A new method for analysing the geometry and timecourse of epicardial potential spreading.

A 256 unipolar electrode matrix fixed at the surface of an isolated rabbit heart was connected to a PC system via an amplifying and analog/digital converting frontend computer. This system allows measurement of 256 electrodes within 100 microseconds with a sampling rate of 0.25 ms. The data are displayed on a PC system either on-line as common ECG-recordings or off-line in projection on a two-dimensional model of the heart surface. Thereby, it is possible to visualize the epicardial potential spreading in a slow-motion presentation on a high resolution computer graphic. The samples are displayed sequentially and can be delayed by choice. This method allows the determination of the origin ("break-through-points") of the epicardial excitation and an analysis of the potential spreading. The electrodes are arranged in four grids with 64 electrodes each at an interelectrode distance of 1 mm. Thereby, it is possible to evaluate the direction of the epicardial excitation wave and the local state of epicardial activation. Furthermore, it is possible to demonstrate irregular pacemakers or re-entry circuits. The method seems to be helpful in analysis of cardiac arrhythmogenesis and mode of action of anti-arrhythmic agents.