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

Continuous-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.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Health and Physical Education

Department dc:contributor.department

Health and Physical Education

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1989

Author dc:creator

• Morris, Ray William

Chair dc:contributor.committeechair

• Herbert, William G.

Committee members dc:contributor.committeemember

• Sebolt, Don R.
• Gwazdauskas, Francis C.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-08012012-040633

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/44126