Hexagonal multi-electrode design for recording local electrograms with superior characteristics

Abstract Background The morphology and amplitude of bipolar electrograms depend on the direction of the activation front, and the local activation cannot be attributed to a single electrode location. Coaxial electrograms that use an evenly distributed local reference should address these shortcomings but require more electrodes. Purpose To determine the feasibility and efficiency of recoding coaxial electrograms using a triangular local reference that can scale up to hexagonal multi-electrode designs. Methods We performed in silico and experimental studies using a custom multi-electrode to validate the activation moment, and to directly compare coaxial electrograms recorded using square and triangular local references. Finally, we compared the efficiency of multi-electrode configurations for the recording of coaxial electrograms that may form the basic design of future catheter designs for clinical use. Results The computed coaxial electrograms retained morphological features of unipolar electrograms and the activation moment determined by –dV/dtmax were almost identical. The triangular and cross shaped local reference of the custom multi-electrode matched closely (r = 0.9999, p<0.0001). In contrast to bipolar electrograms, the morphology of the coaxial electrograms was insensitive to electrode orientation relative to the activation front. The local activation time in unipolar electrograms differed less from coaxial than bipolar electrograms (0.56±0.13ms vs 1.31±0.31ms, p<0.001). The recording of coaxial electrograms was more efficient using hexagonal rather than a square multi-electrode design requiring a minimum of 38 electrodes vs 49 to record 25 coaxial electrograms. Conclusions Coaxial electrograms recorded using a triangular references have superior characteristics over bipolar electrograms. The use of efficient hexagonal multi-electrode designs for their recording may improve the precision of activation mapping.Custom Multi-Electrode Comparison of Activation Times