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2 2005

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Use of body surface potential maps for model-based assessment of local pathological changes in the heart

Tyšler M., Turzová M., Tiňová M., Švehlíková J., Hebláková E., Szathmáry V., Filipová S.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2005

Vol. 53, nr 3

207-215

High resolution body surface potential maps and an equivalent current dipole model of the cardiac generator were used to assess the heart state in two abnormal conditions: WPW syndrome with single accessory pathway and local ventricular ischemia. Results of a simulation study and experimental verification of the method for both cardiologic abnormalities are presented. Single accessory pathway in WPW syndrome was simulated as initial ventricular activation at the atrio-ventricular ring. Using a current dipole model of the cardiac generator, the locus of arrhythmogenic tissue was assessed with a mean error of 11 mm. Experimental localization of the accessory pathway in a WPW patient was in good agreement with the invasively obtained site. Local repolarization changes were simulated as shortening of the myocytes action potentials in three regions typical for stenosis of main coronary arteries. Using surface QRST integral maps and dipolar source model, small subendocardial and subepicardial lesions of myocardium were inversely located with a mean error of 9 mm and larger transmural lesions with a considerable mean error of 17 mm. Extent and prevalence of subepicardial or subendocardial type of the lesion were reflected in the dipole moment and orientation. In experimental verification of the method, in 7 of 8 patients that underwent PCI of a single vessel, estimated equivalent current dipole position matched well the treated vessel. The results suggest that diagnostic interpretation of body surface potential maps based on dipolar source model could be a useful tool to assess local pathological changes in the heart.

Towards online use of body surface potentiaI mapping in clinical research

Stenroos M.

Biocybernetics and Biomedical Engineering

2005

Vol. 25, no. 4

69-75

Body surface potential mapping (BSPM) is commonly used in clinical research. The next step is to bring BSPM to bedside use and also do basic data analysis during the measurement. In this online use, the measurement and analysis methods have to be particularly robust and easy to use. The signal quality should be good and the results repeatable. The BSPM measurement system used by Helsinki group consists of a single-use strip electrode set, a portable amplifier, and a laptop computer with docking station. In online analysis methods, easy display of potential maps plays a key role. The Helsinki group uses a 2D or 3D pseudocolor display with contour lines. In 3D visualization the isopotential surfaces are created by subdividing triangles. In software, the trade-off between reliability and incorporation of new ideas can be solved with interprocess communication. Potential uses of online BSPM are for ex ample guiding of a pacing catheter with dipole fitting. and detection of ischemia by visual analysis of ST-integral maps. Currently the bottleneck in Helsinki online BSPM system is the time-consuming preparation of the electrode set.