Mechanisms for an abnormal radionuclide left ventricular ejection fraction response to exercise in patients with chronic, severe aortic regurgitation

Abstract

To clarify the mechanisms for an abnormal radionuclide left ventricular (LV) ejection fraction response to exercise in patients with chronic, severe aortic regurgitation (AR), we studied seven control patients and 21 patients with AR. We used exercise radionuclide angiography and catheterization of the right and left sides of the heart to obtain a calculation of LV chamber elastance. The control and AR groups had similar heart rates, systolic blood pressure responses to exercise and exercise durations. In both patient groups, LV end-diastolic volume did not change with exercise. In contrast to the decrease in LV end-systolic volume (p p r = 0.79, p r = 0.88, p < 0.02). These data demonstrate that in patients with AR, the radionuclide LV ejection fraction at peak exercise is principally determined by the cumulative effects of chronic, severe AR on LV systolic chamber performance, and the change in radionuclide LV ejection fraction from rest to peak exercise is principally established by peripheral vascular responses.