Effects of alveolar hypoxia during partial mitral valve obstruction in unanesthetized sheep.

10 chronically instrumented unanesthetized sheep

Isocapnic hypoxia (fraction of inspired O2, 0.12) or infused prostaglandin-H2 analog (PGH2-A, 0.2 to 1.0 micrograms/kg/min) with elevated left atrial pressure (10 or 20 cm H2O via inflated Foley catheter in the mitral valve orifice)

Same interventions with normal left atrial pressure

Pulmonary hemodynamic responses (pulmonary artery pressure, cardiac output, pulmonary vascular resistance)surrogate