Artery Research

Volume 12, Issue C, December 2015, Pages 44 - 45

4.4 FORWARD AND BACKWARD WAVES AT THE AORTIC ROOT: STEADY-STATE AND WAVE RE-REFLECTION CONSIDERATIONS

Authors
Timothy Phan*1, John Li1, Vandan Panchal2, Amer Syed2, Ejaz Shah2, Julio Chirinos2
1Rutgers University, Piscataway, NJ, USA
2University of Pennsylvania, Philadelphia, PA, USA
Available Online 23 November 2015.
DOI
10.1016/j.artres.2015.10.023How to use a DOI?
Abstract

Background: The assumption of steady-state oscillation is often overlooked when arterial pressure and flow waveforms are decomposed into backward (Pb) and forward waves (Pf). This has led to various misinterpretations including a significant reflection-free time during early-systole and attribution of the Pf to solely a product of left ventricular contraction and proximal aortic properties.

Methods: Aortic pressure and flow were measured in anesthetized, open-chest dogs (n = 5). Wave reflections were modified with i.v. infusion of methoxamine (MTX) to increase reflections and nitroprusside (NTP) to decrease reflections. In a human sample (n = 226), central pressure and flow were measured using carotid tonometry and phase-contrast MRI, respectively.

Results: Under conditions of baseline and increased reflections in both dogs and humans, peak of the forward wave (FWA) consistently occurred after time of peak flow (P < 0.001). FWA was systematically greater than peak flow multiplied by aortic characteristic impedance (QmaxZc) in dogs (P < 0.01) and humans (P < 0.01). Only when wave reflections were abolished vasoactively (NTP) in dogs was time of FWA and peak flow the same, leading to insignificant differences in FWA and QmaxZc (P = 0.59).

Conclusion: In steady-state, wave reflections set up in previous cardiac cycles, wave re-reflections at the aortic root, and proximal reflections contribute to both the Pf and Pb waves, even during early-systole. Most importantly, peak aortic flow is also determined by aortic input impedance, which includes effects from properties distal of the proximal aorta. Under steady-state conditions, forward wave amplitude and morphology cannot be attributed solely to the LV and proximal aorta.

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Journal
Artery Research
Volume-Issue
12 - C
Pages
44 - 45
Publication Date
2015/11/23
ISSN (Online)
1876-4401
ISSN (Print)
1872-9312
DOI
10.1016/j.artres.2015.10.023How to use a DOI?
Open Access
This is an open access article distributed under the CC BY-NC license.

Cite this article

TY  - JOUR
AU  - Timothy Phan*
AU  - John Li
AU  - Vandan Panchal
AU  - Amer Syed
AU  - Ejaz Shah
AU  - Julio Chirinos
PY  - 2015
DA  - 2015/11/23
TI  - 4.4 FORWARD AND BACKWARD WAVES AT THE AORTIC ROOT: STEADY-STATE AND WAVE RE-REFLECTION CONSIDERATIONS
JO  - Artery Research
SP  - 44
EP  - 45
VL  - 12
IS  - C
SN  - 1876-4401
UR  - https://doi.org/10.1016/j.artres.2015.10.023
DO  - 10.1016/j.artres.2015.10.023
ID  - Phan*2015
ER  -