Beamforming-inspired Spatial Filtering Technique for Intracardiac Electrograms.

Bipolar electrograms (EGM) are widely used to assess intracardiac electrical activity and to find the atrial fibrillation-related sources. However, the interpretation of bipolar EGM is not straightforward. Variables including bipolar lead (vector) orientation relative to the wave propagation dynamics significantly impact the EGM and EGM-derived measures, which are clinically used to select target sources for catheter ablation. In this study, left atrial unipolar EGM were recorded using a 4 × 4 grid of 16 unipolar electrodes. A set (node) of 4 unipolar EGM were used to construct possible 6 bipolar EGM to evaluate the measurement uncertainty within a particular node. A novel beamforming-inspired spatial filtering (BiSF) method is proposed to reduce the potential measurement uncertainty inevitable in bipolar EGM. A set of three bipolar lead orientations that were constructed using a common unipolar electrode towards three different directions at 45°s, were added to form beamforming EGM. Finally, two beamforming EGM were intertwined to acquire BiSF EGM for a node. Results show greater signal power gain (at least around 10dB) for all BiSF EGM with better or similar signal-to-noise ratio as compared to their respective bipolar counterparts. In conclusion, reduced uncertainty in BiSF EGM improve the interpretation of EGM and EGM-derived measures used in clinical practice after further validation on a larger dataset.