New methodologies for investigating wave propagation and reflection in the aorta.

Format:

Book

Thesis/Dissertation

Author/Creator:

Hoydu, Alison Knauth.

Contributor:

Leigh, John S., advisor.

Noordergraaf, Abraham, advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Biomedical engineering.

0541.

Penn dissertations--Bioengineering.

Bioengineering--Penn dissertations.

Local Subjects:

Penn dissertations--Bioengineering.

Bioengineering--Penn dissertations.

0541.

Physical Description:

324 pages

Contained In:

Dissertation Abstracts International 54-06B.

System Details:

Mode of access: World Wide Web.

text file

Summary:

Although the concepts of pulse propagation and reflections in the arterial vasculature were recognized hundreds of years ago, a complete description has not been given. Furthermore, investigators have focused primarily on a normal circulation. The goal of this research was to more completely characterize these phenomena and apply what was learned to the abnormal circulation of children with Hypoplastic Left Heart Syndrome (HLHS).

The author develops new methodologies for investigating these phenomena. These include a theoretical model using two port electrical network theory, serving as the basis for new methods for analyzing and interpreting experimental impedance spectra. The first method increases the frequency resolution of impedance spectra to identify the location of reflection sites. The second method calculates the inverse Fourier transform of impedance. This time domain spectrum yields the origin and magnitude of arterial reflections. Next, a method for identifying repeated reflections seen by the ventricle is detailed. These methodologies are validated in a piglet model, adults with and without heart disease, and children with HLHS.

This research includes the development of a new Magnetic Resonance Imaging (MRI) method, FLow induced Adiabatic fast passage Bolus tagging (FLAB) to noninvasively observe flow profiles and pulse propagation phenomena. This method is superior to other MRI techniques in its temporal resolution. The accuracy of this method for quantifying flow is demonstrated in a flow phantom. The sensitivity of FLAB is investigated with in vivo measurements of postprandial changes in cardiac output and post exercise changes in diastolic popliteal arterial flow. It is further shown that FLAB can provide a measure of pulse propagation speed, and thus, a noninvasive estimate of vascular compliance. Abnormal profiles and turbulence in the reconstructed aorta of HLHS children are observed using bolus tagging.

This dissertation more completely describes pulse propagation and wave reflection in the arterial system through theoretical and experimental models. It argues previous interpretations of arterial wave reflections. Further it presents a new MRI technique for visualizing flow phenomena in vivo.

Notes:

Thesis (Ph.D. in Bioengineering) -- Graduate School of Arts and Sciences, University of Pennsylvania, 1993.

Source: Dissertation Abstracts International, Volume: 54-06, Section: B, page: 3207.

Supervisors: Abraham Noordergraaf; John S. Leigh.

Local Notes:

School code: 0175.

Access Restriction:

Restricted for use by site license.