The burden of pulmonary hypertension

Initial dual oral combination therapy in pulmonary arterial hypertension

Treatment for pulmonary arterial hypertension (PAH) has been underpinned by single-agent therapy to which concomitant drugs are added sequentially when pre-defined treatment goals are not met.

This retrospective analysis of real-world clinical data in 97 patients with newly diagnosed PAH (86% in New York Heart Association functional class III−IV) explored initial dual oral combination treatment with bosentan plus sildenafil (n=61), bosentan plus tadalafil (n=17), ambrisentan plus tadalafil (n=11) or ambrisentan plus sildenafil (n=8).

All regimens were associated with significant improvements in functional class, exercise capacity, dyspnoea and haemodynamic indices after 4 months of therapy. Over a median follow-up period of 30 months, 75 (82%) patients were still alive, 53 (71%) of whom received only dual oral combination therapy. Overall survival rates were 97%, 94% and 83% at 1, 2 and 3 years, respectively, and 96%, 94% and 84%, respectively, for the patients with idiopathic PAH, heritable PAH and anorexigen-induced PAH. Expected survival rates calculated from the French equation for the latter were 86%, 75% and 66% at 1, 2 and 3 years, respectively.

Initial combination of oral PAH-targeted medications may offer clinical benefits, especially in PAH patients with severe haemodynamic impairment.

The effect of dietary antioxidant on the COPD risk: the community-based KoGES (Ansan-Anseong) cohort

Background

Dietary antioxidants have been suggested to have protective role against chronic obstructive pulmonary disease (COPD), but few prospective studies examined this relationship. The prospective study was conducted to evaluate the effect of dietary antioxidants on COPD risk and lung function in the Korean population.

Methods

The data were collected from the community-based Korean Genome Epidemiology Study (KoGES) cohort. To diagnose COPD, forced expiratory volume (FEV₁) and forced vital capacity (FVC) were measured by spirometry. The dietary intake of antioxidant vitamins was estimated from validated Food-Frequency Questionnaire. For the analysis, 325 COPD patients and 6,781 at risk subjects were selected from the cohort of 10,038 subjects. Multiple logistic regression models were used to examine the odds ratio (OR) after adjusting for age, sex, marital status, income, history of asthma, history of tuberculosis, and smoking.

Results

The risk of COPD was positively associated with aging, low education, low household income, lower body mass index, and cigarette smoking. The risk of COPD decreased with increase in the dietary vitamin C (OR_{Q1 vs Q5}=0.66, P_trend=0.03) and vitamin E (OR_{Q1 vs Q5}=0.56, P_trend=0.05) intake, predominantly, in men (P_trend=0.01 and 0.05 for vitamins C and E, respectively). In addition, the lung function was significantly improved with increase in vitamins C (FEV₁, P=0.04; FVC, P=0.03) and E (FEV₁, P=0.03; FVC, P=0.04) intake. No statistically significant interactions were observed between smoking and vitamin C or E intake in relation to COPD risk among men.

Conclusion

Our results suggest the independent beneficial effect of antioxidants, particularly vitamins C and E, on COPD risk and lung function in men.

Magnetic resonance and computed tomography imaging of the structural and functional changes of pulmonary arterial hypertension

The current Dana Point Classification system (2009) distinguishes elevation of pulmonary arterial pressure into pulmonary arterial hypertension (PAH) and pulmonary hypertension. Fortunately, PAH is not a common disease. However, with the aging of the First World's population, heart failure has become an important outcome of pulmonary hypertension, with up to 9% of the population involved. PAH is usually asymptomatic until late in the disease process. Although features that are indirectly related to PAH are found on noninvasive imaging studies, its diagnosis and management still require right heart catheterization. Imaging features of PAH include the following: (1) enlargement of the pulmonary trunk and main pulmonary arteries; (2) decreased pulmonary arterial compliance; (3) tapering of the peripheral pulmonary arteries; (4) enlargement of the inferior vena cava; and (5) increased mean transit time. The chronic requirement to generate high pulmonary arterial pressure measurably affects the right heart and main pulmonary artery. This change in physiology causes the following structural and functional alterations that have been shown to have prognostic significance: relative area change (RAC) of the pulmonary trunk, right ventricular stroke volume index, right ventricular stroke volume, right ventricular end-diastolic volume index, left ventricular end-diastolic volume index, and baseline right ventricular ejection fraction <35%. All of these variables can be quantified noninvasively and followed up longitudinally in each patient using magnetic resonance imaging to modify the treatment regimen. Untreated PAH frequently results in rapid clinical decline and death within 3 years of diagnosis. Unfortunately, even with treatment, fewer than half of these patients are alive at 4 years.

Long term survival of patients with raised pulmonary arterial systolic pressure utilizing echocardiography-a five-year prospective study

Background

Pulmonary arterial systolic pressure (PASP) can be estimated with transthoracic echocardiography. However, the significance of raised PASP on routine echocardiography is uncertain. In this study, we evaluated the mortality and hospitalization rates of subjects with raised PASP in a cohort of patients referred directly by their general practitioners for routine outpatient (open access) echocardiography for further analysis of suspected heart failure.

Results

A total of 485 subjects were referred for open access echocardiography at our hospital in 2002. A cohort of 209/485 (43%) consecutive subjects with measurable tricuspid regurgitation were followed for a minimum of five years investigating hospitalization rates and survival. Some 62 of 209 (30%) subjects had pulmonary hypertension (PH). Subjects with PH were significantly more likely to have four or more hospital admissions (22% vs. 8%; P < 0.01) and > 30 days of cumulative hospital stay over five years (29% vs. 13%; P < 0.01). PH was significantly associated with mortality (P = 0.003), while moderate to severe PH was an independent predictor of mortality (hazard ratio: 4.31; 95% confidence interval (95% CI): 1.51–12.30). Records from the Office of National Statistics revealed that subjects with PH were more likely to have chronic lung diseases recorded as immediate or contributory causes of death (50% vs. 14%; P < 0.05).

Conclusions

PASP ≥ 36 mmHg on routine echocardiography is associated with recurrent hospital admissions, prolonged hospitalizations and increased cause of mortality. Therefore, the diagnosis of PH on echocardiography deserves further clinical evaluation, with future studies designed at defining a suitable diagnostic strategy.

Low-dose fluvastatin reverses the hypoxic pulmonary adventitial fibroblast phenotype in experimental pulmonary hypertension

Hypoxic pulmonary hypertension is a worldwide public health problem. Statins attenuate hypoxic pulmonary hypertension in animal models, but the mechanism of action and applicability of these results to human treatment are not established. In hypoxic models, pulmonary artery fibroblast proliferation contributes substantially to pulmonary vascular remodeling. We previously showed that acute hypoxic pulmonary adventitial fibroblast proliferation can be selectively inhibited by statins and p38 mitogen-activated protein (MAP) kinase inhibitors. Here we used complementary chronic hypoxic and acute hypoxic coculture models to obtain necessary preclinical information regarding the utility of fluvastatin in the treatment of chronic hypoxic pulmonary hypertension. The effects of fluvastatin, cholesterol pathway intermediates, and related inhibitors on hypoxic adventitial fibroblast proliferation, p38 MAP kinase phosphorylation, and pulmonary artery smooth muscle cell proliferation were determined, using complementary chronic hypoxic rat and acute hypoxic bovine cell models. Fluvastatin reversed the proliferative phenotypic switch in adventitial fibroblasts from chronic hypoxic animals. This effect was circulation-specific, and implicated a Rac1-p38 MAP kinase signaling pathway. Coculture and conditioned media experiments also implicated this statin-sensitive signaling pathway in the release of pulmonary artery smooth muscle cell mitogens by hypoxic pulmonary adventitial fibroblasts. Treprostinil, sildenafil, and bosentan exerted no effect on the hypoxic fibroblast phenotype. Phenotypic changes (increased proliferation and mitogen release) in pulmonary artery fibroblasts during chronic hypoxia are dependent on a Rac1-p38 MAP kinase signaling pathway. The inhibition of these phenotypic changes with fluvastatin may be therapeutically relevant in high-altitude residents and in patients with hypoxic lung disease.

Tadalafil for the treatment of pulmonary arterial hypertension

Tadalafil is a selective inhibitor of phosphodiesterase type-5 (PDE-5) that was originally developed for the treatment of male erectile dysfunction and recently approved for the treatment of pulmonary arterial hypertension (PAH). The antipulmonary hypertensive effects of nitric oxide and the natriuretic peptides are mediated via increasing intracellular cGMP and enzymatic degradation by PDE-5 is the major route of cGMP inactivation in the lung. Evidence is accruing that PDE-5 activity is increased in pulmonary vascular diseases and may contribute to the pathogenesis of PAH. The longer half-life of tadalafil allows for once-daily dosing as compared with three-times daily dosing for sildenafil, the only other PDE-5 inhibitor currently approved for treatment of PAH. This article reviews the role of cGMP and PDE-5 in PAH, presents the results of recent clinical trials and discusses the role of tadalafil in the treatment of this rare but difficult-to-treat disease.

Vascular involvement in systemic sclerosis (scleroderma)

Systemic sclerosis (SSc) is an acquired multiorgan connective tissue disease with variable mortality and morbidity dictated by clinical subset type. The etiology of the basic disease and pathogenesis of the systemic autoimmunity, fibrosis, and fibroproliferative vasculopathy are unknown and debated. In this review, the spectrum of vascular abnormalities and the options currently available to treat the vascular manifestations of SSc are discussed. Also discussed is how the hallmark pathologies (ie, how autoimmunity, vasculopathy, and fibrosis of the disease) might be effected and interconnected with modulatory input from lysophospholipids, sphingosine 1-phosphate, and lysophosphatidic acid.

Myocardial delayed enhancement in pulmonary hypertension: pulmonary hemodynamics, right ventricular function, and remodeling

OBJECTIVE

The purpose of this study was to assess predictors of MRI-identified septal delayed enhancement mass at the right ventricular (RV) insertion sites in relation to RV remodeling, altered regional mechanics, and pulmonary hemodynamics in patients with suspected pulmonary hypertension (PH).

SUBJECTS AND METHODS

Thirty-eight patients with suspected PH were evaluated with right heart catheterization and cardiac MRI. Ten age- and sex-matched healthy volunteers acted as controls for MRI comparison. Septal delayed enhancement mass was quantified at the RV insertions. Systolic septal eccentricity index, global RV function, and remodeling indexes were quantified with cine images. Peak systolic circumferential and longitudinal strain at the sites corresponding to delayed enhancement were measured with conventional tagging and fast strain-encoded MRI acquisition, respectively.

RESULTS

PH was diagnosed in 32 patients. Delayed enhancement was found in 31 of 32 patients with PH and in one of six patients in whom PH was suspected but proved absent (p = 0.001). No delayed enhancement was found in controls. Delayed enhancement mass correlated with pulmonary hemodynamics, reduced RV function, increased RV remodeling indexes, and reduced eccentricity index. Multiple linear regression analysis showed RV mass index was an independent predictor of total delayed enhancement mass (p = 0.017). Regional analysis showed delayed enhancement mass was associated with reduced longitudinal strain at the basal anterior septal insertion (r = 0.6, p < 0.01). Regression analysis showed that basal longitudinal strain remained an independent predictor of delayed enhancement mass at the basal anterior septal insertion (p = 0.02).

CONCLUSION

In PH, total delayed enhancement burden at the RV septal insertions is predicted by RV remodeling in response to increased afterload. Local fibrosis mass at the anterior septal insertion is associated with reduced regional longitudinal contractility at the base.

An official American Thoracic Society public policy statement: Novel risk factors and the global burden of chronic obstructive pulmonary disease

RATIONALE

Although cigarette smoking is the most important cause of chronic obstructive pulmonary disease (COPD), a substantial proportion of COPD cases cannot be explained by smoking alone.

OBJECTIVES

To evaluate the risk factors for COPD besides personal cigarette smoking.

METHODS

We constituted an ad hoc subcommittee of the American Thoracic Society Environmental and Occupational Health Assembly. An international group of members was invited, based on their scientific expertise in a specific risk factor for COPD. For each risk factor area, the committee reviewed the literature, summarized the evidence, and developed conclusions about the likelihood of it causing COPD. All conclusions were based on unanimous consensus.

MEASUREMENTS AND MAIN RESULTS

The population-attributable fraction for smoking as a cause of COPD ranged from 9.7 to 97.9%, but was less than 80% in most studies, indicating a substantial burden of disease attributable to nonsmoking risk factors. On the basis of our review, we concluded that specific genetic syndromes and occupational exposures were causally related to the development of COPD. Traffic and other outdoor pollution, secondhand smoke, biomass smoke, and dietary factors are associated with COPD, but sufficient criteria for causation were not met. Chronic asthma and tuberculosis are associated with irreversible loss of lung function, but there remains uncertainty about whether there are important phenotypic differences compared with COPD as it is typically encountered in clinical settings.

CONCLUSIONS

In public health terms, a substantive burden of COPD is attributable to risk factors other than smoking. To prevent COPD-related disability and mortality, efforts must focus on prevention and cessation of exposure to smoking and these other, less well-recognized risk factors.

EGF mediates calcium-activated chloride channel activation in the human bronchial epithelial cell line 16HBE14o-: involvement of tyrosine kinase p60c-src

Particulate atmospheric pollutants interact with the human airway epithelium, which releases cytokines, chemokines, and EGF receptor (EGFR) ligands leading to proinflammatory responses. There is little information concerning the short-term effects of EGFR activation by extracellular ligands on ionic regulation of airway surface lining fluids. We identified in the membrane of human epithelial bronchial cells (16HBE14o(-) line) an endogenous calcium- and voltage-dependent, outwardly rectifying small-conductance chloride channel (CACC), and we examined the effects of EGF on CACC activity. Ion channel currents were recorded with the patch-clamp technique. In cell-attached membrane patches, CACC were activated by exposure of the external surface of the cells to physiological concentrations of EGF without any change in cytosolic Ca(2+) concentration ([Ca(2+)](i)) and inhibited by tyrphostin AG-1478 (an inhibitor of EGFR that also blocks EGF-dependent Src family kinase activation). EGF activation of c-Src protein in 16HBE14o(-) cells was observed, and the signaling pathway elicited by EGFR was blocked by tyrphostin AG-1478. In excised inside-out membrane patches CACC were activated by exposure of the cytoplasmic face of the channels to the human recombinant Src(p60(c-src)) kinase with endogenous or exogenous ATP and inhibited by lambda-protein phosphatase. Secretion of EGFR ligands by epithelial airway cells exposed to pollutants would then elicit a rapid and direct ionic response of CACC mediated by EGFR activation via a Src kinase family-dependent signaling pathway.

Effect of coactivation of tongue protrusor and retractor muscles on pharyngeal lumen and airflow in sleep apnea patients

The present study evaluated the effect of coactivation of tongue protrusors and retractors on pharyngeal patency in patients with obstructive sleep apnea. The effect of genioglossus (GG), hyoglossus (HG), and coactivation of both on nasal pressure (Pn):flow relationships was evaluated in a sleep study (SlS, n = 7) and during a propofol anesthesia study (AnS, n = 7). GG was stimulated with sublingual surface electrodes in SlS and with intramuscular electrodes in AnS, while HG was stimulated with surface electrodes in both groups. In the AnS, the cross-sectional area (CSA):Pn relationships was measured with a pharyngoscope to estimate velopharyngeal compliance . In the SlS, surface stimulation of GG had no effect on the critical pressure (Pcrit), HG increased Pcrit from 2.8 +/- 1.7 to 3.7 +/- 1.6 cmH(2)O, but coactivation lowered Pcrit to 0.2 +/- 1.9 cmH(2)O (P < 0.01 for both). In the AnS, intramuscular stimulation of GG lowered Pcrit from 2.6 +/- 1.3 to 1.0 +/- 2.8 cmH(2)O, HG increased Pcrit to 6.2 +/- 2.5 cmH(2)O (P < 0.01), and coactivation had a similar effect to that of GG (Pcrit = 1.2 +/- 2.4 cmH(2)O, P < 0.05). None of the interventions affected significantly velopharyngeal compliance. We conclude that the beneficial effect of coactivation depends on the pattern of GG fiber recruitment: although surface stimulation of GG failed to protrude the tongue, it prevented the occlusive effect of the retractor, thereby improving pharyngeal patency during coactivation. Stimulation of deeper GG fibers with intramuscular electrodes enlarged the pharynx, and coactivation had no additive effect.