Pulmonary Arterial Hypertension : Current Concepts

precapillary pulmonary resistance. Pulmonary hypertension is deemed present when the mean pulmonary artery pressure exceeds 25 mm Hg at rest, or 30 mm Hg with exercise. The presence of pulmonary arterial hypertension further requires normal left heart filling pressures (i.e. a normal left ventricular end diastolic pressure directly measured, or indirectly approximated by a pulmonary artery occlusion pressure less than 15 mm Hg). Pulmonary hypertensive disorders are classified into groups on the basis of underlying mechanism, presentation, clinical context, histopathology, and response to treatment (Table 1)