Computational Modelling of Passive Cardiac Trabecula Mechanics

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dc.contributor.advisor Tran, K en
dc.contributor.advisor Loiselle, D en
dc.contributor.advisor Nash, M en Schroeder, Alison en 2018-05-25T03:37:22Z en 2018 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Cardiac trabeculae are thin strips of heart tissue that can be readily extricated from the ventricles and used to investigate contractile mechanics. In recent years, the Auckland Bioengineering Institute (ABI) has developed a novel cardiac myometer that can simultaneously measure force, length and shape of actively contracting isolated cardiac trabeculae. The data collected from the cardiac myometer show that under isometric (constant muscle length) contractions there were heterogeneous distributions of muscle cross-sectional areas along the length of the muscle. The ‘thicker’ regions of the trabeculae tended to shorten while the ‘thinner’ regions tended to stretch despite the overall muscle length remaining constant. In this study, as a first step to understanding this phenomenon, a muscle-specific computational model was developed from optical coherence tomography (OCT) geometric surface data that replicates passive trabecula mechanics. It was hypothesised that using the muscle’s surface geometry data, in addition to force-length data, would improve the fit between the model and the experimental data. The constitutive parameters of the trabecula model were optimised using three different methods. Each method was driven by a pressure boundary condition that constrained the model in a unique way. For each method, there was a region of optimal parameters that the optimiser tended towards but due to the coupling between parameters the ability to find the true optimal parameters was hindered. Here, it was found that the addition of surface data did not improve the fit between the model and the experimental data as had been expected and that the use of force-length data only provided sufficient information to produce the best model fit, albeit with parameters that were not uniquely determined. This model of passive trabecula mechanics lays the foundations for future, more complex models that will incorporate active trabecula mechanics. To develop a model of active trabecula mechanics simplified models of cross-bridge cycling, calcium dynamics, and electrical activation can be layered on top of the passive model presented in this study. In the future, the active trabecula mechanics model could be used to explain the experimental observations of ‘thinner’ regions elongating and ‘thicker’ regions shortening by testing whether cross-sectional area alone is sufficient information or if the addition of other effects is necessary. Other effects that may influence this phenomenon are heterogeneous distributions of electrical activation, calcium dynamics, cross-bridge calcium sensitivity, and/or cross-bridge density. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA99265074607802091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
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dc.rights.uri en
dc.title Computational Modelling of Passive Cardiac Trabecula Mechanics en
dc.type Thesis en Bioengineering en The University of Auckland en Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 741277 en
pubs.record-created-at-source-date 2018-05-25 en

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