Classification of Pulmonary Vascular Disease

Traditionally, pulmonary hypertension (PH) has been defined as a mean pulmonary arterial pressure (mPAP) of ≥ 25 mmHg and a pulmonary vascular resistance of ≥ 3 Wood Units at rest, obtained invasively via a right heart catheterization. Based on new data, the 6th World Symposium for Pulmonary Hypertension (WSPH) proposed decreasing the threshold to mPAP > 20 mmHg. Current classification divides PH into five groups, based on clinical and pathological characteristics and the presence or absence of co-morbidities that have been associated with pulmonary vascular disease. This article reviews the historical perspective of PH classification and details the current clinical and hemodynamic definitions.