Commentary
The MEs are circumferentially located on the distal tip of the standard electrode (Figure 2A).2 This configuration is different from that of the MiFiTM IntellaTip ablation catheter, in which MEs are located in a radial fashion on its lateral aspects (Boston Scientific, Natick, MA).3 Therefore, when the distal end of the electrode equipped with MEs is in contact with the tissue perpendicularly, the MEs detect the signals (Figure 2B). However, when the catheter is in contact to the tissue parallelly, there is poor contact between the MEs and tissue; therefore, the standard bipolar electrode detects the signals and the MEs do not (Figure 2C).
Because of their size and interelectrode spacing, MEs can detect near-field signals that the standard bipolar electrode fails to detect. Therefore, MEs improve identification of local electrical activity responsible for arrhythmias.2–5 Bipolar electrograms depend on the contact between the tissue and electrode for recording electrical signals, and on the orientation of the catheter relative to the tissue (from parallel to perpendicular).2–5 The present case described the use of both the standard bipolar electrode and MEs for simultaneously recording the local electrical activity (i.e., LAVA), wherein the standard bipolar electrode recorded LAVA without any corresponding signals being detected on the MEs. This phenomenon may be attributed to the orientation of the catheter relative to the tissue and the configuration of the MEs.