CoV).

RESULTS

The IR agreement and accuracy of RV systolic pressure assessment improved after employing the measurement-based protocol [agreement: 0.39 (95% confidence interval: 0.27,0.5) to 0.62 (0.48,0.76) & accuracy 18/40 to 29/40 p = 0.03]. IR agreement of RV dilation improved [0.36 (0.25,0.48) to 0.63 (0.48,0.79)] while the IR agreement of RV hypertrophy [0.29 (0.17,0.42) to 0.35 (0.15,0.55)] and RV systolic function [0.57 (0.45,0.69) to 0.53 (0.41,0.66)] did not improve. The reliability of the measurements was good (ICC > 0.8) except for RV free wall thickness (ICC: 0.62, CoV: 24%) and RV fractional area change (ICC: 0.47, CoV: 22%) proposing a possible reason for lack of improvement in IR agreement of RV hypertrophy and RV systolic function. Heteroscedasticity was observed in the reliability of RV measurements with the ICC being significantly lower at larger magnitudes for all RV measurements.

CONCLUSIONS

Standardization of reporting protocols using RV measurements in place of subjective assessment improved IR agreement and accuracy of RV systolic pressure assessment. Reliable measurements, RV systolic pressure and dilation, resulted in improvement in IR agreement while unreliable measurements, RV hypertrophy and systolic function, did not. Special attention to measurements' reliability and heteroscedasticity of reliability is required when designing clinical protocols to decrease IR disagreement as a source of error.

Pulmonary artery acceleration time in young children is determined by heart rate and transpulmonary gradient but not by pulmonary blood flow: A simultaneous echocardiography-cardiac catheterization study

INTRODUCTION

Pulmonary artery acceleration time (PAAT) is considered useful for the non-invasive evaluation of pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR). PAAT is dependent on PAP, PVR, pulmonary artery compliance, stroke volume, and heart rate. Its relative dependency on these determinants may differ between young and older children, raising uncertainty regarding its utility in young children. We aim to identify the primary determinants of the PAAT in children less than 36 months undergoing cardiac catheterization and its utility for the diagnosis of elevated PVR.

METHODS

We prospectively studied 42 children undergoing cardiac catheterization and simultaneous echocardiography. We determined the correlations of PAAT to the above-mentioned determinants and evaluated receiver operator characteristic (ROC) curves for diagnosis of PVR indexed to body surface area (PVRi) ≥3 Wu*m² .

RESULTS

Median age was 11.5 (IQR 5.2, 21.2) months. Moderate correlations were found between PAAT and mean PAP (R = -.66, p < .001), PVRi (R = -.54, p = .004), pulmonary artery compliance (R = .65, p < .001), transpulmonary gradient (R = -.67, p < .001), stroke volume (R = .61, p = .002), and heart rate (R = -.63, p < .001). In multivariate regression modeling, only transpulmonary gradient and heart rate were independent determinants of PAAT. PAAT ≤77 msec had acceptable utility for diagnosing PVRi ≥ 3 Wu*m² (AUC .8 [.64, .95], n = 36), low sensitivity (59%), and excellent specificity (94%).

CONCLUSION

Transpulmonary gradient and heart rate, but not pulmonary blood flow, are important determinants of PAAT in children <36 months undergoing cardiac catheterization. PAAT has low sensitivity for diagnosing elevated PVRi, therefore, should not be solely relied upon in screening for elevated PVRi in young children.

Building a Dedicated Pediatric Pulmonary Hypertension Program: A Consensus Statement from the Pediatric Pulmonary Hypertension Network

Pediatric pulmonary hypertension (PH) is a severe, life‐threatening disease associated with diverse cardiac, pulmonary, and systemic disorders, which generally requires expertise from multiple disciplines for management. Unfortunately, expert centers are limited, often due to inadequate resources or unfamiliarity with needed components for success. The Pediatric Pulmonary Hypertension Network (PPHNet) includes expert centers in North America specifically dedicated to advancing the field of pediatric PH through research and excellent clinical care. PPHNet member sites were queried for valuable program components and these findings were discussed for consensus. Here we provide a collective overview of key elements of an optimal pediatric PH program: team composition, access to services, and commitment to education. It is our intention that this document will assist newer and/or smaller programs identify avenues and resources for growth and provide avenues for collaboration.

Pulmonary hypertension in the child with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease of prematurity resulting from complex interactions of perinatal factors that often lead to prolonged respiratory support and increased pulmonary morbidity. There is also growing appreciation for the dysmorphic pulmonary bed characterized by vascular growth arrest and remodeling, resulting in pulmonary vascular disease and its most severe form, pulmonary hypertension (PH) in children with BPD. In this review, we comprehensively discuss the pathophysiology of PH in children with BPD, evaluate the current recommendations for screening and diagnosis of PH, discern associated comorbid conditions, and outline the current treatment options.