Stroke volume changes during dobutamine-atropine stress echocardiography: the influence of heart rate and ischaemia

Background: A decrease in stroke volume during dobutamine-atropine stress echocardiography heralds ischaemia and possible hypotension. Hypotension results from worsening of LV-function (as a result of ischaemia) left ventricular outflow tract obstruction or hypovolemia, while an increase of stroke volume indicates the preservation of myocardial contractile reserve. Objective: To assess stroke volume changes during dobutamine stress echocardiography in relation to heart rate and occurrence of ischaemia and to validate a new automated cardiac output measurement device. Methods: In fifty patients, the stroke volume was assessed using the echocardiographic biplane discs method during a stress echocardiography. These data were reference values for the validation of a new automated cardiac output measurement using the first method as a reference. Results: Stroke volume measured by the biplane discs method and automated cardiac output device decreased from rest to peak stress, respectively, from 54 ± 16 to 34 ± 9 (63%) ml and 63 ± 17 to 38 ± 15 (60%) ml (p < 0.001). Stroke volume decreased with increased heart rate and stress-induced ischaemia when assessed by the biplane discs method, but with the automated device it decreased only with increased heart rate. Conclusions: Both increased heart rate and myocardial ischaemia during dobutamine stress echocardiography cause a reduction of stroke volume. However, the automated device did not detect the effects of stress-induced ischaemia on stroke volume. It appears that the biplane discs method is more sensitive for evaluating the effect of ischaemia.