Dipolarity and dipole location during QRS and T waves in normal men estimated from body surface potential distribution.

The dipolarity of the body surface potential distribution and the locus of the main dipole were estimated mathematically at 2 msec intervals in 27 normal men. The nondipolar content showed time-dependent fluctuation during the QRS. It increased sharply at early and later phases of the QRS. The main dipole moved smoothly within the actual cardiac region and was inscribed in a clockwise direction in most cases. The nondipolar content during the ST-T period was smaller and with less fluctuation than that during the QRS. The main dipole during the T wave moved less than 2 cm near the center of the heart. These results indicated that although a fairly large percentage of the body surface potential could be represented by a single moving dipole, the nondipolar content was larger during initial and late phases of the QRS. It was also suggested that the ventricular repolarization process can be better approximated by a single fixed dipole in normal men.