Postmenopausal estrogen therapy, initiated early in the menopause, seems to protect against development of atherosclerosis and cardiovascular diseases. This thesis concerns studies of artery wall thickness and arterial stiffness estimated by noninvasive ultrasound techniques in long-term estrogen treated postmenopausal women who initiated therapy at the time of the menopause.A noninvasive 25 MHz high-frequency ultrasound technique was validated in the imaging of superficial arteries by using an animal model. Ultrasound estimates of the artery wall layers obtained in vivo in the pig were compared to ex-vivo histomorphometry. Valid estimates of total artery wall and media thickness were found for the most superficial arteries. Adventitia thickness was underestimated and intima thickness overestimated in this animal model when non-atherosclerotic vessels were imaged.To validate the clinical usefulness of separately estimating the artery wall layers in the human, the carotid artery wall was imaged in elderly subjects. Separate estimates of intima thickness, media thickness and intima/media ratio differed significantly between subjects with and without atherosclerosis and CVD, indicating that this noninvasive high-frequency ultrasound method might be a strong tool in monitoring changes in artery wall morphology associated with aging and development of atherosclerosis.The investigation of intima thickness, media thickness and intima/media ratio of the carotid and femoral arteries in long-term estrogen treated postmenopausal women showed a maintenance of a thin intima and a preservation of media thickness and intima/media ratio at values similar to those obtained in women of fertile age…
Contents
Introduction
Cardiovascular disease in women
Can postmenopausal hormone therapy (HT) help to prevent CVD?
Evidence from observational data and randomized trials
Evidence of a cardioprotective effect of estrogen based on animal
experiments
Possible beneficial effects of estrogen on the artery wall
Investigation of effects of postmenopausal estrogen therapy on the
artery wall by using noninvasive ultrasound
Artery wall thickness as a marker of atherosclerosis
Study of the artery wall thickness in postmenopausal women
Need to develop more accurate noninvasive methods in the investigation of atherosclerosis
Use of high-frequency ultrasound in imaging the artery wall
Interest in investigating separately the thickness of the intima and media layers in postmenopausal women
Artery wall stiffness as a marker of atherosclerosis
Interest in evaluating the mechanical properties of the artery
wall in postmenopausal women
Present investigations
Aims
Material and Methods
Animals
Subjects
Assessment of total wall thickness, media and intima thickness
Histomorphometry
Diagnosis of cardiovascular diseases
Arterial stiffness assessments
Serum hormone concentrations
Serum lipids
Statistical methods
Results
Validation of a novel noninvasive high-frequency ultrasound technique in imaging the artery wall (study I)
Precision error for estimates of artery wall thickness obtained in humans by high-frequency ultrasound
Clinical usefulness and validity of separate estimates of intima and media thickness and intima/media ratio (study II)
Long-term estrogen therapy initiated at the time of menopause and thickness of the artery wall layers (study III)
Long-term estrogen therapy initiated at the time of menopause and
arterial stiffness (study IV
Discussion
General conclusions
Figures
Acknowledgements
References
Author: Rodriguez-Macias Wallberg, Kenny A.
Source: Uppsala University Library
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