Originally, tissue stabilizer has been developed by Medtronic, Inc. It is used to prevent a certain part of myocardium from moving. For example, such an approach is utilized during Coronary Artery Bypass Grafting (CABG). Moreover, medical procedures during such operations involve blood arrest, thus, potentially may involve ischemia of myocardium. A construction of the modified tissue stabilizer used during surgery on a beating heart is presented in the paper. We have developed a stabilizer that aside preventing part of myocardium from moving enables recording of epicardial electrograms. Four electrograms are recorded simultaneously together with one lead of standard ECG as a reference signal. Time relations between electrograms, recorded at four different points surrounding potentially ischemic area, are strongly modified by processes triggered by myocardium ischemia. Aside a construction of the stabilizer the associated measurement system is also presented. Measurement properties of the developed stabilizer and measurement system have been examined during tank studies. Finally, the waveforms obtained during in vivo study are also presented.