Conjugated estrogen plus medroxyprogesterone does not impair blood rheological properties in hypertensive postmenopausal women.

OBJECTIVES: Hypertension and estrogens are both prothrombotic. We used the microchannel method to investigate whether hormone replacement therapy (HRT) with conjugated equine estrogen (CEE) plus medroxyprogesterone acetate (MPA) affects blood flow through the microchannels in hypertensive postmenopausal women being treated with antihypertensive drugs and in normotensive postmenopausal women. METHODS: Sixty-two consecutive postmenopausal women were randomly assigned to a hypertensive HRT group (n=16), hypertensive control group (n=15), normotensive HRT group (n=16) and normotensive control group (n=15). Each HRT group received CEE 0.625 mg plus MPA 2.5 mg daily orally for 12 months. Both hypertensive groups were being treated with antihypertensive drugs before the study. Microvascular blood flow was assessed on the basis of blood passage time, the time required for 100 microl of whole blood to pass through a cylinder, was determined before and 12 months after the start of HRT by the microchannel method (micro channel array flow analyzer). RESULTS: CEE plus MPA therapy did not change blood passage time in any of the groups. Microscopic observation showed that the whole blood passed smoothly through the microchannels in every group. CONCLUSIONS: CEE plus MPA therapy may not impair blood flow through the microchannels in hypertensive postmenopausal women receiving antihypertensive drugs or in normotensive postmenopausal women. However, administration of CEE plus MPA to postmenopausal women with hypertension warrants caution against the occurrence of thromboembolic events.

Effect of antihypertensive therapy on blood rheology in patients with essential hypertension.

Hypertension is an important risk factor for cardiovascular disease, and antihypertensive drugs can decrease the occurrence of such events in hypertensive patients. This study compared the rheological properties of blood in 22 untreated hypertensive patients, 42 patients taking antihypertensive drugs and 74 normotensive subjects. Using a microchannel method, the whole blood passage time was measured and blood movement was observed with a microscope connected to an image display unit. The blood passage time in untreated hypertensive patients was significantly higher than in treated hypertensive patients or normotensive subjects, but was similar in the latter two groups. Microscopic observations showed that platelet aggregation and leucocyte adhesion were increased in untreated hypertensive patients, resulting in poor flow, while blood samples from treated hypertensive patients and normotensive subjects passed smoothly through the microchannels. These rheological differences could contribute to the decrease in cardiovascular disease seen when hypertensive patients are treated effectively.