Title page for ETD etd-08012012-040633

Type of Document Master's Thesis
Author Morris, Ray William
URN etd-08012012-040633
Title Changes in CW-Doppler aortic blood flow responses with passive tilting in normo- and borderline hypertensive men
Degree Master of Science
Department Health and Physical Education
Advisory Committee
Advisor Name Title
Herbert, William G. Committee Chair
Gwazdauskas, Francis C. Committee Member
Sebolt, Don R. Committee Member
  • Coronary heart disease.
Date of Defense 1989-03-05
Availability restricted
Continuous—wave (CW) Doppler echocardiographic responses to passive tilting were measured in 39 men using the following protocol: standing; supine; +20° head—up; supine; —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 hand—he1d probe at the supra—sternal notch during recording. For both NTN and B—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 B—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.

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