Abstract: Systems and methods examine heart tissue morphology using a pair of electrodes, at least one of which is located in contact with heart tissue. The systems and methods transmit electrical current in a path through the contacted heart tissue between the pair of the electrodes to derive a tissue electrical characteristic based, at least in part, upon sensing the impedance of the tissue lying in the path. The system and methods also sense with at least one of the electrodes the timing of local depolarization events in the contacted heart tissue. The systems and methods make possible the use of multiple endocardial electrodes for taking multiple measurements of the electrical characteristics of heart tissue. Multiplexing can be used to facilitate data processing. The systems and methods also make possible the identification of regions of low relative electrical characteristics, indicative of infarcted tissue, without invasive surgical techniques.