Dissociation of Carotid and Forearm Pressure Decay Constants (tau), Windkessel Compliances, and Pulse Wave Velocities: Implications for Circulatory Models

DOI

10.2991/artres.k.191210.002How to use a DOI?

Keywords

Arterial tonometry; tau; pressure decay; Windkessel model; arterial compliance; circulatory models

Abstract

Windkessel (WK) models have often been used to simulate the arterial circulation. We studied a critical characteristic of WK function, the arterial pressure-decay constant tau, to test whether all arterial regions share the same WK characteristics, which should theoretically be related to arterial stiffness. We performed carotid and forearm arterial tonometry (Sphygmocor) and modeled arterial pressure (P) as A + (SBP − A)⋅exp[−(t − t₀)/tau], where A = minimum pressure, SBP = systolic BP, t = time, t₀ = start of decay). Model validity was supported by strong between-site correlations for t₀ and A. We also measured central and peripheral Pulse Wave Velocity (PWV, Colin VP1000) and calculated arterial compliances (1/PWV²) in the heart-femoral (hf) and femoral-ankle (fa) regions. For the full cohort [n = 98, mean (SD): age 50 (20) years, weight 81 (17) kg, BP 135/77 (17/12) mmHg, 38% female], carotid and forearm taus were different [283 (126) vs. 199 (88) ms, p < 0.000] and uncorrelated (r² = 0.01). Although hf and fa arterial compliances were well correlated (p < 0.000), neither was closely correlated with carotid or forearm tau (r² < 0.06). In a subset (n = 22), carotid and brachial blood flow (Ultramark 9) were measured and regional WK compliances were calculated (= tau/regional resistance). Carotid blood flow [571 (216) vs. 117 (84) mL/min, p < 0.000] and WK compliance [0.031 (0.017) vs. 0.004 (0.004) mL/mmHg, p < 0.000] were much higher than corresponding forearm values. We conclude that: (1) tau and WK compliance are regional, not systemic indicators, (2) neither carotid nor forearm tau reflects large artery stiffness, and (3) a single WK model cannot adequately describe the arterial circulation.

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/).

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TY  - JOUR
AU  - Joseph Lewis Izzo
AU  - Muhammed Absar Anwar
AU  - Sherif Elsayed
AU  - Peter John Osmond
AU  - Benjamin Gavish
PY  - 2019
DA  - 2019/12/24
TI  - Dissociation of Carotid and Forearm Pressure Decay Constants (tau), Windkessel Compliances, and Pulse Wave Velocities: Implications for Circulatory Models
JO  - Artery Research
SP  - 165
EP  - 169
VL  - 25
IS  - 3-4
SN  - 1876-4401
UR  - https://doi.org/10.2991/artres.k.191210.002
DO  - 10.2991/artres.k.191210.002
ID  - Izzo2019
ER  -