Publications
417 results found
Williams B, Lacy PS, Thurston H, et al., 2006, Response to letters regarding article, "differential impact of blood pressure-lowering drugs on central aortic pressure and clinical outcomes: Principal results of the Conduit Artery Function Evaluation (CAFE) Study", CIRCULATION, Vol: 114, Pages: E540-E541, ISSN: 0009-7322
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- Citations: 7
Dowsey AW, Keegan J, Lerotic M, et al., 2006, Motion-compensated MR valve imaging with COMB tag tracking and super-resolution enhancement, 9th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI 2006), Publisher: Lecture Notes in Computer Science, Pages: 478-491
Ariff B, Zambanini A, Vamadeva S, et al., 2006, Candesartan- and atenolol-based treatments induce different patterns of carotid artery and left ventricular remodeling in hypertension, STROKE, Vol: 37, Pages: 2381-2384, ISSN: 0039-2499
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- Citations: 41
Sun N, Wood NB, Hughes AD, et al., 2006, Fluid-wall modelling of mass transfer in an axisymmetric stenosis: Effects of shear-dependent transport properties, ANNALS OF BIOMEDICAL ENGINEERING, Vol: 34, Pages: 1119-1128, ISSN: 0090-6964
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- Citations: 81
Chaturvedi N, Coady E, Mayet J, et al., 2006, Femoral atherosclerosis is reduced in South Asian compared with European men, 14th Meeting of the International-Society-of-Atherosclerosis, Publisher: ELSEVIER IRELAND LTD, Pages: 104-104, ISSN: 1567-5688
Leung JH, Wright AR, Cheshire N, et al., 2006, Fluid structure interaction of patient specific abdominal aortic aneurysms: a comparison with solid stress models, Biomedical Engineering Online, Vol: 5, ISSN: 1475-925X
BackgroundAbdominal aortic aneurysm (AAA) is a dilatation of the aortic wall, which can rupture, if left untreated. Previous work has shown that, maximum diameter is not a reliable determinant of AAA rupture. However, it is currently the most widely accepted indicator. Wall stress may be a better indicator and promising patient specific results from structural models using static pressure, have been published. Since flow and pressure inside AAA are non-uniform, the dynamic interaction between the pulsatile flow and wall may influence the predicted wall stress. The purpose of the present study was to compare static and dynamic wall stress analysis of patient specific AAAs.MethodPatient-specific AAA models were created from CT scans of three patients. Two simulations were performed on each lumen model, fluid structure interaction (FSI) model and static structural (SS) model. The AAA wall was created by dilating the lumen with a uniform 1.5 mm thickness, and was modeled as a non-linear hyperelastic material. Commercial finite element code Adina 8.2 was used for all simulations. The results were compared between the FSI and SS simulations.ResultsResults are presented for the wall stress patterns, wall shear stress patterns, pressure, and velocity fields within the lumen. It is demonstrated that including fluid flow can change local wall stresses slightly. However, as far as the peak wall stress is concerned, this effect is negligible as the difference between SS and FSI models is less than 1%.ConclusionThe results suggest that fully coupled FSI simulation, which requires considerable computational power to run, adds little to rupture risk prediction. This justifies the use of SS models in previous studies.
Manisty C, Davies J, Whinnett Z, et al., 2006, The role of wave reflection in the pathophysiology of hypertension: Assessed using non-invasive wave intensity analysis, Annual Scientific Conference of the British-Society-Promoting-Cardiovascular-Health, Publisher: B M J PUBLISHING GROUP, Pages: A33-A33, ISSN: 1355-6037
Sharp A, Thom S, Francis D, et al., 2006, Ethnicity and left ventricular diastolic function in hypertension: An ASCOT substudy, Annual Scientific Conference of the British-Society-Promoting-Cardiovascular-Health, Publisher: BMJ PUBLISHING GROUP, Pages: A34-A34, ISSN: 1355-6037
Manisty C, Davies J, Francis D, et al., 2006, The protodiastolic expansion wave: A compensatory mechanism for the reduction in longitudinal relaxation velocity with ageing?, Annual Scientific Conference of the British-Society-Promoting-Cardiovascular-Health, Publisher: B M J PUBLISHING GROUP, Pages: A61-A62, ISSN: 1355-6037
Sharp A, Thom S, Francis D, et al., 2006, The ability of tissue Doppler echocardiography to predict future cardiovascular events in a hypertensive population: An ASCOT substudy, Annual Scientific Conference of the British-Society-Promoting-Cardiovascular-Health, Publisher: BMJ PUBLISHING GROUP, Pages: A34-A35, ISSN: 1355-6037
Witt N, Wong TY, Hughes AD, et al., 2006, Abnormalities of retinal microvascular structure and risk of mortality from ischemic heart disease and stroke, HYPERTENSION, Vol: 47, Pages: 975-981, ISSN: 0194-911X
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- Citations: 264
Sharp A, Mayet J, Francis D, et al., 2006, The effect of ethnicity on BNP levels in hyplkiension - An ASCOT sub-study, Annual Scientific Conference of the British-Society-Promoting-Cardiovascular-Health, Publisher: B M J PUBLISHING GROUP, Pages: A49-A49, ISSN: 1355-6037
Hughes AD, Martinez-Perez E, Jabbar A-S, et al., 2006, Quantification of topological changes in retinal vascular architecture in essential and malignant hypertension, JOURNAL OF HYPERTENSION, Vol: 24, Pages: 889-894, ISSN: 0263-6352
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- Citations: 91
Williams B, Lacy PS, Thom SM, et al., 2006, Differential impact of blood pressure-lowering drugs on central aortic pressure and clinical outcomes - Principal results of the Conduit Artery Function Evaluation (CAFE) study, CIRCULATION, Vol: 113, Pages: 1213-1225, ISSN: 0009-7322
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- Citations: 1898
Dowsey AW, Keegan J, Lerotic M, et al., 2006, Motion-compensated MR valve imaging with COMB tag tracking and super-resolution enhancement, Springer-Verlag, 9th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI), Copenhagen, Denmark, Publisher: Heidelberg, Pages: 364-371, ISSN: 1611-3349
MR imaging of the heart valve leaflets is a challenging problem due to their large movements throughout the cardiac cycle. This paper presents a motion-compensated imaging approach with COMB tagging for valve imaging. It involves an automatic method for tracking the full 3D motion of the valve plane so as to provide a motion-tracked acquisition scheme. Super-resolution enhancement is then applied to the slice-select direction so that the partial volume effect is minimised. In vivo results have shown that in terms of slice positioning, the method has equivalent accuracy to that of a manual approach whilst being quicker and more consistent. The use of multiple parallel COMB tags will permit adaptive imaging that follows tissue motion. This will have significant implications for quantification of myocardial perfusion and tracking anatomy, functions that are traditionally difficult in MRI.
Dowsey AW, Keegan J, Lerotic M, et al., 2006, Motion-Compensated MR Valve Imaging with COMB Tag Tracking and Super-Resolution Enhancement, Medical Image Computing and Computer Aided Intervention - MICCAI 2006
Wood NB, Exarchou I, Xu XY, et al., 2005, Progress with the study of retinal hemodynamics in normotensive and hypertensive patients, Proceedings of the 2005 Summer Bioengineering Conference, Vol: 2005, Pages: 259-260
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- Citations: 1
Leung JH, Wright A, Cheshire N, et al., 2005, Fluid-structure interaction in patient specific models of the abdominal aortic aneurysm, Proceedings of the 2005 Summer Bioengineering Conference, Vol: 2005, Pages: 1450-1451
Augst AD, Xu XY, Ariff B, et al., 2005, Correlation between haemodynamic wall parameters and intima-media thickness in the carotid arteries, Pages: 411-412
Tapp R, Sharp A, Chaturvedi N, et al., 2005, Effects of blood pressure lowering with beta blocker plus diuretic-based therapy and calcium antagonist plus angiotensin converting enzyme inhibitor-based therapy on left ventricular diastolic function, 78th Annual Scientific Session of the American-Heart-Association, Publisher: LIPPINCOTT WILLIAMS & WILKINS, Pages: U399-U400, ISSN: 0009-7322
Hughes AD, Coady E, Byrd S, et al., 2005, Circulating endothelial progenitor cells and atherosclerosis in European and South Asian subjects, 10th Annual Meeting of the European-Council-for-Cardiovascular-Research, Publisher: LIPPINCOTT WILLIAMS & WILKINS, Pages: 900-900, ISSN: 0194-911X
Vermeersch SJ, Glor FP, Crowe LA, et al., 2005, Relationship between carotid artery intima-media thickness and wall shear stress derived parameters., Comput Methods Biomech Biomed Engin, Vol: 8, Pages: 279-280, ISSN: 1025-5842
Zambanini A, Cunningham SL, Parker KH, et al., 2005, Wave-energy patterns in carotid, brachial, and radial arteries: a noninvasive approach using wave-intensity analysis, AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, Vol: 289, Pages: H270-H276, ISSN: 0363-6135
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- Citations: 114
Davies J, Whinnett Z, Francis D, et al., 2005, Effect of nitrate administration on wave speed propagation in the human coronary artery, Annual Conference of G-MEX/MICC, Publisher: B M J PUBLISHING GROUP, Pages: A66-A67, ISSN: 1355-6037
Glor FP, Ariff B, Hughes AD, et al., 2005, Operator dependence of 3-D ultrasound-based computational fluid dynamics for the carotid bifurcation, IEEE TRANSACTIONS ON MEDICAL IMAGING, Vol: 24, Pages: 451-456, ISSN: 0278-0062
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- Citations: 21
Ariff B, Crowe L, Firmin D, et al., 2005, Comparison between three-dimensional volume-selective turbo spin-echo imaging and two-dimensional ultrasound for assessing carotid artery structure and function, Journal of Magnetic Resonance Imaging, Vol: 21
Sharp A, Thom S, Hughes A, et al., 2005, Black hypertensives have significantly lower B-Natriuretic peptide levels than South Asians or Whites, 54th Annual Scientific Session of the American-College-of-Cardiology, Publisher: ELSEVIER SCIENCE INC, Pages: 381A-381A, ISSN: 0735-1097
Wimalasundera RC, Thom SAM, Regan L, et al., 2005, Effects of vasoactive agents on intracellular calcium and force in myometrial and subcutaneous resistance arteries isolated from preeclamptic, pregnant, and nonpregnant woman, AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY, Vol: 192, Pages: 625-632, ISSN: 0002-9378
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- Citations: 30
Augst AD, Ariff B, Barratt DC, et al., 2005, Application of ultrasound-based computational fluid dynamics to modeling blood flow in the carotid bifurcation, Medical Imaging Systems Technology: Volume 5: Methods in Cardiovascular and Brain Systems, Pages: 109-156, ISBN: 9789812569899
Atherosclerotic plaque formation has been linked to haemodynamic risk factors, such as low and oscillating wall shear stresses (WSS). Experimental and numerical methods have been developed to investigate the mechanisms involved. Computational fluid dynamics (CFD) methods have the advantages of low cost and easily manageable numerical results. In order to obtain physiologically realistic results, CFD can be linked with medical imaging methods, which allow the extraction of in vivo vascular geometry and flow data to be used as input for haemodynamic simulations. Most of the image-based CFD approaches have been based on MRI, which has the disadvantages of relatively high cost and limited availability. Hence, a novel technique based on 3D ultrasound was developed with the advantages of low cost, fast acquisition and high spatial resolution. A methodology was developed to extract geometric information from the ultrasound images, reconstruct the surfaces and generate computational grids for flow simulations of the human carotid artery bifurcation. Additionally, a scheme was devised to utilize Doppler flow information for CFD boundary conditions. Accuracy and reproducibility of the combined imaging and modeling approach were evaluated in vitro and in vivo and the developed protocol was applied to normal subjects. The main conclusion of this work is the feasibility of 3D and Doppler ultrasound based CFD simulations for clinical applications. However, there are several limitations when applying this methodology in carotid bifurcations, i.e. the location of the carotid bulb relative to the jaw bone, which obscures the ultrasound path when the bifurcation is high in the neck. Future work should focus on minimizing the limitations and improve automation and reliability of image processing and reconstruction.
Cunningham SL, Parker KH, Mayet J, et al., 2004, Peripheral haemodynamics are altered in diastolic heart failure, HEART, Vol: 90, Pages: 32-32, ISSN: 1355-6037
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