Abstract

The paper is based on the results of an earlier retrospective international WHO study of normal pressure values in the pulmonary circulation and the right heart in 468 healthy individuals. The results of this study suggest that the pulmonary hypertension should be defined by the mean pulmonary artery pressure at rest of > or = 20 mmHg and not > or = 25 mmHg. Pulmonary wedge pressure should be < 12 mmHg. These results have recently been confirmed by the so far largest retrospective international study of normal values published by Kovacs et al and involving 1187 healthy volunteers. However, this study does not include pulmonary wedge pressure values. Normal values ofthe mean pulmonary artery pressure during exercise are determined by age. In healthy individuals younger than 50 years of age, the mean pulmonary artery pressure during exercise increases in parallel with increasing cardiac output. However, the increase in the mean pulmonary artery pressure during exercise is steeper in healthy individuals aged 50 years and over. This results from a sharper increase in the pulmonary wedge pressure caused probably by diastolic dysfunction of the left ventricle in the older population.