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.