Acute efficacy of a sublingual dose of nifedipine on uterine arterial blood flow: Preliminary data in prematurely menopausal women

Abstract

Objectives: To determine whether the calcium blocker nifedipine alters Doppler velocimetry and impedance parameters in the uterine artery in prematurely menopausal women. Methods: Uterine artery Doppler examinations were performed transvaginally in seventeen prematurely menopausal women without the use of calcium blocker (T0). Following a 10-mg sublingual dose of nifedipine patients were subsequently rescanned at successive time intervals (T25 = 25, T40 = 40, T60 = 60 min). PI (normalized (NPI) for heart rate) and maximum, minimum and average velocities of the uterine artery were recorded and waveforms were qualitatively assessed using Goswamy and Steptoe's waveform classification. Results: Quantitative analysis showed a significant decrease in NPI at T25 in the right and left uterine arteries (T0: PI = 2.95 and 3.01; T25: PI = 1.52 and 1.52, respectively; P < 0.001) and until the end of the experiment. Minimum and average blood flow velocities increased strongly (P < 0.001) whereas the maximum velocities did not change significantly (P = 0.12). Qualitative analysis revealed more conspicuous results: eight subjects presented 'abnormal' spectra: one was type A (absence of protodiastole), three were type B (absence of telediastole) and four were type 0 (no diastolic blood flow); all of them recovered type C waveforms (normal spectrum) during the hour following nifedipine administration. Conclusions: Nifedipine induces a reversible decrease in NPI and an increase in blood flow velocities in the uterine artery in prematurely menopausal women. These results suggest that nifedipine is a potent uterine arterial vasodilator. Copyright © 2004 ISUOG.