Flow velocity analysis of umbilical and uterine artery flow in pre-eclampsia treated with propranolol or pindolol

Abstract

In a double blind study, 20 gravidas with pre-eclampsia were randomly allocated to treatment with either propranolol 120 mg/day or pindolol 15 mg/day for 7 days. Flow velocimetry was performed before and after treatment to assess the influence of these two regimens of beta blocker on the feto-placental circulation. A continuous wave Doppler unit was used to measure umbilical and uterine artery flow velocity waveforms. The systolic/diastolic (A/B) ratio and the systolic minus diastolic divided by systolic (A-B)/A ratio (resistance index) were used as indexes of blood flow resistance in the umbilical and uterine arteries, respectively. A resistance to flow in the uteroplacental circulation was significantly less in patients treated with pindolol compared to those treated with propranolol (P less than 0.01). The same pattern was also found in umbilical velocimetry, although the statistical significance was borderline (P = 0.06). Although both drugs were equally effective in reducing blood pressure at rest, their effect on the peripheral resistance was different. Pindolol appears to act in part through a peripheral vascular mechanism. Our data support this assumption because the flow in the uteroplacental bed, as reflected by a decrease in resistance index, improved when patients were treated with the drug pindolol.