Institut für Biomedizinische Technik

Implementation and assessment of a statistical fitting approach for detection of conduction velocity, anisotropy ratio and fiber orientation of cardiac tissue

To gain further knowledge of the substrate specific measurement protocols can be used in which a certain strength, amplitude and frequency of stimuli is used to induce depolarization of the substrate. Of particular interest is the conduction velocity (CV), the main fiber direction (~highest CV) and the anisotropy level (ratio between CV in fiber direction and perpendicular). A commonly used catheter is the lasso catheter which uses a circular arrangement of electrodes. In our case we stimulate from an electrode pair of the lasso catheter and measure at all other electrodes. Then the stimulation electrodes are changed, meaning the stimulation and therefore the depolarization wave front come from a different direction. This is done for 3 different directions, to find the main fiber direction and the CV associated with it. In an existing approach it is sufficient to define the local activation time (LAT) of the electrode measurement of the electrode pair furthest away from the stimulation to achieve all results. However, when measuring in fibrotic tissue it might be the case, that the LAT is not easily definable. Therefore, a new approach should be proposed here which uses all electrode measurements and weights them depending on the quality of the signal.