Patients with sick sinus syndrome and a double-chamber cardiac pacemaker are studied. To investigate the role of heart rate on central hemodynamics, we acutely change pacing rate from atrial paced-atrial sensed (AAI)-mode 60 to 40 to 90 bpm and obtain hemodynamic parameters (brachial and aortic blood pressure, brachial and aortic pulse pressure, central augmentation index, carotid-femoral pulse wave velocity) noninvasively after a short stabilisation period after each pacemaker rate change.