QUANTITATIVE CHARACTERIZATION OF EPICARDIAL WAVE-FRONTS DURING REGIONAL ISCHEMIA AND ELEVATED EXTRACELLULAR POTASSIUM-ION CONCENTRATION

This study applied zero-delay wave number spectral estimation as a mea ns of quantifying the changes in activation and recovery sequences of propagating plane waves on the epicardial surface of in situ porcine h earts during regional hyperkalemia and ischemia Unipolar electrograms (104) were recorded from the left ventricular surface of nine hearts u sing a plaque electrode array with 1 mm spatial sampling intervals. Th e objectives were (1) to define a set of parameters capable of quantif ying the spatial and temporal changes in measured extracellular potent ials associated with localized ischemia prior to the onset of conducti on block; (2) to elevate regional levels of extracellular potassium io n concentration and quantify potential changes due to this known physi ologic manipulation; and (3) to use quantitative parameters to make st atistical comparisons in order to distinguish wave fronts during norma l, ischemic and hyperkalemic conditions. Results showed that the param eters of wave number and average temporal frequency and the associated power, as determined from the wave number spectrum, provided statisti cally significant (p<0.05) quantification of changes in wave front fea tures during normal and ischemic or hyperkalemic conditions. The resul ts were consistent with results obtained from conventional time-space domain methods like isochronal mapping and electrograms, with the adva ntage of a quantitative result enabling simple comparisons and trend a nalysis for large numbers of heart beats. (C) 1998 Biomedical Engineer ing Society. [S0090-6964(98)01506-9].