Modeling the Anatomical Changes During Cardiac

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Models of the human thorax as a volume conductor are employed for forward and ... In order to evaluate the effect of changes in the anatomy due to cardiac.
Modeling the Anatomical Changes During Cardiac Cycle in the Model of the Thorax as a Volume Conductor H Puurtinen*, J Hyttinen, M Kankimäki, J Malmivuo, Ragnar Granit Institute, Tampere University of Technology, Tampere, Finland Poster Session: WE-CXH-148 Poster Session: VIII Physiological Modeling - Modeling Track: 20 Physiological Modelling

Models of the human thorax as a volume conductor are employed for forward and inverse estimation of ECG potentials and cardiac sources, respectively. Models created previously have varied greatly in the level of anatomical details incorporated. Insufficient accuracy of the models may have, however, restricted the accuracy of conducted simulations. In order to evaluate the effect of changes in the anatomy due to cardiac function on the forward solutions, two detailed 3-D FDM models of the human thorax as a volume conductor were constructed. Two MR image sets taken at the end diastolic and the end systolic phases of the cardiac cycle were segmented. Thus, the models represent the anatomical changes due to the mechanical function of the heart, namely the changes in major blood masses and in the shape of the cardiac muscle. The inhomogeneities incorporated in the models include cardiac muscle, intracardiac blood masses and major vessels, lungs, some internal organs (liver, stomach), and some bone structures such as sternum and spine. The effects of the anatomical changes were obtained by comparing computed body surface potentials generated by equivalent dipole sources set at different locations in the cardiac muscle in both end diastolic and end systolic models. The results clearly indicate that the volumetric changes of the blood masses inside the heart must be taken into account for accurate modelling of the human thorax. In addition, this study revealed that the differences vary depending on the location of the dipole source.