Electrophysiology Subject Specific Models Darrell Swenson Scientific Computing and Imaging (SCI) Institute Cardiovascular Research and Training Institute (CVRTI) Department of Bioengineering Dr. Rob MacLeod

Cardiac Ischemia Hearts are electrical organs  Electrical current causes heart contraction  Most heart failures are electrical  ECG’s show hearts electrical activity Coronary Arteries supply blood to the heart.  Coronary blood flow provides the needed nutrients and ions  Conduction rate is dependent on blood flow. Hearts are electrical organs  Electrical current causes heart contraction  Most heart failures are electrical  ECG’s show hearts electrical activity Coronary Arteries supply blood to the heart.  Coronary blood flow provides the needed nutrients and ions  Conduction rate is dependent on blood flow.

Cardiac Ischemia Ischemia is the lack of blood flow  The lack of blood flow changes the conductance.  Changes in conductance alter the activation wave.  This often leads to heart failure  These changes can be detected with an ECG ECGs are insufficient to detect a large percentage of ischemia.  Comparable ischemic regions produce dramatically different ECG signals.  The cause could be Individual structure variability. Ischemia is the lack of blood flow  The lack of blood flow changes the conductance.  Changes in conductance alter the activation wave.  This often leads to heart failure  These changes can be detected with an ECG ECGs are insufficient to detect a large percentage of ischemia.  Comparable ischemic regions produce dramatically different ECG signals.  The cause could be Individual structure variability.

Subject Specific Modeling Subject Specific Geometry Shape of heart Shape and time point of the ischemic region Fiber orientation for anisotropic conduction Subject Specific Geometry Shape of heart Shape and time point of the ischemic region Fiber orientation for anisotropic conduction Problem Specific Models Dynamic ischemic zone that changes based on experimental data. Adaptive meshing based on fiber directions Variable myocardial wall thickness Problem Specific Models Dynamic ischemic zone that changes based on experimental data. Adaptive meshing based on fiber directions Variable myocardial wall thickness

MRI SegmentationSurface Meshing3D MeshingDTISurface Potentials MRI Small animal imaging facility 7 tesla scanner High resolution and DTI scans Gd markers used for registration MRI Small animal imaging facility 7 tesla scanner High resolution and DTI scans Gd markers used for registration

MRI SegmentationSurfacingMeshingDTISurface Potentials

MRI Segmentation DTISurface Potentials Segmentation Seg3D Segment myocardium and ischemic region Each segmentation requires a small amount of manual editing Segmentation Seg3D Segment myocardium and ischemic region Each segmentation requires a small amount of manual editing Surface Meshing 3D Meshing

MRISegmentationDTISurface Potentials Marching Cubes SCIRun implementation Smoothed with fairmesh algorithm ~400,000 tris elements Very detailed Particle System Uses tetgen for surface Not currently in SCIRun Very detailed Marching Cubes SCIRun implementation Smoothed with fairmesh algorithm ~400,000 tris elements Very detailed Particle System Uses tetgen for surface Not currently in SCIRun Very detailed Surface Meshing 3D Meshing

MRISegmentationDTISurface Potentials Surface Meshing 3D Meshing

MRISegmentationDTISurface Potentials Meshing 1,400,000 Elements Tetgen used for both marching cubes and particle system surfaces Meshing 1,400,000 Elements Tetgen used for both marching cubes and particle system surfaces Surface Meshing 3D Meshing

MRISegmentationDTISurface PotentialsSurface Meshing 3D Meshing

MRISegmentation DTI Surface Potentials Fiber Direction Diffusion tensor imaging (DTI) Anisotropic properties Tensor interpolation Fiber Direction Diffusion tensor imaging (DTI) Anisotropic properties Tensor interpolation Surface Meshing3D Meshing

MRISegmentationDTI Surface Potentials Ischemic Model Bidomain model Interactively adaptable ischemic zone Segmented ischemic zones Correlates to experimental results Ischemic Model Bidomain model Interactively adaptable ischemic zone Segmented ischemic zones Correlates to experimental results Surface Meshing3D Meshing

MRISegmentationDTI Surface Potentials Ischemic Model Bidomain model Interactively move ischemic zone Segment ischemic zones Correlate to lab results Ischemic Model Bidomain model Interactively move ischemic zone Segment ischemic zones Correlate to lab results 3D MeshingSurface Meshing

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