crosstalk

Tracing
N° 4
Manufacturer Biotronik Device Remote monitoring Field Periodic Egm
Patient

This 54-year-old man presenting with dilated cardiomyopathy and conduction abnormalities underwent implantation of a Lumax 540 HF-T triple chamber defibrillator; periodic EGM.

Graph and trace

Telecardiology tracing

The 4 channels displayed for 30 sec include 1) the markers and time intervals, 2) the atrial sensing channel, 3) the right ventricular sensing channel and 3) the left ventricular sensing channel.

  1. spontaneous atrial rhythm and biventricular stimulation;
  2. oversensing of a supernumerary atrial signal corresponding to the end of the stimulated QRS: ventriculo-atrial crosstalk;
  3. alternation in the atrium of cycles classified AS and Ars; absence of mode switch.
Comments

Oversensing of spontaneous or stimulated ventricular activation by the atrial channel is diagnosed in presence of alternating short and long AA delays, with sensing of an atrial EGM near a ventricular EGM, and a constant V-A interval, of a duration just longer than the post-ventricular atrial blanking period. This might cause inappropriate mode switch as well as interfere with discrimination based on the counts of atrial and ventricular EGM during tachycardia. This oversensing can be prevented by lowering the atrial sensitivity or by lengthening the post-ventricular atrial blanking period (far-field blanking by default 75 ms after VP or VS). In this case, the issue was resolved by lengthening the post-ventricular stimulation atrial blanking period.

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