Cardiac Autonomic Response to Hypovolemia --- Effect of Age

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dc.contributor.advisorRaven, Peter B.
dc.contributor.committeeMemberShi, Xiangrong
dc.contributor.committeeMemberCaffrey, James L.
dc.creatorWang, Hong-Wei
dc.date.accessioned2019-08-22T21:20:07Z
dc.date.available2019-08-22T21:20:07Z
dc.date.issued1997-08-01
dc.date.submitted2014-04-09T06:36:22-07:00
dc.description.abstractObjective: The beat-to-beat variation in heart rate reflects the dynamic response of the cardiovascular control systems to physiological perturbations such as respiration and postural change. The heart rate variation (HRV) is a part of the rapidly reacting component of cardiovascular homeostasis largely influenced by parasympathetic and sympathetic input. Thus, beat-to-beat variation in heart rate can be used as a measure of cardiac autonomic responses. The standard deviation of R-R interval is a measure of the overall variability in heart rate and has been shown to decrease with aging (9,23). This measure, however, can not identify individual sources of the variation. Spectral analysis reduces a signal to its constituent frequency components and the relative power of these components has been indicated related to parasympathetic mediation, combined sympathetic and parasympathetic mediation, and sympathetic mediation (1, 14, 17). Limited data are available regarding power spectral analysis of heart rate variation to study aging changes under orthostatic stress. An attenuated cardiac sympathetic nerve activity was found in older group vs younger individuals (7, 11, 19) during posture change. However, these studies were carried out using either posture change from to upright or passive head-up tilt. During these posture changes, both cardiopulmonary baroreceptors (i.e., intrathoracic hypovolemia) and arterial baroreceptors (postural hypotension) were unloaded. Therefore, it is unclear whether there is any difference in the HR variability between the young and the elderly during unloading of cardiopulmonary baroreceptors (or low-pressure baroreceptors) alone. In this study, we investigated the age difference in cardiac autonomic modulation of heart rate during unloading of cardiopulmonary baroreceptors with or without systemic arterial hypotension. For the purpose, we examined beat-to-beat heart rate variability in both the time and frequency domain using power spectral analyses in healthy individuals from ages 18 to 68 under basal conditions and in response to graded lower body negative pressure induced central hypovolemia. Not only individual low and high frequency spectral content were analyzed and those parameters were compared in order to find a quantitative evaluation of sympathetic and parasympathetic modulation and under the graded lower body negative pressure.
dc.format.mimetypeapplication/pdf
dc.identifier.urihttps://hdl.handle.net/20.500.12503/29254
dc.language.isoen
dc.provenance.legacyDownloads0
dc.subjectCardiovascular System
dc.subjectCirculatory and Respiratory Physiology
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.subjectPhysiology
dc.subjectSystems and Integrative Physiology
dc.subjectHeart rate
dc.subjectcardiovascular control system
dc.subjectrespiration
dc.subjectpostural change
dc.subjectheart rate variation
dc.subjectparasympathetic input
dc.subjectsympathetic input
dc.subjectspectral analysis
dc.subjectorthostatic stress
dc.subjectattenuated cardiac sympathetic nerve activity
dc.subjectcardiopulmonary baroreceptor
dc.subjectarterial baroreceptor
dc.subjectcardiac autonomic modulation
dc.subjectnegative pressure induced central hypovolemia
dc.subjectlower body negative pressure
dc.titleCardiac Autonomic Response to Hypovolemia --- Effect of Age
dc.typeProfessional Report
dc.type.materialtext
thesis.degree.departmentGraduate School of Biomedical Sciences
thesis.degree.disciplineIntegrative Physiology
thesis.degree.grantorUniversity of North Texas Health Science Center at Fort Worth
thesis.degree.nameMaster of Science

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