Arteries and Algorithms: Computational physiological flow and arterial disease modelling

Lead Research Organisation: Imperial College London
Department Name: Dept of Aeronautics

Abstract

Cardiovascular disease, including atherosclerosis, accounts for almost 50% of deaths in the western world. Our understanding of the causes and progression of atherosclerosis is relatively limited and, in many cases, both diagnosis and treatment require invasive patient specific techniques.An enhanced understanding of the physiological factors related to cardiovascular disease would likely to lead to significant advances in treatment as well as increased accuracy in diagnosis and prognosis. Developing this understanding is particularly difficult because of the complexities of the flow in human arterial networks. These are impossible to understand using existing medical data and expertise alone.Recent developments in numerical methods including greater opportunities for wider use of computational simulation and visualisation can provide the necessary link between patient specific imaging data, physics and biology, to provide a platform for this increased understanding. The impact of the use of these techniques could revolutionise medical science and practice in the way imaging modalities such as X-ray, ultrasound and magnetic resonance have done in succession over the past 40 years.The aim of this research initiative is, through close collaboration with vascular biologists, physiologists and surgeons, to develop a simulation environment capable of capturing the multi-scale, hierarchically coupled nature of both physiological and pathological arterial networks. The research programme is focused around three projects, two physiological incorporating the multiscale nature of arterial networks and one numerical: The first project will apply modelling of the three-dimensional fluid dynamics at arterial branches to improve understanding of the causal relationship of blood flow to arterial disease such as atherosclerosis. The second project is directed towards understanding and modelling pulsatile flow wavefoms in patient specific vascular networks using one-dimensional reduced models. The third project focuses on development of advanced mathematical and numerical techniques, such as uncertainty modelling and spectral/hp element methods, to facilitate such modelling.

Publications

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Alastruey J (2009) Analysing the pattern of pulse waves in arterial networks: a time-domain study in Journal of Engineering Mathematics

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Alastruey J (2008) Reduced modelling of blood flow in the cerebral circulation: Coupling 1-D, 0-D and cerebral auto-regulation models in International Journal for Numerical Methods in Fluids

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Alastruey J (2010) Reply to 'cord clamp insult may predispose to SIDS'. in Early human development

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Ali RL (2015) Automated fiducial point selection for reducing registration error in the co-localisation of left atrium electroanatomic and imaging data. in Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference

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Cantwell C (2015) Nektar++: An open-source spectral/ h p element framework in Computer Physics Communications

 
Description There were three key developments of this research: 1) Modelling and application of arterial pulse waves, 2) Modelling and application of complex 3D flow in the aortic arch and 3) Development of advanced computational fluid dynamics methods.

1) Arterial pulse wave modelling: Analogous to the free surface waves, as the heart beats it sends waves down the arterial systems since arteries are elastic. These waves reflect at arterial bifurcations causing different pulsatile wave forms at different locations of the system such as in the carotid (neck) or femoral (leg) arteries which have different patterns. Depending on the how well ther peripheries of the cardiovascular system are operating (for example due to disease) then the features of these waves can have different diagnostic potential. We have developed modelling and analysis techniques of these waves to help aid clinical understanding (see 10.1016/j.jbiomech.2007.05.027, 10.1016/j.jbiomech.2006.07.008, 10.1016/j.earlhumdev.2009.04.001) . The work has been continued by the research, Dr Jordi Alastruey, who is now an academic in the Department of Bioengineering at Kings College London.

2) Complex flow in the aorta: We applied advanced computational methods to study the association of arterial disease such as atherosclerosis with blood flow. The forces the flow exerts on the artery wall is associated with the transport of blood suspensions such as ldl through the wall. We therefore worked closely with physiologists and radiologist to produce both high resolution flow simulations in aortic arches of rabbits (10.1098/rsif.2011.0116) as well as produced localised models of arterial transport (10.1063/1.2938761). These studies have lead us to identify a new flow metric, called transverse wall shear stress, which is showing a promising correlation with the occurrence of arterial disease (PID:24044966) .


3) Advanced Numerical Methods: Underpinning both of the above studies were the development and application of advanced method for computational fluid dynamics know as spectral/hp element methods. Under this project we started the development of an open package, Nektar++, to allow these methods to be adopted by a wider community and make the methods more readily accessible (www.nektar.info, 10.1016/j.jcp.2010.03.031, 10.1080/10618562.2011.575368).
Exploitation Route Dr Jordi Alastruey is taking forward the pulse wave modelling at Kings College London

Dr Peter Vincent is continuing to develop the 3D modelling as a member of the Aeronautics Department at Imperial College London. We have also had two further PhD projects continuing this work, especially the development of the Transverse Wall Shear stress metric (TransWSS) which is now being adopted by a number of other groups.

Finally the tools behind both these studies are being openly made available through the Netkar++ framework www.nektar.info
Sectors Healthcare

URL http://www.nektar.info
 
Description The reduced pulse wave modelling developed under this grant is now being used to help inform clinical thinking using pulse wave information. One of the researchers, Dr Jordi Alastruey, obtained an academic position and is now working very closely with clinicians at Kings College London using this method. For example he is using it to calculate aortic, left ventricular and pulmonary pressures from non-invasive data as well as calculate aortic stiffness and CO and respiratory rate from catheter based data. Another researcher on this grant, Dr Peter Vincent, has also gone on to start a successful academic career and has continued his work into biomedical modelling working with clinicians at St Marys and Hammersmith hospitals in the area of Arterial Venous grants. They have recently just had a patent accepted on this follow on work.
First Year Of Impact 2009
Sector Healthcare
Impact Types Societal

 
Description BHF Project Grant
Amount £189,168 (GBP)
Funding ID PF/09/088 
Organisation British Heart Foundation (BHF) 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2010 
End 09/2012
 
Description BHF Project Grant
Amount £175,030 (GBP)
Funding ID PG/08/053/25192 
Organisation British Heart Foundation (BHF) 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2008 
End 09/2011
 
Description BHF Research Excellence Centre
Amount £8,900,000 (GBP)
Funding ID BHF RE/08/002 
Organisation British Heart Foundation (BHF) 
Sector Charity/Non Profit
Country United Kingdom
Start 04/2008 
End 03/2013
 
Description EPSRC: LIbHPC I
Amount £483,099 (GBP)
Funding ID EP/I030239/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 07/2011 
End 06/2013
 
Description EPSRC: LIbHPC II
Amount £726,567 (GBP)
Funding ID EP/K038788/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 07/2013 
End 06/2015
 
Description EPSRC: Streak Instability
Amount £353,257 (GBP)
Funding ID EP/F045093/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 07/2008 
End 06/2011
 
Description RAEng/McLaren Research Chair
Amount £200,000 (GBP)
Organisation Royal Academy of Engineering 
Sector Learned Society
Country United Kingdom
Start 10/2012 
End 09/2017
 
Title Nektar++ version 4.0.1 
Description Nektar++ is a tensor product based finite element package designed to allow one to construct efficient classical low polynomial order h-type solvers (where h is the size of the finite element) as well as higher p-order piecewise polynomial order solvers. 
Type Of Technology Software 
Year Produced 2014 
Open Source License? Yes  
Impact The software is being used by a number of national and international groups and our web site is currently being visited up to 100 times a day according to google analytics 
URL http://www.nektar.info/downloads/file/nektar-source-tar-gz-2/