Primary pulmonary hypertension: insights into pathogenesis from epidemiology

Pulmonary Arterial Capacitance Index Is a Strong Predictor for Adverse Outcome in Children with Idiopathic and Heritable Pulmonary Arterial Hypertension

OBJECTIVES

To evaluate the clinical utility of pulmonary artery capacitance index (PACi) in the assessment of disease severity and prognostic value in children with idiopathic and heritable pulmonary arterial hypertension (PAH).

STUDY DESIGN

PACi is defined as the ratio of stroke volume index over pulmonary pulse pressure. A retrospective study was performed to compare PACi, brain natriuretic peptide (BNP), 6-minute walk distance, New York Heart association (NYHA) functional class, and adverse outcomes (hospitalization due to heart failure, lung transplantation, and cardiac mortality) in 72 Japanese children (10 ± 3.6 years) with idiopathic and heritable PAH.

RESULTS

PACi had significant correlations with pulmonary vascular resistance index (r =-0.73, P < .0001), BNP levels (r = -0.40, P = .0008), and 6-minute walk distance (r = 0.57, P < .05). Statistically significant differences in PACi were observed between NYHA functional class II vs combined III and IV (median; 1.1 vs 0.6 mL/mm Hg/m², respectively, P < .05). There were 25 of 72 (35%) children who had an adverse event including initiation of hospitalization due to heart failure, lung transplantation, and death. Cumulative event-free survival rate was significantly lower when PACi was <0.85 mL/mm Hg/m² (log-rank test, P < .0001).

CONCLUSIONS

PACi correlated with BNP and NYHA functional class and may serve as a strong prognostic marker in children with idiopathic and heritable PAH.

Pulmonary arterial hypertension associated to connective tissue diseases

Pulmonary arterial hypertension is a well-known complication of connective tissue diseases such as systemic sclerosis, systemic lupus erythematosus, mixed connective tissue diseases, and to a lesser extent, rheumatoid arthritis, dermatopolymyositis and primary Sjögren’s syndrome. In these patients, pulmonary hypertension may occur in association with left heart disease, interstitial fibrosis or as a result of a isolated pulmonary arteriopathy. The incidence of pulmonary arterial hypertension in the limited form of systemic sclerosis is about 10%. The pathophysiologic mechanisms leading to pulmonary arterial hypertension remain unknown. Symptoms and clinical presentation are very similar to idiopathic pulmonary arterial hypertension but mortality was confirmed to be higher. Echocardiography is the reference investigation for the detection of pulmonary arterial hypertension but the results should be confirmed by right heart catheterization. Treatment appears more complex as compared to idiopathic pulmonary arterial hypertension. Intravenous epoprostenol therapy has been shown to be effective in a special trail. Also, the endothelin receptor antagonists bosentan and sitaxentan, the phosphodyesterase-type-5 sildenafil and subcutaneous treprostinil have shown favourable results.

RV stroke work in children with pulmonary arterial hypertension: estimation based on invasive haemodynamic assessment and correlation with outcomes

BACKGROUND

RV performance is an important determinant of outcomes in children with pulmonary arterial hypertension (PAH). RV stroke work (RVSW), the product of mean pulmonary artery pressure and stroke volume, integrates contractility, afterload and ventricular-vascular coupling. RVSW has not been evaluated in children with PAH. We tested the hypothesis that RVSW would be a predictor of outcomes in children with PAH.

METHODS

Patients in the Children's Hospital Colorado PAH database were evaluated retrospectively, and those with idiopathic PAH and those with minor or repaired congenital heart disease were included. Haemodynamic data were obtained by catheterisation and echocardiography, performed within 3 months. RVSW was calculated: mean pulmonary arterial pressure × stroke volume, and indexed to body surface area. Statistics included Kruskal-Wallis, Wilcoxon rank sum, and Spearman correlation.

RESULTS

Fifty patients were included. Median age of the cohort was 9.5 (6.0, 15.7) years, with a median indexed pulmonary vascular resistance (PVRi) of 6.5 (3.7, 11.6) WU m(2). RVSW had a significant association with PVRi (r=0.6, p<0.0001), tricuspid annular systolic plane excursion (r=0.55, p=0.0001), and RV fractional area change (r=-0.4, p=0.005). Grouped by WHO class, there was a significant difference in RVSW (p=0.04). Need for atrial septostomy and death were associated with higher RVSW (p=0.04 and p=0.03, respectively).

CONCLUSIONS

RVSW can be estimated in children with PAH, and is significantly associated with abnormal WHO class, the need for septostomy, as well as mortality. Indices accounting for RV performance as well as ventricular-vascular coupling may be useful in the prognosis and, hence, management of children with PAH.

Pulmonary arterial hypertension: pharmacologic therapies and potential pulmonary artery denervation treatment

Pulmonary arterial hypertension (PAH) is a group of diseases related to progressively increasing pulmonary vascular resistance, a high incidence of right ventricular failure and premature death. Only a limited number of pharmaceutical therapies have proven to be beneficial for PAH. These therapies improve symptoms, exercise capacity, and haemodynamics; however, the clinical relevance of these effects has been challenged. Therefore, the effect of currently approved treatment options remains inconclusive. Conversely, several new drugs for various aetiologies and clinical stages are expected to provide significant advances for the treatment of PAH. Moreover, percutaneous pulmonary artery denervation treatment may lead to a new therapeutic orientation in patients with PAH. The aim of this review is to present the new developments in PAH treatment, provide a brief overview of future directions in the field and discuss the potential future prospects of these innovative therapies.

Pulmonary Arterial Hypertension and Insulin Resistance

The clinical recognition of pulmonary arterial hypertension (PAH) is increasing, and with recent therapeutic advances, short-term survival has improved. In spite of these advances, however, PAH remains a disease with substantial morbidity and long-term mortality. The pathogenesis of PAH involves a complex interaction of local and distant cytokines, growth factors, co-factors, and transcription factors occurring in the right genetic and environmental setting. These factors ultimately lead to the detrimental changes in vascular anatomy and function seen in PAH patients. An important association between obesity/insulin resistance and PAH has recently been identified. Both conditions occur in the presence of a chronic low-grade inflammatory state, and although it is unlikely that a single pathway is solely responsible for the observed association, deficiencies in adiponectin, apolipoprotein E (ApoE) and peroxisome proliferator-activator receptor gamma (PPAR-γ) activity likely play a prominent role. Although incompletely understood, it is clear that further investigation is warranted and the role of weight loss and improved glycemic control in the treatment of at-risk patients with PAH and obesity should be determined.

Pulmonary Arterial Hypertension in Patients with Primary Sjögren's Syndrome

Introduction. Primary Sjögren's syndrome (pSS) is an autoimmune epithelitis. Pulmonary arterial hypertension (PAH) is an important and severe complication, which is encountered in many collagen tissue disorders. Early diagnostic strategies are required to define it at the asymptomatic stage. Doppler echocardiography is an important, noninvasive screening test for PAH diagnosis. Objective. The aim of this present study is to define the frequency of PAH in patients with pSS and to reveal correlations with laboratory and clinical findings. Material and Methods. A total of 47 patients, who were diagnosed with pSS according to American-European Study Group criteria were enrolled in the study. After all patients were evaluated clinically and by laboratory tests, Doppler echocardiography was performed in the cardiology outpatient clinic. Systolic pulmonary artery pressure (SPAP) >30 mm Hg values, which were measured at the resting state, were accepted as significant for PAH. Results. Forty-seven patients with pSS were included in the study. The mean age of patients was 48 years and the mean disease duration was 5.3 years. PAH was defined in 11 of the 47 patients (23.4%). The SPAP value was over 35 mm Hg in 5 out of 11 patients, whereas six patients had SPAP measuring 30–35 mm Hg. While pulmonary hypertension was related with earlier age and shorter duration of disease (P = 0.04), there was no statistically significant correlation between SPAP increase and clinical findings (P > 0.05). Conclusion. We have defined high PAH frequency in patients with pSS. Since there are different data in the literature, it is obvious that large scale, multicentre studies are required.

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.

Wrist actigraphy predicts outcome in patients with pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) impairs quality of life, exercise performance and survival. Simple measures to monitor the disease are needed.

OBJECTIVES

We tested whether actigraphy by a wrist-worn device in the patient's home reflects disease severity in PH patients.

METHODS

Twenty-three outpatients with pulmonary arterial and chronic thromboembolic PH (15 females), functional classes II-IV, underwent clinical examination and actigraphy over 2 weeks while pursuing their usual life at home. Actigraphies were correlated with clinical data and mean pulmonary artery pressure (mPAP). Deaths, lung transplantations and pulmonary endarterectomy were recorded over 4 years.

RESULTS

Actigraphies revealed a mean ± SD daytime activity duration of 14:57 ± 1:14 h with 146 ± 125 activity counts/min. Very severely impaired patients (mPAP 50 ± 7 mm Hg) were inactive for longer periods at night (8:25 ± 1:18 h) and less active during the day (54 ± 44 counts/min) when compared to modestly impaired patients (mPAP 33 ± 7 mm Hg; inactive at night for 6:58 ± 0:39 h; daytime activity 229 ± 148 counts/min, p < 0.05 in all instances). Out of 19 patients followed for 4 years, 5 died and 1 received a lung transplantation. Kaplan-Meier analysis revealed a shorter survival without lung transplantation in patients with a duration of daytime activity of <15 h/day than those with >15 h/day duration (log rank, p = 0.026).

CONCLUSION

A long nocturnal rest and reduced daytime activity recorded by actigraphy are associated with severe hemodynamic impairment and reduced survival in patients with PH. Therefore, wrist actigraphy performed during everyday life in the patient's home holds promise as a simple tool for the assessment of disease severity and prognosis in patients with PH.

Tissue Doppler imaging predicts adverse outcome in children with idiopathic pulmonary arterial hypertension

OBJECTIVE

To evaluate the clinical utility of tissue Doppler imaging (TDI) in assessment of disease severity and prognostic value in children with idiopathic pulmonary arterial hypertension (PAH).

STUDY DESIGN

A prospective study was performed to evaluate TDI velocities (systolic myocardial velocity, early diastolic myocardial relaxation velocity [Em], late diastolic myocardial velocity associated with atrial contraction), brain natriuretic peptide, New York Heart Association (NYHA) functional class, and hemodynamics in 51 children (mean age; 11.6 years) with idiopathic PAH. Fifty-one healthy children with comparable demographics served as controls.

RESULTS

Em, Em/late diastolic myocardial velocity associated with atrial contraction ratio, and systolic myocardial velocity at mitral annulus, septum, and tricuspid annulus in PAH were significantly reduced compared with controls. Tricuspid Em had significant inverse correlations with plasma brain natriuretic peptide levels (r = -0.60, P < .001), right ventricular end-diastolic pressure (r = -0.79, P < .001), and mean pulmonary arterial pressure (r = -0.67, P < .001). Statistically significant differences were observed in tricuspid Em between NYHA functional class II vs combined III and IV (mean and SD; 11.9 ± 4.2 cm/s vs 8.2 ± 3.6 cm/s, respectively, P = .002). Cumulative event-free survival rate was significantly lower when tricuspid Em was ≤8 cm/s (log-rank test, P < .001)

CONCLUSIONS

Tricuspid Em velocity correlated with NYHA functional class as disease severity and may serve as a useful prognostic marker in children with idiopathic PAH. The present study is the initial report to evaluate TDI velocities against midterm outcome variables in a relatively large pediatric PAH population.

Prostanoids for Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a severe condition that markedly reduces exercise capacity and survival in the affected patient population. PAH includes primary pulmonary hypertension (PPH) and pulmonary hypertension associated with collagen vascular diseases, congenital systemic-to-pulmonary shunts, portal hypertension and HIV infection. All these conditions share virtually identical obstructive pathologic changes of the pulmonary microcirculation and probably similar pathobiologic processes. The pathophysiology is characterized by a progressive increase in pulmonary vascular resistance, leading to right ventricular failure and death. Prostacyclin is an endogenous substance that is produced by vascular endothelial cells and induces vasodilatation, inhibition of platelet activity, and antiproliferative effects. A dysregulation of prostacyclin metabolic pathways has been shown in patients with PAH and this represents the rationale for the exogenous therapeutic administration of this substance. The clinical use of prostacyclin in patients with PAH has been made possible by the synthesis of stable analogs that possess different pharmacokinetic properties but share similar pharmacodynamic effects. Experience in humans has been initially collected with epoprostenol, which is a synthetic salt of prostacyclin. Epoprostenol has a short half-life in the circulation and requires continuous administration by the intravenous route by means of infusion pumps and permanent tunnelized catheters. In addition, epoprostenol is unstable at room temperature, and the complex delivery system required is associated with several adverse effects and potentially serious complications. For these reasons, alternatives to intravenous epoprostenol have been sought and this has led to the development of analogs that can be administered subcutaneously (treprostinil), orally (beraprost sodium) or by inhalation (iloprost). Three unblinded clinical trials and several uncontrolled trials have shown that treatment with epoprostenol improved symptoms and exercise capacity in New York Heart Association (NYHA) class III and IV PAH patients and also survival in patients with PPH. Subcutaneous treprostinil improved symptoms, exercise, hemodynamics and clinical events in the largest clinical trial ever performed in PAH, but local infusion site reactions limited efficacy in a proportion of patients. Oral beraprost sodium improved exercise capacity only in patients with PPH and is the only prostacyclin analog that has also been tested in NYHA class II patients. Inhaled iloprost has improved symptoms, exercise capacity and clinical events in patients with PAH and inoperable chronic thromboembolic pulmonary hypertension. The favorable effects of prostanoids observed in all studies coupled with different profiles of adverse events and tolerability for each prostacyclin analog allow the unique opportunity to select the most appropriate compound for the individual patient with PAH.

Increased right ventricular Septomarginal trabeculation mass is a novel marker for pulmonary hypertension: comparison with ventricular mass index and right ventricular mass

OBJECTIVE

: To prospectively evaluate the cardiac magnetic resonance (MR) imaging-derived measurement of right ventricular (RV) septomarginal trabeculation (SMT) mass as a noninvasive marker for pulmonary hypertension (PH), compared with the ventricular mass index (VMI = RV mass/left ventricular mass) and RV mass.

MATERIALS AND METHODS

: A total of 49 patients (60 ± 12 years; 35 female) with suspected PH underwent cardiac MR and right heart catheterization on the same day. Eighteen normal volunteers were also included. The performance of SMT mass, VMI and RV mass measurement, with regard to PH detection, was analyzed using receiver operating characteristic curves. Logistic regression analysis was used to assess the association between SMT mass, RV mass, VMI, and PH.

RESULTS

: The area under the receiver operating characteristic curve for SMT mass/body surface area (BSA), VMI, and RV mass/BSA in diagnosing the presence or absence of PH was 0.88, 0.87, and 0.73 respectively. In multivariable models, both SMT mass/BSA (P = 0.005, odds ratio: 8.6) and VMI (P = 0. 012, odds ratio: 1.1) were found to be significant, independent predictors of PH.

CONCLUSION

: Compared with right heart catheterization measurement, SMT mass and VMI are reproducible and noninvasive MR imaging markers for the diagnosis of PH.

CT findings in diseases associated with pulmonary hypertension: a current review

Pulmonary hypertension may primarily affect either the arterial (precapillary) or the venous (postcapillary) pulmonary circulation. Pulmonary arterial hypertension may be idiopathic or arise in association with chronic pulmonary thromboembolism; pulmonary embolism caused by tumor cells, parasitic material, or foreign material; parenchymal lung disease; liver disease; vasculitis; human immunodeficiency virus infection; or a left-to-right cardiac shunt. Its histologic characteristics include vascular changes-medial hypertrophy, intimal cellular proliferation, intraluminal thrombosis, and the development of plexiform lesions-that manifest primarily in the muscular pulmonary arteries. Features of pulmonary arterial hypertension that may be seen at computed tomography (CT) are central pulmonary artery dilatation, abrupt narrowing or tapering of peripheral pulmonary vessels, right ventricular hypertrophy, right ventricular and atrial enlargement, dilated bronchial arteries, and a mosaic pattern of attenuation due to variable lung perfusion. Pulmonary venous hypertension may result from pulmonary veno-occlusive disease, pulmonary venous compression by extrinsic lesions (eg, mediastinal fibrosis), left-sided cardiac disease, or pulmonary vein stenosis. Its histologic hallmarks include venous intimal cellular proliferation, medial hypertrophy, and thickening of the internal elastic lamina; capillary congestion and proliferation; interlobular septal thickening; lymphatic dilatation; and, sometimes, venous infarction and vascular changes characteristic of pulmonary arterial hypertension. CT scans in patients with pulmonary venous hypertension show pulmonary interstitial and alveolar edema with signs of pulmonary arterial hypertension. High-resolution CT with standard axial and angiographic acquisitions is useful for identifying underlying disorders and differentiating among the various causes of secondary pulmonary hypertension.

Endothelin receptor antagonists for pulmonary arterial hypertension: an overview

The last decade has seen major advances in the pharmacotherapy of pulmonary arterial hypertension (PAH). One of these advances has been the discovery of endothelin receptor antagonists (ERAs). ERAs are a class of potent vasodilators and antimitotic substances, which could specifically dilate and remodel pulmonary arterial system, and have been proposed as an alternative to traditional therapies for PAH. Current available evidence suggests that ERAs improve exercise capacity, functional status, pulmonary hemodynamics, and delay the time to clinical worsening for patients with PAH. This review attempts to provide an overview of the pharmacology, therapeutic benefits, and safety profile of ERAs in patients with PAH.

Can echocardiographic evaluation of cardiopulmonary hemodynamics decrease right heart catheterizations in end-stage heart failure patients awaiting transplantation?

Candidacy for heart transplantation is influenced by the severity of pulmonary hypertension. In this study, invasive hemodynamics from right-sided cardiac catheterization were compared with values obtained by validated equations from Doppler 2-dimensional transthoracic echocardiography. This prospective study was conducted in 40 patients with end-stage heart failure evaluated for heart transplantation or ventricular assist device implantation. Transthoracic echocardiography and right-sided cardiac catheterization were performed within 4 hours. From continuous-wave Doppler of the tricuspid regurgitation jet, pulmonary artery systolic pressure was calculated as the peak gradient across the tricuspid valve plus right atrial pressure estimated from inferior vena cava filling. Mean pulmonary artery pressure was calculated as (0.61 × pulmonary artery systolic pressure) + 2. Pulmonary vascular resistance (PVR) was calculated as (tricuspid regurgitation velocity/right ventricular outflow tract time-velocity integral × 10) + 0.16. Pulmonary capillary wedge pressure was calculated as 1.91 + (1.24 × E/E'). Pearson's correlation and Bland-Altman analysis of mean differences between echocardiographic and right-sided cardiac catheterization measurements were statistically significant for all hemodynamic parameters (pulmonary artery systolic pressure: r = 0.82, p < 0.05, mean difference 3.1 mm Hg, 95% confidence interval [CI] -0.2 to 6.3; mean pulmonary artery pressure: r = 0.80, p < 0.05, mean difference 2.5 mm Hg, 95% CI 0.3 to 4.6; PVR: r = 0.52, p < 0.05, mean difference 0.8 Wood units, 95% CI 0.3 to 1.4; pulmonary capillary wedge pressure: r = 0.65, p < 0.05, mean difference 2.2 mm Hg, 95% CI 0.1 to 4.3). Compared with right-sided cardiac catheterization, PVR by Doppler echocardiography identified all patients with PVR > 4 Wood units (n = 4), 73% of patients with PVR <2 Wood units (n = 8), and 52% of patients with PVR from 2 to 4 Wood units (n = 10). In conclusion, echocardiographic estimation of cardiopulmonary hemodynamics is reliable in patients with end-stage cardiomyopathy. The noninvasive assessment of hemodynamics by echocardiography may be able to decrease the number of serial right-sided cardiac catheterizations in selected patients awaiting heart transplantation. However, in patients with borderline PVR, right-sided cardiac catheterization is indicated to assess eligibility for transplantation.

Gene therapy techniques for the delivery of endothelial nitric oxide synthase to the lung for pulmonary hypertension

Pulmonary hypertension (PH) is a serious, often fatal disease characterized by remodeling of the pulmonary vascular bed, increased pulmonary arterial pressure, and right heart failure. The increased vascular resistance in the pulmonary circulation is due to structural changes and increased vasoconstrictor tone. Although current therapies have prolonged survival, the long-term outcome is not favorable. Nitric oxide (NO) is synthesized by endothelial nitric oxide synthase (eNOS) and is important in regulating vascular resistance and in vascular remodeling in the lung. NO deficiency due to endothelial dysfunction plays an important role in the pathogenesis of PH. Therefore, local eNOS gene delivery to the lung is a promising approach for the treatment of PH. Adenoviral-mediated in vivo gene therapy and adult stem cell-based ex vivo gene therapy are two attractive current gene therapies for the treatment of cardiovascular and pulmonary diseases. In this chapter we describe the use of two gene transfer techniques, i.e., adenoviral gene transfer of eNOS and eNOS gene-modified rat marrow stromal cells, for eNOS gene delivery to the lung of laboratory animals for the treatment of PH.

Integrated care and optimal management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) may occur as an idiopathic process or as a component of a variety of diseases, including connective tissue diseases, congenital heart disease, and exposure to appetite suppressants or infectious agents such as HIV. Untreated, it is a potentially devastating disease; however, diagnosis can be difficult due to the non-specific nature of symptoms during the early stages, and the fact that patients often present to a range of different medical specialties. The past decade has seen remarkable improvements in our understanding of the pathology associated with the condition and the development of PAH-specific therapies with the ability to alter the natural history of the disease. This article reviews the evidence for screening and diagnosis of susceptible patient groups and discusses treatment selection and recommendations based on data available from randomized controlled trials. In addition, due to the complexity of the diagnostic evaluation required and the treatment options available, this review mandates for a multidisciplinary approach to the management of PAH. We discuss the roles and organizational structure of a specialized PAH center in Perth, Western Australia to highlight these issues.

Dexfenfluramine discontinuous treatment does not worsen hypoxia-induced pulmonary vascular remodeling but activates RhoA/ROCK pathway: consequences on pulmonary hypertension

The anorectic drug, dexfenfluramine has been associated with an increase in the relative risk of developing pulmonary hypertension. 5-hydroxytryptamine (5-HT) is a mitogen for smooth muscle cell, an effect that relies on 5-HT transporter expression and which has been proposed to explain pulmonary side effect of dexfenfluramine, and more particularly its effect on vascular remodeling. However recent data supported a major role of pulmonary artery vasoconstriction through the RhoA/Rho-kinase pathway. We questioned whether or not anorectic treatment aggravates pulmonary hypertension through vascular remodeling and if RhoA/Rho-kinase (ROCK) was potentially involved. In rats exposed to hypoxia, concomitant dexfenfluramine treatment (5 mg/kg/day, i.v.) for 4 weeks had no effect on pulmonary hypertension development. When exposure to 2 weeks of chronic hypoxia followed discontinuation of dexfenfluramine treatment (dexfenfluramine-hypoxic rats), echocardiographic parameters of pulmonary artery flow and right ventricle were further altered (P<0.05) as well as right ventricle systolic pressure was further increased (P<0.001) when compared to hypoxic rats treated with vehicle (hypoxic rats). However, the total number of muscularized distal pulmonary arteries artery was similar in dexfenfluramine-hypoxic vs. hypoxic rats (P>0.05). Western blot, RT-PCR and immunofluorescence analysis revealed a greater expression of 5-HT transporter and ROCK, as well as a greater activation of RhoA in dexfenfluramine-hypoxic rats compared to hypoxic rats. These data show that increased 5-HT transporter expression that follows dexfenfluramine discontinuation is not associated to a greater vascular remodeling despite worsening the development of pulmonary hypertension. Furthermore dexfenfluramine discontinuation promotes a greater RhoA/ROCK pathway activation. This pathway, involved in many cardiovascular diseases, might explain the cardiac and pulmonary toxicity of serotoninergic agonists.

Pulmonary hypertension in children and adolescents with sickle cell disease

The prevalence of pulmonary hypertension (PHTN) in the pediatric sickle cell disease (SCD) population is not known despite its high prevalence in adult patients. Our hypothesis was that increased pulmonary artery pressures (PAPs) would be found in SCD children and adolescents, especially those with a history of pulmonary complications: acute chest syndrome, obstructive sleep apnea, asthma, and reactive airway disease. Fifty-two SCD children, 23 of whom had underlying pulmonary disease, were screened for PHTN, which was defined as a tricuspid regurgitant jet velocity (TRV) of at least 2.5 m/s. Twenty-four (46.15%) SCD patients had increased PAP (i.e., TRV > or =2.5 m/s), and 6 (11.5%) had significant PHTN (i.e., TRV > or =3.0 m/s). Pulmonary disease was marginally associated with PHTN (odds ratio 2.80 and confidence interval 0.88 to 8.86; p = 0.0795). As in adult SCD patients with PHTN, this complication was correlated with the degree of hemolysis as manifested by significantly higher lactate dehydrogenase and bilirubin, lower hemoglobin and hematocrit levels, and a strong association with Hb-SS phenotype. However, after statistical adjustment for age and sex, increased serum LDH was not associated with the development of PHTN. Further studies are needed to clarify the prevalence and mechanisms of PHTN in pediatric and adolescent patients with SCD.

Pathogenic mechanisms of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a complex disease that causes significant morbidity and mortality and is clinically characterized by an increase in pulmonary vascular resistance. The histopathology is marked by vascular proliferation/fibrosis, remodeling, and vessel obstruction. Development of PAH involves the complex interaction of multiple vascular effectors at all anatomic levels of the arterial wall. Subsequent vasoconstriction, thrombosis, and inflammation ensue, leading to vessel wall remodeling and cellular hyperproliferation as the hallmarks of severe disease. These processes are influenced by genetic predisposition as well as diverse endogenous and exogenous stimuli. Recent studies have provided a glimpse at certain molecular pathways that contribute to pathogenesis; these have led to the identification of attractive targets for therapeutic intervention. We will review our current understanding of the mechanistic underpinnings of the genetic and exogenous/acquired triggers of PAH. The resulting imbalance of vascular effectors provoking pathogenic vascular changes will also be discussed, with an emphasis on common and overarching regulatory pathways that may relate to the primary triggers of disease. The current conceptual framework should allow for future studies to refine our understanding of the molecular pathogenesis of PAH and improve the therapeutic regimen for this disease.

Comparison of lung proteome profiles in two rodent models of pulmonary arterial hypertension

We studied the lung proteome changes in two widely used models of pulmonary arterial hypertension (PAH): monocrotaline (MCT) injection and chronic hypoxia (CH); untreated rats were used as controls (n = 6/group). After 28 days, invasive right ventricular systolic pressure (RVSP) was measured. Lungs were immunostained for alpha-smooth muscle actin (alphaSMA). 2-DE (n = 4/group) followed by nano-LC-MS/MS was applied for protein identification. Western blotting was used additionally if possible. RVSP was significantly increased in MCT- and CH-rats (MCT 62.5 +/- 4.4 mmHg, CH 62.2 +/- 4.1 mmHg, control 25.0 +/- 1.7 mmHg, p<0.001). This was associated with an increase of alphaSMA positive vessels. In both groups, there was a significantly increased expression of proteins associated with the contractile apparatus (diphosphoHsp27 (p<0.001), Septin2 (p<0.001), F-actin capping protein (p<0.01), and tropomyosin beta (p<0.02)). In CH, proteins of the nitric oxide (Hsc70; p = 0.002), carbon monoxide (biliverdin reductase; p = 0.005), and vascular endothelial growth factor (VEGF) pathway (annexin 3; p<0.001) were significantly increased. In MCT, proteins involved in serotonin synthesis (14-3-3; p = 0.02), the enhanced unfolded protein response (ERp57; p = 0.02), and intracellular chloride channels (CLIC 1; p = 0.002) were significantly elevated. Therefore, MCT- and CH-induced vasoconstriction and remodeling seemed to be mediated via different signaling pathways. These differences should be considered in future studies using either PAH model.

Sildenafil in the treatment of pulmonary hypertension

The therapy of pulmonary hypertension has evolved rapidly in the last 10 years from the use of non-selective vasodilators to drugs that specifically target pulmonary vasodilation, endothelial function, and vascular remodeling. Sildenafil is a phosphodiesterase type 5 inhibitor that has an expanding role in the treatment of pulmonary hypertension. Case series and small studies, as well as the first large randomized controlled trial, have demonstrated the safety and efficacy of sildenafil in improving mean pulmonary artery pressure, pulmonary vascular resistance, cardiac index, and exercise tolerance in pulmonary arterial hypertension. It may be useful in adults, children, and neonates after cardiac surgery, with left heart failure, in fibrotic pulmonary disease, high altitude exposure, and thromboembolic disease, and in combination with other therapies for pulmonary hypertension, such as inhaled iloprost. The oral formulation and favorable adverse effect profile make sildenafil an attractive alternative in the treatment of selected patients with pulmonary hypertension.

Prevalence and diagnosis of severe pulmonary hypertension in patients with chronic obstructive pulmonary disease

PURPOSE OF REVIEW

The possible development of pulmonary hypertension is a well-known complication in the course of chronic obstructive pulmonary disease. When present, pulmonary hypertension is in general of mild severity at rest. It is therefore generally considered as a second-rank marker of the disease, mainly because the patients are limited in their exercise capacity for respiratory rather than for circulatory reasons. Apart from the common hemodynamic profile, however, some patients have a moderate-to-severe level of mean pulmonary artery pressure.

RECENT FINDINGS

These patients with a predominant vascular disease have been individualized recently. They have in common some particularities, the most characteristic profile being a mild-to-moderate airway obstruction, contrasting with the severity of dyspnea and hypoxemia. Another typical feature in these patients is the apparently poor prognosis.

SUMMARY

Such patients have to be recognized because they are potential candidates for specific therapies aiming at reducing pulmonary vascular resistance.

Pulmonary vascular lesions in end-stage idiopathic pulmonary fibrosis: histopathologic study on lung explant specimens and correlations with pulmonary hemodynamics

In patients presenting with idiopathic pulmonary fibrosis (IPF), modifications of pulmonary vessels are well defined in fibrotic areas but have not been accurately assessed in the intervening patches of preserved lung. Moreover, the relation between pulmonary vessel lesions and pulmonary hemodynamics is not well known. We therefore designed a retrospective study on lung explant specimens from 26 patients with a firm diagnosis of IPF who had undergone lung transplantation. Our aim was to (1) describe the vascular lesions, especially in preserved lung areas, and (2) correlate them with pulmonary hemodynamics. In dense fibrotic zones, thickening of the arterial and venous wall with severe luminal narrowing was present in each patient. In architecturally preserved lung zones, occlusion of venules and small pulmonary veins was observed in 65% of the patients, although there were only mild changes of muscular pulmonary arteries. We found a significant positive correlation between the macroscopic extent of lung fibrosis and mean pulmonary artery pressure, but we failed to find a relation between mean pulmonary artery pressure and venous/venular lesions in nonfibrotic areas. Our study points out that in many patients with IPF, nonfibrotic lung areas demonstrate an occlusive venopathy, the signification of which remains undetermined.

Eisenmenger syndrome and atrial septal defect: nature or nurture?

BACKGROUND

It has long been debated whether patients with atrial septal defect (ASD) Eisenmenger syndrome have idiopathic pulmonary arterial hypertension with an incidental ASD or severe pulmonary hypertension on the basis of their ASD shunt magnitude alone.

HYPOTHESIS

It was hypothesized that if ASD Eisenmenger patients had idiopathic pulmonary arterial hypertension with an incidental ASD, a mutation in the bone morphogenetic protein receptor-2 (BMPR2) would be found in some of these patients.

PATIENTS AND METHODS

All adult patients with ASD Eisenmenger syndrome were identified from the databases of two adult congenital cardiac units, and were matched to a control group with similar types of ASDs and no pulmonary hypertension. Gene coding for BMPR2 was examined for mutation using denaturing high-performance liquid chromatography of the entire coding sequence.

RESULTS

Eighteen adult patients with ASD Eisenmenger syndrome and 18 control patients were identified. ASD Eisenmenger patients had significantly larger ASDs than the control patients (3.7+/-1.2 cm versus 1.9+/-0.7 cm, P<0.01). A mutation in BMPR2 was not detected in either group.

CONCLUSION

ASD Eisenmenger syndrome may occur without BMPR2 mutation. Whether shunt magnitude alone or in combination with yet another genetic mutation is responsible for the development of pulmonary hypertension in these patients remains to be determined.

Absence of human herpesvirus 8 DNA sequences in lung biopsies from Israeli patients with pulmonary arterial hypertension

BACKGROUND

Pulmonary hypertension is a severe pulmonary vascular disease leading to rapid deterioration and death. Histological and clinical evidence suggests that smooth muscle proliferation is part of the pathogenesis of the disease. Human herpesvirus 8 (HHV-8) is a gamma-herpesvirus that is implicated in malignancies and in Kaposi's sarcoma. Recently, the association of HHV-8 with idiopathic pulmonary arterial hypertension (PAH) has been found.

OBJECTIVE

The aim of this study was to investigate the presence of HHV-8 in the lung tissue of Israeli patients with PAH.

METHOD

The presence of HHV-8 sequences was investigated by polymerase chain reaction examination in 6 biopsies of patients with pulmonary hypertension. Three patients had idiopathic pulmonary hypertension, 2 patients pulmonary venoocclusive disease, and 1 patient pulmonary hypertension associated with mixed connective tissue disease.

RESULT

We did not find any association between HHV-8 and PAH in these Israeli patients, as all the samples were negative for polymerase chain reaction.

CONCLUSION

Our findings, together with the epidemiological data of HHV-8 prevalence and incidence rates of Kaposi's sarcoma and PAH in Israel, provide further evidence which argues against an association between HHV-8 infection and PAH.

Lung Transplantation for Pulmonary Langerhans' Cell Histiocytosis: A Multicenter Analysis

BACKGROUND

Lung transplantation (LT) may represent a therapeutic option in case of advanced pulmonary Langerhans' cell histiocytosis (PLCH). Little is known however about the characteristics of the patients considered for LT or its results.

METHODS

We conducted a retrospective multicenter study by questionnaire on 39 patients who underwent LT for end-stage PLCH at seven centers in France.

RESULTS

Of the 39 patients, 15 received single lung transplantation, 15 double lung transplantation and 9 heart-lung transplantation. At evaluation, extrapulmonary involvement was present in 31% of the patients, pulmonary hypertension (PAPm>25 mm Hg) was observed in 92% of cases and was moderate-to-severe (PAPm> or =35 mm Hg) in 72.5%. The survival was 76.9% at 1 year, 63.6% at 2 years, 57.2% at 5 years, and 53.7% at 10 years. Recurrence of the disease occurred in eight cases (20.5%) with no impact on the survival rate. The sole risk factor for recurrence of the disease was the presence of preoperative extrapulmonary involvement.

CONCLUSION

Severe pulmonary hypertension is a common feature in patients with end-stage PLCH. Given the good postransplant survival rate and despite a recurrence rate of the disease of approximately 20% after LT, we conclude that LT is a therapeutic option in this setting.

Inhibition of vascular smooth muscle cell proliferation in vitro by genetically engineered marrow stromal cells secreting calcitonin gene-related peptide

Calcitonin gene-related peptide (CGRP) has a beneficial effect in pulmonary hypertension and is a target for cardiovascular gene therapy. Marrow stromal cells (MSCs), also known as mesenchymal stem cells, hold promise for use in adult stem cell-based ex vivo gene therapy. To test the hypothesis that genetically engineered MSCs secreting CGRP can inhibit vascular smooth muscle cell proliferation, rat MSCs were isolated, ex vivo expanded, and transduced with adenovirus containing CGRP. Immunocytochemical analysis demonstrated that wild type rat MSCs express markers specific for stem cells, endothelial cells, and smooth muscle cells including Thy-1, c-Kit, von Willebrand Factor and alpha-smooth muscle actin. Immunocytochemistry confirmed the expression of CGRP by the transduced rat MSCs. The transduced rat MSCs released 10.3+/-1.3 pmol CGRP/1 x 10(6) cells/48 h (mean+/-S.E.M., n=3) into culture medium at MOI 300 and the CGRP-containing culture supernatant from the transduced cells inhibited the proliferation of rat pulmonary artery smooth muscle cells (PASMCs) and rat aortic smooth muscle cells (ASMCs) in culture. Co-culture of the transduced rat MSCs with rat PASMCs or rat ASMCs also inhibited smooth muscle cell proliferation. These findings suggest that this novel adult stem cell-based CGRP gene therapy has potential for the treatment of cardiovascular diseases including pulmonary hypertension.

Ambrisentan therapy for pulmonary arterial hypertension

OBJECTIVES

The purpose of this study was to examine the efficacy and safety of four doses of ambrisentan, an oral endothelin type A receptor-selective antagonist, in patients with pulmonary arterial hypertension (PAH).

BACKGROUND

Pulmonary arterial hypertension is a life-threatening and progressive disease with limited treatment options. Endothelin is a vasoconstrictor and smooth muscle cell mitogen that plays a critical role in the pathogenesis and progression of PAH.

METHODS

In this double-blind, dose-ranging study, 64 patients with idiopathic PAH or PAH associated with collagen vascular disease, anorexigen use, or human immunodeficiency virus infection were randomized to receive 1, 2.5, 5, or 10 mg of ambrisentan once daily for 12 weeks followed by 12 weeks of open-label ambrisentan. The primary end point was an improvement from baseline in 6-min walk distance (6MWD); secondary end points included Borg dyspnea index, World Health Organization (WHO) functional class, a subject global assessment, and cardiopulmonary hemodynamics.

RESULTS

At 12 weeks, ambrisentan increased 6MWD (+36.1 m, p < 0.0001) with similar and statistically significant increases for each dose group (range, +33.9 to +38.1 m). Improvements were also observed in Borg dyspnea index, WHO functional class, subject global assessment, mean pulmonary arterial pressure (-5.2 mm Hg, p < 0.0001), and cardiac index (+0.33 l/min/m2, p < 0.0008). Adverse events were mild and unrelated to dose, including the incidence of elevated serum aminotransferase concentrations >3 times the upper limit of normal (3.1%).

CONCLUSIONS

Ambrisentan appears to improve exercise capacity, symptoms, and hemodynamics in patients with PAH. The incidence and severity of liver enzyme abnormalities appear to be low.

Left Ventricular Assist Devices as Bridge to Heart Transplantation in Congestive Heart Failure with Pulmonary Hypertension

Severe pulmonary hypertension (PH) has been considered a significant contraindication to cardiac transplantation. Ongoing clinical experience, however, has shown that temporary support using left ventricular assist devices (LVADs) in these patients can result in significant reductions in PH. A comprehensive review of the available literature regarding the use of LVADs in heart failure patients with PH was conducted. The existing literature to date supports the use of LVADs in heart failure patients with PH and demonstrates that significant reductions in PH in these patients can be achieved. This subsequently allows for safe and effective cardiac transplantation in patients who were previously excluded from this modality. For heart failure patients with severe PH, the use of LVADs can provide significant benefits by significantly reducing PH and allowing subsequent staged transplantation.

An overview of pulmonary arterial hypertension: risks, pathogenesis, clinical manifestations, and management

This article focuses on pulmonary arterial hypertension, including both primary pulmonary hypertension (PPH) and those forms of pulmonary arterial hypertension that are related to other factors, including collagen vascular diseases, congenital shunts, portal hypertension, human immunodeficiency viral infection, and exposure to specific drugs and toxins. Risks for different types of pulmonary arterial hypertension are identified. The common pathogenesis for pulmonary arterial hypertension is discussed, and includes an overview of the role of key vasoactive substances such as nitric oxide, prostacyclin, endothelin, and thromboxane. Typical presenting clinical manifestations, recommendations for screening of patients at risk, and key diagnostic findings are discussed. The mainstay of treatment is identified as pharmacologic, and may include diuretics, digoxin, warfarin, calcium channel antagonists, and prostacyclin analogues such as epoprostenol. Surgical interventions are considered as a last resort, and may include unilateral or bilateral lung transplant or atrial septostomy. Treatment options for patients with pulmonary arterial hypertension hold more hope today than they did a decade ago and are identified so as to guide the advanced practice nurse in recognizing and then facilitating the appropriate management of patients with this rare but disabling disease.

Pulmonary hemodynamics in advanced COPD candidates for lung volume reduction surgery or lung transplantation

STUDY OBJECTIVES

To assess the pulmonary hemodynamic characteristics in COPD candidates for lung volume reduction surgery (LVRS) or lung transplantation (LT).

DESIGN

Retrospective study.

SETTING

One center in France.

PATIENTS

Two hundred fifteen patients with severe COPD who underwent right-heart catheterization before LVRS or LT.

RESULTS

Mean age was 54.6 years. Pulmonary function test results were as follows: FEV(1), 24.3% predicted; total lung capacity, 128.3% predicted; residual volume, 259.7% predicted. Mean pulmonary artery pressure (PAPm) was 26.9 mm Hg. Pulmonary hypertension (PAPm > 25 mm Hg) was present in 50.2% and was moderate (PAPm, 35 to 45 mm Hg) or severe (PAPm > 45 mm Hg) in 9.8% and in 3.7% of patients, respectively. Cardiac index was low normal. PAPm was related to Pao(2) and alveolar-arterial oxygen gradient in multivariate analysis. Cluster analysis identified a subgroup of atypical patients (n = 16, 7.4%) characterized by moderate impairment of the pulmonary mechanics (mean FEV(1), 48.5%) contrasting with high level of pulmonary artery pressure (PAPm, 39.8 mm Hg), and severe hypoxemia (mean Pao(2), 46.2 mm Hg).

CONCLUSION

While pulmonary hypertension is observed in half of the COPD patients with advanced disease, moderate-to-severe pulmonary hypertension is not a rare event in these patients. We individualized a subgroup of patients presenting with a predominant vascular disease that could potentially benefit from vasodilators.

Antiproliferative effect of sildenafil on human pulmonary artery smooth muscle cells

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction and by obstructive changes of the pulmonary vasculature including smooth muscle cell proliferation which leads to medial hypertrophy and subsequent luminal narrowing. Sildenafil, an orally active inhibitor of cGMP phosphodiesterase-type-5, exerts pulmonary vasodilator activity in PAH patients. We evaluated the effects of sildenafil on growth of cultured human pulmonary artery smooth muscle cells (PASMC). The results indicate that sildenafil reduced DNA synthesis stimulated by PDGF and dose dependently inhibited PASMC proliferation. These effects were paralleled by a progressive increase in cGMP content, followed by an accumulation of cAMP. The treatment with 8-bromo-cGMP or dibutyryl-cAMP mimicked all the effects of sildenafil. On the other hand, treatment of PASMC with inhibitors of cGMP-dependent protein kinase (PKG) or cAMP-dependent protein kinase (PKA) reversed the antiproliferative effect of sildenafil. In addition, sildenafil inhibited the phosphorylation of ERK, a converging point for several pathways leading to cell proliferation. This effect was partially reduced by PKG inhibition and completely abolished by PKA inhibition.We conclude that sildenafil exerts an antiproliferative effect on human PASMC that is mediated by an interaction between the cGMP-PKG and the cAMP-PKA activated pathways, leading to inhibition of PDGF-mediated activation of the ERK.

Traitement de l'hypertension artérielle pulmonaire de l'enfant

Treatment strategies for pulmonary hypertension in children have dramatically evolved. Traditional therapy with calcium channel blockers and pulmonary transplantation is only indicated in selected patients and does not reduce mortality very significantly. New pulmonary vasodilators are emerging from recent trials in the adult population. Their indications are based on the patient's NYHA classification. The epoprostenol (prostacyclin, Flolan) has shown reduction in mortality and improvement in functional symptoms in pediatric patients. The frequent side effects and continuous intravenous infusion limit the indication of prostacyclin in NYHA class IV children. The endothelin receptor blocker bosentan (Tracleer) is an orally given agent. It improves functional symptoms in adults and hemodynamic measures in children. It can be started in children with moderate functional symptoms (NYHA class II and III). The type V phosphodiesterase inhibitor sildenafil (Viagra) is being evaluated and may represent a promising therapy in the future. Invasive strategies like catheter-based atrial septostomy may be useful in particular cases. Randomized-controlled studies are urgently needed to evaluate the safety and efficacy of these new therapies.

AIDS Associated With Severe Cor Pulmonale and Large Pericardial Effusion With Cardiac Tamponade

Cardiac involvement in patients with advanced HIV/AIDS is common, including pericardial effusion and pulmonary hypertension. Although there is an increased incidence of pericardial effusion in patients with AIDS, most are small and asymptomatic. The presence of a pericardial effusion and/or pulmonary hypertension is associated with shortened survival. We present a case of a 43-year-old man with AIDS and advanced cardiovascular involvement who developed severe cor pulmonale and a large pericardial effusion with cardiac tamponade.

Epoprostenol in Pregnant Patients with Secondary Pulmonary Hypertension

Women who present with pulmonary hypertension during gestation have traditionally been persuaded to terminate their pregnancy. Historically, the mortality associated with this group is very high. Certain patients with a secondary cause of pulmonary hypertension are believed to share similar pathophysiology with primary pulmonary hypertension patients. Recently, new treatments have become available that have slowed disease progression. We present the successful treatment of two patients who presented during late gestation with moderate pulmonary hypertension. Both patients were managed with intravenous vasodilators and anticoagulants without complication. Each patient successfully delivered a healthy child via spontaneous vaginal delivery. The review of the historical management of similar patients including new insights into the etiology of pulmonary arterial hypertension is also included. It highlights the complexity involved in managing such patients and the requirement of a multidisiplinary team approach.

Pulmonary Hypertension in Patients With Chronic Renal Failure

RATIONALE

The aim of this work was to study the association of pulmonary hypertension (PH) with pulmonary artery calcifications (PACs) and hyperparathyroidism in patients with chronic renal failure (CRF) receiving regular hemodialysis.

BACKGROUND

Scarce data are available regarding the prevalence and the predictors of PH in patients with CRF. Abnormal (99m)Tc diphosphonate lung uptake was reported in these patients, suggesting a role of PACs.

METHODS

We studied 51 patients (28 men and 23 women) with end-stage renal disease, who were receiving regular hemodialysis. Patients underwent two-dimensional, Doppler echocardiographic imaging. Laboratory investigations included BUN, serum creatinine, calcium, phosphorus, alkaline phosphatase, and intact molecule parathormone. PH was defined as pulmonary artery systolic pressure > 35 mm Hg as determined by Doppler echocardiographic evaluation.

RESULTS

PH was detected in 15 patients (29%). Women had a higher prevalence of PH (48% vs 14%, p = 0.01). There was no significant differences between patients with PH and those without PH with regards to age, duration of dialysis, serum calcium (9.6 +/- 2 mg/dL vs 10 +/- 2 mg/dL), phosphorus (6 +/- 1.4 mg/L vs 6.2 +/- 1.9 mg/L), alkaline phosphatase (609 +/- 768 U/L vs 473 +/- 574 U/L), parathyroid hormone (PTH) [420 +/- 512 pg/mL vs 354 +/- 519 pg/mL] or the prevalence of an abnormal (99m)Tc diphosphate lung scan result (60% vs 73%, respectively [+/- SD]).

CONCLUSIONS

This study demonstrated that 29% of patients with CRF receiving regular hemodialysis have PH. The presence of PH was not related to the level of PTH or the severity of other metabolic abnormalities. There was no relation between PH and the presence or the severity of PAC. PH is detected more frequently in women. This study does not support a role of secondary hyperparathyroidism and subsequent PAC as the etiology of PH in patients with CRF.

Emerging medical therapies for pulmonary arterial hypertension

Until a few years ago, "conventional" treatment for pulmonary arterial hypertension (PAH) included oral anticoagulants, calcium channel blockers, diuretics, digoxin, and oxygen. In the 1990s, 3 randomized studies demonstrated that the continuous intravenous infusion of epoprostenol improved functional capacity, cardiopulmonary hemodynamics, and survival in patients with severe PAH. Recently, the thromboxane inhibitor terbogrel, the prostacyclin analogues treprostinil, beraprost, and iloprost, and the endothelin receptor antagonist bosentan have been tested in clinical trials in more than 1,100 patients. Except for terbogrel, all compounds have improved by different degrees the mean exercise capacity as assessed by 6 minutes walking distance. Conversely, these trials differ for the severity and etiology of included PAH patients as well as for the effects on combined clinical events, on quality of life, and on hemodynamics. No trials have shown effects on mortality, and each new compound presents different side effects that seem unpredictable in the individual patient. At present, additional new compounds such as sitaxentan, ambisentan, L-arginine, and sildenafil are studied in clinical trials. The new therapeutic options are currently in different phases of approval by regulatory agencies, and when they will become available we will have the opportunity to select the most appropriate treatment for the single patient, according to an individualized benefit-to-risk ratio.

High prevalence of autoimmune thyroid disease in pulmonary arterial hypertension

STUDY OBJECTIVES

An association between thyroid disease and pulmonary arterial hypertension (PAH) has been reported, yet the pathogenetic relationship between these conditions remains unclear. Because immune system dysfunction may underlie this association, we sought to determine the prevalence of autoimmune thyroid disease (AITD) in patients with PAH.

DESIGN AND SETTING

Prospective observational study at a single academic institution.

PATIENTS

Sixty-three consecutive adults with PAH (ie, sustained pulmonary artery systolic pressure, > 25 mm Hg) were evaluated for clinical, biochemical, and serologic features of AITD.

MEASUREMENTS

Thyroid gland dysfunction was determined by clinical examination for goiter, and by biochemical measurements of thyrotropin and free thyroxine. Immune system dysfunction was determined by serologic measurements of antibodies to thyroglobulin and thyroid peroxidase. First-degree family history of AITD also was ascertained in order to investigate for genetic clustering of autoimmunity.

RESULTS

Thirty-one patients (49%; 95% confidence interval [CI], 37 to 62%) received diagnoses of AITD. Eighteen patients were newly diagnosed, and 9 patients required the initiation of pharmacologic treatment. There was no chronologic relationship between the diagnosis or treatment of PAH and that of AITD. Sixteen patients (25%; 95% CI, 15 to 36%) had 24 first-degree family members with AITD.

CONCLUSIONS

Approximately half of the patients with PAH have concomitant AITD. These two conditions may be linked by a common immunogenetic susceptibility, and the elucidation of this association may advance the understanding of the pathophysiology and treatment of PAH. Systematic surveillance for occult thyroid dysfunction in patients with PAH may prevent the hemodynamic exacerbation of right heart failure.

Dexfenfluramine protects against pulmonary hypertension in rats

Dexfenfluramine (Dex), an appetite suppressant and serotonin reuptake inhibitor, is associated with pulmonary vascular disease (PVD) in some patients. The variability might be related to undetermined genetic abnormalities interacting with factors such as gender, weight loss, and vascular injury. We, therefore, assessed the effect of Dex (5 mg. kg(-1). day(-1)) in female obese rats, designated JCR:LA-cp or cp/cp; in lean rats, designated (+/?); and in normal Sprague-Dawley (S-D) rats under control conditions or after endothelial injury induced by monocrotaline (60 mg/kg). Pulmonary arterial pressure, right ventricular hypertrophy, percent medial wall thickness of muscular arteries, and muscularization of peripheral arteries were assessed as indexes of PVD. Although Dex reduced weight gain in cp/cp and S-D rats (P < 0.05 for both), it did not cause PVD. Moreover, PVD in S-D rats after monocrotaline injection was paradoxically ameliorated by Dex (P < 0.05) despite induction of pulmonary artery elastase (P < 0.05), which we showed is critical in inducing experimental PVD. Thus it is possible that Dex is concomitantly offsetting the sequelae of elastase activity.

Current and emerging therapy for primary pulmonary hypertension

OBJECTIVE

To review the epidemiology, pathophysiology, clinical symptoms, and diagnostic workup of primary pulmonary hypertension (PPH) and to discuss the available data on the current and emerging therapies being used to treat this disorder.

DATA SOURCES

Primary and review articles were identified with a MEDLINE search (1966-December 2001) and through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All articles identified from the data sources were evaluated and all information deemed relevant was included in this review.

DATA SYNTHESIS

In the absence of a definable cause, PPH is a disorder classified by a progressive increase in pulmonary vascular resistance and mean pulmonary artery pressure. A relatively rare condition, PPH has an annual incidence of 1-2 cases per million people, slightly higher in women than men. The prognosis is poor, with a mean survival time of 2.8 years after diagnosis if untreated. Vasoconstriction, vascular remodeling, and thrombosis are hallmarks of the disease process. Anticoagulation and vasodilators are the most commonly employed treatment options, showing benefits in clinical outcomes, hemodynamic parameters, and mortality. Several new vasodilators are being evaluated for the treatment of PPH. Bosentan was recently approved as the first oral agent for the treatment of PPH. Iloprost, treprostinil, and beraprost are investigational agents in Phase III studies.

CONCLUSIONS

Until additional studies and experience with these agents become available, calcium-channel blockers (CCBs) remain the first option for therapy. For patients not responding to CCBs, therapeutic options will now include epoprostenol and bosentan. Since there are no comparison trials between these 2 agents, therapeutic decisions should be based on patient-specific concerns. Clinical data and experience support the use of epoprostenol; however, in patients at risk or considered unsuitable candidates, bosentan may become a preferred option. Additional studies are warranted to address the potential therapeutic benefits of combination therapy and long-term benefits of agents to treat PPH.

Inhaled nitric oxide: more than a selective pulmonary vasodilator

Because of its high diffusing capacity through the alveolar-blood barrier and its high selectivity for the pulmonary vasculature, inhaled nitric oxide (NO) has been recently shown to be a viable and efficient approach to restore pulmonary NO deficiency. The most relevant applications of inhaled NO are in infants with primary pulmonary hypertension or hypoxia. In these patients, inhaled NO improves gas exchange and ventilation-perfusion matching, reduces the length of hospitalization and is without severe detrimental effects. The use of inhaled NO has also been extended to adults with pulmonary hypertension and the acute respiratory distress syndrome. In addition, recent clinical evidence supported by data from animal models, shows beneficial extra-pulmonary effects of inhaled NO, including protection against myocardial ischaemia-reperfusion injury.