A graphic record of the direction and magnitude of the electrical forces of the heart’s action by means of a continuous series of vector loops. Analysis of the configuration of these loops permits certain statements to be made about the state of health or diseased condition of the heart. At any moment the electrical activity of the heart can be represented as an electrical vector with a specific direction and magnitude. This is called the instantaneous cardiac vector. A series of these vectors may be established for the entire cardiac cycle. By joining the tips of these vectors with a continuous line, the vectorcardiogram loop is formed. The configuration so obtained may be projected on the frontal plane or viewed as a three-dimensional loop. Three vectorcardiogram loops are formed during each cardiac cycle one for the electrical activity of the atrium; one for ventricular depolarization; one for ventricular repolarization.