A new technique for three-dimensional localization of transmural electrodes.

Simultaneous multichannel cardiac mapping is used to investigate mechanisms of arrhythmia. Transmural cardiac interrogation is useful in the study of ventricular arrhythmias. The construction of needle electrodes capable of transmural recording, although labor-intensive, is relatively straightforward. The three-dimensional localization of these electrodes within the myocardium and the subsequent depiction of the data obtained have customarily been performed manually. A simple technique for automated recording of site registration and subsequent fully automatic data presentation of three-dimensional data, for use in experimental animals, is presented. It entails replacing each recording needle electrode prior to fixation of the heart with a marker needle electrode that is radiographically coded to permit both three-dimensional recording site localization and unique electrode identification. The fixed and excised heart may then be sectioned with the marker needles in place and an x-ray obtained. The needle identification, electrode locations, and actual tissue outlines are then digitized, allowing for completely automated subsequent assignment of relevant data obtained from these recording sites to morphologically correct anatomic locations. This approach should facilitate transmural studies aimed at elucidating electrophysiologic mechanisms.