Epoprostenol treatment of acute pulmonary hypertension is associated with a paradoxical decrease in right ventricular...

Area of Science:

• Cardiovascular Physiology
• Pulmonary Hypertension Research
• Pharmacology

Background:

• Prostacyclins, like epoprostenol, are investigated for potential positive inotropic effects in right ventricular (RV) dysfunction.
• Existing data on prostacyclins' inotropic effects in pulmonary hypertension (PHT) are conflicting and depend on experimental conditions.

Purpose of the Study:

• To investigate the inotropic effects of epoprostenol at clinically relevant doses in an experimental model of acute pulmonary hypertension.
• To clarify the controversial role of prostacyclins in RV dysfunction.

Main Methods:

• Prospective laboratory study in pigs instrumented with biventricular conductance catheters and pressure/flow monitoring.
• Administration of incremental doses of epoprostenol (10-40 ng/kg/min) in healthy animals and after inducing acute hypoxia- PHT.
• Assessment of RV afterload and contractility using pressure-volume relationships.

Main Results:

• Epoprostenol significantly reduced RV afterload in acute PHT.
• A paradoxical, dose-dependent decrease in RV contractility was observed in PHT.
• Left ventricular contractility was unaffected except at the highest epoprostenol dose.
• In healthy animals, epoprostenol had minimal impact on vascular tone and caused a mild biventricular decrease in contractility.

Conclusions:

• Epoprostenol lacks positive inotropic effects in vivo.
• Pulmonary vasodilation induced by epoprostenol in PHT is associated with a paradoxical decrease in RV contractility, likely due to RV afterload coupling.
• Mechanisms beyond vasodilation may contribute to the negative inotropic response observed in healthy animals.