Outcomes in Children With Idiopathic Pulmonary Arterial Hypertension

Pediatric Pulmonary Hypertension: Guidelines From the American Heart Association and American Thoracic Society

Pulmonary hypertension is associated with diverse cardiac, pulmonary, and systemic diseases in neonates, infants, and older children and contributes to significant morbidity and mortality. However, current approaches to caring for pediatric patients with pulmonary hypertension have been limited by the lack of consensus guidelines from experts in the field. In a joint effort from the American Heart Association and American Thoracic Society, a panel of experienced clinicians and clinician-scientists was assembled to review the current literature and to make recommendations on the diagnosis, evaluation, and treatment of pediatric pulmonary hypertension. This publication presents the results of extensive literature reviews, discussions, and formal scoring of recommendations for the care of children with pulmonary hypertension.

Biomarkers in pediatric heart disease

A biomarker is a characteristic that can be used as an indicator of a biological state. A biomarker can be a clinical observation, laboratory test or an imaging parameter. In this review, we discuss the use of biomarkers in differentiating cardiac from noncardiac disease; predicting the prognosis of patients with heart failure, pulmonary hypertension and dilated cardiomyopathy; diagnosing subclinical cardiac involvement in muscular dystrophy and postchemotherapy cancer patients; detecting acute rejection following heart transplantation; diagnosing Kawasaki disease; aiding the management of postoperative cardiac patients; and managing both common (tetralogy of Fallot) and complex (single-ventricle physiology) congenital heart diseases.

Trends in pediatric pulmonary hypertension-related hospitalizations in the United States from 2000-2009

There are few data on the epidemiology of pulmonary hypertension (PH)-related hospitalizations in children in the United States. Our aim was to determine hospital mortality, length of hospitalization, and hospital charges pertaining to PH-related hospitalizations and also the effects of codiagnoses and comorbidities. A retrospective review of the Kids' Inpatient Database during the years 2000, 2003, 2006, and 2009 was analyzed for patients ≤20 years of age with a diagnosis of PH by ICD-9 (International Classification of Diseases, Ninth Revision) codes, along with associated diagnoses and comorbidities. Descriptive statistics, including Rao-Scott χ(2), ANOVA, and logistic regression models, were utilized on weighted values with survey analysis procedures. The number of PH-related hospital admissions is rising, from an estimated 7,331 (95% confidence interval [CI]: 5,556-9,106) in 2000 to 10,792 (95% CI: 8,568-13,016) in 2009. While infant age and congenital heart disease were most commonly associated with PH-related hospitalizations, they were not associated with mortality. Overall mortality for PH-related hospitalizations was greater than that for hospitalizations not associated with PH, 5.7% versus 0.4% (odds ratio: 16.22 [95% CI: 14.78%-17.8%], P < 0.001), but mortality is decreasing over time. Sepsis, respiratory failure, acute renal failure, hepatic insufficiency, arrhythmias, and the use of extracorporeal membrane oxygenation are associated with mortality. The number of PH-related hospitalizations is increasing in the United States. The demographics of PH in this study are evolving. Despite the increasing prevalence, mortality is improving.

Treprostinil indirectly regulates endothelial colony forming cell angiogenic properties by increasing VEGF-A produced by mesenchymal stem cells

Pulmonary vasodilators and prostacyclin therapy in particular, have markedly improved the outcome of patients with pulmonary hypertension (PH). Endothelial dysfunction is a key feature of PH, and we previously reported that treprostinil therapy increases number and proliferative potential of endothelial colony forming cells (ECFC) isolated from PH patients' blood. In the present study, the objective was to determine how treprostinil contributes to the proangiogenic functions of ECFC. We examined the effect of treprostinil on ECFC obtained from cord blood in terms of colony numbers, proliferative and clonogenic properties in vitro, as well as in vivo vasculogenic properties. Surprisingly, treprostinil inhibited viability of cultured ECFC but did not modify their clonogenic properties or the endothelial differentiation potential from cord blood stem cells. Treprostinil treatment significantly increased the vessel-forming ability of ECFC combined with mesenchymal stem cells (MSC) in Matrigel implanted in nude mice. In vitro, ECFC proliferation was stimulated by conditioned media from treprostinil-pretreated MSC, and this effect was inhibited either by the use of VEGF-A blocking antibodies or siRNA VEGF-A in MSC. Silencing VEGF-A gene in MSC also blocked the pro-angiogenic effect of treprostinil in vivo. In conclusion, increased VEGF-A produced by MSC can account for the increased vessel formation observed during treprostinil treatment. The clinical relevance of these data was confirmed by the high level of VEGF-A detected in plasma from patients with paediatric PH who had been treated with treprostinil. Moreover, our results suggest that VEGF-A level in patients could be a surrogate biomarker of treprostinil efficacy.

Treating pulmonary hypertension in pediatrics

INTRODUCTION

Pulmonary hypertension is a hemodynamic condition occurring rarely in pediatrics. Nevertheless, it is associated with significant morbidity and mortality. When characterized by progressive pulmonary vascular structural changes, the disease is called pulmonary arterial hypertension (PAH). It results in increased pulmonary vascular resistance and eventual right ventricular failure. In the vast majority of cases, pediatric PAH is idiopathic or associated with congenital heart disease, and, contrary to adult PAH, is rarely associated with connective tissue, portal hypertension, HIV infection or thromboembolic disease.

AREAS COVERED

This article reviews the current drug therapies available for the management of pediatric PAH. These treatments target the recognized pathophysiological pathways of PAH with endothelin-1 receptor antagonists, prostacyclin analogs and PDE type 5 inhibitors. New treatments and explored pathways are briefly discussed.

EXPERT OPINION

Although there is still no cure for PAH, quality of life and survival have been improved significantly with specific drug therapies. Nevertheless, management of pediatric PAH remains challenging, and depends mainly on results from adult clinical trials and pediatric experts. Further research on PAH-specific treatments in the pediatric population and data from international registries are needed to identify optimal therapeutic strategies and treatment goals in the pediatric population.

Comparison between the Acute Pulmonary Vascular Effects of Oxygen with Nitric Oxide and Sildenafil

OBJECTIVE

Right heart catheterization is performed in patients with pulmonary arterial hypertension to determine the severity of disease and their pulmonary vascular reactivity. The acute pulmonary vascular effect of inhaled nitric oxide is frequently used to identify patients who will respond favorably to long-term vasodilator therapy. This study sought to determine whether the acute pulmonary vascular effects of oxygen with nitric oxide and intravenous sildenafil are similar.

METHODS

A retrospective, descriptive study of 13 individuals with pulmonary hypertension who underwent heart catheterization and acute vasodilator testing was performed. The hemodynamic measurements during five phases (21-53% oxygen, 100% oxygen, 100% oxygen with 20 ppm nitric oxide, 21-51% oxygen, and 21-51% oxygen with 0.05-0.29 mg/kg intravenous sildenafil) of the procedures were compared using analysis of variance. A linear regression analysis and a Bland Altman plot were used to compare the percent change in mean pulmonary arterial pressure and the percent change in pulmonary vascular resistance from baseline with oxygen and nitric oxide, and from baseline with sildenafil.

RESULTS

Mean pulmonary arterial pressure and pulmonary vascular resistance acutely decreased with 100% oxygen with nitric oxide and 21-51% oxygen with sildenafil. Pulmonary blood flow during sildenafil was greater than pulmonary blood flow during 100% oxygen and 100% oxygen with nitric oxide. The pH, right atrial pressure, and left atrial pressure did not change during the five phase of heart catheterization. Mean pulmonary arterial pressure (millimeter of mercury, mean ± standard error of the mean) was 38 ± 4 during 21-53% oxygen, 32 ± 3 during 100% oxygen, 29 ± 2 during 100% oxygen with nitric oxide, 37 ± 3 during 21-51% oxygen, and 32 ± 2 during 21-51% oxygen with sildenafil. There was not a significant correlation between the percent change in pulmonary vascular resistance from baseline with oxygen and nitric oxide, and from baseline with sildenafil (r (2) = 0.011, p = 0.738). The Bland Altman analysis demonstrated statistical agreement between the effects of oxygen with nitric oxide and sildenafil. However, differences were large enough to limit the interchangeable use of these vasodilators in a clinical setting.

CONCLUSION

Oxygen with nitric oxide and sildenafil decreased pulmonary vascular resistance. However, the pulmonary vascular effects of oxygen and nitric oxide do not reliably predict the acute response to sildenafil. Additional studies are needed to determine whether the acute response to sildenafil can be used to predict the long-term response to treatment with an oral phosphodiesterase V inhibitor.

Advances in paediatric pulmonary vascular disease associated with bronchopulmonary dysplasia

Pulmonary hypertension (PH) is a common finding in infants with bronchopulmonary dysplasia (BPD). The aim of this review is to describe recent advances in the diagnosis and treatment of PH and discuss whether they will benefit infants and children with BPD related PH. Echocardiography remains the mainstay of diagnosis but has limitations, further developments in diagnostic techniques and identification of biomarkers are required. There are many potential therapies for PH associated with BPD. Inhaled nitric oxide has been shown to improve short term outcomes only. Sidenafil in resource limited settings was shown in three randomized trials to significantly reduce mortality. The efficacy of other therapies including prostacyclin, PDE3 inhibitors and endothelin receptor blockers has only been reported in case reports or case series. Randomized controlled trials with long term follow up are required to appropriately assess the efficacy of therapies aimed at improving the outcome of children with PH.

Saudi Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Pulmonary hypertension in children

Pulmonary hypertension (PH) is relatively uncommon in children. Pulmonary arterial hypertension (PAH) in pediatric comprises a wide spectrum of diseases, from a transient neonatal condition to a progressive disease associated with morbidity and mortality. Most common PAH in pediatric are idiopathic (IPAH) or PAH associated with congenital heart disease (PAH-CHD), while other associated conditions, such as connective tissue disease (CTD), are less common in pediatrics. Despite better understanding of PH and the availability of new medications during recent decades; the diagnosis, investigation and choice of therapy remain a challenge in children, as evidence-based recommendations depend mainly on adult studies. In this review, we provide a detailed discussion about the distinctive features of PAH in pediatric, mainly emphacysing on classification and diagnostic algorithm.

Saudi Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Medical and surgical management for pulmonary arterial hypertension

Prior to the availability of the pulmonary arterial hypertension (PAH)-specific therapy, PAH was a dreadful disease with a very poor prognosis. Better understanding of the complex pathobiology of PAH has led to a major therapeutic evolution. International regulatory agencies have approved many specific drugs with different pharmacologic pathways and routes of administration. In the year 2013, two new drugs with great potentials in managing PAH have been added to the treatment options, macitentan and riociguat. Additional drugs are expected to come in the near future.

A substantial body of evidence has confirmed the effectiveness of pulmonary arterial hypertension (PAH)-specific therapies in improving the patients’ symptomatic status and slowing down the rate of clinical deterioration.

Although the newer modern medications have significantly improved the survival of patients with PAH, it remains a non-curable and fatal disease. Lung transplantation (LT) remains the only therapeutic option for selected patients with advanced disease who continue to deteriorate despite optimal therapy.

Current and advancing treatments for pulmonary arterial hypertension in childhood

Pulmonary arterial hypertension (PAH) is a severe and progressive intrinsic disease of the precapillary lung vasculature. Since the introduction of PAH-targeted drugs, survival of PAH patients seems to have improved. Randomized controlled trials have led to evidence-based guidelines to direct treatment in adults. However, since disease characteristics differ between adults and children, it is hazardous to simply extrapolate these guidelines to children. Moreover, pediatric data on treatment strategies and how to assess treatment response remain virtually absent. Optimal treatment strategies are highly needed to guide therapy and improve survival in children with PAH. This review provides an overview of currently available treatments for PAH and the limited efficacy and safety data in children (with the exclusion of perinatal pulmonary vascular diseases, as persistent pulmonary hypertension of the newborn). We also discuss potential treatment goals and how the available data can be translated into treatment strategies in pediatric PAH.

Identification of treatment goals in paediatric pulmonary arterial hypertension

To be able to design goal-oriented treatment strategies in paediatric pulmonary arterial hypertension (PAH), we aimed to identify treatment goals by investigating the prognostic value of treatment-induced changes in noninvasive predictors of transplant-free survival.

66 consecutive, treatment-naïve paediatric PAH patients in the Dutch National Network for Paediatric Pulmonary Hypertension who started taking PAH-targeted drugs between January 2000 and April 2013 underwent prospective, standardised follow-up. Clinical, biochemical and echocardiographic measures were longitudinally collected at treatment initiation and follow-up, and their respective predictive values for transplant-free survival were assessed. Furthermore, the predictive values of treatment-induced changes were assessed.

From the identified set of baseline predictors, the variables World Health Organization functional class (WHO-FC), N-terminal pro-brain natriuretic peptide (NT-proBNP) and tricuspid annular plane systolic excursion (TAPSE) were identified as follow-up predictors in which treatment-induced changes were associated with survival. Patients in whom these variables improved after treatment showed better survival (p<0.002).

Therefore, WHO-FC, NT-proBNP and TAPSE are not only predictors of transplant-free survival in paediatric PAH but can also be used as treatment goals, as treatment-induced improvements in these variables are associated with improved survival. The identification of these variables allows for the introduction of goal-oriented treatment strategies in paediatric PAH.

Prenatal programming of pulmonary hypertension induced by chronic hypoxia or ductal ligation in sheep

Pulmonary hypertension of the newborn is caused by a spectrum of functional and structural abnormalities of the cardiopulmonary circuit. The existence of multiple etiologies and an incomplete understanding of the mechanisms of disease progression have hindered the development of effective therapies. Animal models offer a means of gaining a better understanding of the fundamental basis of the disease. To that effect, a number of experimental animal models are being used to generate pulmonary hypertension in the fetus and newborn. In this review, we compare the mechanisms associated with pulmonary hypertension caused by two such models: in utero ligation of the ductus arteriosus and chronic perinatal hypoxia in sheep fetuses and newborns. In this manner, we make direct comparisons between ductal ligation and chronic hypoxia with respect to the associated mechanisms of disease, since multiple studies have been performed with both models in a single species. We present evidence that the mechanisms associated with pulmonary hypertension are dependent on the type of stress to which the fetus is subjected. Such an analysis allows for a more thorough evaluation of the disease etiology, which can help focus clinical treatments. The final part of the review provides a clinical appraisal of current treatment strategies and lays the foundation for developing individualized therapies that depend on the causative factors.

Antenatal hypoxia and pulmonary vascular function and remodeling

This review provides evidence that antenatal hypoxia, which represents a significant and worldwide problem, causes prenatal programming of the lung. A general overview of lung development is provided along with some background regarding transcriptional and signaling systems of the lung. The review illustrates that antenatal hypoxic stress can induce a continuum of responses depending on the species examined. Fetuses and newborns of certain species and specific human populations are well acclimated to antenatal hypoxia. However, antenatal hypoxia causes pulmonary vascular disease in fetuses and newborns of most mammalian species and humans. Disease can range from mild pulmonary hypertension, to severe vascular remodeling and dangerous elevations in pressure. The timing, length, and magnitude of the intrauterine hypoxic stress are important to disease development, however there is also a genetic-environmental relationship that is not yet completely understood. Determining the origins of pulmonary vascular remodeling and pulmonary hypertension and their associated effects is a challenging task, but is necessary in order to develop targeted therapies for pulmonary hypertension in the newborn due to antenatal hypoxia that can both treat the symptoms and curtail or reverse disease progression.

Drug treatment of pulmonary hypertension in children

Pulmonary arterial hypertension (PAH) is a rare disease in infants and children that is associated with significant morbidity and mortality. The disease is characterized by progressive pulmonary vascular functional and structural changes resulting in increased pulmonary vascular resistance and eventual right heart failure and death. In the majority of pediatric patients, PAH is idiopathic or associated with congenital heart disease and rarely is associated with other conditions such as connective tissue or thromboembolic disease. Although treatment of the underlying disease and reversal of advanced structural changes has not yet been achieved with current therapy, quality of life and survival have been improved significantly. Targeted pulmonary vasodilator therapies, including endothelin receptor antagonists, prostacyclin analogs, and phosphodiesterase type 5 inhibitors, have demonstrated hemodynamic and functional improvement in children. The management of pediatric PAH remains challenging, as treatment decisions continue to depend largely on results from evidence-based adult studies and the clinical experience of pediatric experts. This article reviews the current drug therapies and their use in the management of PAH in children.

Right ventricular to left ventricular diameter ratio at end-systole in evaluating outcomes in children with pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) increases right ventricular (RV) pressure, resulting in septal shift and RV dilation. Few echocardiographic measures have been used to evaluate severity and outcomes in children with PH. The aims of this study were to compare the RV to left ventricular (LV) diameter ratio at end-systole (RV/LV ratio) in normal controls and patients with PH, to correlate the RV/LV ratio with invasive hemodynamic measures, and to evaluate its association with outcomes in children with PH.

METHODS

The RV/LV ratio was compared retrospectively between 80 matched normal controls and 84 PH patients without shunts. Of the patients with PH, 49 children underwent 94 echocardiographic studies and cardiac catheterizations within 48 hours (13 patients had simultaneous measurements). The RV/LV ratio was correlated against hemodynamic measures. Kaplan-Meier curves and a Cox proportional-hazards regression model were used to assess relationships between RV/LV ratio and time until an adverse clinical event (initiation of intravenous prostacyclin therapy, atrial septostomy, death, or transplantation).

RESULTS

RV/LV ratios were lower in controls compared with patients with PH (mean, 0.51 [95% confidence interval, 0.48-0.54] vs 1.47 [95% confidence interval, 1.25-1.70], P < .01). The RV/LV ratio correlated significantly with mean pulmonary artery pressure, systolic pulmonary artery pressure, systolic pulmonary artery pressure as a percentage of systemic pressure, and pulmonary vascular resistance index (r = 0.65 [P < .01], r = 0.6 [P < .01], r = 0.49 [P < .01], and r = 0.43 [P < .01], respectively). Twenty-two patients with PH with RV/LV ratios > 1 had adverse events within a median of 1.1 years from their earliest echocardiographic studies. Increasing RV/LV ratio was associated with an increasing hazard for a clinical event (hazard ratio, 2.49; 95% confidence interval, 1.92-3.24).

CONCLUSIONS

The RV/LV end-systolic diameter ratio can easily be obtained noninvasively in the clinical setting and can be used in the management of patients with PH. The RV/LV ratio incorporates both pathologic septal shift and RV dilation in children with PH and correlates with invasive measures of PH. An RV/LV ratio > 1 is associated with adverse clinical events.

Evaluation of circulating proteins and hemodynamics towards predicting mortality in children with pulmonary arterial hypertension

BACKGROUND

Although many predictors have been evaluated, a set of strong independent prognostic mortality indicators has not been established in children with pediatric pulmonary arterial hypertension (PAH). The aim of this study was to identify a combination of clinical and molecular predictors of survival in PAH.

METHODS

This single-center, retrospective cohort study was performed from children with PAH between 2001 and 2008 at Children's Hospital Colorado. Blood samples from 83 patients (median age of 8.3 years-old) were obtained. We retrospectively analyzed 46 variables, which included 27 circulating proteins, 7 demographic variables and 12 hemodynamic and echocardiographic variables for establishing the best predictors of mortality. A data mining approach was utilized to evaluate predictor variables and to uncover complex data structures while performing variable selection in high dimensional problems.

RESULTS

Thirteen children (16%) died during follow-up (median; 3.1 years) and survival rates from time of sample collection at 1 year, 3 years and 5 years were 95%, 85% and 79%, respectively. A subset of potentially informative predictors were identified, the top four are listed here in order of importance: Tissue inhibitors of metalloproteinases-1 (TIMP-1), apolipoprotein-AI, RV/LV diastolic dimension ratio and age at diagnosis. In univariate analysis, TIMP-1 and apolipoprotein-AI had significant association with survival time (hazard ratio [95% confidence interval]: 1.25 [1.03, 1.51] and 0.70 [0.54-0.90], respectively). Patients grouped by TIMP-1 and apolipoprotein-AI values had significantly different survival risks (p<0.01).

CONCLUSION

Important predictors of mortality were identified from a large number of circulating proteins and clinical markers in this cohort. If confirmed in other populations, measurement of a subset of these predictors could aid in management of pediatric PAH by identifying patients at risk for death. These findings also further support a role for the clinical utility of measuring circulating proteins.

Update on pediatric pulmonary arterial hypertension. Differences and similarities to adult disease

Children and adults with pulmonary arterial hypertension (PAH) have similarities and differences in their background characteristics, hemodynamics, and clinical manifestations. Regarding genetic background, mutations in BMPR2-related pathways seem to be pivotal; however, it is likely that other modifier genes and bioactive mediators have roles in the various forms of PAH in children and adults. In pediatric PAH, there are no clear sex differences in incidence, age at onset, disease severity, or prognosis but, as compared with adults, syncope incidence, pulmonary vascular resistance, and mean pulmonary artery pressure are higher, and vasoreactivity to acute drug testing is more frequent, among children. Nevertheless, the pharmacokinetic effects of 3 major pulmonary vasodilators appear to be similar in children and adults with PAH. This review focuses on the specific pathophysiologic features of PAH in children.

Ventilatory efficiency slope correlates with functional capacity, outcomes, and disease severity in pediatric patients with pulmonary hypertension

BACKGROUND

Cardiopulmonary exercise testing is widely used in a variety of cardiovascular conditions. Ventilatory efficiency slope can be derived from submaximal exercise testing. The present study sought to evaluate the relationship between ventilatory efficiency slope and functional capacity, outcomes, and disease severity in pediatric patients with pulmonary hypertension.

METHODS

Seventy six children and young adults with a diagnosis of pulmonary hypertension (PH) performed 258 cardiopulmonary exercise tests from 2001 to 2011. Each individual PH test was matched to a control test. Ventilatory efficiency slope was compared to traditional measures of functional capacity and disease severity including WHO functional classification, peak oxygen consumption, and invasive measures of pulmonary arterial pressures and pulmonary vascular resistance.

RESULTS

Ventilatory efficiency slope was significantly higher in patients with pulmonary arterial hypertension, with an estimated increase of 7.2 for each increase in WHO class (p<0.0001), compared with normal control subjects (38.9 vs. 30.9, p<0.001). Ventilatory efficiency slope correlated strongly with invasive measures of disease severity including pulmonary vascular resistance index (r =0.61), pulmonary artery pressure (r =0.58), mean pulmonary artery pressure/mean aortic pressure ratio (r =0.52), and peak VO2 (r=-0.58). Ventilatory efficiency slope in 12 patients with poor outcomes (9 death, 3 lung transplant), was significantly elevated compared to patients who did not (51.1 vs. 37.9, p<0.001).

CONCLUSIONS

Ventilatory efficiency slope correlates well with invasive and noninvasive markers of disease severity including peak VO2, WHO functional class, and catheterization variables in pediatric patients with PH. Ventilatory efficiency slope may be a useful noninvasive marker for disease severity.

Current challenges in pediatric pulmonary hypertension

Pulmonary arterial hypertension (PAH) in the pediatric population is associated with a variety of underlying diseases and causes, significantly morbidity and mortality. In the majority of patients, PAH in children is idiopathic or associated with congenital heart disease (CHD), with pulmonary hypertension (PH) associated with connective tissue disease, a rare cause in children. Classification of pediatric PH has generally followed the WHO classification, but recognition of the importance of fetal origins of PH and developmental abnormalities have led to the formation of a new pediatric-specific classification. Incidence data from the Netherlands has revealed an annual incidence and point prevalence of 0.7 and 4.4 for idiopathic PAH and 2.2 and 15.6 for associated pulmonary arterial hypertension-CHD cases per million children. Although the treatment with new selective pulmonary vasodilators offers hemodynamic and functional improvement in pediatric populations, the treatments in children largely depend on results from evidence-based adult studies and experience of clinicians treating children. A recent randomized clinical trial of sildenafil and its long-term extension has led to disparate recommendations in the United States and Europe.

Echocardiography in pediatric pulmonary hypertension

Pediatric pulmonary hypertension is a complicated disease with multiple etiologies and high mortality. Echocardiography is at the forefront of evaluation as a noninvasive, portable imaging modality that can yield diagnostic and prognostic information regarding this disease. Echocardiography is known for its ability to give an anatomic assessment of the heart and proximal blood vessels. With the additional use of Doppler echocardiography and myocardial motion assessment, the effects of elevated pulmonary pressures on the heart can be evaluated. This can allow for estimation of pulmonary artery pressures and resistances and assessment of ventricular systolic and diastolic functions. However despite its advantages, echocardiography is still an indirect assessment of pulmonary hypertension and not a substitute for cardiac catheterization. The purpose of this review is to discuss common techniques for the assessment of pulmonary hypertension by echocardiography as well as their limitations.

Acute pulmonary vasodilator testing with inhaled treprostinil in children with pulmonary arterial hypertension

Acute pulmonary vasodilator testing (AVT) is essential to determining the initial therapy for children with pulmonary arterial hypertension (PAH). This study aimed to report the initial experience with inhaled treprostinil used for AVT in children with PAH and to evaluate the hemodynamic change after inhaled treprostinil compared with inhaled nitric oxide. This prospective cohort study was designed for 13 children who underwent AVT with inhaled treprostinil or oxygen plus inhaled nitric oxide (iNO) during catheterization. Inhaled treprostinil was delivered during cardiac catheterization by adapting the Optineb ultrasonic nebulizer via either a flow-inflating bag or the manual mode of the anesthesia system. The median age of the patients was 10 years (range 4-17 years). The etiologies of PAH included idiopathic PAH and associated PAH. All the patients tolerated inhaled treprostinil without marked clinical worsening and received six or nine breaths (36 or 54 μg) of treprostinil. The median of the total treprostinil doses was 1.53 μg/kg (range 0.71-2.89 μg/kg). Inhaled treprostinil was administrated via an endotracheal tube (n = 8), anesthesia mask (n = 3), or laryngeal mask airway (n = 2). Inhaled nitric oxide (iNO) and inhaled treprostinil significantly decreased the mean pulmonary artery pressure and the pulmonary vascular resistance index compared with baseline. Three adverse events were reported after inhaled treprostinil, including cough and mild to moderate hypotension with higher doses. All adverse events resolved without any intervention. This study report is the first to describe the use of inhaled treprostinil for AVT in children with PAH. In this small pediatric cohort, inhaled treprostinil was effectively delivered and well tolerated and may be useful for AVT.

Pulmonary hypertension in bronchopulmonary dysplasia

Pulmonary hypertension (PH) is a common complication of neonatal respiratory diseases, including bronchopulmonary dysplasia (BPD), and recent studies have increased awareness that PH worsens the clinical course, morbidity and mortality of BPD. Recent evidence indicates that up to 18% of all extremely low-birth-weight infants will develop some degree of PH during their hospitalization, and the incidence rises to 25-40% of the infants with established BPD. Risk factors are not yet well understood, but new evidence shows that fetal growth restriction is a significant predictor of PH. Echocardiography remains the primary method for evaluation of BPD-associated PH, and the development of standardized screening timelines and techniques for identification of infants with BPD-associated PH remains an important ongoing topic of investigation. The use of pulmonary vasodilator medications, such as nitric oxide, sildenafil, and others, in the BPD population is steadily growing, but additional studies are needed regarding their long-term safety and efficacy.

Children with pulmonary arterial hypertension and prostanoid therapy: long-term hemodynamics

BACKGROUND

Pediatric patients with severe pulmonary arterial hypertension (PAH) are treated with intravenous epoprostenol or intravenous or subcutaneous treprostinil. Little is known about longitudinal hemodynamics and outcomes of epoprostenol, treprostinil, and transitions from epoprostenol to treprostinil.

METHODS

This was retrospective study of 77 pediatric patients (47 idiopathic PAH, 24 congenital heart disease-PAH) receiving epoprostenol or treprostinil from 1992 to 2010 at 2 centers. Outcomes were defined as living vs dead/transplant.

RESULTS

Mean age at baseline was 7.7 ± 5.2 years, with follow-up of 4.3 ± 3.4 years. Thirty-seven patients were treated with epoprostenol, 20 with treprostinil, and 20 were transitioned from epoprostenol to treprostinil. Mean pulmonary-to-systemic vascular resistance ratio (Rp/Rs) for epoprostenol was 1.0 ± 0.4, 0.8 ± 0.4, 0.8 ± 0.4, 1.0 ± 0.4, and 1.2 ± 0.4, respectively, at baseline, 1, 2, 3, and 4 years. For treprostinil, Rp/Rs was 0.9 ± 0.3, 0.7 ± 0.3, 0.5 ± 0.2, (p < 0.01 vs baseline), and 1.1 ± 0.2, respectively, at baseline, 1, 2, and 3 to 4 years, respectively. There were similar changes in mean pulmonary artery pressure and pulmonary vascular resistance index. The Rp/Rs 1 year after epoprostenol to treprostinil transition increased from 0.6 to 0.8 (n = 7). Changes not statistically significant unless noted. Eight patients died or received a transplant within 2 years of baseline; compared with the rest of the cohort, mean baseline Rp/Rs, right atrial pressure, and pulmonary vascular resistance index were significantly worse in this group. Thirty-nine patients remain on prostanoids, 17 are off, 16 died, and 5 received heart-lung transplant. Kaplan-Meier 5-year transplant-free survival was 70% (95% confidence interval, 56%-80%).

CONCLUSION

There was improvement in Rp/Rs on both therapies at 1 to 2 years that was not sustained. The 5-year transplant-free survival was better than in similar adult studies.

Clinical trials in neonates and children: Report of the pulmonary hypertension academic research consortium pediatric advisory committee

Drug trials in neonates and children with pulmonary hypertensive vascular disease pose unique but not insurmountable challenges. Childhood is defined by growth and development. Both may influence disease and outcomes of drug trials. The developing pulmonary vascular bed and airways may be subjected to maldevelopment, maladaptation, growth arrest, or dysregulation that influence the disease phenotype. Drug therapy is influenced by developmental changes in renal and hepatic blood flow, as well as in metabolic systems such as cytochrome P450. Drugs may affect children differently from adults, with different clearance, therapeutic levels and toxicities. Toxicity may not be manifested until the child reaches physical, endocrine and neurodevelopmental maturity. Adverse effects may be revealed in the next generation, should the development of ova or spermatozoa be affected. Consideration of safe, age-appropriate tablets and liquid formulations is an obvious but often neglected prerequisite to any pediatric drug trial. In designing a clinical trial, precise phenotyping and genotyping of disease is required to ensure appropriate and accurate inclusion and exclusion criteria. We need to explore physiologically based pharmacokinetic modeling and simulations together with statistical techniques to reduce sample size requirements. Clinical endpoints such as exercise capacity, using traditional classifications and testing cannot be applied routinely to children. Many lack the necessary neurodevelopmental skills and equipment may not be appropriate for use in children. Selection of endpoints appropriate to encompass the developmental spectrum from neonate to adolescent is particularly challenging. One possible solution is the development of composite outcome scores that include age and a developmentally specific functional classification, growth and development scores, exercise data, biomarkers and hemodynamics with repeated evaluation throughout the period of growth and development. In addition, although potentially costly, we recommend long-term continuation of blinded dose ranging after completion of the short-term, double-blind, placebo-controlled trial for side-effect surveillance, which should include neurodevelopmental and peripubertal monitoring. The search for robust evidence to guide safe therapy of children and neonates with pulmonary hypertensive vascular disease is a crucial and necessary goal.

Effectiveness and safety of inhaled treprostinil for the treatment of pulmonary arterial hypertension in children

The introduction of prostanoid therapy has revolutionized the treatment of pulmonary arterial hypertension (PAH). However, continuous intravenous prostacyclin infusion poses significant risks and challenges, particularly in children. Inhaled treprostinil has been shown to be safe and efficacious in adults. This study describes the safety and efficacy of inhaled treprostinil in children with PAH. A retrospective analysis of 29 children treated with inhaled treprostinil for ≥6 weeks was performed. Effects of inhaled treprostinil on exercise capacity, functional class, and echocardiographic and hemodynamic data were evaluated. Adverse events were documented. Patients received 3 to 9 breaths (6 μg/breath) of inhaled treprostinil 4 times/day. All were receiving background PAH therapy; 12 had previously received parenteral prostanoid. Inhaled treprostinil was discontinued in 4 patients because of symptoms including cough and bronchospasm (n = 3) and progression of PAH (n = 1). Mild side effects including cough (n = 9) and sore throat (n = 6) did not require discontinuation of therapy. World Health Organization functional class improved in 19 and was unchanged in 10; exercise capacity significantly improved with the 6-minute walk distance, improving on follow-up from 455.7 ± 71.5 to 498 ± 70 m (p = 0.01) and peak oxygen consumption increasing from 25.5 ± 10.2 to 27.4 ± 10 (p = 0.04). In conclusion, inhaled treprostinil was associated with improvement in exercise capacity and World Health Organization functional class when added to background targeted PAH therapy in children and had an acceptable safety profile. Based on these early data, further study of inhaled treprostinil appears warranted in pediatric patients with PAH.

Assessment of pulmonary endothelial function during invasive testing in children and adolescents with idiopathic pulmonary arterial hypertension

OBJECTIVES

The purpose of our study was to assess pulmonary endothelial function by vasodilator response to acetylcholine (Ach) administered in segmental pulmonary arteries in children with idiopathic pulmonary arterial hypertension (IPAH). We hypothesized that there was a relationship among pulmonary endothelial response to Ach, severity of the disease, and clinical outcome.

BACKGROUND

IPAH may be associated with pulmonary endothelial dysfunction; however, data regarding the impact of endothelial dysfunction on severity and prognosis of this disease are limited.

METHODS

Forty-three children and adolescents (mean age: 10.4 ± 5.5 years) with IPAH were included in the study. Changes in pulmonary blood flow in response to Ach were determined using intravascular Doppler flow measurements. Pulmonary flow reserve (PFR) was calculated as the ratio of pulmonary blood flow velocity in response to Ach relative to baseline values.

RESULTS

Mean PFR of all patients was 1.58 ± 0.67. Mean follow-up after catheterization was 55.7 ± 41.9 months. Freedom from serious cardiovascular events (lung transplantation or death) was 83% after 2 years, 76% after 3 years, and 57% after 5 years. PFR was related significantly to World Health Organization functional class. Receiver-operating characteristic curves revealed a PFR of 1.4 as the best cutoff value. Kaplan-Meier analysis demonstrated that a PFR of <1.4 was highly predictive for cardiovascular events (log-rank [Mantel Cox] chi-square: 12.49, p < 0.0001).

CONCLUSIONS

Our study demonstrates a strong relationship between pulmonary endothelial response to Ach and prognosis of children with IPAH. As an adjunct to the usual testing protocol, this method provides additional information for therapeutic guidance.

Plasma proteomics of differential outcome to long-term therapy in children with idiopathic pulmonary arterial hypertension

PURPOSE

The prognosis for children with IPAH unresponsive to therapy is poor. We investigated the plasma proteome for a molecular basis of good versus poor outcome to long-term vasodilator therapy.

EXPERIMENTAL DESIGN

Plasma was collected at baseline or shortly after therapy initiation and following chronic vasodilator therapy, then divided into those with good outcome (n = 8), and those with a poor outcome (n = 7). To identify proteins unique to either outcome, we used differential gel electrophoresis and mass spectrometry. Results were confirmed by commercial enzyme-linked immunosorbent assay.

RESULTS

Before and after therapy, SAA-4 was 4-fold lower in those with good outcome compared to those with poor outcome, while serum paraoxonase/arylesterase-1 was increased 2-fold in those with good outcome versus poor outcome. After therapy, haptoglobin and hemopexin were 1.45- and 1.8-fold lower, respectively, in those with a good versus poor outcome. Among those with a good outcome, SAP was 1.3-fold lower prior to therapy.

CONCLUSIONS AND CLINICAL RELEVANCE

SAP and SAA-4 regulate circulating mononuclear phagocytes. As such, they may contribute to the differential response to chronic vasodilator therapy in the context of inflammation in IPAH.

Pharmacotherapy for pulmonary hypertension

Pulmonary arterial hypertension is a serious disease with significant morbidity and mortality. Although it can occur idiopathically, it is more commonly associated with other cardiac or lung diseases. While most of the available therapies have been tested in adult populations and most therapies in children remain off-label, new reports and randomized trials are emerging that inform the treatment of pediatric populations. This review discusses currently available therapies for pediatric pulmonary hypertension, their biological rationales, and evidence for their clinical effectiveness.

Epidemiology and clinical management of pulmonary hypertension in children

Pulmonary hypertension (PH) is a clinical hemodynamic syndrome characterized by increased pulmonary artery pressure and pulmonary vascular resistance. It can cause right ventricular failure, and even death. Pediatric PH is not very common, but is a greatly hazardous disease that leads to a high mortality rate. Therefore, many registry organizations have been established in the world to strengthen the study of diagnosis and treatment of the disease, and improve the understanding of pediatric PH. This article reviewed recently published researches, as well as presented a comprehensive understanding of PH, including definition, classification, epidemiology, prognosis and treatment.

Inhaled epoprostenol therapy for pulmonary hypertension: Improves oxygenation index more consistently in neonates than in older children

The purpose of this study was to determine the efficacy of inhaled epoprostenol for treatment of acute pulmonary hypertension (PH) in pediatric patients and to formulate a plan for a prospective, randomized study of pulmonary vasodilator therapy in this population. Inhaled epoprostenol is an effective treatment for pediatric PH. A retrospective chart review was conducted of all pediatric patients who received inhaled epoprostenol at a tertiary care hospital between October 2005 and August 2007. The study population was restricted to all patients under 18 years of age who received inhaled epoprostenol for greater than 1 hour and had available data for oxygenation index (OI) calculation. Arterial blood gas values and ventilator settings were collected immediately prior to epoprostenol initiation, and during epoprostenol therapy (as close to 12 hours after initiation as possible). Echocardiograms were reviewed during two time frames: Within 48 hours prior to therapy initiation and within 96 hours after initiation. Of the 20 patients in the study population, 13 were neonates, and the mean OI for these patients improved during epoprostenol administration (mean OI before and during therapy was 25.6±16.3 and 14.5±13.6, respectively, P=0.02). Mean OI for the seven patients greater than 30 days of age was not significantly different during treatment (mean OI before and during therapy was 29.6±15.0 and 25.6±17.8, P=0.56). Improvement in echocardiographic findings (evidence of decreased right-sided pressures or improved right ventricular function) was demonstrated in 20% of all patients. Inhaled epoprostenol is an effective therapy for the treatment of selected pediatric patients with acute PH. Neonates may benefit more consistently from this therapy than older infants and children. A randomized controlled trial is needed to discern the optimal role for inhaled prostanoids in the treatment of acute PH in childhood.

Long-term inhaled iloprost use in children with pulmonary arterial hypertension

BACKGROUND

We performed a retrospective analysis of patients with pulmonary arterial hypertension receiving inhaled iloprost in a single centre to evaluate long-term tolerability, safety, and efficacy of chronic inhaled iloprost therapy in children.

METHODS

A total of 20 patients with either idiopathic or associated pulmonary arterial hypertension were treated with iloprost between April, 2003 and January, 2010. The median age and weight of the patients were 3.8 years--ranging from 4 months to 19 years--and 12.3 kilograms--ranging from 4 to 73 kilograms-- respectively. Pulmonary arterial hypertension was idiopathic or hereditary in eight patients (40%) and associated with congenital cardiac disease in 12 patients (60%).

RESULTS

Of the 20 patients, 15 had combined therapy--12 patients with two and three patients with three different classes of drugs. In all, six patients died during follow-up. The median follow-up time was 18 months, ranging from 6 to 74 months. The 6-minute walking test was performed in 7 out of 20 patients at baseline and on follow-up. The median 6-minute walking test increased from 420 to 490 metres after iloprost therapy (p = 0.028). After initiation of iloprost therapy, one patient complained of headache and another had a rash around his mouth, none necessitating discontinuation of therapy. Overall compliance with inhaled iloprost was good.

CONCLUSION

Pulmonary hypertension is associated with significant morbidity and mortality. Careful assessment of each patient and timely combination of specific vasodilator therapy is needed to improve clinical outcomes. This study suggests that inhaled iloprost, with or without concomitant endotelin receptor antagonist and/or phosphodiesterase inhibitor, is safe and efficacious for treatment of pulmonary arterial hypertension in children.

Significant Differences in Markers of Oxidant Injury between Idiopathic and Bronchopulmonary-Dysplasia-Associated Pulmonary Hypertension in Children

While oxidant stress is elevated in adult forms of pulmonary hypertension (PH), levels of oxidant stress in pediatric PH are unknown. The objective of this study is to measure F(2)-isoprostanes, a marker of oxidant stress, in children with idiopathic pulmonary hypertension (IPH) and PH due to bronchopulmonary dysplasia (BPD). We hypothesized that F(2)-isoprostanes in pediatric IPH and PH associated with BPD will be higher than in controls. Plasma F(2)-isoprostanes were measured in pediatric PH patients during clinically indicated cardiac catheterization and compared with controls. F(2)-Isoprostane levels were compared between IPH, PH due to BD, and controls. Five patients with IPH, 12 with PH due to BPD, and 20 control subjects were studied. Patients with IPH had statistically higher isoprostanes than controls 62 pg/mL (37-210) versus 20 pg/mL (16-27), P < 0.01). The patients with PH and BPD had significantly lower isoprostanes than controls 15 pg/mL (8-17) versus 20 pg/ml (16-27), P < 0.02. F(2)-isoprostanes are elevated in children with IPH compared to both controls and patients with PH secondary to BPD. Furthermore, F(2)-isoprostanes in PH secondary to BPD are lower than control levels. These findings suggest that IPH and PH secondary to BPD have distinct mechanisms of disease pathogenesis.

Pediatric pulmonary arterial hypertension and hyperthyroidism: a potentially fatal combination

CONTEXT

Patients with pulmonary arterial hypertension (PAH) who develop hyperthyroidism are at risk for acute cardiopulmonary decompensation and death.

CASES AND SETTING

We present a series of eight idiopathic PAH/heritable PAH pediatric patients who developed hyperthyroidism between 1999 and 2011. Institutional Review Board approval was obtained; informed consent was waived due to the retrospective nature of the series. All eight patients were receiving iv epoprostenol; five of the eight patients presented with acute cardiopulmonary decompensation in the setting of hyperthyroidism. In the remaining three patients, hyperthyroidism was detected during routine screening of thyroid function tests. The one patient who underwent emergency thyroidectomy was the only survivor of those who presented in cardiopulmonary decline.

EVIDENCE SYNTHESIS

Aggressive treatment of the hyperthyroid state, including emergency total thyroidectomy and escalation of targeted PAH therapy and β-blockade when warranted, may prove lifesaving in these patients. Prompt thyroidectomy or radioactive iodine ablation should be considered for clinically stable PAH patients with early and/or mild hyperthyroidism to avoid potentially life-threatening cardiopulmonary decompensation.

CONCLUSIONS

Although the association between hyperthyroidism and PAH remains poorly understood, the potential impact of hyperthyroidism on the cardiopulmonary status of PAH patients must not be ignored. Hyperthyroidism must be identified early in this patient population to optimize intervention before acute decompensation. Thyroid function tests should be checked routinely in patients with PAH, particularly those on iv epoprostenol, and urgently in patients with acute decompensation or symptoms of hyperthyroidism.

Inhaled iloprost for the control of acute pulmonary hypertension in children: a systematic review

OBJECTIVE

Inhaled iloprost is attracting growing interest as a potential alternative and/or adjuvant to inhaled nitric oxide in the management of pediatric pulmonary hypertension in the acute and intensive care settings. However, there are currently no formal evidence-based guidelines regarding the use of inhaled iloprost in children with pulmonary hypertension. The aim of this systematic review is to assess the literature concerning the use of inhaled iloprost in children with pulmonary hypertension in the acute setting.

DATA SOURCES

Studies were identified from PubMed and Embase. Internal literature databases and recent congress abstracts (2009 onward) were also searched for relevant publications.

STUDY SELECTION

Studies were included if they examined the use of inhaled iloprost in children with pulmonary hypertension in an acute or intensive care setting.

DATA EXTRACTION AND SYNTHESIS

Twenty-eight studies were included in the review. The majority were case studies or case series (n = 17), and in total, the 28 studies represented the treatment of 195 children with iloprost. Iloprost was most frequently studied in children undergoing cardiac surgery (as a bridge to surgery and postoperatively), in children undergoing acute pulmonary vasoreactivity testing, and in neonates with persistent pulmonary hypertension of the newborn. The results of the included studies suggested that inhaled iloprost may have a diverse role in the acute treatment of pediatric pulmonary hypertension and that its acute effects are similar to those of inhaled nitric oxide. However, the iloprost dose was not consistently reported and varied greatly between studies, and several different administration devices were used.

CONCLUSIONS

Inhaled iloprost may be useful in the acute treatment of children and neonates with pulmonary hypertension, but clinical data are scarce, and the appropriate dosing of iloprost in different scenarios is uncertain. Well-designed prospective clinical trials are needed.

Initial experience with tadalafil in pediatric pulmonary arterial hypertension

This study aimed to investigate the safety, tolerability, and effects of tadalafil on children with pulmonary arterial hypertension (PAH) after transition from sildenafil or after tadalafil received as initial therapy. A total of 33 pediatric patients with PAH were retrospectively evaluated. Of the 33 patients, 29 were switched from sildenafil to tadalafil. The main reason for the change from sildenafil was once-daily dosing. The average dose of sildenafil was 3.4 ± 1.1 mg/kg/day, and that of tadalafil was 1.0 ± 0.4 mg/kg/day. For 14 of the 29 patients undergoing repeat catheterization, statistically significant improvements were observed after transition from sildenafil to tadalafil in terms of mean pulmonary arterial pressure (53.2 ± 18.3 vs. 47.4 ± 13.7 mmHg; p < 0.05) and pulmonary vascular resistance index (12.2 ± 7.0 vs 10.6 ± 7.2 Units/m(2); p < 0.05). Clinical improvement was noted for four patients treated with tadalafil as initial therapy. The side effect profiles were similar for the patients who had transitioned from sildenafil to tadalafil including headache, nausea, myalgia, nasal congestion, flushing, and allergic reaction. Two patients discontinued tadalafil due to migraine or allergic reaction. One patient receiving sildenafil had no breakthrough syncope after transition to tadalafil. Tadalafil can be safely used for pediatric patients with PAH and may prevent disease progression.

The pharmacological treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening and progressive disease of various origins characterized by pulmonary vascular remodeling that leads to increased pulmonary vascular resistance and pulmonary arterial pressure, most often resulting in right-sided heart failure. The most common symptom at presentation is breathlessness, with impaired exercise capacity as a hallmark of the disease. Advances in understanding the pathobiology over the last 2 decades have led to therapies (endothelin receptor antagonists, phosphodiesterase type 5 inhibitors, and prostacyclins or analogs) initially directed at reversing the pulmonary vasoconstriction and more recently directed toward reversing endothelial cell dysfunction and smooth muscle cell proliferation. Despite these advances, disease progression is common even with use of combination regimens targeting multiple mechanistic pathways. Overall 5-year survival for PAH has increased significantly from approximately 30% in the 1980s to approximately 60% at present, yet remains abysmal. This review summarizes the mechanisms of action, clinical data, and regulatory histories of approved PAH therapies and describes the latest agents in late-stage clinical development.

Systemic endothelial dysfunction in children with idiopathic pulmonary arterial hypertension correlates with disease severity

BACKGROUND

Idiopathic pulmonary arterial hypertension (IPAH) is a life-threatening disease manifested by progressive pulmonary vascular remodeling, compromised pulmonary blood flow and right heart failure. Most studies have explored how pulmonary endothelial function modulates disease pathogenesis. We hypothesize that IPAH is a progressive panvasculopathy, affecting both pulmonary and systemic vascular beds, and that systemic endothelial dysfunction correlates with disease severity. Recent studies have demonstrated systemic endothelial dysfunction in adults with pulmonary hypertension; however, adults often have additional comorbidities affecting endothelial function. Systemic endothelial function has not been explored in children with IPAH.

METHODS

In this single-center, prospective, cross-sectional study we examined brachial artery flow-mediated dilation (FMD), a nitric oxide-mediated, endothelial-dependent response, in children with IPAH and matched controls. FMD measurements were compared with clinical and echocardiographic measures of IPAH severity.

RESULTS

Thirteen patients and 13 controls were studied, ranging in age from 6 to 20 years. FMD was decreased in IPAH subjects compared with controls (5.1 ± 2.1% vs 9.7 ± 2.0%; p < 0.0001). In IPAH subjects, FMD correlated directly with cardiac index (R(2) = 0.34, p = 0.035), and inversely with tricuspid regurgitation velocity (R(2) = 0.57, p = 0.019) and right ventricular myocardial performance index (R(2) = 0.44, p = 0.028).

CONCLUSIONS

The presence of systemic endothelial dysfunction in children with IPAH and its strong association with IPAH severity demonstrate that IPAH is a global vasculopathy. Although morbidity in IPAH is typically associated with pulmonary vascular disease, systemic vascular changes may also relate to disease pathogenesis and progression. Further study into shared mechanisms of systemic and pulmonary endothelial dysfunction may contribute to future therapies for IPAH.

Advances in pediatric pulmonary arterial hypertension

PURPOSE OF REVIEW

Pulmonary arterial hypertension (PAH) is an important cause of morbidity and mortality in children. Approved medications for the treatment of adult PAH have been used to treat children, but evidence-based treatment algorithms for children are lacking.

RECENT FINDINGS

Pediatric PAH registries have begun to define the incidence and prevalence of idiopathic PAH and PAH associated with congenital heart disease. A pediatric-specific classification of pulmonary hypertensive vascular disease has been proposed. Furthermore, the first randomized placebo-controlled trial of type-5 phosphodiesterase therapy in treatment-naïve children with PAH has been completed and reported. This trial highlights the importance of the difficulties of performing clinical trials in children with targeted PAH therapy as well as the importance of long-term follow-up of adverse events.

SUMMARY

Classification, clinical trials, and therapy for children with PAH must take into account the unique aspects of PAH in children.