Journal of Applied Physiology, Vol 73, Issue 5 2097-2104, Copyright © 1992 by American Physiological Society
Interrelationships between left ventricular volume and output during exercise in healthy subjects
K. F. Adams Jr, S. M. McAllister, H. el-Ashmawy, S. Atkinson, G. Koch and D. S. Sheps
Department of Medicine, University of North Carolina School of Medicine, Chapel Hill 27599.
To better characterize the relationship between left ventricular volume
response and improved ventricular ejection and output during supine
exercise in normal subjects, 36 healthy asymptomatic volunteers (age 39 +/-
17 yr) were studied with radionuclide ventriculography during recumbent
bicycle ergometry. Relative changes in left ventricular end-diastolic and
end-systolic volume were measured at rest and during exercise by a
modification of the radionuclide counts-based method that accounted for
variability in stress blood pool counts. A biphasic response was noted in
left ventricular end-diastolic volume with an initial increase in early
exercise (8.5 +/- 11% at 200 kpm/min and 11 +/- 12% at 300 kpm/min)
followed by a progressive and significant decline at peak exercise (-3.3
+/- 18% at 547 +/- 140 kpm/min; P < 0.05). There was substantial
variation in end-diastolic volume response at peak exercise in the group as
a whole, which could be more closely related to changes in end-systolic
volume (r = 0.84, P < 0.0001) than in heart rate (r = -0.57, P <
0.01) or age (r = 0.36, P < 0.05) of the study subjects. Despite the
decline in ventricular filling, systolic function appeared to improve
dramatically at peak exercise (change in left ventricular ejection fraction
15.5 +/- 6.4, P < 0.0001). Although not directly related to increasing
systolic ejection, end-diastolic volume was directly related to the percent
change in stroke volume at peak exercise among the study subjects (r =
0.88, P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
