Pulmonary artery pressure-flow relations after prostacyclin in primary pulmonary hypertension.
Exercise tolerance improves within a few weeks after prostacyclin initiation in patients with primary pulmonary hypertension even in the absence of significant changes in resting pulmonary vascular resistance and/or in patients who fail to respond to an acute vasodilator challenge. We tested the hypothesis that this early effect of prostacyclin may be ascribable to an improved pressure-flow response of the pulmonary circulation to exercise. Pulmonary hemodynamic variables at rest and during exercise and the 6-min walking distance were determined before and after 6 wk of continuous intravenous prostacyclin treatment (11 +/- 1.5 ng/kg/min) in seven patients unresponsive to an acute nitric oxide vasodilator test. Mean pulmonary arterial pressure/cardiac index coordinates obtained during exercise were pooled, and the slopes of these plots were compared using covariance analysis. All hemodynamic variables at rest were unchanged after prostacyclin. By contrast, the 6-min walking distance improved in all patients (mean increase, 81 m) and the slope of the mean pulmonary artery pressures/cardiac indexes plot decreased with prostacyclin, from 18.2 to 13.1 mm Hg/L/min/m(2) (p < 0.01). These results suggest that the improvement in exercise tolerance seen after 6 wk of prostacyclin therapy may be ascribable to a decrease in incremental pulmonary vascular resistance during exercise.
Castelain
Vincent
V
Department of Pulmonary Medicine (UPRES 2705), Antoine Béclère Teaching Hospital, Clamart, France.
Chemla
Denis
D
Humbert
Marc
M
Sitbon
Olivier
O
Simonneau
Gerald
G
Lecarpentier
Yves
Y
Hervé
Philippe
P
D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001794:Blood Pressure; D011464:Epoprostenol / Q000627:therapeutic use*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D008875:Middle Aged; D011651:Pulmonary Artery / Q000502:physiology*; D011652:Pulmonary Circulation / Q000502:physiology*; D012039:Regional Blood Flow
D000959:Antihypertensive Agents; D011464:Epoprostenol