Saburo Mashima

Body Surface Laplacian Mapping in Patients with Left or Right Ventricular Bundle Branch Block

Body surface Laplacian maps (BSLMs) have been previously reported to provide enhanced capability in localizing and resolving multiple spatially separate myocardial events. However, only a few studies have been reported on the clinical applications of BSLM. To test the clinical utility of BSLMs, BSLMs and body surface potential maps (BSPMs) during ventricular depolarization for complete right or left ventricular bundle branch block (CRBBB or CLBBB) were studied in ten patients in each group. As a control group, ten healthy subjects were also studied using the same procedure. One hundred and twenty‐eight electrodes were placed uniformly over the entire chest and back of the subjects. BSLMs were computed from recorded potentials, using a numerical algorithm. The BSLMs showed multiple and more localized positive and negative activities compared with the BSPMs. In healthy subjects, the BSLMs showed multiple areas of positive activity overlying the RV, LV, and the RV outflow, and negative activity corresponding to RV free‐wall breakthrough and LV anterolateral breakthrough sites, whereas the BSPMs could not separate RV and LV activities. In the patients with CRRRR, the BSLMs showed more localized areas of activity corresponding to the LV apex breakthrough and LV lateral breakthrough, and separated LV lateral and posterior activation. In the patients with CLBBB, the BSLMs showed multiple RV activation, and propagating activation of LV from lateral to posterior. The BSLMs appear to provide enhanced capability in detecting multiple ventricular electrical events associated with normal and abnormal conduction and a more detailed activation sequence of both ventricles in healthy subjects and in the patients with CRBBB and CLBBB. BSLM may provide an important alternative to other imaging modalities in localizing cardiac electrical activity noninvasively.

On the potential of the wilson central terminal with respect to an ideal reference for unipolar electrocardiography

Body surface potential mapping was performed in 60 clinical cases and an ideal 0 potential was calculated in each case at 2msec intervals, which corresponds to the potential at infinity. Maximal deviation of the Wilson terminal voltage the ideal potential was 0.14mv on the average. Time course of potential variations of the central terminal was in proportion to the measured surface potentials. The lead vector of Wilson terminal was determined for each case, with a method to make a minimal difference between calculate and observed Wilson terminal voltage. The lead vector was directed superiorly and posteriorly with the magnitude of 24% of that of lead I on the average.

THE ZERO POTENTIAL AND WILSON'S CENTRAL TERMINAL IN ELECTROCARDIOGRAPHY

Abstract For unipolar electrocardiography, a zero reference electrode is necessary. The zero potential is usually considered as that at infinity but not well understood for a finite conductor. In practice, Wilsons central terminal has been utilized, as a zero equivalent, with remarkable clinical success. The grade of approximation has, however, not been established. In this paper, we discuss related topics including a review of older literature, the definition of zero potential and the method for obtaining the zero potential from the measurements on the body surface. With this method, the potential of Wilsons electrode with respect to that at infinity can be calculated. Our previous calculation in 60 clinical cases showed the time course of the absolute voltage of Wilsons electrode, which is nearly parallel with the body surface potential.