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.