Electrophysiology Subject Specific Models Darrell Swenson Scientific Computing and Imaging (SCI) Institute Cardiovascular Research and Training Institute.

Electrophysiology Subject Specific Models

Darrell SwensonScientific 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

MRISegmentation Surface Meshing 3D Meshing DTI Surface 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 registrationQuickTime™ and a

decompressorare needed to see this picture.

MRISegmentation Surfacing Meshing DTI Surface Potentials

QuickTime™ and a decompressor

are needed to see this picture.

QuickTime™ and ampeg4 decompressor

are needed to see this picture.

MRISegmentation

DTI Surface 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

QuickTime™ and a decompressor

are needed to see this picture.

Surface Meshing 3D Meshing

MRI Segmentation DTI Surface 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

QuickTime™ and ampeg4 decompressor

are needed to see this picture.

MRI Segmentation DTI Surface PotentialsSurface Meshing 3D Meshing

MRI Segmentation DTI Surface 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

MRI Segmentation DTI Surface PotentialsSurface Meshing 3D Meshing

MRI SegmentationDTI

Surface Potentials

Fiber Direction• Diffusion tensor

imaging (DTI)• Anisotropic

properties• Tensor

interpolation

Fiber Direction• Diffusion tensor

imaging (DTI)• Anisotropic

properties• Tensor

interpolation

Surface Meshing 3D Meshing

MRI Segmentation DTISurface 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 Meshing 3D Meshing

MRI Segmentation DTISurface 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

QuickTime™ and ampeg4 decompressor

are needed to see this picture.

3D MeshingSurface Meshing

Thanks!