Electrical Defibrillation

In order to evaluate the efficacy of different electrode designs for external cardiac defibrillators, we have developed a simulation tool within our bioelectric problem-solving environment, BioPSE. Starting from a set of physical and geometric specifications for the electrodes, we import the design into BioPSE and merge it into an existing geometric model of a human thorax. The model consists of approximately one million finite elements and is based on MR imaging of a human subject. After properly adjusting the boundary conditions on the model, we can apply any desired voltage pulses and then compute the resulting distribution of current and potentials within the thorax and the heart.

In the example shown here, we applied a potential difference of 10 volts between two electrodes applied to the front and back of the thorax, as indicated by the concentric circles and squares in the visualization. The color rendering on the surface of the model indicates the local voltage with red the most positive and blue the most negative values.

Tools like this allow engineers to quickly test out a range of electrode shapes, sizes, and locations for their effectiveness in applying high currents to the heart, a necessary component for successful defibrillation.

Real World Applications

• Oil and Gas Exploration
• Fire Spread
• Tumor Visualization
• Defibrillation

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Bioelectric Fields

Applications of scientific computing to topics in biomedicine are a mainstay of SCI Institute research. The main area of interest continues to be the study of bioelectric fields. Electric and magnetic fields originate from sources within the body and can also be imposed externally, typically as a means of diagnosis or treatment.

Bioelectric fields from the heart are responsible for the electrocardiogram (ECG) and SCI Institute research in this area is very active. The overall goal of this research is to represent the electric sources and their behavior in the body by means of a realistic simulation model of the human thorax. Such a model would provide a means of better understanding how much information about the state of the heart is available on the body surface. We have developed geometric models of the human thorax, as well as computational tools for representing the sources of electric fields in the heart. Current areas of interest include developing methods to better estimate the electrical activity in the heart from ECG measurements on the body surface, the “inverse problem of electrocardiography”.