METHOD FOR DETERMINING DISTRIBUTION OF REFLECTION SITES IN THE ARTERIAL SYSTEM

We developed a new method to determine the location and importance of reflection sites in the arterial system. The method is based on the de composition of the aortic pressure wave into its forward and backward components, and it provides the reflection profile of the arterial sys tem as a wave reflection site amplitude versus distance from the heart . The reflection profile can be seen as the response of the arterial s ystem to a pressure delta pulse where reflections upstream from the me asurement location have been eliminated. The method was successfully t ested on a simple model loaded with a pure resistor, a two-element win dkessel, and a bifurcating tube system. It was then applied to the aor tic pressure and flow signals measured in six mongrel dogs whose aorta was occluded at different levels. The profiles obtained from measurem ents 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 a t the iliac bifurcation, could be identified in both amplitude (amount of reflections) and distance from the heart. The spatial resolution o f the profiles was similar to 0.1 m as a result of the limited power s pectrum contained in the arterial pulse, and the identification of ref lection sites decreased rapidly with the distance.