Changes in CW-Doppler aortic blood flow responses with passive tilting in normo- and borderline hypertensive men

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dc.contributor.authorMorris, Ray Williamen
dc.contributor.committeechairHerbert, William G.en
dc.contributor.committeememberSebolt, Don R.en
dc.contributor.committeememberGwazdauskas, Francis C.en
dc.contributor.departmentHealth and Physical Educationen
dc.date.accessioned2014-03-14T21:42:04Zen
dc.date.adate2012-08-01en
dc.date.available2014-03-14T21:42:04Zen
dc.date.issued1989-03-05en
dc.date.rdate2012-08-01en
dc.date.sdate2012-08-01en
dc.description.abstractContinuous-wave (CW) Doppler echocardiographic responses to passive tilting were measured in 39 men using the following protocol: standing; supine; +20° head-up; supine; â 20° head-down. Twenty of the subjects were normotensive (NTN) and the rest were borderline hypertensive (B-HTN) according to prior medical diagnosis. Doppler recordings of blood flow for aortic peak velocity (Pkv), peak acceleration (PkA), and stroke velocity integral (SVI) were taken after 15 minutes in each posture. A skilled technician, using the measurement procedures recommended by the instrument manufacturer, positioned the handâ he1d probe at the supra-sternal notch during recording. For both NTN and Bâ HTN groups, Pkv and PkA were unaffected by the imposed postural changes. The SVI was significantly altered (P<0.05) by postural stress, with the NTN group generally showing greater changes than the Bâ HTNs. The standing-to-supine postural change was associated with the largest change in SVI: NTN = 8.0 to 10.7 cm (+34%) and B-HTN = 7.6 to 8.8 cm (+15%). These results were interpreted as follows (1) SVI appears to be sensitive to changes in ventricular pre-load, while PkA and Pkv are not; (2) SVI changes with passive tilting follow the patterns expected for change in ventricular stroke volume and; (3) attenuated SVI responses to postural tilting may suggest impairment in cardiovascular regulation peculiar to individuals at risk for hypertension.en
dc.description.degreeMaster of Scienceen
dc.format.extentv, 107 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-08012012-040633en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08012012-040633/en
dc.identifier.urihttp://hdl.handle.net/10919/44126en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1989.M677.pdfen
dc.relation.isformatofOCLC# 19834478en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1989.M677en
dc.subject.lcshBlood flowen
dc.subject.lcshCoronary heart diseaseen
dc.subject.lcshHypertensionen
dc.titleChanges in CW-Doppler aortic blood flow responses with passive tilting in normo- and borderline hypertensive menen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineHealth and Physical Educationen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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