References of "Paeme, Sabine"
     in
Bookmark and Share    
Full Text
See detailMathematical modeling od the mitral valve. From local to global hemodynamics
Paeme, Sabine ULg

Doctoral thesis (2014)

Mitral valve dysfunction is a relatively common heart disease which typically requires mechanical valve replacement, with consequent high social and economic costs. More specifically, ischemic mitral ... [more ▼]

Mitral valve dysfunction is a relatively common heart disease which typically requires mechanical valve replacement, with consequent high social and economic costs. More specifically, ischemic mitral insufficiency following myocardial infarction has a dynamic behavior that can lead to failure in its detection in certain patients, creating a situation with increased risk of morbidity and mortality. Improving the tracking and the control of valvular pathologies is therefore crucial, as it offers significant opportunities to improve care, costs and prognosis for patients with this disease. To study heart and cardiac valve dysfunction, cardiologists need information about detailed pressure and flow dynamics around and through the valves, atria and ventricles. However, non-invasive information about pressure is currently limited to indices at specific times and invasive catheterization data, which is more traumatic for the patient, is not usually routinely available. One alternative to this involves mathematical modeling of the cardiovascular system which offers a non-invasive and inexpensive way of studying cardiac and circulatory dynamics. This is particularly beneficial where detailed, continuous measurements may not be practicable. This study consisted of the development of a multi-scale closed-loop model of the cardiovascular system that accounted for progressive mitral valve aperture area over the entire cardiac cycle. This multi-scale model, which included detailed mitral valve and left atrium models, was tested over a range of physiological situations and clinical data. The goal was to validate the model’s ability to reproduce clinically measured physiological and pathophysiological behavior in a manner that would enable a model to be made patient-specific using available data. The resulting model was designed to be made patient-specific, and thus capture and reproduce the patient’s unique hemodynamic state on both global and local scales. In particular, it was shown to provide significant information about the patient’s mitral valve dynamics and the detailed flow dynamics and pressure around it. These data are not currently available without extensive, invasive measurements, and this therefore represents a significant step forward in model-based sensing and diagnosis. It is hoped that the model and methods developed in this study will be a powerful tool in assisting medical teams in investigating, tracking, diagnosing and controlling the cardiovascular system. More specifically, the mitral valve, as well as other similar valves, could be directly monitored to improve the diagnosis, costs and prognosis of valvular dysfunction. Furthermore, the overall results justify detailed in vivo animal experiments to thoroughly validate these models and methods in advance of clinical trials. [less ▲]

Detailed reference viewed: 38 (23 ULg)
Full Text
Peer Reviewed
See detailSimulation of Left Atrial Function Using a Multi-Scale Model of the Cardiovascular System
Pironet, Antoine ULg; Dauby, Pierre ULg; Paeme, Sabine ULg et al

in PLoS ONE (2013), 8(6), 65146

During a full cardiac cycle, the left atrium successively behaves as a reservoir, a conduit and a pump. This complex behavior makes it unrealistic to apply the time-varying elastance theory to ... [more ▼]

During a full cardiac cycle, the left atrium successively behaves as a reservoir, a conduit and a pump. This complex behavior makes it unrealistic to apply the time-varying elastance theory to characterize the left atrium, first, because this theory has known limitations, and second, because it is still uncertain whether the load independence hypothesis holds. In this study, we aim to bypass this uncertainty by relying on another kind of mathematical model of the cardiac chambers. In the present work, we describe both the left atrium and the left ventricle with a multi-scale model. The multi-scale property of this model comes from the fact that pressure inside a cardiac chamber is derived from a model of the sarcomere behavior. Macroscopic model parameters are identified from reference dog hemodynamic data. The multi-scale model of the cardiovascular system including the left atrium is then simulated to show that the physiological roles of the left atrium are correctly reproduced. This include a biphasic pressure wave and an eight-shaped pressure-volume loop. We also test the validity of our model in non basal conditions by reproducing a preload reduction experiment by inferior vena cava occlusion with the model. We compute the variation of eight indices before and after this experiment and obtain the same variation as experimentally observed for seven out of the eight indices. In summary, the multi-scale mathematical model presented in this work is able to correctly account for the three roles of the left atrium and also exhibits a realistic left atrial pressure-volume loop. Furthermore, the model has been previously presented and validated for the left ventricle. This makes it a proper alternative to the time-varying elastance theory if the focus is set on precisely representing the left atrial and left ventricular behaviors. [less ▲]

Detailed reference viewed: 39 (18 ULg)
Full Text
Peer Reviewed
See detailA simplified model for mitral valve dynamics.
Moorhead, K. T.; Paeme, Sabine ULg; Chase, J. G. et al

in Computer Methods & Programs in Biomedicine (2013), 109(2),

Located between the left atrium and the left ventricle, the mitral valve controls flow between these two cardiac chambers. Mitral valve dysfunction is a major cause of cardiac dysfunction and its dynamics ... [more ▼]

Located between the left atrium and the left ventricle, the mitral valve controls flow between these two cardiac chambers. Mitral valve dysfunction is a major cause of cardiac dysfunction and its dynamics are little known. A simple non-linear rotational spring model is developed and implemented to capture the dynamics of the mitral valve. A measured pressure difference curve was used as the input into the model, which represents an applied torque to the anatomical valve chords. A range of mechanical model hysteresis states were investigated to find a model that best matches reported animal data of chord movement during a heartbeat. The study is limited by the use of one dataset found in the literature due to the highly invasive nature of getting this data. However, results clearly highlight fundamental physiological issues, such as the damping and chord stiffness changing within one cardiac cycle, that would be directly represented in any mitral valve model and affect behaviour in dysfunction. Very good correlation was achieved between modeled and experimental valve angle with 1-10% absolute error in the best case, indicating good promise for future simulation of cardiac valvular dysfunction, such as mitral regurgitation or stenosis. In particular, the model provides a pathway to capturing these dysfunctions in terms of modeled stiffness or elastance that can be directly related to anatomical, structural defects and dysfunction. [less ▲]

Detailed reference viewed: 27 (9 ULg)
Full Text
Peer Reviewed
See detailEffect of abrupt preload reduction on left atrial and ventricular pressures in a multi-scale mathematical model of the cardiovascular system
Pironet, Antoine ULg; Dauby, Pierre ULg; Kosta, Sarah ULg et al

in European Heart Journal Supplements : Journal of the European Society of Cardiology (2013), 34

Detailed reference viewed: 20 (4 ULg)
Full Text
Peer Reviewed
See detailA multi-scale cardiovascular system model can account for the load-dependence of the end-systolic pressure-volume relationship.
Pironet, Antoine ULg; Desaive, Thomas ULg; Kosta, Sarah ULg et al

in BioMedical Engineering OnLine (2013), 12(1), 8

ABSTRACT: BACKGROUND: The end-systolic pressure-volume relationship is often considered as a load-independent property of the heart and, for this reason, is widely used as an index of ventricular ... [more ▼]

ABSTRACT: BACKGROUND: The end-systolic pressure-volume relationship is often considered as a load-independent property of the heart and, for this reason, is widely used as an index of ventricular contractility. However, many criticisms have been expressed against this index and the underlying time-varying elastance theory: first, it does not consider the phenomena underlying contraction and second, the end-systolic pressure volume relationship has been experimentally shown to be load-dependent. METHODS: In place of the time-varying elastance theory, a microscopic model of sarcomere contraction is used to infer the pressure generated by the contraction of the left ventricle, considered as a spherical assembling of sarcomere units. The left ventricle model is inserted into a closed-loop model of the cardiovascular system. Finally, parameters of the modified cardiovascular system model are identified to reproduce the hemodynamics of a normal dog. RESULTS: Experiments that have proven the limitations of the time-varying elastance theory are reproduced with our model: (1) preload reductions, (2) afterload increases, (3) the same experiments with increased ventricular contractility, (4) isovolumic contractions and (5) flow-clamps. All experiments simulated with the model generate different end-systolic pressure-volume relationships, showing that this relationship is actually load-dependent. Furthermore, we show that the results of our simulations are in good agreement with experiments. CONCLUSIONS: We implemented a multi-scale model of the cardiovascular system, in which ventricular contraction is described by a detailed sarcomere model. Using this model, we successfully reproduced a number of experiments that have shown the failing points of the time-varying elastance theory. In particular, the developed multi-scale model of the cardiovascular system can capture the load-dependence of the end-systolic pressure-volume relationship. [less ▲]

Detailed reference viewed: 55 (39 ULg)
Full Text
Peer Reviewed
See detailnon invasive estimation of left atrial pressure and mitral valve area waveforms during an entire cardiac cycle
Paeme, Sabine ULg; Pironet, Antoine ULg; LANCELLOTTI, Patrizio ULg et al

in proceeding of 11th national day of the National Committee on Biomedical Engineering (2012, December 07)

Detailed reference viewed: 19 (3 ULg)
Full Text
Peer Reviewed
See detailDevelopment and Identification of a Closed-Loop Model of the Cardiovascular System Including the Atria
Pironet, Antoine ULg; Revie, James A.; Paeme, Sabine ULg et al

Conference (2012, August 31)

Detailed reference viewed: 52 (6 ULg)
Full Text
Peer Reviewed
See detailStructural model of the mitral valve included in a cardiovascular closed loop model. Static and dynamic validation
Paeme, Sabine ULg; Pironet, Antoine ULg; Chase, J. Geoffrey et al

in proceedings of 8th IFAC Symposium on Biological and Medical Systems, Budapest 29-31 août 2012 (2012, August 31)

Detailed reference viewed: 23 (4 ULg)
Full Text
Peer Reviewed
See detailDevelopment and Identification of a Closed-Loop Model of the Cardiovascular System Including the Atria
Pironet, Antoine ULg; Revie, James A.; Paeme, Sabine ULg et al

in Proceedings of the 8th IFAC Symposium on Biological and Medical Systems (2012, August)

Detailed reference viewed: 44 (10 ULg)
Full Text
Peer Reviewed
See detailParameter Identification in a Model of the Cardiovascular System Including the Atria
Pironet, Antoine ULg; Revie, James A.; Paeme, Sabine ULg et al

in 10th Belgian Day on Biomedical Engineering (2011, December 02)

Detailed reference viewed: 22 (7 ULg)
Full Text
Peer Reviewed
See detailParameter Identification in a Model of the Cardiovascular System Including the Atria
Pironet, Antoine ULg; Revie, James A.; Paeme, Sabine ULg et al

Poster (2011, December 02)

Detailed reference viewed: 44 (31 ULg)
Full Text
Peer Reviewed
See detailStructural model of the mitral valve included in a cardiovascular closed loop model
Paeme, Sabine ULg; Moorhead, Kate; Chase, J. Geoffrey et al

Poster (2011, December)

A minimal cardiovascular system (CVS) model including mitral valve dynamics has been previously validated in silico. However parameters of this model are difficult to link with structural and anatomical ... [more ▼]

A minimal cardiovascular system (CVS) model including mitral valve dynamics has been previously validated in silico. However parameters of this model are difficult to link with structural and anatomical components of the valve. This research describes the integration of a structural model of the mitral valve in an existing closed-loop cardiovascular system (CVS) model [less ▲]

Detailed reference viewed: 12 (0 ULg)
Full Text
Peer Reviewed
See detailMathematical multi-scale model of the cardiovascular system including mitral valve dynamics. Application to ischemic mitral insufficiency
Paeme, Sabine ULg; Moorhead, Katherine; Chase, J. Geoffrey et al

in BioMedical Engineering OnLine (2011), 10(1), 86

Valve dysfunction is a common cardiovascular pathology. Despite significant clinical research, there is little formal study of how valve dysfunction affects overall circulatory dynamics. Validated models ... [more ▼]

Valve dysfunction is a common cardiovascular pathology. Despite significant clinical research, there is little formal study of how valve dysfunction affects overall circulatory dynamics. Validated models would offer the ability to better understand these dynamics and thus optimize diagnosis, as well as surgical and other interventions. A cardiovascular and circulatory system (CVS) model has already been validated in silico, and in several animal model studies. It accounts for valve dynamics using Heaviside functions to simulate a physiologically accurate “open on pressure, close on flow” law. However, it does not consider real-time valve opening dynamics and therefore does not fully capture valve dysfunction, particularly where the dysfunction involves partial closure. This research describes an updated version of this previous closed-loop CVS model that includes the progressive opening of the mitral valve, and is defined over the full cardiac cycle. Simulations of the cardiovascular system with healthy mitral valve are performed, and, the global hemodynamic behaviour is studied compared with previously validated results. The error between resulting pressure-volume (PV) loops of already validated CVS model and the new CVS model that includes the progressive opening of the mitral valve is assessed and remains within typical measurement error and variability. Simulations of ischemic mitral insufficiency are also performed. Pressure-Volume loops, transmitral flow evolution and mitral valve aperture area evolution follow reported measurements in shape, amplitude and trends. The resulting cardiovascular system model including mitral valve dynamics provides a foundation for clinical validation and the study of valvular dysfunction in vivo. The overall models and results could readily be generalised to other cardiac valves. [less ▲]

Detailed reference viewed: 65 (28 ULg)
Full Text
Peer Reviewed
See detailMinimal cardiovascular system model including a physiological description of progressive mitral valve orifice dynamics for studying valve dysfunction
Paeme, Sabine ULg; Moorhead, Katerine; Chase, J. Geoffrey et al

in XXIIIrd congress of the International Society of Biomechanics, July 3-7, 2011 (2011, July)

This research presents a new closed-loop cardiovascular system model including a description of the progressive opening and closing dynamic of the mitral valve. Furthermore, this model includes a ... [more ▼]

This research presents a new closed-loop cardiovascular system model including a description of the progressive opening and closing dynamic of the mitral valve. Furthermore, this model includes a mathematical description of the left atrium. This new CVS model enables the study of valve dysfunction in the appropriate clinical context of the overall cardiac and circulatory hemodynamics. [less ▲]

Detailed reference viewed: 65 (9 ULg)
Full Text
Peer Reviewed
See detailminimal cardiovascular system model including physiological mitral valve opening
Paeme, Sabine ULg; Moorhead, Katherine ULg; chase, J. Geoffrey et al

in 9th Belgian National Day on Biomedical Engineering, Bruxelles, 26th november (2010, November 26)

A minimal cardiovascular system (CVS) model has been previously validated in silico, and in several animal model studies. It accounts for valve dynamics by means of a Heaviside function to simulate the ... [more ▼]

A minimal cardiovascular system (CVS) model has been previously validated in silico, and in several animal model studies. It accounts for valve dynamics by means of a Heaviside function to simulate the “open on pressure, close on flow” law. However, this model does not describe the progressive valve opening and therefore, it is not suitable for studying valve dysfunctions. [less ▲]

Detailed reference viewed: 18 (6 ULg)