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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.


Related in: MedlinePlus

Ventricular volume decomposition during a cardiac cycle (Bolger et al., 2007; Carlhall and Bolger, 2010; Hendabadi et al., 2013; Seo and Mittal, 2013b). The direct inflow or ejected atrial blood and delayed ejection or ejected ventricular blood cells from the previous cycle are represented in orange and purple, respectively, at the end-diastolic phase, while the red and green represent retained inflow and residual ventricular blood, respectively. (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 10: Ventricular volume decomposition during a cardiac cycle (Bolger et al., 2007; Carlhall and Bolger, 2010; Hendabadi et al., 2013; Seo and Mittal, 2013b). The direct inflow or ejected atrial blood and delayed ejection or ejected ventricular blood cells from the previous cycle are represented in orange and purple, respectively, at the end-diastolic phase, while the red and green represent retained inflow and residual ventricular blood, respectively. (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: In order to quantify the transport characteristics of the blood cells during the full cardiac cycle, we calculated the proportion of ejected atrial blood or DR and ejected ventricular blood or WR during the cardiac cycle (Bolger et al., 2007; Carlhall and Bolger, 2010; Hendabadi et al., 2013; Seo and Mittal, 2013b). Figure 10 shows the decomposed ventricular volume at the end-diastolic phase for all the four case studies. The direct inflow and delayed ejection blood volumes are represented using orange and purple colors, respectively, while the retained inflow and residual blood volumes are colored red and green, respectively. Further, the DR and the WR for all heart cases are presented in Table 2. Both DR and WR are found to be lower for the heart models with LBBB activation compared to the heart models with SR activation. This is not surprising given that the ejection fraction for LBBB activated heart models is lower compared to the heart models under normal SR (see Table 1). Likewise, the trends in WR also correspond to the trends in ejection fraction for all the heart models. However, it is interesting to note that although the DR for normal hearts is relatively lower than that of WR, although, this trend is reversed for the LBBB failing hearts. This indicates that for failing hearts the atrial blood forms a greater fraction of the ejected blood compared to the ventricular blood. Hence, the blood cells can remain in the ventricle for a long period of time with implications for ventricular thrombogenesis.


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)

Ventricular volume decomposition during a cardiac cycle (Bolger et al., 2007; Carlhall and Bolger, 2010; Hendabadi et al., 2013; Seo and Mittal, 2013b). The direct inflow or ejected atrial blood and delayed ejection or ejected ventricular blood cells from the previous cycle are represented in orange and purple, respectively, at the end-diastolic phase, while the red and green represent retained inflow and residual ventricular blood, respectively. (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 10: Ventricular volume decomposition during a cardiac cycle (Bolger et al., 2007; Carlhall and Bolger, 2010; Hendabadi et al., 2013; Seo and Mittal, 2013b). The direct inflow or ejected atrial blood and delayed ejection or ejected ventricular blood cells from the previous cycle are represented in orange and purple, respectively, at the end-diastolic phase, while the red and green represent retained inflow and residual ventricular blood, respectively. (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: In order to quantify the transport characteristics of the blood cells during the full cardiac cycle, we calculated the proportion of ejected atrial blood or DR and ejected ventricular blood or WR during the cardiac cycle (Bolger et al., 2007; Carlhall and Bolger, 2010; Hendabadi et al., 2013; Seo and Mittal, 2013b). Figure 10 shows the decomposed ventricular volume at the end-diastolic phase for all the four case studies. The direct inflow and delayed ejection blood volumes are represented using orange and purple colors, respectively, while the retained inflow and residual blood volumes are colored red and green, respectively. Further, the DR and the WR for all heart cases are presented in Table 2. Both DR and WR are found to be lower for the heart models with LBBB activation compared to the heart models with SR activation. This is not surprising given that the ejection fraction for LBBB activated heart models is lower compared to the heart models under normal SR (see Table 1). Likewise, the trends in WR also correspond to the trends in ejection fraction for all the heart models. However, it is interesting to note that although the DR for normal hearts is relatively lower than that of WR, although, this trend is reversed for the LBBB failing hearts. This indicates that for failing hearts the atrial blood forms a greater fraction of the ejected blood compared to the ventricular blood. Hence, the blood cells can remain in the ventricle for a long period of time with implications for ventricular thrombogenesis.

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