Chronic use of 17β‑Ethinyl estradiol on cardiovascular hemodynamic profile: “Friend or foe”?

Abstract

Introduction: The effects of ovariectomy (Ovx), menopause, and estrogen replacement
on the hemodynamic remain controversial. This study employed the technique of
impedance cardiography analysis to measure the effect of chronic use of estrogen
replacement on cardiovascular hemodynamic in the Ovx rats. Materials and Methods:
Colony‑bred adult Ovx female Sprague‑Dawley rats were randomized into three
groups: 17 β‑Ethinyl Estradiol treated ovariectomized group (OvxE), vehicle treated
ovariectomized group (OvxV), and Sham Operated (SO). Animals received 17 β‑Ethinyl
Estradiol (17 β‑EE) once daily for 90 days. Cardiovascular hemodynamic parameters
such as left ventricular ejection time (LVET), pre‑ejection period (PEP), Systolic time
interval (STI), cardiac output (CO), cardiac index (CI), stroke volume (SV), and stroke
volume index (SVI) were assessed 24 h after last treatment on 7, 15, 30, 60, or 90 days.
Results: Compared to SO group, Ovx with or without estrogen replacement did not
significantly affect the mean blood pressure, CO, CI, SV, and SVI. No significant changes
were observed in LVET and PEP from SO. Treatment with estradiol increased the STI by
66.62% and 53.60% (P < 0.05), from control after 60 and 90 days, respectively. Blood
velocity, base impedance (Zo) and maximum change in impedance during systole (Zt)
corresponding to time‑varying fluid volume (blood) remained within normal limits of
variation. Conclusion: These results demonstrate that on long‑term administration of
estrogen significantly increased STI in rats.