OBJECTIVE:Choices of pharmacologic therapies for pulmonary arterial hypertension (PAH) are ideally guided by high-level evidence. Th e objective of this guideline is to provide clinicians advice regarding pharmacologic therapy for adult patients with PAH as informed by available evidence. METHODS:Th is guideline was based on systematic reviews of English language evidence published between 1990 and November 2013, identified using the MEDLINE and Cochrane Library databases. Th e strength of available evidence was graded using the Grades of Recommendations, Assessment, Development, and Evaluation methodology. Guideline recommendations, or consensus statements when available evidence was insufficient to support recommendations, were developed using a modifi ed Delphi technique to achieve consensus. RESULTS:Available evidence is limited in its ability to support high-level recommendations. Th erefore, we draft ed consensus statements to address many clinical questions regarding pharmacotherapy for patients with PAH. A total of 79 recommendations or consensus statements were adopted and graded.CONCLUSIONS: Clinical decisions regarding pharmacotherapy for PAH should be guided by high-level recommendations when suffi cient evidence is available. Absent higher level evidence, consensus statements based upon available information must be used. Further studies are needed to address the gaps in available knowledge regarding optimal pharmacotherapy for PAH. ABBREVIATIONS : 6MWD 5 6-min walk distance ; AHRQ 5 Agency for Healthcare Research and Quality ; ARIES 5 Ambrisentan in Pulmonary Arterial Hypertension, Randomized Double-Blind, PlaceboControlled, Multicenter, Efficacy Study ; BNP 5 brain natriuretic peptide ; CB 5 consensus-based ; CCB 5 calcium channel blocker ; CO 5 cardiac output ; COI 5 conflict of interest ; CTEPH 5 chronic thromboembolic pulmonary hypertension ; EPC 5 Evidence-Based Practice Center ; ETRA 5 endothelin receptor antagonist ; FC 5 functional class ; FDA 5 US Food and Drug Administration ; GOC 5 Guidelines Oversight Committee ; GRADE 5 Grades of Recommendations, Assessment , Development , and Evaluation ; HR 5 hazard ratio ; IOM 5 Institute of Medicine ; IPAH 5 idiopathic pulmonary arterial hypertension ; mPAP 5 mean pulmonary artery pressure ; PAH 5 pulmonary arterial hypertension ; PDE5 5 phosphodiesterase-5 ; PH 5 pulmonary hypertension ; PVR 5 pulmonary vascular resistance ; RCT 5 randomized controlled trial ; WHO 5 World Health Organization For treatment naive PAH patients with WHOFC I symptoms, we suggest continued monitoring for the development of symptoms that would signal disease progression and warrant the initiation of pharmacotherapy (Grade CB) . 5. We suggest that patients at risk for the development of PAH (eg, patients with systemic sclerosis or the presence of a known mutation placing the patient at risk for PAH) be monitored for the development of symptoms of PAH (Grade CB) . 6. We suggest also that contributing causes of PH (eg, sleep apnea and systemic hypertension) in patients wi...

Lee CG. IL-13 receptor ␣ 2-arginase 2 pathway mediates IL-13-induced pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 304: L112-L124, 2013. First published November 2, 2012; doi:10.1152/ajplung.00101.2012.-Although previous literature suggests that interleukin (IL)-13, a T-helper type 2 cell effector cytokine, might be involved in the pathogenesis of pulmonary hypertension (PH), direct proof is lacking. Furthermore, a potential mechanism underlying IL-13-induced PH has never been explored. This study's goal was to investigate the role and mechanism of IL-13 in the pathogenesis of PH. Lung-specific IL-13-overexpressing transgenic (Tg) mice were examined for hemodynamic changes and pulmonary vascular remodeling. IL-13 Tg mice spontaneously developed PH phenotype by the age of 2 mo with increased expression and activity of arginase 2 (Arg2). The role of Arg2 in the development of IL-13-stimulated PH was further investigated using Arg2 and IL-13 receptor ␣2 (R␣2) null mutant mice and the small-interfering RNA (siRNA)-silencing approach in vivo and in vitro, respectively. IL-13-stimulated medial thickening of pulmonary arteries and right ventricle systolic pressure were significantly decreased in the IL-13 Tg mice with Arg2 null mutation. On the other hand, the production of nitric oxide was further increased in the lungs of these mice. In our in vitro evaluations, the recombinant IL-13 treatment significantly enhanced the proliferation of human pulmonary artery smooth muscle cells in an Arg2-dependent manner. The IL-13-stimulated cellular proliferation and the expression of Arg2 in hpaSMC were markedly decreased with IL-13R␣2 siRNA silencing. Our studies demonstrate that IL-13 contributes to the development of PH via an IL-13R␣2-Arg2-dependent pathway. The intervention of this pathway could be a potential therapeutic target in pulmonary arterial hypertension.

Various treatments approved by the United States Food and Drug Administration for the management of pulmonary arterial hypertension (PAH) target three of the many pathways implicated in the development of PAH: prostacyclin-, endothelin-1 (ET-1)-, and nitric oxide-mediated pathways. The objectives of this manuscript are to provide background information on the role of ET-1 in the pathogenesis of PAH, to provide theoretical considerations for the advantages and disadvantages of dual vs single endothelin receptor antagonists (ERAs) for the management of PAH, and to describe the clinical study results from randomized, double-blind, placebo-controlled trials for the various ERAs. ET receptors (ET(A) and ET(B)) have different densities and distributions throughout the body and are dynamically regulated, such that blockade of ET(A) and ET(B) receptors may have different results in normal vs pathological conditions. Although differences in biological effects can be found in studies of isolated cells, blood vessels and animal models, clinical treatment studies have not identified clear differences in efficacy among the various ERAs. The main differences appear to be in safety profiles, with a greater frequency of serum liver function abnormalities occurring with the available dual ET(A)/ET(B) antagonist, and possibly higher rates of peripheral edema noted with selective ET(A) agents. Head-to-head studies will be necessary to resolve the question of whether single vs dual blockade produces better clinical results with fewer side effects in patients with PAH.

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Accurate diagnosis of pulmonary arterial hypertension is a challenging and complex process that requires a high index of clinical suspicion from even the most astute clinician. This article discusses the use of a variety of noninvasive tests that can help define the population of patients in whom invasive cardiac catheterization should be pursued. It points out the vagaries and limitations of electrocardiography and the radiographic and echocardiographic clues to the diagnosis. Ultimately, right- and, often, concomitant left-heart catheterization is required to establish the diagnosis and distinguish pulmonary arterial hypertension from pulmonary venous hypertension.