CARDIOVASCULAR EFFECTS OF DOBUTAMINE STRESS-TESTING IN WOMEN WITH SUSPECTED CORONARY-ARTERY DISEASE

Objective-To investigate the central and peripheral haemodynamic respo nse to dobutamine stress testing in women with suspected ischaemic hea rt disease and to seek an explanation for the hypotension phenomenon. Design-18 women aged 54-73 years were investigated with Doppler echoca rdiography and venous occlusion plethysmography during intravenous inf usion of dobutamine 5-10 d after an episode of unstable angina. Result s-An average peak dose of 33 (SD 9.7) mu g/kg/min was given. Heart rat e and cardiac output increased by 49% and 59%, respectively (P<0.001). Total and leg peripheral vascular resistance decreased by 44% and 26% , respectively (P<0.001). Four patients developed hypotension (decreas e in systolic blood pressure > 10 mm Hg), one of whom had a paradoxica l bradycardia and two a low increase in cardiac output. Patients with hypotension had a more pronounced decrease in total peripheral vascula r resistance but a similar change in leg peripheral vascular resistanc e compared with patients without hypotension. Conclusions-Dobutamine i nfusion leads to marked peripheral vasodilatation and an increase in c ardiac output. Some patients experience hypotension during the test fo r reasons which include paradoxical vasovagal reactions and diminished capacity for adequate increase in cardiac output. There is also a dis parity between the pattern of total and leg peripheral vascular resist ance in patients with hypotension which might reflect a baroreceptor m ediated compensatory increase in vasoconstrictor tone of muscle vessel s not matched in other vascular territories.