Effect of Endogenous Estrogen on Blood Flow Through Carotid Arteries

Abstract

Background and Purpose-Recent evidence suggests that physiological changes in the concentration of endogenous estrogens may influence stroke outcome. The purpose of this study was to determine a menstrual cycle-related profile of blood flow through the carotid arteries and its correlation with estrogen concentration. Methods-The flow velocity and cross-sectional area of the common carotid artery, internal carotid artery (ICA), and external carotid artery (ECA) were measured with duplex Doppler sonography throughout the menstrual cycle in 14 healthy women. Concentration of plasma 17␤-estradiol, progesterone, hematocrit, hemoglobin, and blood pressure were also determined. Results-In the follicular phase, the concentration of estrogen increased to reach a peak on day 14, whereas concentration of progesterone remained low. The mean and end-diastolic velocities in the ICA increased on average by 15% of their base values, along with increasing concentrations of estrogen (rϭ0.59 and 0.65, respectively). The profile of flow velocity changes in this artery corresponded to the profile of estrogen concentration. In contrast to the ICA, flow velocities in the ECA decreased from their base value, reaching their minimum in the luteal phase. The mean flow velocity in the common carotid artery increased on day 14 by just 2% of its base value. The lumen of the carotid arteries was stable throughout the cycle. Hematocrit, hemoglobin, and systolic blood pressure also remained unchanged. Conclusions-Increased

Cerebral blood flow is increased during controlled ovarian stimulation

“…Increased concentrations of endogenous estrogen during normal menstrual cycles were associated with a 15% increase in enddiastolic velocities in the ICAs (15). This change was subsequently shown to be related to a decreased resistance index in the ICAs, signifying decreased cerebrovascular impedance (16).…”

Cerebrovascular reactivity across the menstrual cycle in young healthy women

“…varied from woman to woman and cycle to cycle. Based on serial measurements of plasma concentration of sex hormones, we showed that even the standard model of the ovarian cycle in humans, with regular mid-cycle ovulation is inaccurate in predicting the actual plasma hormone concentration 15 . The spread of ovulation across the cycle varies widely, and it is only sometimes possible to determine the subjects' accurate ovulation time by relying on the calendar method alone.…”

“…The cycles were counted from the first day of menses and were standardized to a 28-day period as described in our previous study 15 . Table 1 Fluctuations of systolic and diastolic arterial blood pressure (ABP), heart rate (HR), 17-beta estradiol (E2) and progesterone (PG) during the menstrual cycle in 19 young healthy women.…”

Sources of Variability of Resting Cerebral Blood Flow in Healthy Subjects: A Study Using 133Xe SPECT Measurements

“…23,34 Metabolic Basis of Between-Subject Variability Previous studies show a very similar between-subject variability in healthy young subjects with between-subject coefficient of variation of 16% using the Kety Schmidt technique 1 and of 15% to 20% using various magnetic resonance imaging and positron emission tomography methods. 4 Relative between-subject variability in the present study was B13%.…”