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paper in conference proceedings

abstract

Several types of computational studies of the heart require the incorporation of realistic cardiac geometry. The demands of the different applications, like forward and inverse modeling of the cardiac activation and recovery, ion kinetics, and mechanics, give rise to different requirements on spatial resolution, meshing techniques, and model components.

The models used in our groups include surface descriptions by means of a widely varying number of triangles and volume descriptions by means of cubes, tetrahedrons, and hexahedrons. For some applications the description of the surface or the volume has to be extended with a description of the internal structures (such as fiber orientation, conduction system, or blood vessels). For some applications the geometric models need to be tuned to those of individual patients. This is a very time-consuming procedure if the desired accuracy is high. For the forward and inverse computations not only a description of heart geometry is needed but also that of various other structures and of the body surface. Results obtained in one application, e.g. inverse modeling of the cardiac activation times, can not easily be applied in another application, e.g. for mechanical deformation during the heart cycle, unless the heart models used can be matched.

We designed a unifying framework where the torso shape, heart, its blood-filled cavities, lungs, liver, etc, are represented by means of continuously deformable hexahedra. This implies a non-linear mapping from a Cartesian coordinate system to an anatomical one. Volume and surface meshes at various resolutions and other models are defined within this framework. The mapping algorithm used enables the easy adaptation of specific generic models for specific applications. Moreover, it greatly facilitates inter-subject comparisons of anatomy in a quantitative manner. Specific software is written to support the matching of this generic model to MRI and CT data.

In this paper we will present the first results of the application of this software to the creation of numerical representations of overall heart geometry, including the ventricles and the - more complex - atria.