Factors influencing left-ventricular stiffness |
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| Institution: | 1. School of Strategy & Leadership, Coventry University, Coventry, UK;2. School of Design, University of Leeds, Leeds, UK;3. Centre for Instructional Technology & Multimedia, Universiti Sains Malaysia, Penang, Malaysia;4. Computer Science Department, Community College, King Saud University, Riyadh, Saudi Arabia;5. Institute of Computer Science and Digital Innovation, UCSI University, Kuala Lumpur, Malaysia;1. Jagiellonian University Medical College, Kraków, Poland;2. Lucerne University of Applied Sciences and Arts, HSLU, Lucerne, Switzerland;3. Department of Cardiology, University Medical Center Utrecht, Utrecht, the Netherlands;4. Department of Automation and Robotics, AGH University of science and technology, Kraków, Poland;1. Department of Internal Medicine, Päijät-Häme Central Hospital, Keskussairaalankatu 7, 15850 Lahti, Finland;2. Heart Center, Central Hospital of North Karelia, Tikkamäentie 16, 80210 Joensuu, Finland;3. Research Unit of Internal Medicine, Medical Research Center, Oulu University Hospital and University of Oulu, Faculty of Medicine, PO Box 5000, FI-90014 Oulu, Finland;4. Center for Machine Vision and Signal Analysis, University of Oulu, PO Box 4500, Oulu FI-90014, Finland;5. Finnish Institute for Health and Welfare, PO Box 30, FI-00271 Helsinki, Finland.;6. Division of Cardiology, Heart and Lung Center, University of Helsinki and Helsinki University Hospital, Meilahti Tower Hospital, PL 340, 00029 HUS Helsinki, Finland. |
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| Abstract: | The aim of the study was to investigate the relative contributions of geometrical and material factors to overall left-ventricular cavity stiffness. Left-ventricular cavity shapes were reconstructed using a computer and the variation of myocardial elastic modulus was calculated, by the finite element method, through the passive phase of diastole when rising volume coincided with rising pressure. Geometric data were obtained from biplane cineangiography, with micromanometer pressure measurements, for ten patients with left ventricular disease. Dimensional analysis was applied to the initial and derived data from which the influences of myocardial compliance, wall thickness-to-long dimension ratio, and aspect ratio (long-to-short axes) were determined. The ratio between the volume elasticity and the myocardial modulus of elasticity, the normalized stiffness ratio (NSR), is proposed as a useful index of left ventricular mechanical behaviour in diastole. The volume elasticity of the chamber is dependent not only upon the myocardium elastic modulus and the wall thickness ratio, but also on the shape of the chambe. Changes in the thickness/radius ratio of the ventricle have less effect upon its distention than those in the long dimension/radius ratio. The left ventricle becomes more spherical in shpae through diastole and hence becomes stiffer by this geometric mechanism. |
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