A UNIVERSAL VECTOR CARDIOGRAPH

Abstract

The electric action of the heart can be represented by a vector (heart-vector), varying during the heart beat in magnitude and direction. If this vector is drawn from a fixed zero point, the end point describes a three-dimensional curve-the vector cardiogram. Several investigators have constructed a vector cardiograph, i.e. an instrument designed to visualize or photograph one or more projections of this curve (Cantonnet and Milovanovitch, 1947; As these must be derived from electrocardiographic leads, the method depends on the relation between heart-vector and leads. Some investigators have used the well-known triangle rule of Einthoven; others have not used extremity leads according to Einthoven, but have placed the electrodes in such a way, that the lines connecting them are mutually perpendicular. All these methods are founded on arbitrary suppositions. It is, however, possible to generalize these methods and to use a linear relation between heart-vector and leads Using three leads, this gives three linear equations for the components X, Y, Z of the heart-vector, from which the latter can be solved: X= c1(lead)1 +oc2(lead)2 + a3(lead)3 Y=-l1(lead)1 +92(lead)2+fl3(lead)3.(1) Z=y1(lead)1+y2(lead)2+y3(lead)3