Figure 1.
Electrograms (EGMs) during left atrial appendage (LAA) pacing at a pacing cycle length of 600 ms demonstrating posterior mitral isthmus (MI) block and its reconnection with an endocardial conduction gap.
(Left panel) Before achieving MI block. (Middle panel) After achieving MI block. Atrial EGMs recorded in the coronary sinus (CS) demonstrate a proximal-to-distal activation sequence. MAP is located at the endocardial MI lesion. The interval between the stimulus and EGM recorded on the MAP is 190 ms. (Right panel) Atrial EGMs recorded in the CS showing the reconnection of MI lesion. EGMs in the CS showing double components: far-field left atrium (LA) EGMs with low amplitude and frequency (arrows) precede the near-field CS EGMs with high amplitude and frequency (arrowheads). LAA pacing demonstrates a distal-to-proximal activation sequence of the LA (arrows) followed by middle-to-distal and -proximal activation sequences of the CS (arrowheads). MI, mitral isthmus; S, stimulus.