The radionuclide assessment of left ventricular function using graded exercise in normal subjects.

In 20 normal volunteers, two minute equilibrium gated blood pool scanning (GBPS) was used to assess left ventricular function during rest and three stages of graded supine exercise on a bicycle ergometer. The three work loads were individualised for each subject from a previously performed exercise test and corresponded to mild, moderate and severe stress. The short imaging time was validated against standard GBPS. With exercise all subjects increased their left ventricular ejection fraction and in the majority, most of this rise occurred with the lowest work load. This change was predominantly due to a marked fall in end-systolic volume. The end-diastolic volume initially fell, then at peak exercise returned to baseline values. The major change in stroke volume occurred at peak exercise.