A reference potential for unipolar electrocardiographic measurements on models.

Abstract 1. 1. Measurements of potentials produced by a finite dipole immersed in an insulating torso model filled with a homogeneous conducting fluid are discussed. 2. 2. The need for a reference potential is presented as well as a discussion of the accuracy with which the reference potential must be determined. 3. 3. The equivalent bridge viewpoint is introduced and is shown to give considerable insight into the electrical nature of both unipolar and bipolar measurements. 4. 4. A center-electrode reference system is described which has several advantageous features. The inherent defect of this system, a shift of equipotentials between the two current electrodes owing to the distant boundary, is pointed out and analyzed. 5. 5. The experimental difficulties and interrelationship of the more important design factors of a practical reference potential system are presented.