Properly diagnosing pulmonary arterial hypertension

Pulmonary hypertension (PH) is found in many clinical conditions and is associated with increased morbidity and mortality. Pulmonary arterial hypertension (PAH) is a clinical condition characterized by precapillary PH without causes such as lung disease, chronic thromboembolic PH, or other rare conditions. Evaluating a patient with suspected PH requires a series of investigations intended to confirm the diagnosis, determine the clinical PH group (and, in the case of PAH group 1, the specific etiology), and evaluate the functional and hemodynamic impairment. The workup should identify the risk factors for PH (e.g., left heart disease, lung diseases associated with alveolar hypoxia, and chronic thromboembolism) versus the conditions associated with PAH group 1 (e.g., scleroderma, human immunodeficiency virus, anorexigen use, liver disease). A detailed algorithm is presented to help physicians determine the appropriate PH category. Because the presence of one condition associated with PH does not exclude another etiologies, clinicians are strongly encouraged to follow the entire algorithm. Discussions and case studies are presented describing the differentiation of PAH group 1 from PH group 2 and PAH group 1 from PH group 3; diagnosing PH group 4; determining the long-term calcium channel blocker response in those with idiopathic PAH; and determining the severity of PH.