A method for determining the distribution of reflection sites in
the arterial system.
Pythoud, F., Stergiopulos, N., Westerhof, N. and Meister, J. J.
Biomedical Engineering Laboratory, Swiss Federal Institute of
Technology, PSE-Ecublens, 1015 Lausanne, Switzerland, Laboratory for
Physiology, ICaR-VU, Free University, van der Boechorststraat 7, 1081
BT Amsterdam, the Netherlands
APStracts 3:0190H, 1996.
We developed a new method to determine the location and importance of
reflection sites in the arterial system. The method is based on the
decomposition of the aortic pressure wave into its forward and
backward components and provides the reflection profile of the
arterial system as a wave reflection site amplitude versus distance
from the heart. The reflection profile can be seen as the response of
the arterial system to a pressure delta pulse where reflections
upstream the measurement location have been eliminated. The method
was successfully tested on a simple model loaded with a pure
resistor, a two-element Windkessel, and a bifurcating tube system. It
was then applied to the aortic pressure and flow signals measured on
six mongrel dogs whose aorta was occluded at different levels. The
profiles obtained from measurements at control showed two main
reflection regions, one located in the vicinity (0.1-0.2 m) of the
heart, and the other located in the region of the iliac bifurcation.
All occlusions, even the most distant one at the iliac bifurcation,
could be identified in both amplitude (amount of reflections) and
distance from the heart. The spatial resolution of the profiles was
about 0.1 m as a result of limited power spectrum contained in the
arterial pulse, and the identification of reflection sites decreases
rapidly with the distance.
Received 1 December 1995; accepted in final form 8 April 1996.
APS Manuscript Number H1122-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 May 96