Cardiovascular response in patients with and without myocardial ischaemia during dobutamine echocardiography stress test for coronary artery disease

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Abstract
Dobutamine is widely used in cardiac stress testing for coronary artery disease and myocardial viability. To assess the systemic cardiovascular response during dobutamine echocardiography stress testing, we investigated nine patients without myocardial ischaemia (group 1, aged 48 to 72 years) and nine patients with myocardial ischaemia during the test (group 2, aged 53 to 73 years), by use of Doppler/echocardiography and subclavian artery pulse trace calibrated with brachial artery pressures. Peripheral resistance, total arterial compliance, and aortic characteristic impedance were estimated using a 3-element windkessel model of the systemic circulation. During infusion of dobutamine up to 40 micrograms kg-1 min-1, arterial pressure was maintained near baseline levels, whereas heart rate and cardiac index increased, more so in group 1 (mean: 89 and 79%) than in group 2 (58 and 52%; P < 0.05 vs. group 1). Peripheral resistance was decreased by > or = 32% at peak stress, whereas characteristic impedance was maintained at or above baseline in both groups, and total arterial compliance was not significantly altered. The cardiovascular response in group 2 was not influenced by the wall motion abnormalities. Thus, in these patients the inotropic, chronotropic, and vasodilatory effects of dobutamine balanced the ischaemic impairment of left ventricular function during the stress test.

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