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.
Cardiac Ischemia
•
Ischemia is the lack of blood flow




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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
Problem Specific Models
• Shape of heart
• Shape and time point of the
ischemic region
• Fiber orientation for
anisotropic conduction
• Dynamic ischemic zone that
changes based on
experimental data.
• Adaptive meshing based on
fiber directions
• Variable myocardial wall
thickness
MRI
Segmentation
Surface Meshing
3D Meshing
DTI
MRI
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Small animal
imaging facility
7 tesla scanner
High resolution and
DTI scans
Gd markers used
for registration
QuickTime™ and a
decompressor
are needed to see this picture.
Surface Potentials
MRI
Segmentation
Surfacing
Meshing
DTI
QuickTime™ and a
mpeg4 decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
Surface Potentials
MRI
Segmentation
Surface Meshing
3D Meshing
DTI
Segmentation
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Seg3D
Segment
myocardium and
ischemic region
Each segmentation
requires a small
amount of manual
editing
QuickTime™ and a
decompressor
are needed to see this picture.
Surface Potentials
MRI
Segmentation
Marching Cubes
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•
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SCIRun
implementation
Smoothed with
fairmesh algorithm
~400,000 tris
elements
Very detailed
Particle System
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Uses tetgen for
surface
Not currently in
SCIRun
Very detailed
Surface Meshing
3D Meshing
DTI
Surface Potentials
MRI
Segmentation
Surface Meshing
3D Meshing
QuickTime™ and a
mpeg4 decompressor
are needed to see this picture.
DTI
Surface Potentials
MRI
Segmentation
Meshing
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•
1,400,000
Elements
Tetgen used for
both marching
cubes and particle
system surfaces
Surface Meshing
3D Meshing
DTI
Surface Potentials
MRI
Segmentation
Surface Meshing
3D Meshing
DTI
Surface Potentials
MRI
Segmentation
Fiber Direction
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Diffusion tensor
imaging (DTI)
Anisotropic
properties
Tensor
interpolation
Surface Meshing
3D Meshing
DTI
Surface Potentials
MRI
Segmentation
Ischemic Model
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Bidomain model
Interactively
adaptable ischemic
zone
Segmented
ischemic zones
Correlates to
experimental
results
Surface Meshing
3D Meshing
DTI
Surface Potentials
MRI
Segmentation
Surface Meshing
3D Meshing
Ischemic Model
•
•
•
•
Bidomain model
Interactively move
ischemic zone
Segment ischemic
zones
Correlate to lab
results
QuickTime™ and a
mpeg4 decompressor
are needed to see this picture.
DTI
Surface Potentials
Thanks!