E.C.G. is stand of Electrocardiography.  It is the process of producing an electrocardiogram. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart  using electrodes placed on the skin. It is a simple test that can be used to check your heart's rhythm and electrical activity. Sensors attached to the skin are used to detect the electrical signals produced by your heart each time it beats.