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Pulmonary arterial wave intensity analysis in health and disease.

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Dwyer, NB (2010) Pulmonary arterial wave intensity analysis in health and disease. PhD thesis, University of Tasmania.

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Abstract

Wave intensity analysis (WIA) is a time-domain technique utilising high fidelity
pressure and velocity measurements to determine the intensity, direction, type
and timing of waves that may simultaneously exist. Travelling wavefronts
represent elemental units of energy transmitted within and between the heart and
blood vessels. Thus, WIA allows us to study ventricular-arterial interactions
providing information on ventricular performance and the state of the circulation.
In the pulmonary circulation WIA allows the study of upstream and downstream
events that influence net pulmonary arterial blood flow.
WIA was performed in the pulmonary arteries of anaesthetised open-chest sheep,
determining a normal mean wave speed of 2.1 ms-1. Whilst wave reflection was
minimal in healthy resting pulmonary arteries, two minor but clearly discernible
backward travelling waves were identified that serve as important physiological
markers. The first was an early systolic backward expansion wave representing
open-end reflection from a site approximately 3 cm downstream, most likely
from the main pulmonary bifurcation, and would serve to augment flow out of the
right ventricle. The second was a late systolic backward compression wave
representing closed-end reflection from a site approximately 20 cm downstream,
most likely from the pulmonary microcirculation, and would serve to oppose flow
out of the right ventricle. The open-end reflection was enhanced by increased
pulmonary blood flow or circulating blood volume. With pulmonary
vasoconstriction or obstruction, WIA was able to accurately determine the
distance to the newly developed closed-end reflection site from which a
backward compression arrives in mid-systole and opposes flow out of the right
ventricle.
In human volunteers with normal or diseased pulmonary vasculature, wave speed
was shown to increase linearly with pulmonary vascular resistance. The
difficulties in reproducing instantaneous pulmonary blood velocity accurately invivo
limited assessment of reflected waves.

Item Type: Thesis (PhD)
Keywords: Wave speed, wave reflection, pulmonary, wave intensity, analysis, pulmonary hypertension
Copyright Holders: The Author
Copyright Information:

Copyright 2010 the Author

Date Deposited: 12 May 2011 00:55
Last Modified: 11 Mar 2016 05:53
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