Abstract

In previous studies from this laboratory, we found that approximately 30 of women with chest pain and normal coronary arteries demonstrated either a decrease in or a failure to increase radionuclide ejection fraction during exercise. To examine the hypothesis that this apparent abnormality in left ventricular function represents a physiologic difference between men and women, we prospectively studied central and peripheral cardiovascular responses to exercise in 31 age-matched healthy volunteers (16 women and 15 men). Normal male and female volunteers demonstrated comparable baseline left ventricular function and similar aerobic capacity. However, their cardiac responses to exercise were significantly different. Ejection fraction increased during exercise in men, but was unchanged during exercise in women. Enddiastolic counts increased by 30 in women, but was unchanged in men. Because decreases in ejection fraction were matched by increases in end-diastolic counts, relative increases in stroke counts and count output were the same for men and women. These data demonstrate a basic difference between men and women with respect to the mechanism by which they achieve a normal response of stroke volume to exercise. Verf.-Referat