Dislodgement of the defibrillation lead in the atrium

N° 6
Manufacturer Boston Scientific Device ICD Field Sensing

This 65-year-old man received a Boston Science single chamber defibrillator for secondary prevention of sustained VT with syncope and ischemic cardiomyopathy. The day after implantation, he perceived an electrical shock.

Graph and trace


  1. sensing of clearly visible atrial activity on the ventricular high-voltage channel and intermittent sensing of ventricular activity;
  2. complete undersensing of ventricular activity with intermittent sensing of atrial activity;
  3. ineffective ventricular pacing, falling in the refractory period of a non-sensed spontaneous QRS;
  4. onset of atrial tachycardia detected at the level of the ventricular channel;
  5. detection of an episode in the VF zone, charge of the capacitors and inappropriate electrical shock (not visible), which, however, terminated the episode of atrial tachycardia.

This tracing is consistent with the early dislodgement of the defibrillation lead. A chest X-ray showed a lead floating inside the atrial chamber. Pending the lead repositioning, the therapies were temporarily turned OFF to prevent the occurrence of further inappropriate therapies.

Other articles that may be of interest to you
MDT Atrial Dislodgement
EGM recordings