Ambulatory pulmonary arterial pressure in primary pulmonary hypertension: variability, relation to systemic arterial pressure, and plasma catecholamines.

The variability of pulmonary arterial pressure, the relation of pulmonary pressure to systemic pressure, pulmonary pressure responses to stimuli (exercise, hypoxia, smoking, free ambulation), and plasma catecholamine responses were assessed in five patients with primary pulmonary hypertension. Ambulatory monitoring techniques provided data for the computerised analysis of continuous, beat-to-beat, direct recordings of both pulmonary and systemic arterial pressures for 8 to 10 hours. The absolute variability of pulmonary arterial pressure and the magnitude of absolute changes in this variable in response to stimuli were increased in primary pulmonary hypertension. The variability of systemic pressure was similar to that in healthy volunteers. Basal and stimulated plasma catecholamine values were normal, suggesting preservation of normal sympathetic nervous system activity in primary pulmonary hypertension.