Depolarization changes during ischemia detected through time-frequency analysis of the intracardiac electrogram

Epicardial and endocardial electrograms were recorded from isolated perfused rabbit hearts in which local ischemia was induced by occluding the LAD for short periods of time. Intracavitary and epicardial bipolar leads were found to be sensitive to ischemia in paced and non-paced beats. Both the intra-QRS electrogram and the ST level respond to ischemia whereas there are cases with the one showing differences with ischemia while the other is not. Intracardial leads can detect ischemia in a distal site. Hence the intra-QRS electrogram may be a valuable alternative to ST analysis in ischemia detection. This may find application in implantable devices