Update in Pulmonary Hypertension 2008

PAH is a disease of the small pulmonary arteries, characterized by intense remodeling resulting in a progressive increase in pulmonary vascular resistance (2). PAH is a condition that can occur in an idiopathic form or in association with other disease states or exposures and is believed to result from environmental or disease-inciting factors coupled with genetically determined susceptibilities (1, 2). By definition, patients with PAH do not have significant left heart disease, lung disease, or chronic thrombo-embolic disease (1, 2). A diagnosis of PAH requires invasive hemodynamic criteria, including a mean pulmonary artery pressure greater than 25 mm Hg at rest and a normal pulmonary capillary wedge or left ventricular end-diastolic pressure less than 15 mm Hg (2). Multiple risk factors and associated conditions that trigger and/or worsen the progression of the disease have been recognized (1, 2).