Display of the vectorcardiograms with a new complementary loop of formula Z = f (square root X2 + Y2)

It is important in vectorcardiography to be able to determine the position and magnitude of a given vector, e.g., the left maximum spatial vector, or the vector occurring 20 ms after beginning of QRS, etc. In this aim the authors present besides the three classical planar projections , a fourth curve of Lissajous, known asthe "modulus curve" and which corresponds to the formula Z = f (square root X2 + Y2). In general applications, this curve is very simple to use, and several examples of application are given. The technical realization, which involves no great modification of standard equipment, is described.