Decrease in the percentage of biventricular pacing due to ventricular tachycardia

N° 24
Manufacturer Medtronic Device CRT Field Management of atrial arrhythmias

66-year-old man implanted with a triple chamber defibrillator Protecta XT for very severe ischemic cardiomyopathy with left bundle branch block; episode of cardiac decompensation and palpitations.

Graph and trace


  1. 1:1 atrioventricular rhythm;
  2. acceleration of the ventricular rhythm (in the VT zone) with no modification of the atrial rhythm;
  3. the ventricular rhythm remains faster than the atrial rhythm but remains below the VT zone;


  1. atrial rhythm and biventricular pacing (AS-BV);
  2. onset of the episode triggered by a PVC; VT with AV dissociation in the VT zone and labeled (TS);
  3. slowing of the tachycardia rate below the VT zone; false diagnosis of tachycardia termination;
  4. slowing of the VT rate around 150 bpm.  

This tracing demonstrates the difficulty in managing relatively slow VTs. In this patient, the tachycardia rate was too low to be treated and the VT lasted for several hours. Finally, it was responsible for an episode of cardiac decompensation, related to different mechanisms: loss of biventricular pacing, tachycardia, atrioventricular dissociation... Lowering the lower limit of the VT zone allowed for the treatment of this arrhythmia by anti-tachycardia pacing and prevented the occurrence of a new episode of cardiac decompensation.