[Acute hemodynamic effects of prostacyclin in severe or malignant hypertension]

The antihypertensive effect of Prostacyclin (PGI2) was investigated in 7 patients with severe or malignant hypertension. Cardiac output (dilution method), arterial blood pressure and total blood volume (TBV, radio-albumin dilution method) were measured before and during a PGI2 infusion, the effective dose ranging from 10 to 20 ng/kg/min. Cardiac index(CI) rose from 2.8 to 3.9 1/min/m2 and heart rate (HR) from 75 to 94 beats/min (p less than 0.01) Mean blood pressure decreased from 154 to 120 mmHg (p less than 0.001) and total peripheral resistances from 4650 to 2540 dynes.s.cm-5 (p less than 0.001). The ratio: central blood volume/total blood volume increased from 0.21 to 0.26 (p less than 0.001). The results confirm that PGI2 produces a potent vasodilatation of the systemic compartment with a marked decrease in blood pressure; however the antihypertensive effect is blunted by the increase in CI mainly related to the increase in HR; significant central translocation of blood suggests that PGI2 does not produce dilatation of the capacitance vessels. Sympathetic nervous system is highly stimulated by PGI2 very likely through the baroreceptor system.