Effects of dihydralazine infusion on the fetoplacental blood flow and maternal prostanoids.

The hemodynamic effects of intravenously infused dihydralazine (incremental doses up to 125 micrograms per minute during 60 minutes) were studied in ten women with acute or superimposed severe preeclampsia. The intervillous and umbilical vein blood flow were measured before and during dihydralazine infusion with 133Xenon method and with a combination of real-time and Doppler ultrasonic equipment, respectively. Maternal blood pressure decreased and pulse rate increased during the infusion. Dihydralazine did not change the intervillous blood flow but it increased the blood flow in umbilical vein. No effect on the 6-ketoprostaglandin F1 alpha in maternal plasma and urine or thromboxane B2 in maternal serum was observed. The results indicate that dihydralazine affects the placental and fetal circulations differently.