Margaret Rose

Date of Award

11-15-2006

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

David Silverman

Abstract

Estrogen is well-known to be protective against cardiovascular disease in women. In addition to improving lipid metabolism, it also decreases vascular resistance and enhances vascular reflexes, thereby improving vasomotor stability and increasing the arterial capacity for dilatation. Laser Doppler flowmetry (LDF) has demonstrated these changes in research trials, and is emerging as having potential application in many clinical and surgical situations. In this study, our aim was to examine the impact of estrogen upon baseline blood flow as well as the response to vasodilatory interventions and to further evaluate the utility of laser Doppler as a clinical non-invasive measurement of blood flow in such contexts. We compared blood flow in the forehead cutaneous microvasculature of women during both high and low estrogen states of their menstrual cycle, and compared this to the flow in male subjects. To evaluate differences in vascular reactivity, we subjected the microvasculature to two challenges: the cutaneous application of nitroglycerin to the site of the probe; and transient occlusion of flow to evince a hyperemic response. Furthermore, to investigate the reproducibility of laser Doppler data, we examined both temporal and spatial variability, and used each subject as his/her own control. We found significant spatial variability in the LDF measure of baseline flow rates. Temporal variability was also seen within subjects, but was decreased by using median baseline values. Hormone state in females did not significantly affect baseline flow, response to topical nitroglycerin, or hyperemic response to occlusive pressure. In males, the difference between session 1 and session 2 LDF readings was not significant. Although LDF has potential clinical applications, the clinical scenarios and patient populations must be further defined. Furthermore, the most practical technique with consistent reproducibility must be developed.

Comments

This is an Open Access Thesis.

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