Assessment of the unipolar and bipolar electrograms on the mapping module
All unipolar electrograms were assessed automatically by the CARTOFINDER algorithm as follows. The window of interest (WOI) was determined based on the total activation phase of the bipolar electrogram, and annotation points were assigned to the maximum negative slope of the unipolar electrogram within each WOI. Every cycle length (CL) was measured from each local activation interval during the entire recording period, and the mean CL and CL standard deviation (CLSD) for each channel were calculated (Fig. 1A). Among all CL measurements collected from the 20 electrodes of the PentaRay catheter at each recording site, the most frequent value of CL was considered the DCL (Fig. 1B). Focal activations were defined as ≥ 2 consecutive QS patterns on the unipolar electrogram registered ≤ 50 ms earlier than the proximal electrodes located within a 10-mm radius (Fig. 1C) and were visually displayed as a 3-dimensional map (CARTOFINDER map), along with the CL, CLSD, and the number of repetitions of focal activations (focal intensity).
The bipolar electrograms were recorded simultaneously during CARTOFINDER mapping (Fig. 2). The maximal bipolar voltage and electrogram morphologies were evaluated at sites of focal activation. Bipolar electrogram morphologies were divided into the following three categories based on the presence or absence of an isoelectric line: (1) discrete type, (2) fractionated type, and (3) combination type.14 The combination type involved both types of discrete and fractionated electrograms during the simultaneous recording period. The discrete type was further divided based on the electrical potential components: single potentials characterized by single deflection and non-single potentials.