TELEMONITORING OF INTRACARDIAC ELECTROGRAMS

H. Hutten, G. Schreier, P. Kastner, M. Schaldach*
Institute of Biomedical Engineering, Technical University Graz (Austria)
*Institute of Biomedical Engineering, University Erlangen-Nürnberg (Germany)

INTRODUCTION: Telemonitoring of intracardiac electrograms is a promising new approach for rejection monitoring after heart transplantation, but also for diagnostic purposes and drug therapy management.

METHODS: The recent development of advanced pacemaker technology with extended bandwidth telemetry feature in combination with with fractally coated electrodes renders possible the monitoring of intracardiac electrograms from the spontaneously beating and the paced heart. The pacemaker telemetry bandwidth covers the range 0.3 - 200 Hz and can be utilized with polarization-artefact free electrodes. The recorded electrograms contain relevant information concerning all influences on membrane permeability and excitability (e.g. activity of the autonomous nervous system, electrolyte concentrations, hormons, drugs). Depending on the type of employed electrode and the site of measurement, the recorded electrograms monitor either the behaviour of only few cells (i.e. monophasic action potentials) or a global view on the process of excitation spreading (e.g. unipolar measurement using an epimyocardially fixed electrode against the pacemaker housing). After transmission to an extracorporeal data acquisition station the electrograms can be further processed employing averaging, feature extraction etc.

RESULTS: The first applied method for routinely telemonitoring intracardiac electrograms has been established during the last 5 years for the computerized monitoring of acute rejection after heart transplantation. The electrograms are recorded in five centers worldwide with more than 110 patients and transmitted via internet from the local data acquisition station to the central computer in Graz using either the FTP protocol or e-mail. The electrograms are evaluated with regard to rejection or infection diagnosis. After signal processing the hospital receives a record that supports further decisions in therapy management. More then 10.000 transmissions have been performed without any serious problems.

DISCUSSION: Intramyocardial electrograms contain useful information for diagnostic or therapeutical purposes. Signal processing can be performed in specialized centers.