[Doppler echocardiography determination of the minute heart volume in ergometric stress]

To prove the use of Doppler-echocardiography in the determination of cardiac output during supine bicycle exercise, 14 patients suffering from dilatative cardiomyopathy were studied. Cardiac output was simultaneously determined by Doppler-echocardiography and with radionuclide ventriculography. In some cases, cardiac output was additionally measured using the thermodilution technique. In 12 patients (success rate 86%) flow velocity signals from the ascending aorta could be recorded with sufficient quality. Both methods were closely correlated, the r-value was 0.91 and the standard error of estimate was found to be 2.09 l/min. Mean deviation was 1.50 l/min (0.09-5.45 l/min) or 13% (1%-64%) respectively. For changes in cardiac output with exercise, the correlation was r = 0.88 with a mean deviation of 69% (2%-453%). The coefficient of variation for exercise measurements was 19% and did not differ from the resting value of 20%. Comparing the mean values of the whole group, no differences between the two methods could be found at rest, during exercise or for changes from rest to maximal exercise. Using the suprasternal approach, aortic flow velocities can be assessed by Doppler-echocardiography during exercise. Gross estimation of cardiac output during exercise seems possible; judgement of changes in cardiac output in individual cases appears to be uncertain.