Biomedical Engineering Reference
In-Depth Information
oedema and instances of heart attack. Computational models have been used to gain
a better understanding of mitral valve biomechanics which can lead to improved
medical and surgical planning to restore normal mitral valve function. In this sec-
tion we provide an example of FSI modelling for investigating the asymmetric mi-
tral valve dynamics during diastolic filling by Dahl et al. (2010).
8.8.2
Asymmetric Mitral Valve Dynamics During
Diastolic Filling
During diastole, the left atrium directs flow from the pulmonary veins towards the
mitral valve. Simultaneously the left ventricle relaxes, increasing the pressure dif-
ference between the two chambers. This assists in the valve opening and allows
blood to from the left atrium into the left ventricle. As the ventricle fills it becomes
stiffer, and an atrial contraction at end-diastole is needed to force blood into the
distended ventricle.
Dahl et al. (2010) implemented an implicit ALE procedure for the rigid body mo-
tion of the mitral leaflets. The leaflets were simulated with an asymmetric geometry
and their motion computed with an FSI coupling scheme that accounts for the mu-
tual interaction of the leaflets. To achieve physiological realism in the simulations,
ultrasound recordings with speckle tracking were used to render the subject-specific
left ventricular wall movement of a healthy young person. The specific movement
was imposed as a boundary condition in a 2D transient simulation of diastolic fill-
ing.
Ultrasound recordings of the left-ventricle wall geometry moving were obtained
using the speckle tracking algorithm in EchoPAC PC (version 6.0.0, GE Vingmed
Ultrasound, Norway) and a sample image is shown in Fig.
8.69
. The green vertical
line marks the start of the simulation, i.e. early diastole. The short red line depicts
Fig. 8.69
Ultrasound record-
ing of the left-ventricle wall.
ECG shown in the
lower
right corner
. (Image from
Dahl et al. 2010)
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