Resting and stress radionuclide angiography was performed before and, on average, one year after surgery for adult aortic stenosis in 26 patients. The left ventricular ejection fraction, ventricular volumes, left ventricular stroke volume and peak velocity of ventricular filling were studied under basal conditions and at the peak of exercise. Right and left heart catheterisation and coronary angiography were performed before surgery with determination of the conventional indices of left ventricular function. Investigations were completed by pre and postoperative echocardiography. The same procedures were carried out in a control population of the same age. Before surgery, hemodynamic adaptation to exercise, judged by the change in left ventricular stroke volume, solicits the passive properties of the left ventricle: the left ventricular stroke volume increases by an increase in the end diastolic volume. In the control group, the increase in stroke volume is obtained by a decrease in end systolic volume, that is to say by increasing systolic shortening. The peak velocity of ventricular filling increases on exercise but to a lesser degree than in the control population. After surgery the hemodynamic adaptation to exercise results from an improved systolic shortening of the left ventricle but also from an increase in end diastolic volume. The peak velocity of left ventricular filling increases with respect to the preoperative values but remains less than that observed in the control population. No relationship was observed between the hemodynamic adaptation to exercise, the peak velocity of ventricular filling and myocardial mass whichever method was used for calculating the latter parameter.(ABSTRACT TRUNCATED AT 250 WORDS)