title: Interrelationships between left ventricular volume and output during exercise in healthy subjects.
abstract: 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)
authors: Department of Medicine, University of North Carolina School of Medicine, Chapel Hill 27599.
authors: K F
authors: KF
authors: Adams
authors: S M
authors: SM
authors: McAllister
authors: H
authors: H
authors: el-Ashmawy
authors: S
authors: S
authors: Atkinson
authors: G
authors: G
authors: Koch
authors: D S
authors: DS
authors: Sheps
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006321:Heart / Q000033:anatomy & histology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D013318:Stroke Volume / Q000502:physiology*; D016276:Ventricular Function