T-wave oversensing

N° 20
Manufacturer Medtronic Device CRT Field Standard parameters

53-year-old woman implanted with a triple-chamber defibrillator Protecta XT CRT-D for ischemic cardiomyopathy with left bundle branch block; routine follow-up.

Graph and trace

Temporary programming ODO;

  1. atrial sensing and biventricular pacing (AS-BV);
  2. oversensing of the T-wave on a spontaneous ventricular event;
  3. biventricular pacing is turned ON;
  4. oversensing of the T-wave during biventricular pacing;
  5. persistent T-wave oversensing;
  6. programming change; decrease in ventricular sensing;
  7. oversensing resumed.

In this patient, oversensing of the T-wave was present after a spontaneous ventricular event but also after a paced ventricular event.  It was not responsible for a significant drop in the percentage of biventricular pacing. The device recorded a large number of premature ventricular contractions corresponding to the T-wave oversensing episodes.

Oversensing of the T-wave can in some cases promote the absence of biventricular pacing. The T-wave is considered as a ventricular premature contraction, which causes a prolongation of the PVARP if the “response to a PVC” algorithm is turned ON. The next sinus P-wave falls into the PVARP, and therefore does not trigger a new AV delay, and the phenomenon perpetuates as shown in the previous case.

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