Abstract 13636: A Novel Magnetocardiographic Approach for Estimating the Whole Ventricular Activation With Use of 3-Directional Recordings
Background: Multi-channel magnetocardiography (MCG) is potentially useful for noninvasively evaluating cardiac activation with high spatio-temporal resolution. However, standard recordings over anterior chest alone may be insufficient to estimate the whole heart activation (especially in the posterior site), because magnetic fields rapidly decay with distance.
Methods: Using a 64-channel MCG system (Hitachi), we repeated 3 measurements (1-ms sample) with sensors placed close to anterior, posterior, and left lateral chest wall (supine, prone, and lateral decubitus positions, respectively) in 25 healthy volunteers (Cont) and 26 dilated cardiomyopathy patients with narrow QRS duration (QRSd) < 120ms (DCM, LVEF 29±14%). We averaged MCG signals (>20 beats) with simultaneously digitized ECG, which was also used to synchronize 2-D current arrow mapping for each recording.
Results: In all of Cont (Fig), we visualized 3 distinct currents during ventricular activation. After rightward anterior-directed currents (i.e., "septal activation", Max at 17±4 ms after QRS onset), we observed 2 different currents virtually simultaneously arising from separate sites; anterior downward and posterior upward propagating currents (appearing at 27±4, and 26±4 ms, respectively), that were reasonably considered as propagations via left anterior and posterior fascicles, respectively. LV activation was completed at 51±5 ms, followed by RV activation (QRSd 89±6 ms). In DCM, LV activation was prolonged (74±16 ms, p<0.001, QRSd 104±14 ms). Moreover, we occasionally recognized apparently abnormal conduction which was not discernible on ECG, such as that shown in Fig.
Conclusions: We, for the first time to our knowledge, noninvasively visualized two separate electrical propagations in LV arising from left anterior and posterior fascicles. Our new approach may allow to evaluate abnormal intraventricular conduction (delay and block) accompanied by myocardial damage.
- © 2010 by American Heart Association, Inc.