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A New MRI-Based Model of Heart Function with Coupled Hemodynamics and Application to Normal and Diseased Canine Left Ventricles.

Choi YJ, Constantino J, Vedula V, Trayanova N, Mittal R - Front Bioeng Biotechnol (2015)

Bottom Line: The time-dependent endocardial surfaces are registered using a diffeomorphic mapping algorithm, while the intraventricular blood flow patterns are simulated using a sharp-interface immersed boundary method-based flow solver.The utility of the combined heart-function model is demonstrated by comparing the hemodynamic characteristics of a normal canine heart beating in sinus rhythm against that of the dyssynchronously beating failing heart.We also discuss the potential of coupled CE and hemodynamics models for various clinical applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Johns Hopkins University , Baltimore, MD , USA ; Institute for Computational Medicine, Johns Hopkins University , Baltimore, MD , USA.

ABSTRACT
A methodology for the simulation of heart function that combines an MRI-based model of cardiac electromechanics (CE) with a Navier-Stokes-based hemodynamics model is presented. The CE model consists of two coupled components that simulate the electrical and the mechanical functions of the heart. Accurate representations of ventricular geometry and fiber orientations are constructed from the structural magnetic resonance and the diffusion tensor MR images, respectively. The deformation of the ventricle obtained from the electromechanical model serves as input to the hemodynamics model in this one-way coupled approach via imposed kinematic wall velocity boundary conditions and at the same time, governs the blood flow into and out of the ventricular volume. The time-dependent endocardial surfaces are registered using a diffeomorphic mapping algorithm, while the intraventricular blood flow patterns are simulated using a sharp-interface immersed boundary method-based flow solver. The utility of the combined heart-function model is demonstrated by comparing the hemodynamic characteristics of a normal canine heart beating in sinus rhythm against that of the dyssynchronously beating failing heart. We also discuss the potential of coupled CE and hemodynamics models for various clinical applications.

No MeSH data available.


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Time-evolution of intraventricular vortex structures for the four canine heart models. Vortex structures are identified by the swirl strength criterion (Jeong and Hussain, 1995) and are colored by the vertical velocity component w. (A) Normal heart with SR activation; (B) normal heart with LBBB activation; (C) failing heart with SR activation; (D) failing heart with LBBB activation. SR, sinus rhythm; LBBB, left bundle branch block.
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Figure 6: Time-evolution of intraventricular vortex structures for the four canine heart models. Vortex structures are identified by the swirl strength criterion (Jeong and Hussain, 1995) and are colored by the vertical velocity component w. (A) Normal heart with SR activation; (B) normal heart with LBBB activation; (C) failing heart with SR activation; (D) failing heart with LBBB activation. SR, sinus rhythm; LBBB, left bundle branch block.

Mentions: We first compare the time-dependent diastolic flow patterns and the vortex structures in the normal and failing LVs to qualitatively examine ventricular efficiency. It has been shown in previous studies that optimal vortex formation during diastole is a characteristic of healthy ventricles (Kilner et al., 2000; Pedrizzetti and Domenichini, 2005; Gharib et al., 2006; Watanabe et al., 2008; Pasipoularides, 2010; Sengupta et al., 2012; Charonko et al., 2013; Chnafa et al., 2014; Seo et al., 2014). The vortex structures at selected time instances during diastole are shown in Figure 6. The colored contours represent the vertical (or longitudinal) velocity component. For the normal hearts, under SR (Figure 6A) or LBBB activation (Figure 6B), a distinct vortex ring is generated at the mitral annulus around t = 0.05 s. The vortex ring is pinched-off from the mitral annulus and propagates through the LV (t = 0.10 s) until it becomes unstable and begins to break down (t = 0.15 s) (Seo et al., 2014) into smaller vortex structures that penetrate past the mid-ventricular level by end-diastole for the normal hearts (t = 0.20–0.25 s). In contrast, the vortex ring that is formed for the failing hearts (Figures 6C,D) is extremely weak as characterized by the volume occupied by the isosurface of the swirl strength; it remains near the mitral inlet during diastole and does not propagate into the bulk of the ventricle throughout the filling phase.


A New MRI-Based Model of Heart Function with Coupled Hemodynamics and Application to Normal and Diseased Canine Left Ventricles.

Choi YJ, Constantino J, Vedula V, Trayanova N, Mittal R - Front Bioeng Biotechnol (2015)

Time-evolution of intraventricular vortex structures for the four canine heart models. Vortex structures are identified by the swirl strength criterion (Jeong and Hussain, 1995) and are colored by the vertical velocity component w. (A) Normal heart with SR activation; (B) normal heart with LBBB activation; (C) failing heart with SR activation; (D) failing heart with LBBB activation. SR, sinus rhythm; LBBB, left bundle branch block.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585083&req=5

Figure 6: Time-evolution of intraventricular vortex structures for the four canine heart models. Vortex structures are identified by the swirl strength criterion (Jeong and Hussain, 1995) and are colored by the vertical velocity component w. (A) Normal heart with SR activation; (B) normal heart with LBBB activation; (C) failing heart with SR activation; (D) failing heart with LBBB activation. SR, sinus rhythm; LBBB, left bundle branch block.
Mentions: We first compare the time-dependent diastolic flow patterns and the vortex structures in the normal and failing LVs to qualitatively examine ventricular efficiency. It has been shown in previous studies that optimal vortex formation during diastole is a characteristic of healthy ventricles (Kilner et al., 2000; Pedrizzetti and Domenichini, 2005; Gharib et al., 2006; Watanabe et al., 2008; Pasipoularides, 2010; Sengupta et al., 2012; Charonko et al., 2013; Chnafa et al., 2014; Seo et al., 2014). The vortex structures at selected time instances during diastole are shown in Figure 6. The colored contours represent the vertical (or longitudinal) velocity component. For the normal hearts, under SR (Figure 6A) or LBBB activation (Figure 6B), a distinct vortex ring is generated at the mitral annulus around t = 0.05 s. The vortex ring is pinched-off from the mitral annulus and propagates through the LV (t = 0.10 s) until it becomes unstable and begins to break down (t = 0.15 s) (Seo et al., 2014) into smaller vortex structures that penetrate past the mid-ventricular level by end-diastole for the normal hearts (t = 0.20–0.25 s). In contrast, the vortex ring that is formed for the failing hearts (Figures 6C,D) is extremely weak as characterized by the volume occupied by the isosurface of the swirl strength; it remains near the mitral inlet during diastole and does not propagate into the bulk of the ventricle throughout the filling phase.

Bottom Line: The time-dependent endocardial surfaces are registered using a diffeomorphic mapping algorithm, while the intraventricular blood flow patterns are simulated using a sharp-interface immersed boundary method-based flow solver.The utility of the combined heart-function model is demonstrated by comparing the hemodynamic characteristics of a normal canine heart beating in sinus rhythm against that of the dyssynchronously beating failing heart.We also discuss the potential of coupled CE and hemodynamics models for various clinical applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Johns Hopkins University , Baltimore, MD , USA ; Institute for Computational Medicine, Johns Hopkins University , Baltimore, MD , USA.

ABSTRACT
A methodology for the simulation of heart function that combines an MRI-based model of cardiac electromechanics (CE) with a Navier-Stokes-based hemodynamics model is presented. The CE model consists of two coupled components that simulate the electrical and the mechanical functions of the heart. Accurate representations of ventricular geometry and fiber orientations are constructed from the structural magnetic resonance and the diffusion tensor MR images, respectively. The deformation of the ventricle obtained from the electromechanical model serves as input to the hemodynamics model in this one-way coupled approach via imposed kinematic wall velocity boundary conditions and at the same time, governs the blood flow into and out of the ventricular volume. The time-dependent endocardial surfaces are registered using a diffeomorphic mapping algorithm, while the intraventricular blood flow patterns are simulated using a sharp-interface immersed boundary method-based flow solver. The utility of the combined heart-function model is demonstrated by comparing the hemodynamic characteristics of a normal canine heart beating in sinus rhythm against that of the dyssynchronously beating failing heart. We also discuss the potential of coupled CE and hemodynamics models for various clinical applications.

No MeSH data available.


Related in: MedlinePlus