Ground-Free ECG Recording with Two Electrodes

ECG recordings normally use three electrodes-two for the differential inputs of the ECG amplifier and the third for ground. We analyze those situations where the ground electrode can be eliminated. We propose a model for the source of electrical interference and determine various parameter values. Making use of experimentally obtained data for the model parameters we suggest optimal design for a two-electrode amplifier. The two-electrode design is useful for biotelemetry, portable Holter monitors, and portable arrhythmia monitors. Under certain circumstances it may be useful for grounded monitoring equipment. The two-electrode technique has the advantage that it improves patient safety by eliminating the ground electrode. Fewer electrodes make patient attachment easier and lower electrode costs.