<?xml version="1.0" encoding="utf-8"?>
<!--
This CellML file was generated on 1/11/2009 at 11:05:19 at a.m. using:
COR (0.9.31.1329)
Copyright 2002-2009 Dr Alan Garny
http://cor.physiol.ox.ac.uk/ - cor@physiol.ox.ac.uk
CellML 1.0 was used to generate this model
http://www.cellml.org/
-->
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<article>
<articleinfo>
<title>Computational modeling of cardiovascular response to orthostatic stress</title>
<author>
<firstname>Catherine</firstname>
<surname>Lloyd</surname>
<affiliation>
<shortaffil>Bioengineering Institute, University of Auckland</shortaffil>
</affiliation>
</author>
</articleinfo>
<section id="sec_status">
<title>Model Status</title>
<para>
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.
</para>
</section>
<sect1 id="sec_structure">
<title>Model Structure</title>
<para>
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.
</para>
<informalfigure float="0" id="fig_reaction_diagram">
<mediaobject>
<imageobject>
<objectinfo>
<title>model diagram</title>
</objectinfo>
<imagedata fileref="heldt_2002a.png"/>
</imageobject>
</mediaobject>
<caption>Schematic diagram of the Heldt et al. 2002 heart model.</caption>
</informalfigure>
<para>
The original paper reference is cited below:
</para>
<para>
Computational modeling of cardiovascular response to orthostatic stress, T. Heldt, E.B. Shim, R.D. Kamm, and R.G. Mark, 2002, <emphasis>Journal of Applied Physiology</emphasis>, 92, 1239-1254. <ulink url="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11842064&query_hl=1&itool=pubmed_docsum">PubMed ID: 11842064</ulink>
</para>
</sect1>
</article>
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The Heldt et al. 2002 computational model of the heart
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This is the CellML description of Heldt et al.'s computational model of the heart. Specifically the left ventricle.
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<dc:title>
Computational modeling of cardiovascular response to orthostatic stress
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