Computational modeling of cardiovascular response to orthostatic stress
Catherine
Lloyd
Bioengineering Institute, University of Auckland
Model Status
This CellML model runs in both COR and PCEnv to reproduce the published results. The units have been checked and they balance. This is a lumped parameter model for cardiac activation based on the work of Heldt et al. 2002. This CellMl model represents the left ventricle but it can be easily modified to represent left and right atria and both ventricles.
Model Structure
ABSTRACT: The objective of this study is to develop a model of the cardiovascular system capable of simulating the short-term (less than or equal to 5 min) transient and steady-state hemodynamic responses to head-up tilt and lower body negative pressure. The model consists of a closed-loop lumped-parameter representation of the circulation connected to set-point models of the arterial and cardiopulmonary baroreflexes. Model parameters are largely based on literature values. Model verification was performed by comparing the simulation output under baseline conditions and at different levels of orthostatic stress to sets of population-averaged hemodynamic data reported in the literature. On the basis of experimental evidence, we adjusted some model parameters to simulate experimental data. Orthostatic stress simulations are not statistically different from experimental data (two-sided test of significance with Bonferroni adjustment for multiple comparisons). Transient response characteristics of heart rate to tilt also compare well with reported data. A case study is presented on how the model is intended to be used in the future to investigate the effects of post-spaceflight orthostatic intolerance.
model diagram
Schematic diagram of the Heldt et al. 2002 heart model.
The original paper reference is cited below:
Computational modeling of cardiovascular response to orthostatic stress, T. Heldt, E.B. Shim, R.D. Kamm, and R.G. Mark, 2002, Journal of Applied Physiology, 92, 1239-1254. PubMed ID: 11842064
Cumin
David
d.cumin@auckland.ac.nz
Auckland Bioengineering Institute
2009-10-26
The Heldt et al. 2002 computational model of the heart
This is the CellML description of Heldt et al.'s computational model of the heart. Specifically the left ventricle.
Catherine Lloyd
left ventricle
keyword
lumped parameter
cardiac
ventricle
cardiac activation
11842064
Heldt
T
Shim
E
B
Kamm
R
D
Mark
R
G
Computational modeling of cardiovascular response to orthostatic stress
2002
Journal of Applied Physiology
92
1239
1254
$\mathrm{hrf}=\frac{\mathrm{HR}}{60}$
$\mathrm{beattime}=\mathrm{realtime}-\lfloor \frac{\mathrm{realtime}}{\mathrm{hrf}}\rfloor \mathrm{hrf}-\mathrm{PRint}$
$\mathrm{Ts}=\mathrm{TsK}\sqrt{1\mathrm{hrf}}\mathrm{E\_LV}=\begin{cases}\mathrm{Edia}+\frac{(\mathrm{Esys}-\mathrm{Edia})(1-\cos \left(\frac{\pi \mathrm{time}}{\mathrm{Ts}}\right))}{2} & \text{if $(\mathrm{time}\ge 0)\land (\mathrm{time}\le \mathrm{Ts})$}\\ \mathrm{Edia}+\frac{(\mathrm{Esys}-\mathrm{Edia})(1+\cos \left(\frac{2\pi (\mathrm{time}-\mathrm{Ts})}{\mathrm{Ts}}\right))}{2} & \text{if $(\mathrm{time}< 1.5\mathrm{Ts})\land (\mathrm{time}\ge \mathrm{Ts})$}\\ \mathrm{Edia} & \text{otherwise}\end{cases}$
$\frac{d \mathrm{dummy}}{d \mathrm{time}}=\mathrm{dummy}-3$