Detection of atrial arrhythmia in superconducting quantum interference device magnetocardiography; preliminary result of a totally-noninvasive localization method for atrial current mapping.

Map-guided surgery is the goal for treatment of atrial fibrillation (AF), because it minimizes unnecessary incisions or procedures. We propose a totally-noninvasive and even non-contact method to detect atrial arrhythmia with a superconducting quantum interference device magnetocardiography (MCG) system, and report the first clinical application case of MCG map-guided AF surgery. To detect weak atrial excitation, we utilized a high sensitive 64-channel MCG system measuring tangential magnetic field components, which is known to be more sensitive to a deeper current source. We measured the MCG signals from eight patients with chronic AF. Then, we separated the f-wave from the other components by using independent component analysis. The extracted f-wave caused by reentrant myocardial excitation was three-dimensionally localized on the mesh model of a human heart by a novel beamformer technique having a surface action potential activity as its filter output. We localized the abnormal stimulation source of an atrial arrhythmia non-invasively and visualized the current source distribution corresponding to the atrial excitation successfully on the three-dimensional atrial surface, which was separated from the ventricular excitation. Using this atrial mapping, we underwent minimal AF surgery in three patients and converted their AF to sinus rhythm successfully.