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Work in Progess
- Thoracic potentials and currents
[6/9/2000 ]
- Thoracic potentials and currents
[4/10/2000 ]
- Torso tank experiment on March 23 , 2000. Geometric modeling.
[4/6/2000 ]
- Excitation wave in the ventricular wall from an epicardial
stimulation. [2/16/2000 ]
- Electrical potentials on the heart and body surfaces, and thoracic
currents during cooling;
[11/23/1999]
- Structure of the FEM global stiffness matrix;
[11/15/1999]
- Electrical Current Fields in the Thorax
[10/1/1999]
- Three dimensional potential fields in the heart
[9/1/1999]
- Visualization of Simulated Excitation Wave Using MATLAB Volume
Visualization Beta [8/24/1999]
- Excitation Wave in the Ventricles.
[8/22/1999]
The left panels are potential distributions in a control state on
the heart (top) and body surfaces (bottom); The right panels are
potentials during cooling. Notice that the current sink on the
right of the heart surface during cooling was not revealed on the
body surface potentials.
Thoracic current pathways during cooling show currents flow into the
above mentioned current sink.
Nonzeros of a FEM global stiffness matrix. The matrix is a result from
the FEM solution of the forward problem in electrocardiology, which is
to compute the electrical potential fields in the volume conductor in
the thorax.
Single values of the above global stiffness matrix.
Electric current pathways during an intramural stimulation in the left
ventricle. Electric potentials were measured from the epicardial surface.
These measurements provided boundary conditions for a finite element solution
of the forward problem in electrocardiography, which gave electric potential
distribution theoughout the thorax, the volume conductor. Then electric
currents were computed from potential gradients, the integral of which are
shown as the streamtube in this figure as the electric current
pathways.
Electric potentials from a intramural stimulation in the left ventricle.
Potentials were measured with intramural needle electrods at 560 locations in a
slab of myocardium. They were then interpolated to 3000+ locations, shown on
small dots, using WEB interpolation. This figure shows potentials at 20 ms
after stimulation. Left panels shows iso-potential surfaces, red at +3 mV, and
green at -10 mV; right panel shows potentials on a cutting plane.
This panel of figures show excitation wave and associated conduction velocity
fields in the heart. I think MATLAB has done an excellent job in developing
these volume visualization tools, especially for scalar field data such as
excitation times. But note the difficulty in the vector field visualization
such as the conduction velocity fields in the heart using the conventional
streamline type of techniques. It is still very hard to grasp the feature of
these fields from a fixed number of traces. I think an interactive feature of
choosing seed locations of streamline will improve these funtions
dramatically. In the mean time, 'streamslice' provides a nice overall
picture of the field, which I liked very much.
This group of figures show the impulse propagation in the left ventricle.
Excitation times were obtained from a canine left ventricle at 560 intramural
locations with electrodes mounted on 56 plunge needles ( see the experiment set up). We then represent
the propagation based on an interpolation of the measured values using a radial
function based technique. The interpolant is then evalued at 3000+ locations
shown in these figures, which provide an overall and detailed description
of the excitation wave.
Excitation wave initiated from the middle wall of the left ventricle.
Panels from left to right contain wave front at 15, 20, 25, 30, 35, and
40 ms after the stimulation.
Excitation wave initiated from the epicardium of the left ventricle.
Panels from left to right contain wave front at 10:5:50 ms
after the stimulation.
Excitation wave initiated from the endocardium of the left ventricle.
Panels from left to right contain wave front at 15:5:40 ms
after the stimulation.
