Dobutamine stress testing in chronic heart failure--dose-response effects assessed by echo-Doppler

In patients with cardiac failure, data on haemodynamic function at rest may indicate impaired cardiac function but do not assess the capacity of the heart to respond to stress which may be useful in determining prognosis. Inotropic challenge with dobutamine has been shown to be at least as effective as exercise testing in assessing cardiac pumping capability. One of the limitations of dobutamine stress testing has been the need for invasive haemodynamic measurements. A new non-imaging echo-Doppler cardiac output device, incorporating the principle of attenuated compensation volume flow (ACVF), has been shown to be accurate, reproducible and useful in pharmacodynamic studies. In this study we examined the dose-response effects of dobutamine in 8 patients with chronic heart failure. Dobutamine was infused at 2, 5, 10 and 15 micrograms/kg/min with the dose being increased at 5 minute intervals and haemodynamics being determined (using the echo-Doppler) in the final 2 minutes of infusion. Our results were comparable to previous studies. There were dose-related increases in heart rate (P less than 0.05), cardiac output (P less than 0.05), and cardiac power output (work done by the heart per unit time) (P less than 0.05). Systolic blood pressure increased (P less than 0.001) and there were modest increases in mean arterial blood pressure without change in diastolic blood pressure. Time averaged mean velocity increased significantly with a trend to increase in flow acceleration. Three patients developed arrythmias during the early recovery period. The echo Doppler attenuated compensated volume flow method of determining haemodynamics proved useful but in view of the high incidence of dysrhythmia we feel that dobutamine testing in severe heart failure should be employed cautiously.