Pulmonary arterial hypertension: a look to the future

Hotspots and frontiers in pulmonary arterial hypertension research: a bibliometric and visualization analysis from 2011 to 2020

Pulmonary arterial hypertension (PAH) is a group of devastating and progressive disorders, resulting in relentless increases in pulmonary vascular resistance. The number of studies related to PAH has been increasing in recent years. Our study aims to illustrate trends in PAH research over the past decade using bibliometric analysis. Science Citation Index-Expanded was adopted to search studies concerning PAH between 2011 and 2020. The bibliographic information was converted and analyzed automatically using a bibliometric package in R software and citespace. The annual quantity of publications on PAH showed an overall increase last decade. The United States was the most prolific country with 2,479 publications, and it was also the country that cooperated most with other countries. Hôpital Bicêtre made important research achievements on PAH and was a leader in study cooperation. Marc Humbert led the PAH field by publishing 150 articles in the past decade. During the past decade, there was a close transnational relation among countries or regions, institutions and authors. Further, Circulation was the most cited journal, followed by the Journal of the American College of Cardiology and the American Journal of Respiratory and Critical Care Medicine, with 3,895, 3,406, and 3,170 citations, respectively. The global research status and trend of PAH are deeply understood for the first time using bibliometric and visual methods, and the results of our study bring us a valuable reference for clinical researchers.

This is the first study to illustrate trends in pulmonary arterial hypertension research using bibliometric analysis.

Our study provides extensive and in-depth directions for researchers.

Our study may benefit further researches on the etiology, diagnosis, and treatment of pulmonary arterial hypertension.

Exercise-Based Rehabilitation to Improve Exercise Capacity and Quality of Life in Pulmonary Arterial Hypertension

<LEAP> highlights the findings and application of Cochrane reviews and other evidence pertinent to the practice of physical therapy. The Cochrane Library is a respected source of reliable evidence related to health care. Cochrane systematic reviews explore the evidence for and against the effectiveness and appropriateness of interventions-medications, surgery, education, nutrition, exercise-and the evidence for and against the use of diagnostic tests for specific conditions. Cochrane reviews are designed to facilitate the decisions of clinicians, patients, and others in health care by providing a careful review and interpretation of research studies published in the scientific literature. Each article in this PTJ series summarizes a Cochrane review or other scientific evidence on a single topic and presents clinical scenarios based on real patients or programs to illustrate how the results of the review can be used to directly inform clinical decisions. This article focuses on people diagnosed with pulmonary arterial hypertension. Can exercise-based rehabilitation programs improve exercise capacity and quality of life in people with pulmonary arterial hypertension?

[A patient with severe idiopathic pulmonary arterial hypertension: Is there a way out?]

The paper considers a clinical example of current therapy for idiopathic pulmonary arterial hypertension in a female patient with its clinical deterioration. It shows the tactics of switching from one drug (bosentan) to others (macitentan) within in the same pathogenetic therapy group (endothelin receptor antagonists). The latest pulmonary hypertension classification (Nice, 2013) is presented. The current strategies of pathogenetic therapy for pulmonary hypertension are discussed.

Management of prostacyclin side effects in adult patients with pulmonary arterial hypertension

Therapies that target the prostacyclin pathway are considered effective, yet are complex to dose and may cause dose-limiting side effects for patients with pulmonary arterial hypertension (PAH). Careful side effect management and the ability to discern side effects from worsening disease are essential in order for patients to continue, and benefit from, prostacyclin therapy. This manuscript was developed through a collaborative effort of allied health providers with extensive experience in managing patients with PAH who are treated with medications that target the prostacyclin pathway. This article provides an overview of individual prostacyclin pathway therapies approved in the United States, side effects most commonly associated with these therapies, and practical suggestions for side effect management. Most patients will experience significant side effects on prostacyclin therapy. Creating a proactive and careful side effect management program will increase the likelihood that patients are able to stay on therapy and receive the benefits afforded by prostacyclin therapy.

Nanocomposite microparticles (nCmP) for the delivery of tacrolimus in the treatment of pulmonary arterial hypertension

Tacrolimus (TAC) has exhibited promising therapeutic potential in the treatment of pulmonary arterial hypertension (PAH); however, its application is prevented by its poor solubility, instability, poor bioavailability, and negative systemic side effects. To overcome the obstacles of using TAC for the treatment of PAH, we developed nanocomposite microparticles (nCmP) for the pulmonary delivery of tacrolimus in the form of dry powder aerosols. These particles can provide targeted pulmonary delivery, improved solubility of tacrolimus, the potential of penetration through mucus barrier, and controlled drug release. In this system, tacrolimus-loaded polymeric nanoparticles (NP) were prepared via emulsion solvent evaporation and nCmP were prepared by spray drying these NP with mannitol. The NP were approximately 200nm in diameter with narrow size distribution both before loading into and after redispersion from nCmP. The NP exhibited smooth, spherical morphology and the nCmP were raisin-like spheres. High encapsulation efficacy was achieved both in the encapsulation of tacrolimus in NP and that of NP in nCmP. nCmP exhibited desirable aerosol dispersion properties, allowing them to deposit into the deep lung regions for effective drug delivery. A549 cells were used as in vitro models to demonstrate the non-cytotoxicity of TAC nCmP. Overall, the designed nCmP have the potential to aid in the delivery of tacrolimus for the treatment of PAH.

Patients', relatives', and practitioners' views of pulmonary arterial hypertension: A qualitative study

INTRODUCTION

To study practitioners', patients' with PAH, and relatives' views regarding pulmonary arterial hypertension (PAH) and identify potential improvements in medical care strategies.

METHODS

A qualitative study based on semi-structured interviews involving 16 patients, 4 relatives, and 9 practitioners.

RESULTS

Patients with PAH, their relatives, and physicians who treat persons with PAH had divergent perspectives on PAH. The discrepancies identified concerned their perceptions of the illness and its impact on patients' with PAH daily lives. Patients with PAH had a broader view, including social, identity, financial, and functional dimensions of PAH's impact on their lives, whereas practitioners were more focused on functional aspects. The study also pointed out divergent approaches among physicians to assessing patients' New York Heart Association functional class. The expectations of patients with PAH, relatives, and physicians also differed. Patients with PAH expected improvement in PAH diagnosis and better coordination between primary care physicians and PAH medical centers. They also valued reducing side effects, less restrictive medications, and greater consideration of their views in the medical decision making process. Physicians' expectations focused more on identifying and validating therapeutic strategies.

CONCLUSION

Our results suggest several potential improvements in patient management, especially in order to better tailor treatment to patients' needs and to achieve a more uniform approach to the PAH functional impact assessment process. The findings may also be useful in enhancing therapeutic education for patients and their relatives, and in enabling practitioners to better interpret dyspnea in patients with PAH. Finally, this qualitative database will help in developing patient-reported outcome measures with better content validity. It lays the groundwork for developing new instruments to investigate the impact of PAH on patients' daily lives in terms of symptom assessment and functional impact.

Medical therapeutics for pulmonary arterial hypertension: from basic science and clinical trial design to evidence-based medicine

Pulmonary arterial hypertension is a severe disease with poor prognosis, caused by obliteration of the pulmonary vasculature as a result of pulmonary-vascular remodeling, active vasoconstriction and in situ thrombosis. Left untreated, pulmonary arterial hypertension results in right-ventricular failure and death. There has been dramatic progress in the treatment of pulmonary arterial hypertension during recent years. A remarkable number of randomized-controlled trials with agents known to target specific abnormalities present in pulmonary arterial hypertension have been completed. Most commonly, therapeutic efficacy was judged by the ability of the drug under study to improve exercise capacity and to decrease the rate of severe complications. Completed clinical trials have mainly evaluated patients with relatively advanced disease. Despite these advances, responses to therapy in pulmonary arterial hypertension are not uniformly favorable and frequently incomplete. In addition, the methods of delivery and the adverse effect profile of the currently available pulmonary arterial hypertension-specific drugs create further management difficulties. Based on newly identified pathobiologic abnormalities in the pulmonary vasculature, future studies are likely to focus on the discovery of new therapeutic targets. Clinical trial design will continue to evolve in an attempt to enable inclusion of patients with less advanced disease and evaluation of treatment combinations or comparisons of the currently approved drugs.

IVI epoprostenol as salvage therapy in pulmonary arterial hypertension: an Australian perspective

BACKGROUND

IVI epoprostenol is the only therapy for pulmonary arterial hypertension (PAH) with a randomized controlled trial demonstrating improved survival, when used as first-line monotherapy. In Australia it is used as salvage therapy for those failing treatment with other targeted therapies or presenting in World Health Organization functional class (FC) IV.

AIMS

Report experience with IVI epoprostenol, administered as salvage therapy for the treatment of adults with PAH in a single Australian PAH centre.

METHODS

Retrospective case series of all patients commenced on IVI epoprostenol for PAH, between 2002 and 2010. Review of case notes with collection of data at baseline and after treatment, including FC, 6-min walk test (6MWT), right ventricular systolic pressure (RVSP) on echocardiogram, patient survival and treatment complications. Change in indices was assessed using the Wilcoxon Sign Rank Test and is expressed as median (inter-quartile range).

RESULTS

A total of 23 patients was included. Treatment was generally well tolerated with few major complications. At the end of the study period, nine patients were successfully bridged to transplant, five had a sustained response to IVI epoprostenol, six had an incomplete response but were clinically stabilized, two died awaiting transplant and one died who was not a candidate for transplantation. Overall, when measured at best level post initiation of IVI epoprostenol, there were significant improvements in FC -1 [0 to -1] (P < 0.0001), 6MWT (m) +117 [70-264] (P= 0.002) and RVSP (mmHg) -7.0 [4.0 to -45] (P= 0.03).

CONCLUSION

Findings support efficacy of epoprostenol as salvage therapy for patients with PAH.

Effect of nesiritide in isolated right ventricular failure secondary to pulmonary hypertension

Treatment of right ventricular failure (RVF) can be challenging due to the correlation between RVF and worsening renal function with diuretic therapy. Nesiritide has been studied in patients with left ventricular failure but has not been evaluated in isolated RVF. The authors retrospectively analyzed 140 patients admitted with RVF, pulmonary hypertension (PH), and preserved left ventricular systolic function. Seventy patients were treated with nesiritide while the remaining patients received only furosemide (no nesiritide group). Serum creatinine and GFR at baseline, 72 hours, discharge, and 1 month post-treatment, as well as hemodynamic data were compared between the groups. In the nesiritide group, there was a significant decrease in mean GFR (42.77±25.33, P<.001) at day of discharge and 1 month post-nesiritide infusion (41.17±24.94, P<.001) but not in the no nesiritide group. There was a significant difference in >25% decrease in GFR anytime through day 30 (47.14% vs. 25.71%, P=.036) between the two groups. On multivariate analysis, nesiritide remained an important predictor of renal function at discharge and at 1 month (P<.01) as well as a predictor of >25% decrease in GFR anytime through day 30 (P=.007). Thus, nesiritide is associated with worsening kidney function in patients with RVF in the setting of PH.

Etiology, diagnosis, and pharmacologic treatment of pediatric pulmonary hypertension

Major advances have been made in the understanding and treatment of pulmonary hypertension in the last few years. Without treatment (medication) for idiopathic pulmonary arterial hypertension, which is a rare and potentially fatal condition, the survival time is only about 3 years after diagnosis. However, if pulmonary hypertension is secondary to other causes such as congenital heart disease, it is possible to survive for 30 years or more without treatment. The condition can affect children at any age, from fetal life to adulthood. Patients with pulmonary hypertension can present to the respiratory pediatrician with unresponsive asthma, to the neurologist with faints, or to the general pediatrician with failure to thrive. Over the last few years there have been significant developments in the available therapy for managing this complicated disease. There is now a generally recognized ladder of long-term therapy for chronic pulmonary hypertension. Treatment can start with oxygen at home at night or even during the day. Next is the use of oral phosphodiesterase inhibitors, mostly type V, such as sildenafil, which enhance endogenous nitric oxide. More potent are the endothelin receptor antagonists and the most potent are the prostanoids, especially epoprostenol, which is given by constant intravenous infusion. In addition to interventional catheterization with atrial septostomy, these agents have improved the prognostic outlook. This article reviews the current knowledge about the etiology, investigation, and treatment of children with pulmonary hypertension in the clinical setting.

Treatment of pulmonary hypertension in children with chronic lung disease with newer oral therapies

Chronic lung disease (CLD) is often complicated by chronic pulmonary vascular changes and pulmonary hypertension (PH) in young children. Current therapies for severe PH in such patients, including oxygen, inhaled nitric oxide, and parenteral prostacyclin, are often suboptimal, cumbersome, and expensive. Recently, oral endothelin receptor blockers and phosphodiesterase-5 inhibitors have been used successfully to control and reverse pulmonary vascular disease in idiopathic PH, but the use and efficacy of these agents in pediatric CLD have not been previously reported. We report a series of six children with CLD and severe PH treated with bosentan (six of six) and sildenafil (four of six). Vascular reactivity was assessed by cardiac catheterization prior to and after 6 months of therapy. Serial echocardiography was also used to assess response. Patients have been treated for 2.1-2.9 years (mean, 2.53 years). Response to therapy has included improvement in oxygenation, symptoms, echocardiographic parameters, and hemodynamics by cardiac catheterization. Transiently elevated liver enzymes were noted associated with viral respiratory infections in two subjects; no other adverse effects were noted. Three patients with large cardiac right-to-left shunts prior to therapy had subsequent shunt reversal, two of whom underwent shunt closure later. Oral therapy with bosentan alone or in combination with sildenafil improves PH in patients with CLD over a period of 3-4 years.

Evaluation of disease-specific health-related quality of life in patients with pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) remains a debilitating and life-threatening disease despite improvements in hemodynamics, exercise capacity and survival with recent therapeutic advances. Health-related quality of life (HRQOL) has, therefore, been proposed as an important outcome for evaluating care. Relatively little, however, is known regarding HRQOL or its determinants in PAH. The Minnesota Living with Heart Failure questionnaire was recently adapted and validated for HRQOL measurement in PAH. We applied this pulmonary hypertension-specific version (MLHF-PH) to a larger population of PAH patients.

METHODS

Ninety-three consecutive outpatients with PAH completed the MLHF-PH. Scores were assessed for correlations with demographics, symptoms, hemodynamics and treatments.

RESULTS

Patients with PAH had significantly impaired HRQOL as assessed by the disease-specific MLHF-PH. Each physical and emotional component, as well as total scores on the MLHF-PH indicated severely depressed HRQOL. As compared to other diagnoses, PAH associated with scleroderma had the worst HRQOL. Patients with WHO functional Class II symptoms reported better HRQOL than Class III patients. Fatigue, weakness and abdominal discomfort were each associated with more severely depressed HRQOL, as was current epoprostenol use. With the sole exception of the right atrial pressure, hemodynamic measurements did not correlate with HRQOL scores. Simultaneous evaluation of HRQOL with a non-disease-specific questionnaire (SF-36) revealed a similarly impaired status, although identified fewer associations with patient-specific factors.

CONCLUSION

Severely impaired HRQOL is present in this population of patients with PAH evaluated with a disease-specific questionnaire. The availability of a pulmonary hypertension-specific HRQOL questionnaire may enable further targeted investigations of factors that might improve outcomes.

Human herpesvirus-8 infection of primary pulmonary microvascular endothelial cells

Human herpesvirus-8 (HHV-8) is the causative agent of Kaposi's sarcoma and is associated with the angioproliferative disorders primary effusion lymphoma and multicentric Castleman's disease. Evidence of HHV-8 infection within the pulmonary vasculature of patients with idiopathic pulmonary arterial hypertension (IPAH) has been described. We hypothesize that HHV-8 infection of pulmonary microvascular endothelial cells results in an apoptotic-resistant phenotype characteristic of severe pulmonary arterial hypertension. Our objective was to investigate the ability of HHV-8 to infect human pulmonary microvascular endothelial cells in vitro and characterize the phenotypic effect of this infection. Human pulmonary microvascular endothelial cells were exposed to HHV-8 using two methods (direct virus and co-culture technique). The presence of lytic and latent infection was confirmed. Changes in endothelial cell gene and protein expression and effects on cellular apoptosis were measured. HHV-8 can both lytically and latently infect primary human pulmonary microvascular endothelial cells in vitro. HHV-8 infection results in significant changes in gene expression, including alterations of pathways important to cellular apoptosis. HHV-8 infection also alters expression of genes integral to the bone morphogenic protein pathway, including down-regulation of bone morphogenic protein-4. Other genes previously implicated in the development of PAH are affected by HHV-8 infection, and cells infected with HHV-8 are resistant to apoptosis.

Combination therapy and new types of agents for pulmonary arterial hypertension

This review assesses the available evidence supporting the use of drug combinations for the management of the various forms of pulmonary arterial hypertension (PAH). Ongoing and forthcoming randomized trials evaluating this strategy are also highlighted. Furthermore, new types of agents to treat PAH in the future are explored.

Epidemiology of Pulmonary Arterial Hypertension

Progress in understanding the basic biology and the development of new therapies for pulmonary arterial hypertension have led to improvements in survival. This article reviews clinically important changes in the classification of the pulmonary hypertensive diseases, as well as the epidemiology of various forms of pulmonary hypertension. The risk factors for the development of pulmonary arterial hypertension, prognostic markers, and the effects of current therapies on survival are discussed.

Favorable Effects of Inhaled Treprostinil in Severe Pulmonary Hypertension

OBJECTIVES

This study sought to investigate the effects of inhaled treprostinil on pulmonary hemodynamics and gas exchange in severe pulmonary hypertension.

BACKGROUND

Inhaled iloprost therapy has a proven clinical efficacy in pulmonary arterial hypertension, but this therapy necessitates 6 to 9 inhalation sessions per day. Treprostinil has a longer plasma half-life and might provide favorable properties when applied by inhalation.

METHODS

Three different studies were conducted on a total of 123 patients by means of right heart catheterization: 1) a randomized crossover-design study (44 patients), 2) a dose escalation study (31 patients), and 3) a study of reduction of inhalation time while keeping the dose fixed (48 patients). The primary end point was the change in pulmonary vascular resistance (PVR).

RESULTS

The mean pulmonary arterial pressure of the enrolled patients was approximately 50 mm Hg in all studies. In study 1, both treprostinil and iloprost at an inhaled dose of 7.5 mug displayed a comparable PVR decrease, with a significantly different time course (p < 0.001), treprostinil showing a more sustained effect on PVR (p < 0.0001) and fewer systemic side effects. In study 2, effects of inhalation were observed for 3 h. A near-maximal acute PVR decrease was observed at 30 mug treprostinil. In study 3, treprostinil was inhaled at increasing concentrations with a pulsed ultrasonic nebulizer, mimicking a metered dose inhaler. A dose of 15 mug treprostinil was inhaled with 18, 9, 3, 2 pulses, or 1 pulse, each mode achieving comparable, sustained pulmonary vasodilation without significant side effects.

CONCLUSIONS

Inhaled treprostinil exerts sustained pulmonary vasodilation with excellent tolerability at relatively low doses and may be inhaled in a few breaths.

Long-term Results After Addition of Sildenafil in Idiopathic PAH Patients on Bosentan

Idiopathic pulmonary arterial hypertension is a disease involving small muscular pulmonary arteries and arterioles. Treatment with prostacyclin analogs and endothelin receptor antagonists is the cornerstone of therapy in these patients. Recent evidence suggests that phosphodiesterase-5 inhibitors such as sildenafil may improve functional capacity and hemodynamics in patients with pulmonary arterial hypertension. Despite these advances, pulmonary arterial hypertension remains a deadly and progressive disease and it has been suggested that combination therapy aimed at multiple targets may produce a greater improvement while minimizing adverse effects. We report three patients who declined after initial improvement on bosentan and subsequently showed an improvement in their functional capacity and brain natriuretic peptide (BNP) with the addition of sildenafil. This benefit has been sustained over a mean follow-up period of 19 (range 12-24) months.

Potential application for mesenchymal stem cells in the treatment of cardiovascular diseases

Stem cells isolated from various sources have been shown to vary in their differentiation capacity or pluripotentiality. Two groups of stem cells, embryonic and adult stem cells, may be capable of differentiating into any desired tissue or cell type, which offers hope for the development of therapeutic applications for a large number of disorders. However, major limitations with the use of embryonic stem cells for human disease have led researchers to focus on adult stem cells as therapeutic agents. Investigators have begun to examine postnatal sources of pluripotent stem cells, such as bone marrow stroma or adipose tissue, as sources of mesenchymal stem cells. The following review focuses on recent research on the use of stem cells for the treatment of cardiovascular and pulmonary diseases and the future application of mesenchymal stem cells for the treatment of a variety of cardiovascular disorders.

Health-related quality of life in patients with pulmonary arterial hypertension

Background

Improved outcomes with expanding treatment options for patients with pulmonary arterial hypertension present the opportunity to consider additional end-points in approaching therapy, including factors that influence health-related quality of life. However, comparatively little is known about health-related quality of life and its determinants in patients with pulmonary arterial hypertension.

Methods

Health-related quality of life was evaluated in a cross sectional study of 155 outpatients with pulmonary arterial hypertension using generic and respiratory-disease specific measurement tools. Most patients had either World Health Organization functional Class II or III symptoms. Demographic, hemodynamic and treatment variables were assessed for association with health-related quality of life scores.

Results

Patients with pulmonary arterial hypertension suffered severe impairments in both physical and emotional domains of health-related quality of life. Patients with idiopathic ("primary") pulmonary arterial hypertension had the best, and those with systemic sclerosis the worst health-related quality of life. Greater six-minute walk distance correlated with better health-related quality of life scores, as did functional Class II versus Class III symptoms. Hemodynamic measurements, however, did not correlate with health-related quality of life scores. No differences in health-related quality of life were found between patients who were being treated with calcium channel antagonists, bosentan or continuously infused epoprostenol at the time of quality of life assessment.

Conclusion

Health-related quality of life is severely impaired in patients with pulmonary arterial hypertension and is associated with measures of functional status. Specific associations with impaired health-related quality of life suggest potential areas for targeted intervention.