The signal quality of tripolar Laplacian electrogram compared to bipolar electrogram in cardiac electrophysiology

FIGURE 1. The concept of EGM construction. This figure shows the electrode catheter being used to create an activation map. Unipolar EGMs are recorded at each of the three electrodes (electrodes A1 to A3). Bipolar EGMs consist of a subtraction between two unipolar electrodes. The corresponding tripolar EGM is calculated by subtracting the unipolar EGM at the center electrode from the surrounding close‐by electrodes. EGM, electrogram.

FIGURE 2. The six phenotypes were determined according to the activation pattern and the relationship between the direction of the wavefront and the catheter electrodes (wavefront angle). The black arrows indicate the wavefront direction. Representative potentials for each type are shown on their right side. The blue tracing indicates TLE and the black tracing indicates BE. BE, bipolar electrogram; Ho, horizontal; NC, normal conduction; SC, slow conduction; TLE, tripolar Laplacian electrogram; Ve, vertical; WC, wavefront collision.

FIGURE 3. Method for measuring the noise level. The blue tracing indicates TLE and the black tracing indicates BE which are simultaneously recorded. They were observed for 1 s at the point acquired by the stationary catheter under general anesthesia. (A) The level of low frequency noise was defined as the difference between the peak and nadir of drift in the isoelectric line. (B) The level of high frequency noise was defined as the difference between the peak and nadir of a high frequent oscillation at isoelectric line. They were measured at the isoelectric line between the R‐R interval where the influence of LFN was minimal. BE, bipolar electrogram; TLE, tripolar Laplacian electrogram.

FIGURE 4. Method of measuring FFPs. (A) Ventricular FFP. The mapping catheter was located at the anterior side of the mitral annulus during atrial tachycardia. Three tracing indicates the surface ECG, TLE, and BE that were simultaneously recorded. The FFP of a ventricular potential was coincided with the timing of the QRS complex (red shadow), and it could be identified by comparing them with other beats. (B) Atrial FFP. The mapping catheter was located at electrically isolated right superior PV during atrial pacing. The FFPs of a right atrium were identified in isolated PV. The premature beat from the PV showed an exit‐block to atrium, indicating the PV isolation was completed. BE, bipolar electrogram; CS, coronary sinus; ECG, electrocardiogram; FFP, far‐field potential; PV, pulmonary vein; TLE, tripolar Laplacian electrogram.

FIGURE 5. There was an inverse relationship between the voltage amplitude and the EGM duration at the SC area in various conditions. The pink shadows indicate values below the average level of drift noise (0.08 mV for TLE, 0.15 mV for BE). The pink shadow indicates points with lower noise levels that may be difficult to identify. Low‐voltage EGMs below the mean noise levels were more common for BE than for TLE (29% vs. 8%, p = .04). The R 2 value for the correlation between the voltage and EGM duration was lowest for BE/Ve. BE, bipolar electrogram; EGM, electrogram; Ho, horizontal; SC, slow conduction; TLE, tripolar Laplacian electrogram; Ve, vertical.