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

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 < 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.