Alterations of Flow-Mediated Dilation of the Brachial Artery in Women after Menopause

Introduction Risk of cardiovascular diseases increases after menopause. Decrease in estrogen alters endothelium function, the first event in the atherosclerotic process. Endothelium function can be assessed by flow-mediated dilatation (FMD) during reactive hyperemia. We compared differences in brachial artery FMD in women before and after menopause. Methods Average ages of control (n = 35) and postmenopausal (n = 38) women were 34 ± 8 (SD) and 57 ± 7 years respectively. No subjects were on estrogen therapy or had known risk factors for cardiovascular disease. Brachial artery FMD was measured 5 cm above the cubital crease, using a 14 MHz transducer. B-mode images were selected during diastole using the flow waveform. Diameter measurements were performed before brachial artery occlusion and 60 seconds after release of a 5-min occlusion accomplished with pneumatic cuff inflation. FMD expressed the percentage change in diameter during reactive hyperemia versus baseline. Results Average FMD was 19 ± 6% (11 – 30%) for controls, decreasing significantly to 14 ± 6% (3–26%) post-menopause ( p < 0.001 by t-test). FMD was abnormally lower than 10% in 9 post-menopausal women, 7 older than 60 years, and 8 with menopause ≥10 years. Conclusions FMD decreased significantly post menopause and were abnormally low in older women with longer menopause. Changes in FMD with age, duration of menopause and relation of low FMD to risk development deserves further investigation to determine if FMD can be used as an independent risk factor.