Pulmonary hypertension: work in progress.

Pulmonary arterial hypertension is a rare disorder defined by mean pulmonary artery pressures that exceed 25 mm Hg at rest or are greater than 30 mm Hg with exercise. The mortality rate is high for untreated patients, mainly as a result of progressive right heart dysfunction. Pulmonary arterial hypertension has been historically classified as primary pulmonary hypertension or pulmonary hypertension resulting from an underlying disease process. Ongoing research in the nuclear medicine field holds great promise for understanding the pathophysiologic pathways for this condition, as well as the monitoring of the continually evolving therapeutic options.