P137 Reflections Revisited: Reinterpretation Required

DOI

10.2991/artres.k.191224.160How to use a DOI?

Abstract

Introduction: Pressure waveshape derived parameters such as the augmentation index are related to unfavourable cardiovascular events [1]. Wave reflections determine wave shape [2], however, several findings seem to contradict the current views. Current view. The arterial system can be modelled by a tube with a reflection site at the end: the heart sets up waves propagating down the system, reflecting at the end and returning to the heart after twice the travel time, i.e. aortic length over Pulse Wave Velocity (PWV).Data. Return time of the reflected wave is not inversely proportional to PWV [3]. Also, reflected waves appear to run downstream rather than to the heart [4]. These findings conflict with the current concepts.

Interpretation: At all locations in the arterial system, wave reflection is determined by the characteristic impedance of the supplying vessel and the input impedance of the downstream system. The input impedance results from a system of many arteries with multiple reflection sites [5]. Time delay between forward and reflected wave is mainly determined by the phase angle of the downstream impedance, and does not systematically increase or decrease with distance. This implies that the time difference between reflected and forward wave is not increasing towards the heart as assumed by the single-tube model. As a consequence, the return time of the reflected wave is not inversely proportional to PWV.

Conclusion: The single tube model should be abandoned as conceptual model as is does not explain the measured data. A frequency domain (impedance) model is required.

Copyright

© 2019 Association for Research into Arterial Structure and Physiology. Publishing services by Atlantis Press International B.V.

Open Access

This is an open access article distributed under the CC BY-NC 4.0 license (http://creativecommons.org/licenses/by-nc/4.0/).

Download article (PDF)
View full text (HTML)

TY  - JOUR
AU  - Berend Westerhof
AU  - Nico Westerhof
PY  - 2020
DA  - 2020/02/17
TI  - P137 Reflections Revisited: Reinterpretation Required
JO  - Artery Research
SP  - S175
EP  - S175
VL  - 25
IS  - Supplement 1
SN  - 1876-4401
UR  - https://doi.org/10.2991/artres.k.191224.160
DO  - 10.2991/artres.k.191224.160
ID  - Westerhof2020
ER  -