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
Keywords	Coronary heart disease.
Date of Defense	1989-03-05
Availability	restricted
Abstract 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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