Updated clinical classification of pulmonary hypertension

Human γ-herpesviruses Epstein-Barr virus and human herpesvirus-8 are not detected in the lungs of patients with severe pulmonary arterial hypertension

BACKGROUND

In susceptible individuals, multiple events may trigger pulmonary vascular remodeling and pulmonary arterial hypertension (PAH). Human herpesvirus-8 (HHV-8), a γ-herpesvirus homologous with Epstein-Barr virus (EBV), was suggested to act as a "second hit" in the development of PAH in susceptible patients. Although there is indirect evidence from in vitro and animal studies in favor of a link between γ-herpesviruses and the pathophysiology of PAH, results remain controversial. Therefore, we investigated the presence of EBV and HHV-8 in the lungs of patients with PAH.

METHODS

Thirty-four lungs explanted from French patients with end-stage PAH (mean age, 38 ± 14 years; 19 women) were studied. Tissue samples were incorporated into tissue microarrays. Normal lung tissues served as negative controls. Kaposi sarcoma tissue served as a positive control for HHV-8, and EBV-associated lymphoma served as a positive control for EBV. The presence of HHV-8 was investigated with immunohistochemistry and polymerase chain reaction. The presence of EBV was investigated with immunohistochemistry and in situ hybridization.

RESULTS

For HHV-8, none of PAH lung samples showed a "stippling" nuclear pattern classically observed in HHV-8-positive Kaposi sarcoma lesions. When studied by polymerase chain reaction, all cases remained negative. For EBV, none of the PAH lung samples showed positive staining, whatever the technique applied.

CONCLUSIONS

HHV-8 and EBV cannot be detected in the lungs of patients with end-stage PAH. The role of these γ-herpesviruses in the pathophysiology of PAH is, therefore, unlikely.

Pulmonary hypertension in systemic sclerosis

OBJECTIVES

To discuss the clinical subtypes, pathogenesis, pathology, diagnostic evaluation, treatment options, and prognosis of pulmonary hypertension in systemic sclerosis (SSc-PH) and highlight its fundamental differences from idiopathic pulmonary arterial hypertension (IPAH).

METHODS

A Medline search for articles published between January 1969 and June 2010 was conducted using the following keywords: scleroderma, systemic sclerosis, pulmonary hypertension, pulmonary arterial hypertension, pulmonary veno-occlusive disease, pathogenesis, pathology, investigation, treatment, and prognosis. The essential differences from IPAH in pathogenesis and histopathologic findings were highlighted and the limitations of some of the investigations used were emphasized. The differences in response to currently accepted therapy and prognosis were also reviewed.

RESULTS

In scleroderma, pulmonary hypertension can be present in isolation or along with interstitial lung disease and left heart disease. In SSc-PH, the unique histopathologic findings in the lungs include intimal fibrosis, absence of plexiform lesions, and a high prevalence of pulmonary veno-occlusive disease-like lesions. Both "6-minute walk test" and NT-proBNP have their limitations in the evaluation of SSc-PH. For treatment, calcium channel blockers are ineffective and anticoagulation should be used with caution. Currently approved therapies are not as effective and prognosis is much worse in SSc-PH compared with IPAH.

CONCLUSIONS

SSc-PH is a complex condition with poorer response to therapy and worse outcome compared with that of IPAH. Recent findings have shed some light about the pathophysiology and pathogenesis of SSc-PH. Further research in this area is warranted to better understand the complex pathogenesis and devise better therapeutic strategies.

New therapies for pulmonary arterial hypertension: an update on current bench to bedside translation

IMPORTANCE OF THE FIELD

Treatments of pulmonary arterial hypertension (PAH) that have so far proven efficacious are all based on the restoration of endothelium control of pulmonary vascular tone and structure, by administration of prostacyclins, endothelin receptor antagonists and phosphodiesterase-5 inhibitors. However, results remain unsatisfactory, with persistent high mortality, insufficient clinical improvement and no convincing report of any reversal of the disease process.

AREAS COVERED IN THIS REVIEW

New antiproliferative approaches that aim to actively limit pulmonary vascular remodeling are being sought. Several such treatments have shown promise in experimental models and in preliminary clinical studies. Noteworthy among these are dichloroacetate, survivin antagonists, nuclear factor of activated T-cell inhibitors, PPAR-gamma agonists, tyrosine kinase inhibitors, Rho-kinase inhibitors, statins, vasoactive intestinal peptide, soluble guanylate cyclase stimulators/activators, adrenomedullin, elastase inhibitors, serotonin reuptake inhibitors, anti-inflammatory agents, and bone marrow-derived progenitor cells.

WHAT THE READER WILL GAIN

Update on various strategies targeting proliferative, inflammatory and regenerating processes currently under evaluation in patients with PAH.

TAKE HOME MESSAGE

In spite of favorable results in experimental models, none of these strategies has achieved the ultimate goal of curing PAH. Further developments will depend on progress made in our pathobiological understanding of the disease and carefully designed randomized, controlled trials.

Pulmonary hypertension in women

Female predominance in pulmonary arterial hypertension (PAH) has been known for several decades and recent interest in the effects of sex hormones on the development of disease has substantially increased our understanding of this epidemiologic observation. Basic science data suggest a beneficial effect of estrogens in the pulmonary vasculature both acutely and chronically, which seems to contradict the known predilection in women. Recent human and rodent data have suggested that altered levels of estrogen, differential signaling and altered metabolism of estrogens in PAH may underlie the gender difference in this disease. Studies of the effects of sex hormones on the right ventricle in animal and human disease will further aid in understanding gender differences in PAH. This article focuses on the effects of sex hormones on the pulmonary vasculature and right ventricle on both a basic science and translational level.

Metabolic and hormonal derangements in pulmonary hypertension: from mouse to man

Pulmonary arterial hypertension (PAH) is a complex disease with significant morbidity and mortality. Recent animal and human studies have highlighted abnormalities in regulation and metabolism of insulin, sex hormones, adipokines and lipids that may play a role in disease development. Mouse studies suggest features of the metabolic syndrome (MS) including insulin resistance, deficiencies in peroxisome proliferator-activated receptor γ and apolipoprotein E, and low adiponectin are linked to development of PAH. In humans, insulin resistance, the MS and low levels of high-density lipoprotein have been associated with PAH. In addition, abnormal metabolism of oestrogens has been demonstrated in human and animal models of PAH, suggesting an important relationship of sex hormones and pulmonary vascular disease. Improved understanding of how metabolic and hormonal derangements relate to development and progression of pulmonary hypertension may lead to better disease therapies and understanding of potential risk factors. This review will focus on the animal and human data regarding metabolic and sex hormone derangements in PAH.

The adult patient with eisenmenger syndrome: a medical update after dana point part I: epidemiology, clinical aspects and diagnostic options

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 epidemiology, clinical aspects and specific diagnostic options.

Autocrine fibroblast growth factor-2 signaling contributes to altered endothelial phenotype in pulmonary hypertension

Pulmonary vascular remodeling is key to the pathogenesis of idiopathic pulmonary arterial hypertension (IPAH). We recently reported that fibroblast growth factor (FGF)2 is markedly overproduced by pulmonary endothelial cells (P-ECs) in IPAH and contributes significantly to smooth muscle hyperplasia and disease progression. Excessive FGF2 expression in malignancy exerts pathologic effects on tumor cells by paracrine and autocrine mechanisms.We hypothesized that FGF2 overproduction contributes in an autocrine manner to the abnormal phenotype of P-ECs, characteristic of IPAH. In distal pulmonary arteries (PAs) of patients with IPAH, we found increased numbers of proliferating ECs and decreased numbers of apoptotic ECs, accompanied with stronger immunoreactivity for the antiapoptotic molecules, B-cell lymphoma (BCL)2, and BCL extra long (BCL-xL) compared with PAs from control patients. These in situ observations were replicated in vitro, with cultured P-ECs from patients IPAH exhibiting increased proliferation and diminished sensitivity to apoptotic induction with marked increases in the antiapoptotic factors BCL2 and BCL-xL and levels of phosphorylated extracellular signal-regulated (ERK)1/2 compared with control P-ECs. IPAH P-ECs also exhibited increased FGF2 expression and an accentuated proliferative and survival response to conditioned P-EC media or exogenous FGF2 treatment. Decreasing FGF2 signaling by RNA interference normalized sensitivity to apoptosis and proliferative potential in the IPAH P-ECs. Our findings suggest that excessive autocrine release of endothelial-derived FGF2 in IPAH contributes to the acquisition and maintenance of an abnormal EC phenotype, enhancing proliferation through constitutive activation of ERK1/2 and decreasing apoptosis by increasing BCL2 and BCL-xL.

Autophagic protein LC3B confers resistance against hypoxia-induced pulmonary hypertension

RATIONALE

Pulmonary hypertension (PH) is a progressive disease with unclear etiology. The significance of autophagy in PH remains unknown.

OBJECTIVES

To determine the mechanisms by which autophagic proteins regulate tissue responses during PH.

METHODS

Lungs from patients with PH, lungs from mice exposed to chronic hypoxia, and human pulmonary vascular cells were examined for autophagy using electron microscopy and Western analysis. Mice deficient in microtubule-associated protein-1 light chain-3B (LC3B(-/-)), or early growth response-1 (Egr-1(-/-)), were evaluated for vascular morphology and hemodynamics.

MEASUREMENTS AND MAIN RESULTS

Human PH lungs displayed elevated lipid-conjugated LC3B, and autophagosomes relative to normal lungs. These autophagic markers increased in hypoxic mice, and in human pulmonary vascular cells exposed to hypoxia. Egr-1, which regulates LC3B expression, was elevated in PH, and increased by hypoxia in vivo and in vitro. LC3B(-/-) or Egr-1(-/-), but not Beclin 1(+/-), mice displayed exaggerated PH during hypoxia. In vitro, LC3B knockdown increased reactive oxygen species production, hypoxia-inducible factor-1α stabilization, and hypoxic cell proliferation. LC3B and Egr-1 localized to caveolae, associated with caveolin-1, and trafficked to the cytosol during hypoxia.

CONCLUSIONS

The results demonstrate elevated LC3B in the lungs of humans with PH, and of mice with hypoxic PH. The increased susceptibility of LC3B(-/-) and Egr-1(-/-) mice to hypoxia-induced PH and increased hypoxic proliferation of LC3B knockdown cells suggest adaptive functions of these proteins during hypoxic vascular remodeling. The results suggest that autophagic protein LC3B exerts a protective function during the pathogenesis of PH, through the regulation of hypoxic cell proliferation.

Survival in schistosomiasis-associated pulmonary arterial hypertension

OBJECTIVES

The objective of this study was to evaluate the natural history of untreated schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH) patients as compared to idiopathic pulmonary arterial hypertension (IPAH) with respect to hemodynamics recorded at presentation and 36 months survival.

BACKGROUND

Schistosomiasis (Sch) is one of the most prevalent chronic infectious diseases in the world. Nevertheless data regarding one of its most severe clinical complications, pulmonary arterial hypertension (PAH), is scarce.

METHODS

We retrospectively analyzed case notes of all consecutive patients diagnosed of Sch-PAH and IPAH referred to the Heart Institute in São Paulo, Brazil, between 2004 and 2008. None of the Sch-PAH received PAH specific treatment whereas all IPAH patients did.

RESULTS

Sch-PH patients (n = 54) had less severe pulmonary hypertension as evidenced by lower levels of pulmonary vascular resistance (11.3 +/- 11.3 W vs. 16.7 +/- 10.6 W; p = 0.002) and mean pulmonary artery pressure (56.7 +/- 18.7 mm Hg vs. 64.6 +/- 17.4 mm Hg; p = 0.01) and higher cardiac output (4.62 +/- 1.5 l/min vs. 3.87 +/- 1.5 l/min; p = 0.009) at presentation than IPAH patients (n = 95). None of the Sch-PAH patients demonstrated a positive response to acute vasodilator testing, whereas 16.2% of IPAH patients did (p = 0.015). Survival rates at 1, 2, and 3 years were 95.1%, 95.1%, and 85.9% and 95%, 86%, and 82%, for Sch-PAH and IPAH, respectively (p = 0.49). Both groups had a higher survival rate when compared to IPAH survival as estimated by the NIH equation (71%, 61%, and 52%, respectively).

CONCLUSIONS

Sch-PAH has a more benign clinical course than IPAH despite a lack of demonstrable acute vasoreactivity at hemodynamic evaluation.

Severe β-thalassemia intermedia in a compound heterozygous patient for the -30 (T>A) β(+)-thalassemia mutation and the δ(0)β(+)-Senegalese deletion

We report the clinical and biochemical studies of a patient initially diagnosed with β-thalassemia intermedia (β-TI), which, with age, has progressed to a severe transfusion-dependent form. The patient is a compound heterozygote for the -30 (T>A) β(+)-thalassemia (β(+)-thal) mutation and the rare δ(0)β(+)-Senegalese deletion. Many complications are reported as well as the specific treatments initiated.

Phosphodiesterase-5 inhibitors in management of pulmonary hypertension: safety, tolerability, and efficacy

Pulmonary arterial hypertension (PAH) is a progressive disease that causes severe disability and has no cure. Over the past 20 years, a variety of treatment options have evolved for the management of PAH. With an expanded therapeutic armamentarium come more complex decisions regarding treatment options. Agent selection depends upon several factors including efficacy, side effect profile, and cost, as well as convenience of administration. We have undertaken a review of phosphodiesterase-5 (PDE-5) inhibitors in PAH with a focus on efficacy and safety. A literature search was conducted using the Medline and Cochrane Central Register of Controlled Trials databases (1966-February 2010) for relevant randomized clinical studies. Overall, 10 studies met our inclusion criteria. Sildenafil was the most commonly studied agent, followed by tadalafil and vardenafil. Most trials found that the PDE-5 inhibitors significantly improved exercise capacity and lowered pulmonary pressures. However, there were conflicting results regarding these agents' impact on improving cardiac function and functional class. Overall, these medications were effective and well tolerated with a relatively benign side effect profile. The PDE-5 inhibitors are an important option in treating PAH. While most of the published clinical data involved sildenafil, the other PDE-5 inhibitors show promise as well. Further studies are needed to determine the optimal doses of this therapeutic drug class, as well as its effects as adjunctive therapy with other agents in PAH.

[A critical analysis of survival in idiopathic pulmonary arterial hypertension]

Idiopathic pulmonary arterial hypertension (PAH) is a rare disease characterized by a progressive increase in pulmonary vascular resistance leading to right heart failure and death. Recent survival data in PAH cohorts have been biased by the inclusion of prevalent patients ("survivors") who have a better prognosis than incident cases. Nevertheless, a critical analysis of recent multicenter incident cohorts has shown survival improvements in the current management era, thanks to better management. However idiopathic PAH remains a severe disease with a poor prognosis. Current recommendations emphasize the necessity of an aggressive goal-oriented management of symptomatic PAH. Modern survival figures also highlight the relevance of lung transplantation in eligible PAH patients refractory to current best standard of care.

Key role of the RhoA/Rho kinase system in pulmonary hypertension

Pulmonary hypertension (PH) is a general term comprising a spectrum of pulmonary hypertensive disorders which have in common an elevation of mean pulmonary arterial pressure (mPAP). The prototypical form of the disease, termed pulmonary arterial hypertension (PAH), is a rare but lethal syndrome with a complex aetiology characterised by increased pulmonary vascular resistance (PVR) and progressive elevation of mPAP; patients generally die from heart failure. Current therapies are inadequate and median survival is less than three years. PH due to chronic hypoxia (CH) is a condition separate from PAH and is strongly associated with chronic obstructive pulmonary disease (COPD). An early event in the pathogenesis of this form of PH is hypoxic pulmonary vasoconstriction (HPV), an acute homeostatic process that maintains the ventilation-perfusion ratio during alveolar hypoxia. The mechanisms underlying HPV remain controversial, but RhoA/Rho kinase (ROK)-mediated Ca²+-sensitisation is considered important. Increasing evidence also implicates RhoA/ROK in PASMC proliferation, inflammatory cell recruitment and the regulation of cell motility, all of which are involved in the pulmonary vascular remodelling occurring in all forms of PH. ROK is therefore a potential therapeutic target in treating PH of various aetiologies. Here, we examine current concepts regarding the aetiology of PAH and also PH due to CH, focusing on the contribution that RhoA/ROK-mediated processes may make to their development and on ROK inhibitors as potential therapies.

PPARgamma as a potential therapeutic target in pulmonary hypertension

Pulmonary hypertension (PH) is a progressive disorder of the pulmonary circulation associated with significant morbidity and mortality. The pathobiology of PH involves a complex series of derangements causing endothelial dysfunction, vasoconstriction and abnormal proliferation of pulmonary vascular wall cells that lead to increases in pulmonary vascular resistance and pressure. Recent evidence indicates that the ligand-activated transcription factor, peroxisome proliferator-activated receptor gamma (PPARgamma) can have a favorable impact on a variety of pathways involved in the pathogenesis of PH. This review summarizes PPARgamma biology and the emerging evidence that therapies designed to activate this receptor may provide novel approaches to the treatment of PH. Mediators of PH that are regulated by PPARgamma are reviewed to provide insights into potential mechanisms underlying therapeutic effects of PPARgamma ligands in PH.

Adult patients with pulmonary arterial hypertension due to congenital heart disease: a review on advanced medical treatment with bosentan

Pulmonary arterial hypertension (PAH) is a progressive disease with poor survival outcome. PAH is classified by the 2009 updated clinical classification of pulmonary hypertension and a major subgroup is PAH due to congenital heart disease (CHD) with systemic-to-pulmonary shunt. CHD-PAH is a result of systemic-to-pulmonary shunting and chronic increased flow that ultimately results in adaptations of pulmonary vasculature and endothelial dysfunction. The advanced stage is called Eisenmenger syndrome which forms a small percentage (1%) of all CHD patients. Therapies targeted on PAH symptoms are called primary therapy for PAH, but most CHD-PAH patients progress to advanced therapy which is directed at the PAH itself. In CHD-PAH, advanced therapies are extensively investigated for all three major pathways: endothelin-1 receptor antagonists such as bosentan, prostanoids such as epoprostenol and phosphodiesterase 5 inhibitors such as sildenafil. Endpoints in most trials were catheterization hemodynamics, World Health Organization functional class, six-minute walking distance and patient-focused outcomes, based on quality of life questionnaires and Borg dyspnea index. The BREATHE-5 and EARLY study were two important randomized controlled trials showing efficacy of bosentan at short follow-up. Moreover in patients with Eisenmenger syndrome, one recent survival retrospective study with majority of patients on bosentan showed strong survival benefit over conservative therapy. A diversity of prospective cohort and retrospective studies were performed but all with limited data, due to small numbers and heterogeneity of underlying CHD diagnoses. Further larger studies are needed to determine optimal treatment for adults with CHD-PAH. This review focuses on bosentan in CHD-PAH. In particular, we discuss outcome of various clinical trials and compare efficacy and safety of bosentan to other advanced therapies.

Idiopathic pulmonary arterial hypertension

Despite improved understanding of the pathobiology of pulmonary arterial hypertension (PAH), it remains a severe and progressive disease, usually culminating in right heart failure, significant morbidity and early mortality. Over the last decade, some major advances have led to substantial improvements in the management of PAH. Much of this progress was pioneered by work in animal models. Although none of the current animal models of pulmonary hypertension (PH) completely recapitulate the human disease, they do provide insight into the cellular pathways contributing to its development and progression. There is hope that future work in model organisms will help to define its underlying cause(s), identify risk factors and lead to better treatment of the currently irreversible damage that results in the lungs of afflicted patients. However, the difficulty in defining the etiology of idiopathic PAH (IPAH, previously known as primary pulmonary hypertension) makes this subset of the disease particularly difficult to model. Although there are some valuable existing models that are relevant for IPAH research, the area would value from the development of new models that more closely mimic the clinical pathophysiology of IPAH.

Plasma levels of high-density lipoprotein cholesterol and outcomes in pulmonary arterial hypertension

RATIONALE

High-density lipoprotein cholesterol (HDL-C) promotes healthy vascular function, and it is decreased in insulin resistance. Insulin resistance predisposes to pulmonary vascular disease.

OBJECTIVES

We hypothesized that HDL-C is associated with clinical outcomes in pulmonary arterial hypertension (PAH).

METHODS

Plasma HDL-C concentrations were measured in 69 patients with PAH (age, 46.7 +/- 12.9 yr; female, 90%) and 229 control subjects (age, 57 +/- 13 yr; female, 48%). Clinical outcomes of interest included hospitalization for PAH, lung transplantation, and all-cause mortality. Survival and time to clinical worsening curves were derived by the Kaplan-Meier method. Cox regression modeling of outcome versus HDL-C with individual covariate adjustments was performed.

MEASUREMENT AND MAIN RESULTS

HDL-C was low in subjects with PAH compared with control subjects (median, interquartile range: PAH: 36, 29-40 mg/dl; control subjects: 49, 40-60 mg/dl; P < 0.001). An HDL-C level of 35 mg/dl discriminated survivors from nonsurvivors, with a sensitivity of 100% and specificity of 60%. After a median follow-up of 592 days, high HDL-C was associated with decreased mortality (hazard ratio for every 5-mg/dl increase in HDL-C, 0.643; 95% confidence interval, 0.504-0.822; P = 0.001) and less clinical worsening (hazard ratio for every 5-mg/dl increase in HDL-C, 0.798; 95% confidence interval, 0.663-0.960; P = 0.02). HDL-C remained a significant predictor of survival after adjusting for cardiovascular risk factors, C-reactive protein, indices of insulin resistance, and severity of PAH (all P < 0.05).

CONCLUSIONS

Low plasma HDL-C is associated with higher mortality and clinical worsening in PAH. This association does not appear to be explained by underlying cardiovascular risk factors, insulin resistance, or the severity of PAH.

Current diagnostic and prognostic assessment of pulmonary Hypertension

Recently, our view of pulmonary hypertension has been changed by the significant progress made in understanding the pathobiology, epidemiology and prognosis of the disease. The increasing number of different conditions now associated with pulmonary hypertension and the appearance of new diagnostic techniques have led to a need for a systematic diagnostic approach and a new disease classification. This review article presents an update on developments in the epidemiology and pathobiology of pulmonary hypertension, on changes in the clinical classification of the disease, and on alterations in the diagnostic algorithm. In addition, it contains detailed descriptions of the treatment recommended for patients in whom an elevated systolic pulmonary pressure is discovered on echocardiography, of the differential diagnosis of pulmonary arterial hypertension and pulmonary hypertension associated with left heart disease, and of multifactorial approaches to determining prognosis, which are three of the most actively debated topics today. Finally, a care program for patients with pulmonary arterial hypertension is proposed.

Management of dyspnea in advanced pulmonary arterial hypertension

PURPOSE OF REVIEW

Pulmonary hypertension leads to progressive increase in pulmonary vascular resistance, heart failure, and death. Pulmonary arterial hypertension (PAH) is a subset of pulmonary hypertension affecting small pulmonary arteries and not associated with underlying heart or lung disease. Dyspnea and exercise intolerance are hallmarks of PAH and are used to monitor disease progression. This review focuses on recent advances in the pathophysiology and treatment of dyspnea in PAH.

RECENT FINDINGS

The etiological classification of pulmonary hypertension and World Health Organization functional class clinical classification, as used to guide management, have recently been revised. Dyspnea and PAH disease progression are best assessed by cardiopulmonary exercise testing and the six-minute walk test. Understanding of the molecular pathogenesis of PAH has led to new classes of treatments, including prostacyclin analogues, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors. Prostanoids have the longest track record in treatment of PAH but a short half-life and cumbersome delivery systems limit their utility. More convenient endothelin receptor antagonists are becoming mainstream in PAH management. Phosphodiesterase-5 inhibitors improve exercise capacity and quality of life, although long-term outcome data are pending. Combination therapy with different medication classes appears promising for progressive disease.

SUMMARY

Establishing the cause and clinical severity of pulmonary hypertension is critical for management. The pathophysiology of dyspnea in PAH is complex and related to pulmonary vascular resistance. Although disease-specific treatments are now available, a cure for PAH remains elusive and trials of combination treatments to improve symptoms and outcomes are ongoing.

Safety and efficacy of ambrisentan for the treatment of portopulmonary hypertension

BACKGROUND

Ambrisentan is a selective endothelin-receptor antagonist that is approved by the US Food and Drug Administration for the treatment of pulmonary arterial hypertension. We describe hemodynamic responses and clinical outcomes of patients with portopulmonary hypertension (POPH) treated with ambrisentan.

METHODS

In this observational study, we prospectively identified and followed consecutive adult patients with POPH who received monotherapy with ambrisentan ≤ 10 mg daily from January 2007 until December 2009. Liver enzymes were assessed monthly. Pulmonary hemodynamic responses were assessed using echocardiograms and right-sided heart catheterizations.

RESULTS

We identified 13 patients (seven men) with POPH and began monotherapy with ambrisentan. The median age was 57 (interquartile range [IQR], 52-60). Patients were followed for a median of 613 days (IQR, 385-1,011). The median model for end-stage liver disease score was 10 (IQR, 8.5-15); eight patients had Child-Turcotte-Pugh A classification. Median time on ambrisentan therapy was 390 days (IQR, 363-611). Two patients died, one of advanced hepatocellular carcinoma and one of septic shock following pneumonia. The mean pulmonary artery pressure decreased from a baseline median of 58 mm Hg (IQR, 37-63) to 41 mm Hg (IQR, 27-48) (P = .004). The pulmonary vascular resistance median was reduced from 445 dynes/s/cm(5) (IQR, 329-834) to 174 dynes/s/cm(5) (IQR, 121-361) (P = .008). There was no difference in the longitudinal analysis of liver function tests (aspartate aminotransferase, alanine aminotransferase, total bilirubin, and international normalized ratio) after 12 months of therapy. One patient underwent successful liver transplantation and normalized pulmonary hemodynamic responses after transplantation.

CONCLUSIONS

In this small cohort of patients with moderate to severe pulmonary hypertension in the setting of POPH, we have shown that ambrisentan monotherapy can significantly improve pulmonary hemodynamic responses without adverse effect on hepatic function.

Worldwide physician education and training in pulmonary hypertension: pulmonary vascular disease: the global perspective

Pulmonary hypertension (PH) affects > 25 million individuals worldwide and causes premature disability and death for many. The diagnosis and treatment of PH have advanced dramatically through the development of a clearly defined diagnostic classification, an evidence-based treatment algorithm for adults with pulmonary arterial hypertension using life-saving medications, and life-saving surgical procedures. However, worldwide education and training of physicians has lagged behind advances in the management of PH. Expertise in the diagnosis and management of PH is uncommon, even though physicians receive training on PH during their graduate and postgraduate education. Advances in worldwide physician education and training in PH will require substantial organization and work. Organizations working in this field will need to work collaboratively to maximize funding for education and to optimize the achievement of educational goals. Political, economic, and cultural barriers must be identified and overcome as part of any strategic plan. Global education should include training objectives for generalist, non-PH specialist, and PH specialist physicians.

The right heart and pulmonary circulation (III). The pulmonary circulation in heart failure

Pulmonary hypertension due to left heart disease is a pathophysiological and hemodynamic state which is present in a wide range of clinical conditions that affect left heart structures. Although the pulmonary circulation has traditionally received little attention, it is reasonable to say that today it is a fundamental part of cardiological evaluation. In patients with heart failure, the most important clinical factors are the presence of pulmonary hypertension and right ventricular function. These factors are also essential for determining prognosis and must be taken into account when making some of the most important therapeutic decisions. The pathophysiological process starts passively but later transforms into a reactive process. This latter process, in turn, has one component that can be reversed with vasodilators and another component that is fixed, in which the underlying mechanism is congestive vasculopathy (i.e. essentially medial hypertrophy and pulmonary arterial intimal fibrosis). Currently no specific therapy is available for this type of pulmonary hypertension and treatment is the same as for heart failure itself. The drugs that have been shown to be effective in pulmonary arterial hypertension have generally had a neutral effect in clinical trials. Nevertheless, we are involved in the clinical development of a number of groups of pharmacological compounds that will enable us to make progress in the near future.

Combined pulmonary fibrosis and emphysema alters physiology but has similar mortality to pulmonary fibrosis without emphysema

Studies have described individuals with combined pulmonary fibrosis and emphysema (CPFE), with preserved lung volumes, significant reductions in gas exchange, and high prevalence of pulmonary hypertension. While physiologic changes in CPFE are well documented, there is little mortality data in the CPFE population compared to appropriate controls. A study was performed to determine the features and outcomes of a group of individuals with imaging and/or pathologic evidence of CPFE to determine if individuals with combined pulmonary fibrosis and emphysema have different features and survival than individuals with pulmonary fibrosis alone. We conducted a retrospective study at a Veterans Affairs Medical Center. Included in the study were individuals hospitalized over a 5-year period who were given a clinical diagnosis of pulmonary fibrosis. Individuals with confirmed imaging or pathologic evidence of pulmonary fibrosis were divided into a study group with concomitant emphysema (CPFE group, n = 20) and a control group without emphysema (isolated pulmonary fibrosis (PF) group, n = 24). The CPFE group, all current or former cigarette smokers, had significantly larger lung volumes, more expiratory airflow obstruction, and worse gas exchange than the isolated pulmonary fibrosis group. Mortality did not differ between the groups. Combined pulmonary fibrosis and emphysema results in unique physiologic features but no difference in survival compared with a group with pulmonary fibrosis alone.

PPARgamma activation: a potential treatment for pulmonary hypertension

The pathobiology of pulmonary arterial hypertension (PAH) involves multiple molecular pathways and environmental modifiers and is characterized by progressive obliteration of pulmonary arterioles, leading to increased pulmonary vascular resistance (PVR), right heart failure, and death in approximately 40 to 60% of patients 5 years after diagnosis. There is emerging evidence that many key genes involved in PAH development are targets of the insulin-sensitizing transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), and that pharmacological PPARgamma activation would lead to their beneficial induction or repression and subsequent antiproliferative, anti-inflammatory, proapoptotic, and direct vasodilatory effects in the vasculature. PPARgamma acts downstream of bone morphogenetic protein receptor II (BMP-RII), which is the cell surface receptor that is mutated or dysfunctional in many forms of PAH. Because our recent clinical observations indicate that insulin resistance may be an environmental risk factor or disease modifier ("second hit"), we suggest that PPARgamma-activating agents might be beneficial in the future treatment of both insulin-resistant and insulin-sensitive PAH patients with or without BMP-RII mutations.

Echocardiography may help detect pulmonary vasculopathy in the early stages of pulmonary artery hypertension associated with systemic sclerosis

BACKGROUND

Pulmonary arterial hypertension (PAH) in patients with systemic sclerosis is associated with a poor prognosis, but this can be improved by early disease detection. Abnormal pulmonary and cardiac function can be detected early by means of echocardiography, whereas right heart catheterization is usually performed later.

OBJECTIVES

The purpose of this prospective study was to detect early the presence of pulmonary artery vasculopathy in patients with verified systemic sclerosis without significant pulmonary fibrosis, normal lung volumes and a mildly reduced lung diffusion capacity of carbon monoxide (DLCO).

METHODS

Nineteen consecutive female NYHA class I-II patients with scleroderma and a PAPs of < 35 mm/Hg measured by echocardiography, were enrolled between September 2007 and September 2009. They had a mean age of 51 +/- 13 years, body mass index of 25 +/- 5 kg/m2). They all underwent complete Doppler echocardiography, CPET, a pulmonary ventilation test (carbon monoxide lung diffusion, DLCO), HRCT. To investigate PAH by means of complete resting Doppler echocardiography estimates of systolic pulmonary artery pressure (PAPs) derived from tr icuspid regurgitation, mean PAP derived from pulmonary regurgitation, pulmonary vessel resistance (PVR) derived from the acceleration time of the pulmonary outflow tract (ACTpo), and right ventricular function derived from tricuspid annular plane systolic excursion (TAPSE). Right heart catheterisation was conducted only, if pulmonary hypertension was suggested by echocardiography and an abnormal ventilator test.The data are given as mean values +/- SD, unless otherwise stated. The correlations between the variables were analysed using Pearson's r coefficient, and the predictive value of the variables was calculated using linear regression analysis. A p value of > 0.05 was considered significant.

RESULTS

Right heart catheterization detected PAH in 15/19 patients; mean PAP was 30.5 mm/Hg and RVP 3.6 UW. Coronary angiography of the patients aged more than 55 years showed some evidence of significant coronary artery disease. Echocardiography showed high systolic PAP values (46 +/- 8 mmHg), whereas right ventricular function was normal (TAPSE 23 +/- 3 mm), and in line with the NYHA class. ACTpo was reduced in the patients with a systolic PAP of < 46 mm/Hg (p > 0.001) and positively correlated with DLCO (p > 0.001) and the hemodynamic data.There was a good correlation between ACTpo and PVR (hemodynamic data) (r = -0615; p > 0.01).

CONCLUSIONS

Although they need to be confirmed by studies of larger series of patients, our findings suggest that, in comparison with hemodynamic data, non-invasive echocardiographic measurements are an excellent means of identifying early-stage PAH.

Role of somatic mutations in vascular disease formation

Coronary artery disease, cerebrovascular disease, pulmonary artery hypertension and Alzheimer's disease all lead to substantial morbidity and mortality, and we currently lack effective treatments for these vascular diseases. Since the discovery, decades ago, that atherosclerotic lesions display clonal growth, atherosclerosis and other vascular diseases have been postulated to be neoplastic processes, arising through a series of critical somatic mutations. There is conflicting evidence supporting this but studies of DNA damage and mutagenesis, both genomic and mitochondrial, in atherosclerotic and vascular lesions, have yielded evidence that somatic mutations are involved in atherogenesis and vascular disease development. The roles of mitochondrial DNA damage, oxidative stress and signaling by members of the TGF-beta receptor family are implicated. With the increasing convenience and cost-effectiveness of genome sequencing, it is feasible to continue to seek specific genetic targets in the pathogenesis of these devastating diseases, with the hope of developing personalized genomic medicine in the future.

Outcome of pediatric patients with pulmonary arterial hypertension in the era of new medical therapies

Little is known about the effects of "second-generation drugs" (prostanoids, endothelin receptor antagonists, 5-phosphodiesterase inhibitors) in children with pulmonary arterial hypertension (PAH). This study describes the outcome of a national cohort of children with PAH in an era when these drugs became available. From 1993 to 2008, 52 consecutive children with idiopathic PAH (n = 29) or systemic-to-pulmonary shunt-associated PAH (n = 23) underwent baseline and follow-up assessments. Treatment was initiated depending on functional class, acute pulmonary vasoreactivity response, and drug availability. Observed survival was evaluated depending on time of diagnosis in relation to second-generation drug availability and subsequently compared to calculated predicted survival. Children for whom second-generation drugs were available had improved survival compared to their predicted survival (1-, 3-, and 5-year survival rates 93%, 83%, and 66% vs 79%, 61%, and 50%, respectively). However, this improved survival was observed only in patients for whom second-generation drugs became available during their disease course. No improved survival was observed in patients for whom drugs were available already at diagnosis. Baseline variables associated with decreased survival included higher functional class, higher pulmonary-to-systemic arterial pressure ratio, lower cardiac index, and higher serum levels of N-terminal pro-brain natriuretic peptide and uric acid. After start of second-generation drugs, functional class, 6-minute walking distance, and N-terminal pro-brain natriuretic peptide improved but gradually decreased after longer follow-up. In conclusion, survival of pediatric PAH seemed improved since the introduction of second-generation drugs only in selected patients for whom these drugs became available during their disease course. Start of second-generation drugs initially induced clinical improvements, but these effects decreased after longer follow-up.

Survival in patients with idiopathic, familial, and anorexigen-associated pulmonary arterial hypertension in the modern management era

BACKGROUND

Novel therapies have recently become available for pulmonary arterial hypertension. We conducted a study to characterize mortality in a multicenter prospective cohort of patients diagnosed with idiopathic, familial, or anorexigen-associated pulmonary arterial hypertension in the modern management era.

METHODS AND RESULTS

Between October 2002 and October 2003, 354 consecutive adult patients with idiopathic, familial, or anorexigen-associated pulmonary arterial hypertension (56 incident and 298 prevalent cases) were prospectively enrolled. Patients were followed up for 3 years, and survival rates were analyzed. For incident cases, estimated survival (95% confidence intervals [CIs]) at 1, 2, and 3 years was 85.7% (95% CI, 76.5 to 94.9), 69.6% (95% CI, 57.6 to 81.6), and 54.9% (95% CI, 41.8 to 68.0), respectively. In a combined analysis population (incident patients and prevalent patients diagnosed within 3 years before study entry; n=190), 1-, 2-, and 3-year survival estimates were 82.9% (95% CI, 72.4 to 95.0), 67.1% (95% CI, 57.1 to 78.8), and 58.2% (95% CI, 49.0 to 69.3), respectively. Individual survival analysis identified the following as significantly and positively associated with survival: female gender, New York Heart Association functional class I/II, greater 6-minute walk distance, lower right atrial pressure, and higher cardiac output. Multivariable analysis showed that being female, having a greater 6-minute walk distance, and exhibiting higher cardiac output were jointly significantly associated with improved survival.

CONCLUSIONS

In the modern management era, idiopathic, familial, and anorexigen-associated pulmonary arterial hypertension remains a progressive, fatal disease. Mortality is most closely associated with male gender, right ventricular hemodynamic function, and exercise limitation.

Long-term outcomes in pulmonary arterial hypertension in the first-line epoprostenol or first-line bosentan era

BACKGROUND

The aim of this study was to describe the long-term outcomes in idiopathic pulmonary arterial hypertension (IPAH) treated with first-line bosentan or intravenous (IV) epoprostenol, and additional therapy as needed.

METHODS

In a single-center, retrospective, longitudinal cohort, data on right heart catheterization, 6-minute walk distance (6MWD), disease progression and mortality were collected. Outcomes were assessed in first-line bosentan and first-line epoprostenol patients. To reduce selection bias due to differences between groups, two independent analyses were performed. First, a comparison was made of World Health Organization (WHO) Functional Class (FC) III patients. Second, to control for disease severity, a matched-pairs analysis was performed, with matching according to baseline cardiac output and exercise capacity and irrespective of FC at baseline.

RESULTS

Thirty-seven IPAH patients initiated first-line bosentan treatment and 37 first-line IV epoprostenol. Twenty-nine of the bosentan patients and 16 of the IV epoprostenol patients were in WHO FC III; demographic profiles were similar, although hemodynamic measurements and 6MWD suggested more severe disease in the IV epoprostenol group at treatment initiation. At 1 and 3 years, median change in 6MWD for patients initiating bosentan was +54 m (95% confidence interval: -3 to 76) and +71 m (-123 to 116), respectively, and +92 m (17 to 128) and +142 m (-6 to 242) for those on IV epoprostenol. Absence of disease progression of WHO FC III at 1 and 3 years was 72% and 45% with bosentan and 75% and 44% with IV epoprostenol, respectively. Survival at 1 and 3 years was 93% and 89% with bosentan and 94% and 75% with IV epoprostenol, respectively. Results were confirmed in matched-pairs analysis of 16 bosentan and 16 IV epoprostenol patients with similar disease severity.

CONCLUSIONS

First-line epoprostenol treatment may lead to greater improvement in exercise capacity than first-line bosentan. However, these greater exercise improvements did not translate into longer time to disease progression or survival.

Somatic chromosome abnormalities in the lungs of patients with pulmonary arterial hypertension

RATIONALE

Vascular remodeling in pulmonary arterial hypertension (PAH) involves proliferation and migration of endothelial and smooth muscle cells, leading to obliterative vascular lesions. Previous studies have indicated that the endothelial cell proliferation is quasineoplastic, with evidence of monoclonality and instability of short DNA microsatellite sequences.

OBJECTIVES

To assess whether there is larger-scale genomic instability.

METHODS

We performed genome-wide microarray copy number analysis on pulmonary artery endothelial cells and smooth muscle cells isolated from the lungs of patients with PAH.

MEASUREMENTS AND MAIN RESULTS

Mosaic chromosomal abnormalities were detected in PAEC cultures from five of nine PAH lungs but not in normal (n = 8) or disease control subjects (n = 5). Fluorescent in situ hybridization analysis confirmed the presence of these abnormalities in vivo in two of three cases. One patient harbored a germline mutation of BMPR2, the primary genetic cause of PAH, and somatic loss of chromosome-13, which constitutes a second hit in the same pathway by deleting Smad-8. In two female subjects with mosaic loss of the X chromosome, methylation analysis showed that the active X was deleted. One subject also showed completely skewed X-inactivation in the nondeleted cells, suggesting the pulmonary artery endothelial cell population was clonal before the acquisition of the chromosome abnormality.

CONCLUSIONS

Our data indicate a high frequency of genetically abnormal subclones within PAH lung vessels and provide the first definitive evidence of a second genetic hit in a patient with a germline BMPR2 mutation. We propose that these chromosome abnormalities may confer a growth advantage and thus contribute to the progression of PAH.

Bosentan

IMPORTANCE TO THE FIELD

Pulmonary arterial hypertension (PAH) is a morbid condition with high mortality if left untreated. Bosentan is an effective treatment option for group 1 pulmonary arterial hypertension. Bosentan improves exercise tolerance and functional class and delays the time to clinical worsening in these patients. Investigation is ongoing to determine its efficacy in other groups of pulmonary hypertension.

AREAS COVERED IN THIS REVIEW

This review provides a background on endothelin activity in PAH, as a rationale for the use of bosentan in this disease. It also presents evidence from key clinical trials of bosentan and discusses future directions in the study of bosentan to help the clinician better understand the role of bosentan in PAH management.

WHAT THE READER WILL GAIN

i) An understanding of the rationale for using endothelin receptor antagonists in treating PAH; ii) an understanding of the clinical evidence to support bosentan for the treatment of PAH; and iii) an understanding of how to use bosentan optimally in the treatment of PAH.

TAKE HOME MESSAGE

Bosentan is an effective and safe treatment for patients with PAH. Patients with suspected PAH should be evaluated carefully as the use of bosentan in non-group 1 pulmonary hypertension is still being investigated. Patients on bosentan should be monitored with monthly liver transaminase testing. Coadministration with other drugs should be reviewed carefully as drug-drug interactions may be important.

Clinical use of sildenafil in pulmonary artery hypertension

Severe pulmonary hypertension is a debilitating disease with short life expectancy that often affects young people. It is usually idiopathic pulmonary artery hypertension and is characterized by progressive elevation of pulmonary artery pressure and vascular resistance, right ventricular failure and death with a limited median survival time. There is an imbalance in vasoconstrictive and vasodilatory substances. The phosphodiesterase-5 inhibitor sildenafil, a pulmonary and penile vasodilator initially approved for erectile dysfunction, is found to be efficacious in severe pulmonary artery hypertension. There are limited treatment options for the management of pulmonary artery hypertension in developing countries and sildenafil is a reasonable treatment option. This article reviews the relevant clinical data in pulmonary hypertension and the role of sildenafil in its management.