An octaxial reference system derived from a nonequilateral triangle for frontal plane vectorcardiography

Abstract

The weight of evidence indicates that the frontal plane triangle commonly used in electrocardiography is not equilateral from the electrical standpoint. 1–5 This triangle is scalene as illustrated in Fig. 1, a. Such a triangle should be more representative of the true situation pertaining to the electrical field of the heart than is the equilateral triangle. It is the purpose of tis paper to illustrate the use of this nonequilateral triangle and an octaxial system derived from it for the estimation of the direction and magnitude of mean QRS and T vectors in the frontal plane. The configuration of the nonequilateral triangle ∗ ∗ The triangle in Fig. 1 was constructed from data of Frank and Kay 6 using a dipole location at the same level as their location 2, Fig. 2, but 1.5 cm. to the left and 0.5 cm. toward the back. shown in Fig. 1 is derived from experimental data using accurately formed homogeneous torso models 1,4 with an immersed current dipole. These data are plotted as an image surface 1,4 from which surface potentials may be derived by geometric construction. In this paper only three points on the image surface, the right arm, left arm, and left leg, are utilized. However, the image surface concept is a very useful and illuminating one in electrocardiography and is basic to a proper understanding of vector methods.