Papers by Caitríona Lally
ASME 2009 Summer Bioengineering Conference, Parts A and B, 2009
ABSTRACT Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Associat... more ABSTRACT Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
Lecture Notes in Computational Vision and Biomechanics, 2012
Medical engineering & physics, 2015
Characterization of the mechanical properties of arterial tissues usually involves an invasive pr... more Characterization of the mechanical properties of arterial tissues usually involves an invasive procedure requiring tissue removal. In this work we propose a non-invasive method to perform a biomechanical analysis of cardiovascular aortic tissue. This method is based on combining medical imaging and finite element analysis (FEA). Magnetic resonance imaging (MRI) was chosen since it presents relatively low risks for human health. A finite element model was created from the MRI images and loaded with systolic physiological pressures. By means of an optimization routine, the structural material properties were changed until average strains matched those measured by MRI. The method outlined in this work produced an estimate of the in situ properties of cardiovascular tissue based on non-invasive image datasets and finite element analysis.
An anisotropic inelastic constitutive model to describe stress softening and permanent deformatio... more An anisotropic inelastic constitutive model to describe stress softening and permanent deformation in arterial tissue.
Journal of Biomechanics, Volume 41, Issue null, Pages S388, July 2008, Authors:Ian Pericevic; Cai... more Journal of Biomechanics, Volume 41, Issue null, Pages S388, July 2008, Authors:Ian Pericevic; Caitríona Lally; Deborah Toner; Daniel Kelly. ...
ABSTRACT Quantifying the properties of atherosclerotic plaques is critical to improving our under... more ABSTRACT Quantifying the properties of atherosclerotic plaques is critical to improving our understanding of the pathogenesis of the disease. Furthermore realistic tissue properties are vital in order to obtain legitimate results from finite element models of surgical interventions used to treat cardiovascular disease. The aim of this study is to determine the mechanical properties of fresh human carotid plaques immediately following removal during endarterectomy. A number of studies have reported atherosclerotic plaque properties previously [1–3], however all of these tested cadaveric tissue. This study will further investigate in-patient and inter-patient variability, the relationship between plaque properties and their clinical classification (calcified, mixed or echolucent) and the location of the sample (common, internal, external carotid).
Computational models of mechanobiological systems have been widely used to provide insight into t... more Computational models of mechanobiological systems have been widely used to provide insight into these systems and also to predict their behaviour. In this context, vascular tissue engineering benefits from further attention given the challenges involved in developing functional low calibre vascular grafts with long-term patency. In this study, a novel multiscale mechanobiological modelling framework is presented, which takes advantage of lattice-free agentbased models coupled with the finite element method to investigate the dynamics of VSMC growth in vascular tissue engineering scaffolds. The results illustrate the ability of the mechanobiological modelling approach to capture complex multiscale mechanobiological phenomena. Specifically, the framework enabled the study of the influence of scaffold compliance and loading regime in regulating the growth of VSMCs in vascular scaffolds and their role in development of intimal hyperplasia (IH). The model demonstrates that low scaffold compliance compared to host arteries leads to increased luminal ingrowth and IH development. In addition, culture of a tissue-engineered blood vessel under a pulsatile luminal pressure reduced luminal ingrowth and enhanced collagen synthesis within the scaffold compared to non-pulsatile culture. The mechanobiological framework presented provides a robust platform for testing hypotheses in vascular tissue engineering and lends itself to use as an optimisation design tool.
Applied Biological Engineering - Principles and Practice, 2012
ASME 2009 Summer Bioengineering Conference, Parts A and B, 2009
Cardiovascular disease is the major cause of morbidity and mortality in the adult population and ... more Cardiovascular disease is the major cause of morbidity and mortality in the adult population and treatment of many of the patients struggling with such diseases requires surgical interventions involving replacement of diseased arteries. Although currently it is possible to replace ...
The surface texture and chemistry of WE43 absorbable magnesium stents (AMS) and tube specimens pr... more The surface texture and chemistry of WE43 absorbable magnesium stents (AMS) and tube specimens processed by chemical and reactive ion etching (RIE) were investigated. Tube specimens were produced in three different conditions, namely asreceived, chemically etched and plasma etched. The results of scanning electron microscopy, atomic force microscopy and energy dispersive X-ray spectroscopy studies showed that plasma etching and cleaning reduced surface roughness by 10 % compared to chemical etching alone, and completely removed surface deposits remaining from the chemical etch process. The same combination of chemical and plasma etching processes was employed to produce AMS. Expansion tests demonstrated uniform stent expansion characteristics and confirmed the viability of the device. The results of this study show that RIE is an effective surface modification technique for absorbable magnesium devices.
ABSTRACT Atherosclerosis frequently occurs at the carotid bifurcation and plaque rupture at this ... more ABSTRACT Atherosclerosis frequently occurs at the carotid bifurcation and plaque rupture at this site is one of the leading causes of stroke. Over 50% of these strokes occur in asymptomatic patients and thus better indicators of the disease need to be developed. Finite element studies of arterial wall segments have provided key information on the biomechanics of arteries, from prediction of atherosclerotic plaque rupture [1] to the effectiveness of stents [2]. Most studies however have focused on simple straight arterial segments and few on complex geometries such as bifurcations or aneurysms. Studies which have addressed the carotid bifurcation have been based on either idealised geometries [3] or on a single patient specific geometry often generated from cadaveric material [4].
ASME 2009 Summer Bioengineering Conference, Parts A and B, 2009
ABSTRACT One of the most significant limitations of percutaneous coronary intervention using sten... more ABSTRACT One of the most significant limitations of percutaneous coronary intervention using stents is the growth of tissue within the stent, leading to re-occlusion of the target vessel. There is a wide range of stents available, and stent designs differ in their efficacy [1]. Stent parameters such as stent length, strut configuration, diameter and expansion method have been shown to influence the amount of restenosis provoked [2]. Despite many generations of coronary stents — and the advent of drug elution — up to 10% of percutaneous coronary interventions require revision, climbing to 50% in some high risk lesions [3].
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2008
Mechanical stimuli have been shown to affect cell behaviour in terms of proliferation, apoptosis,... more Mechanical stimuli have been shown to affect cell behaviour in terms of proliferation, apoptosis, and protein expression. In terms of cardiovascular diseases, for example, endothelial and smooth muscle cells exposed to an abnormal strain environment have been associated with atherosclerosis and in-stent restenosis. The FX-4000 system (Flexercell Tension Plus System, Flexcell Corporation, McKeesport, Pennsylvania, USA) is an in-vitro system that is widely used to strain cells in order to evaluate their response to strain. The precision, accuracy, and repeatability of the strains controlled by the system are therefore crucial to analyse and interpret the results confidently. The aim of this study was to investigate the mechanical behaviour of the FX-4000 Flexercell six-well-plate silicon membranes for static and dynamic cyclic strains by measuring the maximum peak strain and analysing the change in the membrane deformation after cyclic strain for 0 h, 24 h, and 48 h at different strain amplitudes and frequencies. The results of the tests conducted demonstrate notable differences between the measured strains of the membranes in comparison with both the inputs and the outputs of the Flexcell software. The calibration method used by Flexcell International assumes that the strain values determined for a given vacuum pressure on the silicone membranes are reliable for different waveforms and frequencies. The data reported here clearly indicate that this is not the case. The results indicate that a unique calibration pressure-strain curve must be determined for each test given the viscoelastic nature of the Flexcell system. A new method to calibrate the machine in house was applied using new pressure-strain equations. This new calibration method has been presented and should enable researchers using the Flexcell machine to set up their cell experiments more accurately.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2010
The design of medical devices could be very much improved if robust tools were available for comp... more The design of medical devices could be very much improved if robust tools were available for computational simulation of tissue response to the presence of the implant. Such tools require algorithms to simulate the response of tissues to mechanical and chemical stimuli. Available methodologies include those based on the principle of mechanical homeostasis, those which use continuum models to simulate biological constituents, and the cell-centred approach, which models cells as autonomous agents. In the latter approach, cell behaviour is governed by rules based on the state of the local environment around the cell; and informed by experiment. Tissue growth and differentiation requires simulating many of these cells together. In this paper, the methodology and applications of cell-centred techniques-with particular application to mechanobiology-are reviewed, and a cell-centred model of tissue formation in the lumen of an artery in response to the deployment of a stent is presented. The method is capable of capturing some of the most important aspects of restenosis, including nonlinear lesion growth with time. The approach taken in this paper provides a framework for simulating restenosis; the next step will be to couple it with more patient-specific geometries and quantitative parameter data.
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Papers by Caitríona Lally