An instrument designed to measure electrical potentials on the body surface to generate a record of the electrical currents associated with heart muscle activity [i.e., an electrocardiogram (ECG)] for the assessment of cardiac physiology. It records electrical signals from two or more multiple electrode sets (leads) simultaneously, thus simplifying and facilitating the interpretation of the record by enabling the comparison of multiple-lead recording of the same heartbeat. It records data in electronic or printed form for later analysis by software or a healthcare professional.