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 to simplify and facilitate interpretation of the record by enabling the comparison of multiple-lead recording of the same heartbeat. It is noninterpretive and reduces signal noise level by performing an average of multiple cycles of the signal; it may be used to detect late potentials for the identification of patients prone to ventricular tachycardia.