Echocardiographic assessment of overt or latent unexplained pulmonary hypertension.

Primary (idiopathic or unexplained) pulmonary hypertension is a rare disease of the pulmonary vasculature characterized by sustained elevation of pulmonary artery pressure, normal pulmonary artery wedge pressure and absence of secondary causes. Because of the nonspecific nature of early symptoms and physical findings, the diagnosis, essentially one of exclusion, is often made in the later stages of primary pulmonary hypertension. Echocardiography, providing an accurate noninvasive estimate of pulmonary pressure at rest and during exercise, is an essential component in the initial assessment and serial evaluation of patients with primary pulmonary hypertension. Furthermore, it is important to monitor the efficacy of specific therapeutic interventions, to estimate the prognosis and to detect preclinical stages of this disease.