Frank法ベクトル心電図のI, E, C, A, M電極の位置の検討(Three step technic, Y-Precordial technicによる) 第2編 健常,高血圧例による臨床的検討

The transverse level of chest electrodes is important in the accuracy of the dipole component derived from the Frank lead system of vectorcardiography. The transverse level of the electrical center of the heart vector was determined in supine subjects utilizing a three step technic and a Y-Precordial technic, and the effect of shift in the electrode level from the fifth intercostal space to the level of electrical center was studied. Vectorcardiograms were obtained from 154 adult male subjects: normal men (46), hypertensive patients with normal electrocardiogram (45), hypertensive patients with high voltage of the QRS complex (34) and hypertensive patients showing high voltage of the QRS complex with S-T segment and T wave changes (29). The following results were obtained: 1) The cases in which the electrical center were present above the fifth intercostal space were more than those in which it was below that intercostal space. However, in most cases (101 out of 126 cases, 80.2%), the electrical center was present within ± 20 mm of the level of the fifth intercostal space. In 28 out of 154 cases, these technics could not indicate the level of the electrical center. 2) With chest electrodes shifted from the level of the fifth intercostal space to the level of the electrical center, the magnitude of each component of the vectorcardiogram changes; especially the maximum posterior component increased in all groups regardless of whether the electrical center was above or below the fifth intercostal space. However, in most cases these changes were equal to or smaller than beat-to-beat or observer variation.