EFFECT OF ISRADIPINE ON MATERNAL RENAL-ARTERY PULSATILITY INDEX IN HYPERTENSIVE PREGNANCY

Objective: To investigate the effect of the calcium antagonist isradipine on maternal renal Doppler blood flow indices in pregnancies complicated with hypertension. Methods: Thirty-one women with hypertension in pregnancy were consecutively recruited in an open study. Fifteen women received oral slow-release isradipine 5 mg twice daily for a 2-week period. Measurements of blood pressure and Doppler blood flow velocity pulsatility index (PI) in the renal artery were obtained before treatment and were repeated 1 and 2 weeks after the treatment was started. The velocity-pressure index (VPI) was calculated as a ratio of PI and the pressure pulsatility index (PPI). A control group of 16 untreated hypertensive women was investigated in the same way. Results: In the control group blood pressure increased, while in the treatment group it decreased, giving a significant difference in percent change of mean arterial pressure between groups. The PI in the treatment group decreased significantly by 10% after 2 weeks, while in the control group PI did not change. There was a significant positive correlation between PPI and PI (r = 0.41, P < 0.05). The percent change in VPI from baseline was significantly different in the treatment compared to the control group. Conclusions: The finding of a decrease in both PI and VPI, together with a moderately reduced maternal blood pressure induced by isradipine, might reflect a decreased preglomerular resistance and maintained or relatively increased intraglomerular pressure. If isradipine were found to have a renoprotective effect also in pregnancy, it should not be due to the hemodynamic effects on the kidney.