These different tracings correspond to an early dislodgement of the atrial lead that has fallen into the ventricle. On the first tracing, the atrial lead drives the ventricle intermittently. On the second tracing, a slowing of the minimum rate allows highlighting the sensing of ventricular depolarization by the atrial lead. A repositioning of the atrial lead enabled the resumption of normal operation. The third tracing illustrates the value of the transmission of a periodic EGM enabling to make the diagnosis in this asymptomatic patient. One of the interesting features of the Biotronik^TM devices is to approximate, during this periodic EGM, what is actually performed during the consultation, with transmission of a real-time EGM without modification of the programming (Normal), followed by transmission of an EGM with reduction in pacing rate in order to favor spontaneous activation and verify the quality of the sensing (Encouraged sensing), and lastly, transmission with an increase in pacing rate in order to favor pacing and verify the effective capture.

When an abnormal tracing is revealed in the immediate aftermath of implantation of a dual-chamber pacemaker, the diagnosis of lead dislodgement should be evoked when the functioning of a single lead appears abnormal. Inverting the 2 leads seems more likely when the lead connected to the atrial channel senses and/or paces the ventricle and the lead connected to the ventricular canal senses and/or paces the atrium.