Date of Award

Spring 1991

Project Type

Dissertation

Program or Major

Engineering

Degree Name

Doctor of Philosophy

First Advisor

John R LaCourse

Abstract

A single artery-single junction model is evaluated independently and relative to existing models to determine if it can provide additional or better information for detecting the presence of atherosclerotic plaques from blood pressure or flow waveforms. The effects of a single stenosis on the arterial pressure pulse are assessed. A 30 cm segment of aorta without branches is modeled with a stenosis of varying parameters located 15 cm from the heart. The aortic pressure pulse serves as input. The effects of the stenosis on the reflected and transmitted peak pressures are analyzed as well as the harmonic amplitudes of the composite and transmitted waveforms. The reflected, transmitted and composite waveforms were most sensitive to stenosis length and percent constriction variation. In the harmonic analysis, the fundamental and second harmonic were most significantly affected suggesting restricting future analyses to these two frequencies.

A single bifurcation with upstream stenosis is simulated to assess transmission through a junction. The time-domain approach is validated through comparison with the traditional frequency-domain analysis. To preserve junction dynamics, geometric taper of the mother artery was incorporated. The taper produced greater reflection than the junction (25% vs. 5.6%).

The time-domain approach allowed greater spatial resolution than is generally possible in the frequency-domain or lumped parameter type models. However, the magnitude of the stenosis effects in these ranges suggests that the resolution of the other approaches may be sufficient.

Suggestions are made for future noninvasive instrumentation for the early detection of carotid stenosis with an interest toward mass screening. In particular, an ocular pulse measurement system and Doppler ultrasound velocimetry are discussed.

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