On the Determination and Expressions of Equivalent Quadrupole of the Cardiac Generator

This paper comprises certain theoretical considerations and the proposal of a lead system which seem to be valuable for the determination of the equivalent dipole and quadrupole of the isolated heart. The first section gives the geometrical analysis of the quadrupole field. The quadrupole is represented by a rhombus with equal sides and Taylor components are utilized throughout, in order to describe properties of the field graphically and to define necessary parameters. In the second section, a practical lead system is introduced which gives dipole and quadrupole components of the isolated heart directly, provided that octupolar and higher order terms are negligible. The modification which makes the lead system insensitive to the octupole is also given.