The American College of Chest Physicians (ACCP) has released evidence-based practice guidelines for the early detection and diagnosis of pulmonary arterial hypertension (PAH). The guidelines are available online at http://www.chestjournal.org/content/vol126/1_suppl/
Although there is no uniformly accepted definition for PAH, the ACCP used the hemodynamic definition developed by the National Institutes of Health Registry on Primary Pulmonary Hypertension: a mean pulmonary artery pressure of 25 mm Hg or greater and a pulmonary capillary wedge pressure of 15 mm Hg or less, both measured at rest by right-heart catheterization.
Because PAH does not become manifest until the pulmonary vascular disease is advanced, mild elevations in pulmonary arterial pressure can reflect diffuse and extensive vascular damage. Changes in right ventricular function and structure occur later in the clinical course of PAH. Therefore, early detection is needed by identification and validation of biomarkers or other easily obtained parameters to assess the vascular process. The ACCP recommends that genetic testing and counseling be offered to relatives of patients with familial PAH. Patients with idiopathic PAH should be advised about the availability of genetic testing and counseling for their relatives.
The ACCP recommends that patients with suspected PAH be screened with echocardiography to detect cardiac anatomic and arrhythmic problems. Although this method is not sufficiently sensitive to effectively screen for PAH, it can provide prognostic information in patients with confirmed PAH. Doppler echocardiography can be used to detect pulmonary hypertension and evaluate right ventricular systolic pressure. In asymptomatic, high-risk patients, Doppler echocardiography should be used to detect elevated pulmonary arterial pressure. Chest radiographs should be obtained to reveal features that support a diagnosis of PAH and to detect underlying diseases.
Right-heart catheterization is required in patients with suspected PAH to confirm pulmonary hypertension, establish the specific diagnosis, determine the severity of disease, and guide therapy. Ventilation-perfusion scanning can rule out chronic thromboembolic pulmonary hypertension (CTEPH) in patients with PAH. Contrast-enhanced computed tomography or magnetic resonance imaging should not be used to exclude CTEPH. Pulmonary angiography is required in patients with a ventilation-perfusion scan suggestive of CTEPH for accurate diagnosis and best anatomic definition to assess operability. Serial determination of functional class and exercise capacity assessed by the six-minute walk test provide benchmarks for disease severity, response to therapy, and progression.
Testing for connective tissue disease and human immunodeficiency virus infection should be performed in patients with unexplained PAH, and an assessment of sleep-disordered breathing is recommended in patients with PAH. Pulmonary-function testing and determination of arterial blood oxygenation should be performed to detect lung disease. Lung biopsy is not routinely recommended except in cases in which a specific question can be answered only by tissue examination.
Patients with idiopathic PAH should undergo acute vasoreactivity testing with a short-acting agent such as adenosine, intravenous epoprostenol, or inhaled nitric oxide. Patients with idiopathic PAH and no right-heart failure who have a favorable response to a vasodilator should be considered for a trial of oral calcium channel antagonists. These agents should not be used empirically in patients without proven acute vasoreactivity. New York Heart Association (NYHA) class III patients with PAH who have failed or who are not candidates for calcium channel blocker therapy may be considered for long-term therapy with endothelin-receptor antagonists, intravenous epoprostenol, subcutaneous treprostinol, inhaled iloprost, or beraprost.
Patients with suspected CTEPH should be referred for pulmonary thromboen-darterectomy, and patients with PAH and NYHA class III and IV symptoms should be referred for evaluation for lung or heart-lung transplantation.