Visualization method of current distribution in cardiac muscle using a heart model

Our aim in this study is to obtain images of current distributions including morphological information on the heart. Such images are obtained by projecting two-dimensional (2.D) current-arrow maps, calculated from magnetocardio. gram (MCG) signals, onto a three-dimensional (3-D) heart model obtained from magnetic resonance (MR) images. We used a superconducting quantum interference device (SQUID) system to measure the normal component (Bz) of MCG signals. The signals were measured at 64 points with an 8X8 array above the chest, and were acquired at a sampling rate of 1 kITz. The MR images were obtained by scanning coronal planes with a 6 mm vertical separation. We made individual heart models for three healthy subjects from heart-outline points extracted from the MR images of the subjects. Current-arrow maps were calculated by taking the orthogonal partial derivatives of the MCG signal normal component. The current-arrow maps for three healthy subjects were then projected on the individual heart models by means of displacement-free mapping of the current vectors to the corresponding heart-outline points. The currentarrow maps, which were projected to the individual heart model, strongly reflect the respective electrophysiological phases (P-wave, QRS-complex, and T-wave), and give us a clear view of the anatomical sites of activation in the heart.