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Forward Simulations

An image of the electrolytic torso tank, which based on a mold of a human torso and instrumented with 1302 electrodes mounted on the tank surface and in adjustable rods.

One example of the Utah NCRR Center bringing advanced modeling, simulation, and visualization tools to the experimental scientist is the computing of electrocardiographic forward solutions. Drs. Taccardi and Punske have measured electric potentials at 1300 sites throughout the volume of a human shaped electrolytic torso tank (Figure 1) in which they suspended a canine heart. In the heart they placed multi-electrode needles to record from an additional 1830 sites.

From the resulting measurement point locations, we first created a geometric model of tetrahedra de-scribing the torso tank. The needle electrodes located closest to the outer surface of the heart measured epicardial potentials, which then served as the source for a forward simulation of potentials at all nodes of the torso tank model.

Two superio-posterior views of the torso tank with spheres and disks marking the locations of measurement sites. Sphere color represents computed potential amplitude while the disk color corresponds to measured potentials. The right hand view shows part of the tetrahedral geometric mesh that was the basis for the computations. Also visible here is the surface consisting of heart electrode locations, with color-coded potentials. These potentials were the sources for the forward problem simulation.

To compute these potentials, we created a finite element approximation of Laplace's equation and applied the epicardial potentials as boundary conditions on the inner surface of the geometric model. The outer surface did not permit any current to leave the torso--the Neumann boundary condition. We then selected time instants of interest and solved the associated forward problem for potentials throughout the volume and on the outer surface of the tank.

Measurements at the same locations provided a valuable opportunity for validation of the forward solution. We visualized torso tank surface potentials from both the simulation and measurements, as shown in Figures 2 and 3. The colors of the spheres on the tank surface represent the computed potentials, while the surrounding disks are colored according to the measured values at these same locations. By comparing the colors of the spheres and disks, one can easily appreciate the size and locations of differences between computed and measured values.

• Publications -- Forward Simulation
• Image Gallery -- Forward Simulation

Principal Researchers:

• Dr. Robert S. MacLeod
• Collaborators at the Cardiovascular Research and Training Institute