Crosstalk, mode switch and decrease in the percentage of BiV stimulation

Tracing
N° 9
Manufacturer Microport CRM Device CRT Field Standard parameters
Patient

This 59-year-old man received a Microport CRM-Sorin Intensia SonR triple chamber defibrillator in the context of ischemic cardiomyopathy with long PR interval and left bundle branch block. Episodes of mode switch were detected during a follow-up device interrogation.
Graph and trace

Graph

  1. 1:1 AV association.
  2. alternans of short - long cycles at the atrial level.
  3. 1:1 AV association.
  4. alternans of short - long cycles at the atrial level.
  5. 1:1 AV association.

Tracing

  1. atrial sensing, BiV stimulation (with programmed V-V delay) and crosstalk (sensing of ventricular depolarization by the atrial channel).
  2. mode switch in DDI mode.
  3. AV conduction with long PR.
Comments

This tracing is similar to the previous one, with mode switch prompted by prolonged crosstalk. In this pacemaker non-dependent patient, this inappropriate mode switch was associated with an interruption of BiV stimulation and return of spontaneous rhythm. The rail-like appearance of the graph is characteristic of crosstalk. As in the previous case, crosstalk could be suppressed by a) lowering the atrial sensitivity (at the risk of undersensing episodes of AF), or b) extending the post-ventricular atrial blanking (at the risk of undersensing 2:1 atrial flutter), or c) both interventions. 

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