Noninvasive assessment of the cardiovascular effects of prostacyclin (PGI2) in man.

The cardiovascular actions of prostacyclin (PGI2) were investigated in a double-blind, randomised, balanced study. Six healthy volunteers received intravenous infusions of PGI2 in a range of doses up to 4 ng/kg per min, which is the lowest dose which consistently inhibits platelet aggregation. Measurements of systolic time intervals, peak normalised first derivative of the apexcardiogram, high-speed surface electrocardiogram and arterial blood pressure were made during each infusion. PGI2 caused dose-related decreases in diastolic blood pressure, preejection period and QS2 index, and an increase in heart rate. Systolic blood pressure, left ventricular ejection time index, the peak normalised first derivative of the apexcardiogram, and PR interval, QRS duration, QT index and T-wave amplitude were unchanged. Facial flushing was seen in all subjects at PGI2 4 ng/kg per min. These results suggest that PGI2 has an important arteriolar vasodilator action, but do not exclude a minor direct effect on contractility.