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Establishing the material parameters of the neonatal porcine ventricular myocardium

Ahmad, Faizan 2018. Establishing the material parameters of the neonatal porcine ventricular myocardium. PhD Thesis, Cardiff University.
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Abstract

Neonatal heart disorders represent a major clinical challenge and congenital heart disease alone affects 36,000 new-borns annually within the European Union. Engineering-based computational modelling is increasingly used in adult cardiology to simulate normal and pathophysiological conditions, leading to the development of new clinical interventions. However, the application of such technologies to advance care in young patients is limited by the need to characterise the structural and biomechanical properties of neonatal tissue in estimating the material parameters. Consequently, this research aims to establish the first material parameters that describe neonatal cardiac tissue. A porcine model was used to perform the microstructural and biomechanical analysis. Established (histology) and emerging—two-photon excited fluorescence and second-harmonic generation (TPEF/SHG) and diffusion tensor magnetic resonance imaging (DT-MRI)—imaging methodologies enabled quantification of the in-plane and out-plane cardiomyocytes’ and collagen fibrils’ orientation and dispersion, in addition to the cardiomyocytes’ architecture and regional fractional anisotropy. The biomechanical analysis was performed via uniaxial tensile, biaxial and simple shear tests. The analyses identified the regional variations within the anterior and posterior aspects of both ventricles. The surface area analysis quantified the greater ratio of collagen to cardiomyocytes in the posterior wall in both ventricles. TPEF/SHG identified the greater cardiomyocytes rotation in the posterior wall of both ventricles. The anterior ventricular walls were stiffest. The one-day-old porcine tissue was identified as exhibiting one-half the stiffness of adult porcine tissue in uniaxial testing, one-third in biaxial testing, and one-fourth Thesis summary iv stiffness in simple shear testing. Finally, these data were used with the structurally-based Holzapfel–Ogden model of the myocardium to establish the material parameters. The estimated material parameters in this study will enable a simulation that specifically reflects neonatal ventricular tissue behaviour. This will ultimately create new opportunities for researchers, bioengineers and clinicians to identify novel treatments and interventions of neonatal heart diseases.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Engineering
Uncontrolled Keywords: Neonatal Cardiac mechanics; Passive mechanical behaviour; Neonatal heart structure; Cariodmyocyte architecture; Material parameters of the myocardium; Age-dependent variations.
Funders: NRN
Date of First Compliant Deposit: 5 October 2018
Last Modified: 18 Mar 2019 13:29
URI: http://orca.cf.ac.uk/id/eprint/115528

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