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Transmission

The alert shows: “A Threshold value is over the max tested amplitude (4.0 V)” and indeed on the Real time EGM, we see complete loss of atrial capture. While the atrial lead is pacing with high amplitude (4.5V), we can see the intrinsic atrial rhythm (sensed and shown as Ar markers) which is slightly faster than the paced rhythm. The sensed values of these intrinsic events are also quite low at 0.9 mV showing up as a second alert: “Current low P wave measurement: 0.9 mV”. In addition, the blue bars (second page, atrial lead segment) touching the atrial sensitivity threshold suggest intermittent undersensing. Therefore the diagnosis of subacute atrial lead displacement can be made.

Next steps

During the post-implantation period, the risk of lead displacement is relatively high. The patient should be called within hospital to confirm the diagnosis using device interrogation and chest X-ray. And then the lead should be repositioned or replaced. Except for very rare cases in which re-intervention is not possible, one should not accept a non-functioning lead so close after implantation, also because of the risk of the lead moving into the ventricle, possibly causing arrhythmia.