Date of Award

1-1-2016

Document Type

Masters Thesis

Degree Name

M.S.

Organizational Unit

Daniel Felix Ritchie School of Engineering and Computer Science

First Advisor

Ali N. Azadani, Ph.D.

Second Advisor

Peter Laz

Third Advisor

Yun Bo Yi

Fourth Advisor

James Fogleman

Keywords

Atrial appendage, Biaxial testing, Cardiac mechanics, Microstructure, Passive mechanical behavior, Ventricle, Atrium

Abstract

Mechanical properties of cardiac tissue play an important role in the normal heart function. As a baseline for understanding of physiology and pathophysiology of the heart, and for development and validation of new therapies, it is crucial to first understand the mechanical behavior of the normal heart tissue. Although heart chambers have the same embryonic origin, differences in the development of mechanical properties are expected to manifest over time during the adulthood period. Therefore, the goal of this study was to determine the passive mechanical properties of all heart chambers through a paired comparison study in an ovine model. Ovine heart was used due its physiological and anatomical similarities to human heart. A total of 189 specimens from anterior and posterior portions of the left and right ventricles, atria, and appendages underwent biaxial mechanical testing. A Fung-type strain energy function was used to fit the experimental data. Tissue behavior was quantified based on the magnitude of strain energy, as an indicator of tissue stiffness, at equibiaxial strains of 0.10, 0.15, and 0.20. Statistical analysis revealed no significant difference in strain energy storage between anterior and posterior portions of each chamber, except for the right ventricle where strain energy storage in the posterior specimens were higher than the anterior specimens. Additionally, all chambers from the left side of the heart had significantly higher strain energy storage than the corresponding chambers on the right side. Furthermore, the highest to lowest stored strain energy were associated with ventricles, appendages, and atria, respectively. Microstructure of tissue specimens from different chambers was also compared using histology. The average surface area ratio of collagen to myocyte was found to be highest for the atria and lowest for the ventricles. This fact could explain the underlying basis for the differences in tissue stiffness between the regions.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Shahnaz Javani

Provenance

Received from ProQuest

File Format

application/pdf

Language

en

File Size

68 p.

Discipline

Mechanical Engineering, Biomechanics, Biomedical Engineering

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