Measuring activation patterns of the heart at a microscopic size scale with thin-film sensors.
To study the spread of excitation in ventricular heart preparations we have designed a fast, high-resolution recording and mapping system. Papillary muscles were dissected from the isolated guinea pig hearts. The preparation was fixed in a tissue bath and superfused with Tyrode solution. Linear and two-dimensional arrays of Ag/AgCl electrodes were made on glass with a thin-film technique. The transparent sensors with up to 24 electrodes (spaced 50, 90, or 180 microns apart) were positioned close to the surface of the preparation with a custom-designed three-dimensional micromanipulator. Extracellular signals were simultaneously recorded by a 24-channel data acquisition system with a 200 kHz per channel sample rate, with 12-bit amplitude resolution and a maximum data length of up to 3 MB. Digitized video images of the electrode array and the underlaying preparation were used to identify the locations of the recording sites. A UNIX-based computer system with a custom-designed data acquisition and database program was used to control the instruments and to manage the experimental data. This technique gave signals with excellent signal-to-noise ratios (up to 65 dB) and permitted accurate evaluation of the time and the site of the local activation with high resolution (to within 5 microseconds, 50 microns). We describe the spread of excitation within the area of a few cells and found a substantial dispersion of conduction velocities. Beat-to-beat comparison of activation patterns showed relatively small variations in the spread of excitation (a few microseconds).
Hofer
E
E
Institut für Medizinische Physik und Biophysik, Karl-Franzens-Universität, Graz, Austria.
Urban
G
G
Spach
M S
MS
Schafferhofer
I
I
Mohr
G
G
Platzer
D
D
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D003201:Computers; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D004594:Electrophysiology / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D008839:Microelectrodes; D010210:Papillary Muscles / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology
D011188:Potassium