PMC8305645_01
Device Interrogation Without Connected ECG Lead. From top to bottom, this image shows the EGM channel, the marker channel, and the ECG channel (not connected). Circles indicate what seem to be T-wave-only EGMs (the 4th circle indicates the timing of the anticipated EGM), and solid arrows indicate the anticipated ventricular sensing markers, correspondingly, assuming a stable heart rate. Dashed arrows indicate the expected pacing spikes given a lower rate limit of 50 beats/min. ECG = electrocardiogram; EGM = electrogram.
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fig1
There was a lack of electrograms (EGMs) and a lack of annotations on the marker channel suggestive of the absence of ventricular depolarization (Figure 1).