- The purpose of the Electrocardiogram test is to monitor and measure the quantity and quality of the electrical rhythm of the heart. Understanding the electrical rhythms of the heart is important because your heart's electrical system controls the timing of your heartbeat and you would have to understand how the electrical rhythm of the heart should be to know what problems may be occurring. There are three common variables that are encountered in an electrocardiogram which are the direction in which the signal is moving, the speed at which the signal is moving and the mass of the tissue through which the signal is moving. There are three different parts of an electrical signal which are P wave, QRS complex and T wave. P wave passes slowly
