The effects of increasing and decreasing cardiac preload by 15% on the left ventricular (LV) performance of 11 carefully screened normal subjects aged 61 to 73 years were examined. Comparisons were made with 11 subjects aged 21 to 28 years. Two-dimensional echocardiograms were obtained before and at the termination of 5 degrees of head-down tilt for 90 minutes and at the termination of graded lower body negative pressure to -40 mm Hg. Heart rates and blood pressures were unchanged after physiologic interventions. Changes in LV end-diastolic and stroke volumes were similar but of a smaller magnitude in the older subjects compared with changes in younger subjects. When LV end-diastolic volumes obtained at each extreme of preload variation were compared, the range of mean change was less in the older (23 ml, 26%) than in the younger subjects (31 ml, 41%). Control LV end-diastolic and end-systolic volumes were greater in the older subjects. This study shows that despite larger control LV volumes, alterations in preload produce changes in the LV end-diastolic and stroke volumes of these older subjects that conform to the normal LV function curve, but that these responses are diminished compared with changes in younger subjects, suggesting an age-related change in diastolic stiffness.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine