OBJECTIVE: To investigate the central and peripheral haemodynamic response to dobutamine stress testing in women with suspected ischaemic heart disease and to seek an explanation for the hypotension phenomenon. DESIGN: 18 women aged 54-73 years were investigated with Doppler echocardiography and venous occlusion plethysmography during intravenous infusion of dobutamine 5-10 d after an episode of unstable angina. RESULTS: An average peak dose of 33 (SD 9.7) micrograms/kg/min was given. Heart rate 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 (decrease in systolic blood pressure > 10 mm Hg), one of whom had a paradoxical bradycardia and two a low increase in cardiac output. Patients with hypotension had a more pronounced decrease in total peripheral vascular resistance but a similar change in leg peripheral vascular resistance compared with patients without hypotension. CONCLUSIONS: Dobutamine infusion leads to marked peripheral vasodilatation and an increase in cardiac output. Some patients experience hypotension during the test for reasons which include paradoxical vasovagal reactions and diminished capacity for adequate increase in cardiac output. There is also a disparity between the pattern of total and leg peripheral vascular resistance in patients with hypotension which might reflect a baroreceptor mediated compensatory increase in vasoconstrictor tone of muscle vessels not matched in other vascular territories.
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