A new computer model of mitral valve hemodynamics during ventricular filling☆

Szabó, Gábor; Soans, Davis; Graf, Andy; Beller, Carsten J.; Waite, Lee; Hagl, S.

doi:10.1016/j.ejcts.2004.03.018

Cited by 15 publications

(28 citation statements)

References 20 publications

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“…Some studies have focused on the fluid dynamics only, avoiding a detailed description of the solid properties using ad hoc boundary conditions (Baccani, Domenichini & Pedrizzetti 2003), or assuming a held-open mitral valve when studying left ventricular fluid dynamics (Lemmon & Yoganathan 2000;Domenichini, Pedrizzetti & Baccani 2005). Some progress has been achieved with lumped-parameter models (Szabo et al 2004, and references therein) that are aimed at reproducing specific measurements, based on a number of model parameters, and are not intended to explain the corresponding vorticity dynamics. A different approach, to overcome the difficulties found when describing the solid properties, was considered by Pedrizzetti (2005) with a derivation of the leaflet motion based on fluid dynamical concepts only.…”

Section: Introductionmentioning

confidence: 99%

Flow-driven opening of a valvular leaflet

Pedrizzetti

Domenichini

2006

J. Fluid Mech.

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The understanding of valvular opening is a central issue in cardiac flows, whose analysis is often prohibited by the unavailability of (in vivo) data about tissue properties. Asymptotic or approximate representations of fluid-structure interaction are thus sought. The dynamics of an accelerated stream, in a two-dimensional channel initially closed by a rigid inertialess movable leaflet, is studied as a simple model problem aimed at demonstrating the main phenomena contributing to the fluidstructure interaction. The problem is solved by the coupled numerical solution of equations for the flow and solid. The results show that the leaflet initially opens in a no-shedding regime, driven by fluid mass conservation and a predictable dynamics. Then the leaflet motion jumps, after the saturation of a very rapid intermediate vortex-shedding phase, to the asymptotic slower regime with a stable self-similar wake structure. IntroductionThe interaction between a fluid stream and a moving boundary is common in several contexts; numerous examples can be found in the cardiovascular system where flows inside deformable vessels and through cardiac valves are of primary physiological relevance. The original motivation for this work is our interest in the flow through the mitral valve that controls the blood motion from the left atrium to the left ventricle of the heart. More generally, similar phenomena can be found in technological devices when valves are used to control the fluid motion through orifices and possibly to avoid back-flow. Despite the applied background this work is a theoretical one, on the interaction of the flow and a leaflet under ideal conditions. It represents a step towards the understanding of phenomena in a fluid-structure interaction of potentially high applied relevance.When a closed valve is forced to open by a stream, the (typically thin) leaflets rapidly move with the fluid with only a weak resistance to it. A rigorous mathematical model of the flow-structure dynamics should be based on the fluid and solid equations, for the flow and the tissue, respectively, and on the proper coupling relations. Along these lines, a simplified approach, developed for a thin solid without bending stiffness, was introduced by Peskin & McQueen (1989). However, in our experience, the numerical implementation of this mathematically attractive model has several disadvantages, such as the lack of resolution close to the body and unrealistic stress distributions on it. A major difficulty in studying the fluid-solid interaction is the rapidity of the leaflet response to the action of the incoming fluid, and its large movement within the flow domain. A complete numerical solution of the fluid-solid system has been presented for the flow in models of the aortic valve (De Hart et al. 2003; Stijnen et al.

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Section: Introductionmentioning

confidence: 99%

Flow-driven opening of a valvular leaflet

Pedrizzetti

Domenichini

2006

J. Fluid Mech.

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“…We have noted above that the findings of Thomas and Weyman 12 and Szabo et al 10 are particularly important as motivation for our study. And our findings that statistical estimation of parameters can be disease predictors add additional corroborating evidence to the conclusions of the above pioneering studies: that the controlling variables of transmitral flow are the atrial-ventricle pressure differential, which controls LV filling volume, and LV volume and pressure which determine LV stiffness.…”

Section: Model Validitymentioning

confidence: 87%

“…2,6,9 Early modeling efforts, 12 and a recent corroborating follow-up study, 10 provide a unique opportunity to test a suggested hypothesis 11 that estimated parameters of LV filling models and LV chamber stiffness models could be of clinical diagnostic value for distinguishing, detecting, and grading cardiac diseases. The data of Szabo et al 10 is particularly appropriate to test this hypothesis because he and his colleagues not only collected excellent data from animal experiments, they also fitted a like number of animals with prosthetic mitral valves and repeated their careful measurements on these animals with prosthetic valve replacements thereby creating a set of control (normal) data and a set of ''diseased'' (prosthetic) data.…”

Section: Introductionmentioning

confidence: 98%

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The Diagnostic Efficacy of Left Ventricle Hemodynamic Parameters: Classifying Normal Mitral Valves Against Prosthetic Disease Proxies

Shuhaiber

O'Neill

2011

Cardiovasc Eng Tech

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The dynamics of left ventricle diastolic filling and chamber stiffness are such critical processes in cardiac performance it has been suggested that the parameters of these processes could have important diagnostic power. This study has two objectives: (1) to estimate LV parameters from animal studies and test these parameters for diagnostic efficacy and (2) use Monte Carlo simulation techniques to determine if estimated LV parameters can be used to statistically classify subjects by disease state. The disease state we test are swine fitted with prosthetic mitral valves. Literature data on six swine instrumented for measuring left atrial and ventricle pressures and left ventricle volume before and after mitral valve replacement provide a unique data set for testing the diagnostic efficacy of estimated LV parameters since the prosthetic data can be considered a proxy for a diseased state, for example, mitral valve insufficiency. LV filling models and chamber stiffness models are estimated and their parameters subjected to rigorous statistical tests to elicit their ability to discriminate between normals and animals with prosthetic valve replacement. Additionally, the filling and chamber stiffness models are used to simulate subject-based Monte Carlo data to test empirical distributions for clinical applications of the statistical hypothesis. The E-wave normal and prosthetic filling models each have three parameters, similar structures, and both fit their respective data sets with remarkable accuracy and yet their parameters can be used to readily distinguish between a cohort of normal and a cohort of animals with prosthetic valve replacement. The chamber stiffness models and the E-wave filling models are sufficiently different between normal and animals with prosthetic valve replacement that it is possible to project their parameter vectors onto a scalar axis and develop individual subject z-scores for clinical applications. While it is preferable to compare normal animal data against chronically implanted animals, we argue from a statistical point of view that the filling and stiffness models estimated are sufficiently robust so as to provide evidence that their parameters do indeed have diagnostic power. Further, even in the presence of simulated data with added noise it is possible to make informed decisions as to subject disease classification or disease grade level. While it is recognized a prosthetic valve is an exaggerated disease state it is also true the statistical differences between normal and prosthetic animals were found to be exaggerated.

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“…The normal motion of the mitral valve during a cardiac cycle has been analyzed by Saito et al [17]. From this qualitative analysis and quantitative values from literature [19][20][21][22][23][24], normal mitral aperture evolution as well as transmitral blood flow during the diastole has been reconstructed, regarding the driving pressure. Figure 5 describes the two peaks E-wave and A-wave corresponding respectively to the passive filling of the ventricle and the active one, due to the atrial contraction.…”

Section: Static Response Validationmentioning

confidence: 99%

Structural model of the mitral valve included in a cardiovascular closed loop model. Static and dynamic validation

Paeme

Pironet

Chase

et al. 2012

IFAC Proceedings Volumes

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A minimal cardiovascular system (CVS) model including mitral valve dynamics has been previously validated in silico. It accounts for valve dynamics using a second order differential equation to simulate the physiological opening valve law. This second order equation is based on output heart signals and is really difficult to bind with anatomical or physiological parameters, making this model difficult to interpret and to particularise to pathological situations.On the other hand, a simple non-linear rotational spring model implemented to model the motion of mitral valve, located between the left atrium and ventricle has been validated on a literature dataset. A measured pressure difference curve was used as the input into the model, which represents an applied torque to the valve chords. Various damping and hysteresis states were investigated to find a model that best matches reported animal data of chord movement during a heartbeat. This model is based on simple physiological behavior modeling, defining parameters linked with physiological or anatomical data.This research describes a new closed-loop CVS model corresponding to the integration of the simple non-linear rotational spring model to describe the progressive aperture of the mitral valve in the minimal cardiovascular system closed loop model. This new model is proved to fit static and dynamic heart behaviour.

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A new computer model of mitral valve hemodynamics during ventricular filling☆

Abstract: The new lumped parameter model of left ventricular filling allows for the first time a detailed simulation of pressure and flow curves in the left heart including transmitral hemodynamics.

Cited by 15 publications

References 20 publications

Flow-driven opening of a valvular leaflet

Flow-driven opening of a valvular leaflet

The Diagnostic Efficacy of Left Ventricle Hemodynamic Parameters: Classifying Normal Mitral Valves Against Prosthetic Disease Proxies

Structural model of the mitral valve included in a cardiovascular closed loop model. Static and dynamic validation

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