Fergal J Boyle

Publications (4)4.4 Total impact

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  Available from: arrow.dit.ie

  Article: A Numerical Methodology to Fully Elucidate the Altered Wall Shear Stress in a Stented Coronary Artery

  Jonathan B. Murphy, Fergal J. Boyle
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  ABSTRACT: Arterial restenosis after coronary stenting is caused by excessive tissue growth which is stimulated by arterial injury and alterations to the hemodynamic wall shear stress (WSS). Recent numerical studies have predicted only minor differences in the altered WSS between different stent designs using a commonly employed threshold assessment technique. While it is possible that there are only minor differences, it is more likely that this assessment technique is incapable of fully elucidating the alterations to the WSS created by stent implantation. This paper proposes a methodology that involves a more complete investigation into the stent-induced alterations of WSS by incorporating the full suite of WSS-based variables: WSS, WSS gradient (WSSG), WSS angle gradient (WSSAG) and oscillatory shear index (OSI). The four variables are analyzed quantitatively and qualitatively to assess the effect of the stent implantation. The methodology is applied to three stents with contrasting designs: the Palmaz Schatz (PS), Gianturco Roubin II (GR-II) and Bx-Velocity (Bx) stents. For WSS the methodology ranks the stents (best to worst) as follows: PS, GR-II, Bx (Cohen’s d: −0.01, −0.613), for WSSG: PS, Bx, GR-II (d: 0.159, 0.764), for WSSAG: PS GR-II Bx (d: 0.213, 0.082), and for OSI: PS, GR-II, Bx (d: 0.315, 0.380). The suggested quantitative and qualitative assessment of the WSS-based variables is shown to improve upon, and highlight the weakness of, the previously used threshold assessment technique. The proposed methodology could be utilized to minimize WSS alterations at the design stage of future coronary stents. KeywordsPulsatile flow-Restenosis-Multi-variable analysis
  04/2012; 1(4):256-268.
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  Available from: dit.ie

  Article: Computational structural modelling of coronary stent deployment: a review.

  David Martin, Fergal J Boyle
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  ABSTRACT: The finite element (FE) method is a powerful investigative tool in the field of biomedical engineering, particularly in the analysis of medical devices such as coronary stents whose performance is extremely difficult to evaluate in vivo. In recent years, a number of FE studies have been carried out to simulate the deployment of coronary stents, and the results of these studies have been utilised to assess and optimise the performance of these devices. The aim of this paper is to provide a thorough review of the state-of-the-art research in this area, discussing the aims, methods and conclusions drawn from a number of significant studies. It is intended that this paper will provide a valuable reference for future research in this area.
  Computer Methods in Biomechanics and Biomedical Engineering 04/2011; 14(4):331-48. · 0.85 Impact Factor
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  Available from: dit.ie

  Article: Drug-eluting stents for coronary artery disease: a review.

  David M Martin, Fergal J Boyle
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  ABSTRACT: Over the past decade the introduction of drug-eluting stents (DESs) has revolutionised the treatment of coronary artery disease. However, in recent years concern has arisen over the long-term safety and efficacy of DESs due to the occurrence of late adverse clinical events such as stent thrombosis. With this concern in mind, research and development is currently centred on increasing the long-term safety and efficacy of DESs. The aim of this paper is to provide a thorough review of currently approved and promising investigational DESs. With dozens of companies involved in the development of new and innovative anti-restenotic agents, polymeric coatings and stent platforms, it is intended that this review paper will provide a clear indication of how DESs are currently evolving and prove a valuable reference tool for future research in this area.
  Medical Engineering & Physics 11/2010; 33(2):148-63. · 1.62 Impact Factor
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  Available from: dit.ie

  Article: A full-range, multi-variable, CFD-based methodology to identify abnormal near-wall hemodynamics in a stented coronary artery.

  Jonathan B Murphy, Fergal J Boyle
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  ABSTRACT: The benefit of coronary stent implantation is reduced by excessive intimal hyperplasia which re-narrows the artery and the prevention of which is still a primary concern for clinicians. Abnormal hemodynamics create non-physiological viscous stress on the artery wall, one of the root causes of intimal hyperplasia following stent implantation. A methodology to comprehensively evaluate the viscous stress on the artery wall following stent implantation would be useful to evaluate a stent's hemodynamic performance.The proposed methodology employs 3D computational fluid dynamics, the variables wall shear stress (WSS), WSS gradient (WSSG), WSS angle gradient (WSSAG) and a statistical analysis to evaluate the viscous stress. The methodology is demonstrated and compared to a commonly used "threshold technique" for evaluating a stent's hemodynamic performance.It is demonstrated that the threshold technique is not adequate to fully analyse the viscous stress on the artery wall and can even be misleading. Furthermore, all three of the aforementioned variables should be considered as each provides a different perspective on the abnormalities that can arise in the arterial viscous stress.The hemodynamic performance of a stent can be assessed more comprehensively than with previously used methods by examining the arterial viscous stresses using the proposed methodology.
  Biorheology 01/2010; 47(2):117-32. · 1.93 Impact Factor