Body surface isopotential mapping in Wolff-Parkinson-White syndrome: noninvasive method to determine the localization of the accessory atrioventricular pathway.

The body surface isopotential maps of 22 patients with WPM syndrome were obtained from the 85 unipolar lead ECG's using the on-line minicomputer system newly devised by the author's group. The map patterns were classified into three types-I, II, and III (Type I, eight; Type II, seven; Type III, three; and unclassified, four cases). In Type I, the back surface displayed the negative potential throughout the entire ventricular activation, and at the terminal stage the lower precordial area displayed the positive potential and the upper precordial area, the negative one. Type II was characterized by two longitudinal lines, one staying at its place on the back and the other moving right to left on the precordial area following the process of ventricular activation. In Type III, the right precordial area displayed negative potential in the early stage, and in the terminal stage the upper part of the right side of chest surface displayed positive potential and the lower part, negative potential. It was surmised from these patterns that the pre-excited area was located at the posterior region of the ventricles in Type I, at the right ventricle in Type II, and the right ventricular base near the posterior margin of the ventricular septum in Type III. Type A patients in the conventional ECG classification fell under Type I; Type C patients, under Type III; Type B patients under either Type I or Type II.