The authors evaluated in 19 patients with Dual Chamber pacemakers, using pulsed Doppler echocardiography, changes of the cardiac output after stimulation type DDD with an A-V interval of 100, 150, 175 and 200 ms. They evaluated also haemodynamic changes when changing the stimulation programme type DDD to ventricular stimulation type VVI. The group of patients was characterized by a left ventricular ejection fraction of 50.3 +/- 9.1%, a dimension of the left atrium of 37.1 +/- 5.6 mm and a end diastolic left ventricular dimension of 52.8 +/- 3.9 mm. The highest values of the cardiac output were recorded in 11 patients with an A-V interval of 175 ms, in 7 patients at 150 ms and in one patient at 200 ms. The difference of the cardiac output between the haemodynamically optimal and pessimal A-V interval assessed for individual patients during stimulation type DDD was 15.5 +/- 9.5%. The difference of the cardiac output during a change of stimulation type DDD with a haemodynamically optimal A-V interval to ventricular stimulation type VVI was 22.8 +/- 8.3%. Doppler echocardiography is a satisfactory non-invasive method for the evaluation of haemodynamic changes when assessing optimal parameters in patients with multiprogrammable dual chamber pacemakers.