The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Theory, Modelling and Applications of Electrocardiographic Mapping

Kim Simelius

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Engineering Physics and Mathematics for public examination and debate in Auditorium F1 at Helsinki University of Technology (Espoo, Finland) on the 10th of November, 2004, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7028-5)   [6235 KB]
Dissertation is also available in print (ISBN 951-22-7027-7)

Abstract

In this thesis, the genesis and applications of electromagnetic signals from the human heart are investigated through theory, modelling, signal processing and clinical studies.

One objective of the thesis was to develop and test signal processing methods that would be applicable to multichannel electro- and magnetocardiographic data. A signal processing method based on a type of neural networks called the self-organizing maps is introduced for spatiotemporal analysis of the body surface potential maps produced by the beating heart. This method is capable of utilizing both the spatial morphology of the potential distributions on the body surface as well as their temporal development. A signal processing method aimed at providing a reliable electric baseline for more traditional isointegral analysis of the body surface potential mapping (BSPM) data is also introduced.

Another objective of the thesis was to show the utility of electrocardiographic mapping in clinical use. This was demonstrated by applying electro- and magnetocardiographic mapping to evaluation of the propensity to life-threatening arrhythmias in postinfarction patients. Electrocardiographic mapping was found to perform equally well compared to more traditional SA-ECG, but electrocardiographic mapping may be more robust against individual variability in anatomy.

A third objective of the thesis was to build a computer model of the human heart that is capable of simulating the normal ventricular activation. The propagation model is based on a bidomain formulation of the cardiac tissue applied to realistic geometry of the ventricles. An anatomically accurate model of the human conduction system that reproduces measured activation sequence of the human heart was developed in this thesis. The body surface potentials and the magnetic fields computed from the simulated activation corresponded to recordings from normal subjects.

In summary, the thesis demonstrates the utility of electrocardiographic mapping in clinical use and introduces new signal processing methods that can be applied to this use. Finally, a computer model of the human heart binds together the physiology and anatomy of the human heart and body, classical electromagnetic theory, and computer science to explain the genesis and characteristics of the electromagnetic signals from the human heart.

This thesis consists of an overview and of the following 6 publications:

  1. Simelius K., Stenroos M., Reinhardt L., Nenonen J., Tierala I., Mäkijärvi M., Toivonen L. and Katila T., 2003. Spatiotemporal characterization of paced cardiac activation with body surface potential mapping and self-organizing maps. Physiological Measurement 24, number 3, pages 805-816. © 2003 Institute of Physics Publishing Ltd. By permission.
  2. Jokiniemi T., Simelius K., Nenonen J., Tierala I., Toivonen L. and Katila T., 2003. Baseline reconstruction for localization of rapid ventricular tachycardia from body surface potential maps. Physiological Measurement 24, number 3, pages 641-651. © 2003 Institute of Physics Publishing Ltd. By permission.
  3. Väänänen H., Korhonen P., Montonen J., Mäkijärvi M., Nenonen J., Oikarinen L., Simelius K., Toivonen L. and Katila T., 2000. Non-invasive arrhythmia risk evaluation in clinical environment. Herzschrittmachertherapie und Elektrophysiologie 11, number 4, pages 229-234. © 2000 Steinkopff Verlag. By permission.
  4. Korhonen P., Tierala I., Simelius K., Väänänen H., Mäkijärvi M., Nenonen J., Katila T. and Toivonen L., 2002. Late QRS activity in signal-averaged magnetocardiography, body surface potential mapping, and orthogonal ECG in postinfarction ventricular tachycardia patients. Annals of Noninvasive Electrocardiology 7, number 4, pages 389-398. © 2002 Blackwell Publishing. By permission.
  5. Simelius K., Nenonen J., Mäntynen V., Clements J. C. and Horáček B. M., 2004. A hybrid model of cardiac electrical conduction. Helsinki University of Technology, publications in Engineering Physics, Report A829 (TKK-F-A829). © 2004 by authors.
  6. Simelius K., Nenonen J. and Horáček B. M., 2001. Modeling cardiac ventricular activation. International Journal of Bioelectromagnetism 3, number 2, pages 51-58. © 2001 International Society for Bioelectromagnetism. By permission.

Keywords: electrocardiography, BSPM, multichannel, heart model, bidomain, conduction system

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© 2004 Helsinki University of Technology

Last update 2011-05-26