Real-time mapping of a whole heart chamber using a novel sparse ultrasonic catheter array

Purpose: Atrial fibrillation (AF), the most prevalent form of cardiac arrhythmia, afflicts millions worldwide. Here, we developed an imaging algorithm for the diagnosis and online guidance of radio-frequency ablation, which is currently the first line of treatment for AF and other arrhythmia. This requires the simultaneous mapping of the left atrium anatomy and the propagation of the electrical activation wave, and for some arrhythmia, within a single heartbeat. Methods: We constructed a multi-frequency ultrasonic system consisting of 64 elements mounted on a spherical basket, operated in a synthetic aperture mode, that allows instant localization of thousands of points on the endocardial surface and yields a MRI-like geometric reconstruction. Results: The system and surface localization algorithm were extensively tested and validated in a series of in silico and in vitro experiments. We report considerable improvement over traditional methods along with theoretical results that help refine the extracted shape. The results in left atrium-shaped silicon phantom were accurate to within 4 mm. Conclusions: A novel catheter system consisting of a basket of splines with multiple multi-frequency ultrasonic elements allows 3D anatomical mapping and real-time tracking of the entire heart chamber within a single heartbeat. These design parameters achieve highly acceptable reconstruction accuracy.