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A characteristic feature on the EGM - Viva XT CRT-D

Patient


Male implanted with a triple-chamber defibrillator (Viva XT CRT-D) receiving an electric shock in a particular context.


Trace

1-What is shown on the interval plot?
The plot shows a railroad track appearance on the ventricular channel in the VF zone; the VF counter is implemented and the device delivers an electric shock.

2- What is your diagnosis of the EGM?
The ventricular EGM shows cycles detected in the VF zone alternating between a first acute signal, also visualised on the atrial channel and resembling a pacing spike, and a second signal that may correspond to ventricular depolarisation; the diagnosis evoked by this observation is the presence of external rapid ventricular pacing with double counting (pacing artefact + ventricular depolarisation) leading to the delivery of an electric shock.

3- What is missing from the diagnosis?
The missing element here is the context in which this episode occurred; in this patient, the electric shock was delivered during a TAVI implantation procedure at the time of rapid external pacing.

Comments

  • In the presence of a problem of oversensing, knowledge of the context sometimes enables the diagnosis to be made (use of a poorly insulated household electrical product, etc.); in this case the diagnosis is obvious when we know that the shock was delivered during a TAVI implantation procedure.
  • Since the first percutaneous aortic valve implantation in 2002, the indications for TAVI (transcatheter aortic valve implantation) have evolved considerably, with a steady increase in the number of procedures performed worldwide.
  • During the TAVI implantation procedure, rapid ventricular pacing is usually delivered to induce severe transient hypotension and reduce the risk of embolisation of the prosthesis.
  • The features of oversensing observed in this context is characteristic.
  • During the TAVI implantation procedure, the implantable defibrillator must be temporarily deprogrammed to avoid the occurrence of inappropriate therapies (detection of pacing artefact, rapid ventricular rhythm, etc.) as in this example.
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