An electrogram is a graphical representation of the electrical activity of the heart. It is typically used to diagnose and monitor cardiac arrhythmias. It is created using electrodes placed on the skin to measure and record electrical signals from the heart. The resulting waveforms are then displayed on a monitor or printed out for further analysis. Electrograms are used to identify abnormal heart rhythms, such as atrial fibrillation or ventricular tachycardia, as well as to assess the effectiveness of treatments for these conditions.