MEASUREMENT AND ANALYSIS OF MONOPHASIC AC TION-POTENTIALS USING FRACTALLY COATED LEADS .1.

The monophasic action potential (MAP) contains a wealth of information about the state of the myocardium, which makes it very useful for num erous diagnostic and therapeutic applications in patients with heart d isease. The silver-silver chloride electrodes which are currently used for the measurement of MAP have poor long-term stability in contact w ith biological tissue. This study was therefore undertaken with the ai m of investigating the electrochemical behaviour of fractally coated l eads in terms of their signal-detection performance. Experience gained with these leads in cardiac pacemakers has already demonstrated the l ong-term stability and biocompatibility of the fractally coated leads. Present results show that, due to their large electrochemically activ e surface area, fractally coated leads have a very low impedance over a wide frequency range. The negligible polarization artifact of these leads permits the measurement of cardiac potentials immediately after a stimulus. Fractally coated leads are thus highly suitable for the me asurement of MAP, and have clear advantages over Ag/AgCl electrodes. T he second part of this study reports on the results of MAP measurement s using fractally coated leads.