First experience with an oral combination therapy using bosentan and sildenafil for pulmonary arterial hypertension

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 many 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. PAH associated with developmental lung diseases such as bronchopulmonary dysplasia or congenital diaphragmatic hernia is increasingly more recognized in infants and children. Although treatment of the underlying disease and reversal of advanced structural changes have not yet been achieved with current therapy, quality of life and survival have improved significantly. Targeted pulmonary vasodilator therapies, including endothelin receptor antagonists, prostacyclin analogs, and phosphodiesterase type 5 inhibitors have resulted in hemodynamic and functional improvement in children. The management of pediatric PAH remains challenging as treatment decisions 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.

Effect of Combination Therapy of Endothelin Receptor Antagonist and Phosphodiesterase-5 Inhibitor on Clinical Outcome and Pulmonary Haemodynamics in Patients with Pulmonary Arterial Hypertension: A Meta-Analysis

BACKGROUND

The combination of an endothelin receptor antagonist and a phosphodiesterase-5 inhibitor having different biological targets has become an integral part of the treatment of pulmonary arterial hypertension; however, several clinical studies have reported conflicting results.

OBJECTIVE

The objective of this meta-analysis was to evaluate the effect of an endothelin receptor antagonist and phosphodiesterase-5 inhibitor combination in pulmonary arterial hypertension.

METHODS

After performing a comprehensive literature search in MEDLINE, Cochrane and the International Clinical Trial Registry Platform, reviewers assessed eligibility and extracted data from seven relevant articles (publications till December 2018). PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed in the selection, analysis and reporting of findings. The odds ratio and mean difference were calculated to estimate the difference in clinical worsening, 6-minute walking distance, pulmonary vascular resistance and N-terminal pro-brain natriuretic peptide between the groups. Quality assessment was performed using the risk of bias assessment tool and a meta-regression for probable variables affecting effect size.

RESULTS

The random-effect model analysis revealed an odds ratio of 0.56 [95% confidence interval (CI) 0.41-0.76; p = 0.0002] for clinical worsening, mean difference of 15.64 (95% CI 2.67-28.61; p = 0.02) for 6-minute walking distance, - 1.66 (95% CI - 3.82 to 0.50; p = 0.13) for pulmonary vascular resistance and - 21.04 (95% CI - 26.87 to - 15.22; p < 0.00001) for N-terminal pro-brain natriuretic peptide. The meta-regression showed no statistically significant association between the dose and duration of treatment and outcomes (odds ratio of clinical worsening and mean difference of 6-minute walking distance).

CONCLUSIONS

In pulmonary arterial hypertension, endothelin receptor antagonist and phosphodiesterase-5 inhibitor combination therapy significantly improved 6-minute walking distance, clinical worsening and N-terminal pro-brain natriuretic peptide compared with the monotherapy but did not offer any advantage in improving pulmonary vascular resistance.

PROSPERO REGISTRATION NO

CRD42018091133.

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

OBJECTIVE

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

DATA SOURCES

Nonsystematic PubMed literature search and authors' expertise.

STUDY SELECTION

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

RESULTS

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

CONCLUSION

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

Reverse Remodeling of Pulmonary Arterioles After Pulmonary Artery Banding in Patients ≥ 2 Years Old with Severe Pulmonary Arterial Hypertension and Congenital Heart Disease

The purpose of this study was to evaluate the pathological changes of the pulmonary arterioles in patients ≥ 2 years of age who first underwent a pulmonary artery banding (PAB) procedure, followed by bidirectional Glenn or Fontan according to their specific conditions. This was a prospective study of 15 children diagnosed and treated with PAB at the Department of Cardiothoracic Surgery of Anzhen Hospital between January 2009 and December 2012. The percentage of media area (%MS) of pulmonary arteriole, the percentage of media thickness (%MT), and pulmonary arterial density (APSC) were calculated from lung tissue sections. Pulmonary artery pressure decreased significantly after PAB surgery (P < 0.01). Postoperative mean pulmonary artery pressure declined significantly (P < 0.01), the cardiothoracic ratio was reduced (P < 0.05), and percutaneous oxygen saturation (inhaled air) decreased to 80-85% (P < 0.01). %MT (from 35.1 ± 5.6% to 26.9 ± 4.3%, P < 0.01), %MS (from 51.4 ± 6.7% to 32.2 ± 7.4%, P < 0.01), and APSC (from 108.3 ± 38.5 to 83.6 ± 19.6, P < 0.01) were decreased significantly after PAB. Five patients underwent the bidirectional Glenn procedure and four underwent Fontan. In conclusion, the results suggest that PAB can reduce pulmonary artery pressure and that pulmonary arterial lesions can be reversed after PAB.

Sildenafil dosed concomitantly with bosentan for adult pulmonary arterial hypertension in a randomized controlled trial

Background

Few controlled clinical trials exist to support oral combination therapy in pulmonary arterial hypertension (PAH).

Methods

Patients with PAH (idiopathic [IPAH] or associated with connective tissue disease [APAH-CTD]) taking bosentan (62.5 or 125 mg twice daily at a stable dose for ≥3 months) were randomized (1:1) to sildenafil (20 mg, 3 times daily; n = 50) or placebo (n = 53). The primary endpoint was change from baseline in 6-min walk distance (6MWD) at week 12, assessed using analysis of covariance. Patients could continue in a 52-week extension study. An analysis of covariance main-effects model was used, which included categorical terms for treatment, baseline 6MWD (<325 m; ≥325 m), and baseline aetiology; sensitivity analyses were subsequently performed.

Results

In sildenafil versus placebo arms, week-12 6MWD increases were similar (least squares mean difference [sildenafil–placebo], −2.4 m [90% CI: –21.8 to 17.1 m]; P = 0.6); mean ± SD changes from baseline were 26.4 ± 45.7 versus 11.8 ± 57.4 m, respectively, in IPAH (65% of population) and −18.3 ± 82.0 versus 17.5 ± 59.1 m in APAH-CTD (35% of population). One-year survival was 96%; patients maintained modest 6MWD improvements. Changes in WHO functional class and Borg dyspnoea score and incidence of clinical worsening did not differ. Headache, diarrhoea, and flushing were more common with sildenafil.

Conclusions

Sildenafil, in addition to stable (≥3 months) bosentan therapy, had no benefit over placebo for 12-week change from baseline in 6MWD. The influence of PAH aetiology warrants future study.

Trial registration

ClinicalTrials.gov NCT00323297 (registration date: May 5, 2006).

Electronic supplementary material

The online version of this article (10.1186/s12872-017-0674-3) contains supplementary material, which is available to authorized users.

Sildenafil in pediatric pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening disease of varied etiologies. Although PAH has no curative treatment, a greater understanding of pathophysiology, technological advances resulting in early diagnosis, and the availability of several newer drugs have improved the outlook for patients with PAH. Sildenafil is one of the therapeutic agents used extensively in the treatment of PAH in children, as an off-label drug. In 2012, the United States Food and Drug Administration (USFDA) issued a warning regarding the of use high-dose sildenafil in children with PAH. This has led to a peculiar situation where there is a paucity of approved therapies for the management of PAH in children and the use of the most extensively used drug being discouraged by the regulator. This article provides a review of the use of sildenafil in the treatment of PAH in children.

Risk-benefit considerations when prescribing phosphodiesterase-5 inhibitors in children

INTRODUCTION

Sildenafil (Revatio®) and tadalafil (Adcirca®) are specific inhibitors of the phosphodiesterase-5 enzyme and produce pulmonary vasodilation by inhibiting the breakdown of cyclic guanosine monophosphate (cGMP) in the walls of pulmonary arterioles.

AREAS COVERED

We focus on the efficacy and safety of sildenafil and tadalafil in the treatment of pulmonary hypertension (PH) in children through a PubMed literature search.

EXPERT OPINION

Although used since 1999 in the treatment of PH in children, it is only in the past few years that robust evidence for the use of sildenafil has emerged principally in the pivotal STARTS-1 study. The open-label extension of this study, STARTS-2, has revealed safety concerns substantiated by FDA post marketing surveillance leading to recommendations to use lower doses. More recently, tadalafil has been introduced allowing once daily dosing with apparently similar efficacy to sildenafil in children. Recently there have been suggestions that sildenafil and tadalafil may have a place in treating muscular dystrophy.

The role of phosphodiesterase inhibitors in the management of pulmonary vascular diseases

Phosphodiesterase inhibitors (PDE) can be used as therapeutic agents for various diseases such as dementia, depression, schizophrenia and erectile dysfunction in men, as well as congestive heart failure, chronic obstructive pulmonary disease, rheumatoid arthritis, other inflammatory diseases, diabetes and various other conditions. In this review we will concentrate on one type of PDE, mainly PDE5 and its role in pulmonary vascular diseases.

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.

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.

Combination therapy in pulmonary arterial hypertension

Despite major advances in understanding the mechanisms of disease and development of specific drug therapy, pulmonary arterial hypertension (PAH) remains a progressive, fatal disease. At present there are 3 classes of drug therapy for PAH: prostaglandins, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors. To maximize therapeutic benefit, and according to national and international guidelines, many patients are treated with combinations of these medications. This review presents a detailed account of the published data on the use of combination therapy in PAH. There are few randomized, placebo-controlled trial data to strongly support efficacy of most combination therapy, particularly oral combination therapy.

Combination therapy in pulmonary arterial hypertension

Many potential therapeutic options are now available for patients with pulmonary arterial hypertension. Interest has emerged in using therapies in various combinations. Retrospective experience has suggested that this approach is common and can be efficacious. Data are emerging supporting the benefit of combination therapy; however, limitations and questions remain about this strategy. This report reviewed the rationale for combination therapy and summarized the results from clinical trials.

Pulmonary arterial hypertension: new insights into the optimal role of current and emerging prostacyclin therapies

Pulmonary arterial hypertension (PAH), which is a subset of pulmonary hypertension, is a group of diseases distinguished by vascular remodeling of the small pulmonary arteries with associated elevated pulmonary arterial pressure and right ventricular failure. This progressive and sometimes fatal disease occurs as an idiopathic disease or as a component of other disease states. Estimates of the incidence of PAH have varied from 5 to 52 cases/1 million population. Symptoms begin with shortness of breath with exertion and progress to dyspnea with normal activities and, finally, dyspnea at rest. Untreated patients with PAH have a 1-, 3-, and 5-year survival rate of 68%, 48%, and 34%, respectively. Treated, the survival rates improve to 91% to 97% after 1 year and 84% to 91% after 2 years. The current definition of PAH consists of 3 specific hemodynamic assessments confirmed by right heart catheterization findings. One of several important pathophysiologic mechanisms involved in PAH is pulmonary vascular remodeling, which is caused by endothelial and smooth muscle cell hyperproliferation. This is coincident with overexpression of the vasoconstrictor endothelin-1 and a reduction in the vasodilators nitric oxide and prostacyclin, which further impedes proper vasomotor tone, among other effects. Prostacyclin therapies augment the decreased prostacyclin levels in patients with PAH. The currently approved prostacyclins for the treatment of PAH include epoprostenol, iloprost, and treprostinil. Among the 3 medications, the delivery options include intravenous infusion, subcutaneous infusion, and inhaled formulations. Epoprostenol has been shown to have a positive effect on survival in patients with PAH. All prostacyclins have demonstrated improvements in functional class, exercise tolerance, and hemodynamics in patients with PAH. Intravenously and subcutaneously administered formulations of prostacyclins require continuous infusion pump administration, which presents clinical challenges for both the patient and the care provider. Dosing must be individualized and also presents a clinical challenge. Inhaled formulations seem efficacious in moderately symptomatic patients with PAH and might be appropriate when combined with an oral medication. Combination therapies are commonly used in clinical practice, with the decision to do so based on randomized controlled trial data and case study evidence. The present report provides an overview of PAH, the scientific rationale for treatment with prostacyclin therapy, and the benefits and risks of prostacyclin therapy, both as monotherapy and combined with other medications approved for the treatment of PAH.

Congenital heart disease and pulmonary hypertension

Many patients with congenital heart disease and systemic-to-pulmonary shunts develop pulmonary arterial hypertension (PAH), particularly if the cardiac defect is left unrepaired. A persistent increase in pulmonary blood flow may lead to obstructive arteriopathy and increased pulmonary vascular resistance, a condition that can lead to reversal of shunt and cyanosis (Eisenmenger syndrome). Cardiac catheterization is crucial to confirm diagnosis and facilitate treatment. Bosentan is the only medication to date to be compared with placebo in a randomized controlled trial specifically targeting congenital heart disease-associated PAH. Lung transplantation with repair of the cardiac defect or combined heart-lung transplantation is reserved for recalcitrant cases.

Quality of life after children undergo a radical arterial switch operation at an older age

OBJECTIVE

The goal of the study was to evaluate the quality of life of children after the older corrective arterial switch operation (ASO) by means of the Pediatric Quality of Life Inventory (PedsQL), version 4.0.

METHODS

The records of 86 patients who had complete transposition of the great arteries plus a nonrestrictive ventricular septal defect, or a Taussig-Bing anomaly, and severe pulmonary arterial hypertension, and who underwent a corrective ASO at an older age (>6 months) between May 2000 and October 2008 were reviewed retrospectively. Eighty survivors were followed up, and the health-related quality of life of the survivors was evaluated with the PedsQL, version 4.0.

RESULTS

There were 6 hospital deaths. The mean (SD) follow-up interval was 3.5 ± 2.3 years, and the mean age at last visit was 7.0 ± 1.2 years. Two late deaths occurred, and 8 patients were lost to follow-up. Patients who underwent a corrective ASO at an older age showed acceptable scores for all scales, and they were all comparable with those of a healthy population.

CONCLUSIONS

Our data suggest that the quality of life of children who undergo a corrective ASO at an older age (>6 months) is acceptable, compared with that of healthy children in China.

Dual therapy in IPAH and SSc-PAH. A qualitative systematic review

BACKGROUND

Use of endothelin receptor antagonists (ERA), phosphodiesterase type-5 (PDE-5) inhibitors and prostaglandin analogues has resulted in improved outcomes in idiopathic pulmonary arterial hypertension (IPAH) and systemic sclerosis-associated PAH (SSc-PAH) patients. However, patients often deteriorate on monotherapy. The objective of this study is to evaluate the effect of dual therapy on outcomes in IPAH and SSc-PAH.

METHODS

A systematic review of MEDLINE (1950-2011), EMBASE (1980-2011) and CINAHL (inception-2011) was conducted to identify studies that evaluated the effect of any dual combination of ERA, PDE-5 inhibitors or prostaglandin analogues on 6-min walk distance (6MWD), functional class (FC), haemodynamics, quality-of-life (QoL) or time-to-clinical-worsening in IPAH or SSc-PAH. A standardized form was used to abstract design, sample size, aetiology, outcome and treatment effect.

RESULTS

Twenty-six observational studies and 6 randomized trials were identified. Using combination PDE-5 inhibitor and prostaglandin analogues, 6/7 studies reported improvement in 6MWD, 6/8 studies reported improvement in FC, 6/6 studies reported improvement in haemodynamics and 1 trial demonstrated improvement in QoL and time-to-clinical-worsening. Using combination ERA and prostaglandin analogues, 4/6 studies and 1 trial reported improvement in 6MWD, 3/3 studies and 1 trial reported improvement in FC, 4/5 studies and 1 trial reported improvement in PAP. Using combination ERA and PDE-5 inhibitor, 4/7 studies reported an improvement in 6MWD, and 2/6 report improvement in FC.

CONCLUSION

The evidence suggests a beneficial effect of dual therapy in IPAH and SSc-PAH, particularly those who are deteriorating on monotherapy. Research should focus on subsets of patients to identify the optimal timing and combination of dual therapy.

The Adult Patient with Eisenmenger Syndrome: A Medical Update after Dana Point Part II: Medical Treatment - Study Results

Eisenmenger syndrome is the most severe form of pulmonary arterial hypertension and arises on the basis of congenital heart disease with a systemic-to-pulmonary shunt. Due to the chronic slow progressive hypoxemia with central cyanosis, adult patients with the Eisenmenger syndrome suffer from a complex and multisystemic disorder including coagulation disorders (bleeding complications and paradoxical embolisms), renal dysfunction, hypertrophic osteoarthropathy, heart failure, reduced quality of life and premature death.

For a long time, therapy has been limited to symptomatic options or lung or combined heart-lung transplantation. As new selective pulmonary vasodilators have become available and proven to be beneficial in various forms of pulmonary arterial hypertension, this targeted medical treatment has been expected to show promising effects with a delay of deterioration also in Eisenmenger patients. Unfortunately, data in Eisenmenger patients suffer from small patient numbers and a lack of randomized controlled studies.

To optimize the quality of life and the outcome, referral of Eisenmenger patients to spezialized centers is required. In such centers, specific interdisciplinary management strategies of physicians specialized on congenital heart diseases and PAH should be warranted.

This medical update emphasizes the current diagnostic and therapeutic options for Eisenmenger patients with particularly focussing on the medical treatment and corresponding study results.

Acute effect of sildenafil is maintained in pulmonary arterial hypertension patients chronically treated with bosentan

The chronic use of bosentan has been reported to reduce the plasma concentration of sildenafil. However, it remains unclear how sildenafil exerts the effect at reduced concentrations in pulmonary arterial hypertension (PAH) patients chronically treated with bosentan.We examined the hemodynamic effects of sildenafil (50 mg) in 8 Japanese patients with PAH, and simultaneously measured the plasma concentration of sildenafil ([Sil]) and its major metabolite, desmethylsildenafil ([Des]).The overall effects of sildenafil were 12.4% decrease in mean pulmonary arterial pressure, 19.9% increase in cardiac index (CI), and 25% reduction in derived pulmonary vascular resistance (PVR). When the patients were divided into two groups, a group with bosentan pretreatment [BOS (+), n = 4] and a group without bosentan pretreatment [BOS (-), n = 4], both [Sil] and [Des] were lower at the peak concentration (C(max)) and the area under the plasma concentration versus time curve (AUC(0-6h)), and the time to reach C(max) was longer in BOS (+), although only the difference in AUC(0-6h) of [Des] reached statistical significance (P = 0.02). In spite of lower concentration, the effect of sildenafil on CI was maintained in the BOS (+) group, while the decrease in PVR was less marked.Sildenafil acutely dilated the pulmonary artery and increased CI in the PAH patients. These effects were still observed or maintained in the PAH patients chronically treated with bosentan, even when [Sil] was reduced.

Long-term outcomes in children with pulmonary arterial hypertension treated with bosentan in real-world clinical settings

Treatment algorithms in pediatric pulmonary arterial hypertension (PAH) are derived from clinical trials in adult populations and from clinical practice, but experience in children is limited. In this retrospective cohort study, we analyzed outcomes in a previously identified cohort of 86 consecutive children with PAH treated with bosentan as part of their treatment regimen. All children with idiopathic PAH or heritable PAH and PAH associated with congenital heart disease or connective tissue disease who started bosentan treatment from May 2001 to April 2003 in 2 tertiary pediatric referral centers were followed, with data collection ending August 2006. Eighty-six children (37 male, 49 female) 11 ± 5 years of age with idiopathic/heritable PAH (n = 36), PAH associated with congenital heart disease (n = 48), or PAH associated with connective tissue disease (n = 2) received bosentan as monotherapy (n = 42) or as an add-on to pre-existing continuous intravenous epoprostenol or subcutaneous treprostinil (n = 44). Median observation period was 39 months (range 2 to 60). Thirty-four patients (40%) received ≥1 additional PAH-specific therapy during follow-up. At end of data collection, 25 patients (29%) remained on bosentan, 43 (50%) had stopped bosentan, 11 (13%) had died while on bosentan, and 7 were lost to follow-up. At 4 years, the Kaplan-Meier estimate of disease progression in patients while on bosentan was 54% (7 patients at risk) with a survival estimate of 82% (16 patients at risk). Risk factors significantly associated with survival were World Health Organization functional class and indexed pulmonary vascular resistance. In conclusion, outcome in children with PAH managed with current treatment regimens appears favorable. However, despite current therapy options, disease progression remains a concern.

The management of acute pulmonary arterial hypertension

Acute pulmonary arterial hypertension (PAH), which may complicate the course of many complex disorders, is always underdiagnosed and its treatment frequently begins only after serious complications have developed. Acute PAH is distinctive because they differ in their clinical presentation, diagnostic findings, and response to treatment from chronic PAH. The acute PAH may take either the form of acute onset of chronic PAH or acute PAH or surgery-related PAH. Significant pathophysiologic differences existed between acute and chronic PAH. Therapy of acute PAH should generally be aimed at acutely relieving right ventricular (RV) pressure overload and preventing RV dysfunction. There are three classes of drugs targeting the correction of abnormalities in endothelial dysfunction, which have been approved recently for the treatment of PAH: (1) prostanoids; (2) endothelin receptor antagonists; and (3) phosphodiesterase-5 inhibitors. The efficacy and safety of these compounds have been confirmed in uncontrolled studies in patients with PAH. Intravenous epoprostenol is suggested to serve as the first-line treatment for the most severe patients. In the other situations, the first-line therapy may include bosentan, sildenafil, or a prostacyclin analogue. Recent advances in the management of PAH have markedly improved prognosis.

Advances in therapies for pediatric pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by progressive obliteration of the pulmonary vasculature, leading to right heart failure and death if left untreated. Prior to the current treatment era, pulmonary hypertension carried a poor prognosis with a high mortality rate, but its prognosis has changed over the past decades in relation to new therapeutic agents. Nevertheless, pulmonary hypertension continues to be a serious condition, which is extremely challenging to manage. The data in children are often limited owing to the small number of patients, and extrapolation from adults to children is not straightforward. While none of these new therapeutic agents have been specifically approved for children, there is evidence that each can appropriately benefit the PAH child. We review the current understanding of pediatric pulmonary hypertension, classification, diagnostic evaluation and available treatment. A description of targeted pharmacological therapy and new treatments in children is outlined.

Advances in diagnosis and treatment of pulmonary arterial hypertension in neonates and children with congenital heart disease

BACKGROUND

This article aims to review recent advances in the diagnosis and treatment of pulmonary arterial hypertension in neonates and children with congenital heart disease.

DATA SOURCES

Articles on pulmonary arterial hypertension in congenital heart disease were retrieved from PubMed and MEDLINE published after 1958.

RESULTS

A diagnosis of primary (or idiopathic) pulmonary arterial hypertension is made when no known risk factor is identified. Pulmonary arterial hypertension associated with congenital heart disease constitutes a heterogenous group of conditions and has been characterized by congenital systemic-to-pulmonary shunts. Despite the similarities in histologic appearance of pulmonary vascular disease, there are differences between pulmonary arterial hypertension secondary to congenital systemic-to-pulmonary shunts and those with other conditions with respect to pathophysiology, therapeutic strategies, and prognosis. Revision and subclassification within the category of secondary pulmonary arterial hypertension based on pathophysiology were conducted to improve specific treatments. The timing of surgical repair is crucial to prevent and minimize risk of postoperative pulmonary arterial hypertension. Drug therapies including prostacyclin, endothelin-receptor antagonist, phosphodiesterase inhibitor, and nitric oxide have been evolved with promising results in neonates and children.

CONCLUSIONS

Among the different forms of congenital heart diseases, an early correction generally prevents subsequent development of pulmonary arterial hypertension. Emerging therapies for treatment of patients with idiopathic pulmonary arterial hypertension also improve quality of life and survival in neonates and children with congenital heart disease associated with pulmonary arterial hypertension. Heart and lung transplantation or lung transplantation in combination with repair of the underlying cardiac defect is a therapeutic option in a minority of patients. Partial repair options are also beneficial in some selected cases. Randomized controlled trials are needed to evaluate the safety and efficacy of these therapies including survival and long-term outcome.

Sildenafil for the treatment of pulmonary hypertension in pediatric patients

Sildenafil is a phosphodiesterase 5 inhibitor widely used for the treatment of pulmonary hypertension in children. Despite limited available safety and efficacy evidence, use of sildenafil continues to increase. To date, sildenafil use for pediatric pulmonary hypertension has been characterized for 193 children through 16 studies and 28 case series and reports. The primary efficacy data suggest that sildenafil is beneficial for facilitating the weaning of inhaled nitric oxide in children after cardiac surgery. Compiled safety data suggest that sildenafil is well tolerated among children with idiopathic pulmonary arterial hypertension and pulmonary arterial hypertension associated with congenital heart disease. This review summarizes the available data describing the use, safety, and efficacy of sildenafil for children with pulmonary hypertension.

Treatment of severe pulmonary hypertension secondary to scleroderma: a three-drug approach

We present a case of scleroderma complicated by severe pulmonary hypertension. The use of a three-drug (bosentan, iloprost, and sildenafil) approach contributed to significant improvement of both the clinical conditions and the pulmonary hemodynamics. Combining three pulmonary vasodilators with different mechanisms of action could benefit patients with severe pulmonary hypertension resistant to conventional therapy.

Mutual pharmacokinetic interactions between steady-state bosentan and sildenafil

OBJECTIVE

The aim of this study was to systematically investigate the mutual pharmacokinetic interactions in healthy volunteers between sildenafil, a phosphodiesterase-5 inhibitor, and bosentan, a dual endothelin receptor antagonist, both approved for treating pulmonary arterial hypertension (PAH).

METHODS

A randomised, double-blind, placebo-controlled, parallel-group study with three treatment arms (sildenafil plus placebo, bosentan plus placebo and sildenafil plus bosentan) was conducted in 55 healthy male volunteers (51 completers). Study duration was 18 days per treatment group. Sildenafil was administered three times daily on Days 1-6 and 11-16 (20 mg initially, increased to 80 mg after 3 days), and bosentan (125 mg) was administered twice daily on Days 7-17.

RESULTS

On Day 16, bosentan decreased the maximum plasma concentration of sildenafil (c)(max)) by 55.4% [90% confidence interval (CI) 40.3-66.6%] and the area under the plasma concentration versus time curve over a dosing interval (AUC(tau)) by 62.6% (90% CI 56.8-67.7%). Sildenafil increased bosentan C(max) by 42.0% (90% CI 15.4-74.8%) and (AUC(tau)) by 49.8% (90% CI 28.7-74.5%). Bosentan and sildenafil in combination were well tolerated, with no serious adverse events reported. All adverse events were of mild or moderate intensity.

CONCLUSIONS

In healthy volunteers, there is a mutual pharmacokinetic interaction between bosentan and sildenafil that may influence the dosage of each drug in a combination treatment. The clinical implications of combination therapy with bosentan and sildenafil are as yet unknown, and further trials in patients with PAH are needed.

Effect of sildenafil on ventilatory efficiency and exercise tolerance in pulmonary hypertension

BACKGROUND

The pulmonary vasculopathy in pulmonary arterial hypertension (PAH) results in increased resistance to pulmonary blood flow, limiting the cardiac output required for the increased O(2) demands of exercise.

AIMS

We sought to determine the physiologic basis for clinical improvement in PAH patients receiving sildenafil, hypothesizing that the key mechanisms of improvement are improved blood flow and ventilatory efficiency, leading to improved exercise capacity and O(2) pulse over time.

METHODS

We studied 28 PAH patients with (n=14) and without (n=14) sildenafil treatment. All received warfarin and diuretic therapy, and 13/14 sildenafil-treated patients were already receiving specific PAH drugs. Cardiopulmonary exercise testing was performed before and after sildenafil.

RESULTS

Peak VO2 , peak O(2) pulse, V E/CO2 and PETCO2, were 0.84+/-0.1 L/min, 6.1+/-0.7 mL beat(- 1), 49+/-2 and 26+/-1.5 mm Hg, and improved after adding sildenafil to 0.91+/-0.1 L/min, 6.8+/-0.8 mL beat(- 1), 43+/-2, and 30+/-1.9, respectively, whereas control patients worsened (p=0.012, 0.008, 0.008 and 0.0002, treated vs. controls, respectively).

CONCLUSIONS

Sildenafil improves PETCO2, V E/V CO(2), peak O2 pulse and peak VO2 during exercise compared to controls. A prospective, placebo-controlled study is needed to validate these findings.

Surgical therapies for pulmonary arterial hypertension

Surgical therapies for the treatment of pulmonary arterial hypertension typically are reserved for patients who are deemed to be refractory to medical therapy and have evidence of progressive right-sided heart failure. Atrial septostomy, a primarily palliative procedure, may stave off hemodynamic collapse from right-sided heart failure long enough to permit a more definitive surgical treatment such as lung or combined heart-lung transplantation. This article discusses indications for and results of atrial septostomy and lung and heart-lung transplantation in patients who have pulmonary arterial hypertension.