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Identification of the mechanical parameters for the human uterus in vivo using intrauterine pressure measurements
Institute of Solid Mechanics, Department of Mechanical Engineering, Braunschweig University of Technology, Braunschweig, Germany.
Linköping University, Department of Management and Engineering, Machine Design. Linköping University, Faculty of Science & Engineering.
Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
2016 (English)In: International Journal for Numerical Methods in Biomedical Engineering, ISSN 2040-7939, E-ISSN 2040-7947Article in journal (Refereed) Epub ahead of print
Abstract [en]

There are limited experimental data to characterize the mechanical response of human myometrium. A method is presented in this work to identify mechanical parameters describing the active response of human myometrium from the in vivo intrauterine pressure measurements. A finite element model is developed to compute the intrauterine pressure during labor in response to an increase in the intracellular calcium ion concentration within myometrial smooth muscle cells. The finite element model provides the opportunity to tune mechanical parameters in order to fit the computed intrauterine pressure to in vivo measurements. Since the model is computationally expensive, a cheaper meta-model is generated to approximate the model response. By fitting the meta-model response to the in vivo measurements, the parameters used to determine the active response of human myometrial smooth muscle are identified.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016.
Keyword [en]
Intrauterine pressure, Response surface methodology, Parameter Identification, Meta-modeling
National Category
Applied Mechanics Mechanical Engineering
Identifiers
URN: urn:nbn:se:liu:diva-121014DOI: 10.1002/cnm.2778OAI: oai:DiVA.org:liu-121014DiVA: diva2:850823
Note

At the time of the thesis presentation this publication was in status Manuscript.

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2016-04-13Bibliographically approved
In thesis
1. A Continuum Framework for Modeling the Excitation–Contraction Coupling of Smooth Muscle
Open this publication in new window or tab >>A Continuum Framework for Modeling the Excitation–Contraction Coupling of Smooth Muscle
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Excitation-contraction coupling of smooth muscle refers to a chain of coupled physiological processes which convert a stimulus to a mechanical response. These processes can be disassociated into ionic transport during cell membrane excitation, activation of myosin light chains, and muscle contraction caused by actin-myosin interaction (filament sliding). This thesis concerns the development of a framework which allows to model the smooth muscle excitation-contraction coupling constitutively by applying the principle of virtual power and dissipation inequality. In doing so, the transport of ions through membrane channels is characterized by an ionic flux and an ionic supply, both governed by an electrochemical potential energy. By letting the Helmholtz free energy to be dependent on the myosin light chain configurations during contraction, the myosin light chain activation process, i.e., myosin phosphorylation, is included. The activation process links the membrane excitation to the filament sliding. A contractile element is presented to replicate the active deformation caused by the filament sliding within the smooth muscle cell. This deformation is coupled to the overall deformation of the muscle tissue by assuming a distinct principal alignment for the contractile elements.

By employing this framework, an electro-chemo-mechanical model is derived by which the mechanical response of smooth muscle to an electrical stimulus is determined. This model is evaluated by comparing the model response to the experimental isometric stress data obtained from rat uterine smooth muscle tissue. By implementing this model in a finite element program, human uterine contractions during labor are simulated. This simulation determines important clinical factors, e.g., intrauterine pressure and provides the opportunity to investigate the effect of physiological and structural parameters on the uterine contractility.

Finally, a methodology to accommodate individualized parameters from intrauterine pressure measurements is established. This methodology allows to develop models with potentials of being used clinically to diagnose difficulties during labor and delivery.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. 39 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1687
National Category
Mechanical Engineering Applied Mechanics Materials Engineering
Identifiers
urn:nbn:se:liu:diva-121015 (URN)978-91-7519-020-4 (print) (ISBN)
Public defence
2015-09-08, C3, Hus C, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-09-02Bibliographically approved

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Sharifimajd, BabakÖlvander, JohanStålhand, Jonas
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