Body surface mapping (BSM) is an electrocardiographic (ECG) technique that uses numerous leads on a patient's anterior and posterior chest, enabling more complete visualization of cardiac electrical activity. The rationale behind BSM is an extension of additional lead ECG. Output from BSM is displayed in a 12-lead ECG format, an 80-lead ECG format, and on color contour maps. The color contour maps can be displayed on a torso image or as a flat map.