Sensing of noise on the right ventricular channel and loss of biventricular stimulation

Tracing
N° 8
Manufacturer Microport CRM Device CRT Field Management of atrial arrhythmias
Patient

This 63-year-old man presenting with a valvular cardiomyopathy, wide QRS complex and sinus node dysfunction, received a Microport CRM-Sorin Paradym triple chamber defibrillator. Interrogation of his device revealed the presence of 2 episodes of non-sustained VF stored in memory.

Graph and trace
  1. atrial pacing and BiV stimulation (AP-BV).
  2. ultra rapid ventricular signal sensed at the limit of the ventricular blanking period (125 ms). The signal was also visible, though not sensed, on the atrial channel. Diagnosis of VF. Interruption of oversensing and therapy not delivered.

    Same tracing at 100 mm/sec sweep speed.

  3. the sinusoidal characteristic of the 50 Hz signal (20 ms between signals) is apparent.
Comments

This tracing illustrates oversensing by the RV lead of a 50 Hz signal emitted by a poorly insulated household appliance, which temporarily inhibited BiV stimulation. In pacemaker-dependent patients (unlike in this case), this kind of episode may be symptomatic and associated with ventricular pauses of variable duration. As in the previous case, the treatment consisted of identifying the emitting source to prevent recurrences and eliminate the risk of inappropriate therapy.

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