Study objectives: Aerosolized iloprost, a stable prostacyclin analog, improves functional capacity even in patients with pulmonary hypertension who did not show a vigorous hemodynamic response after iloprost inhalation at rest. We therefore speculated that aerosolized iloprost elicits more beneficial effects on pulmonary hemodynamics during exercise than at rest.
Design and setting: A prospective, open, uncontrolled study at a university hospital.
Patients: Sixteen patients with primary or secondary pulmonary hypertension.
Interventions: Right-heart catheterization at rest and during exercise before and after the inhalation iloprost, 14 to 28 microg.
Results: Before iloprost treatment, exercise increased mean (+/- SD) pulmonary artery pressure (PAPm) from 45 +/- 8 to 70 +/- 13 mm Hg, cardiac output from 3.7 +/- 1.0 to 5.8 +/- 2.4 L/min, and pulmonary vascular resistance (PVR) from 904 +/- 322 to 1,013 +/- 432 dyne.s.cm(-5) (each p < 0.05). After recovery, iloprost reduced PAPm from 44 +/- 8 to 41 +/- 6 mm Hg, increased cardiac output from 3.7 +/- 1.0 to 4.9 +/- 1.4 L/min, and lowered PVR from 902 +/- 350 to 636 +/- 248 dyne x s x cm(-5) (each p < 0.05). During exercise after iloprost, PAPm increased to 57 +/- 8 mm Hg, cardiac output to 7.0 +/- 3.0 L/min, and PVR to 673 +/- 279 dyne x s x cm(-5) (each p < 0.05 vs first exercise test). Systemic BP was not altered significantly by iloprost treatment during exercise.
Conclusions: Aerosolized iloprost treatment exerts more favorable effects on pulmonary hemodynamics during exercise than at rest. These findings explain the functional improvement observed in patients with pulmonary hypertension who show only a moderate pulmonary vasodilatory response during iloprost inhalation at rest. Whether these beneficial effects have prognostic significance needs to be elucidated by further study.