Pacing & Defibrillation

ECG

Library

News

Back

PR Logic versus Wavelet - Evera XT DR

Patient

Male implanted with a dual-chamber defibrillator (Evera XT DR) for dilated cardiomyopathy.

Trace

1- What is the diagnosis made by the defibrillator for this episode?
This episode was classified VT by the device.

2- How many detection zones are programmed?
Two detection zones have been programmed with a VT zone of 400 to 260 ms.

3- What diagnosis does the interval plot suggest?
The graph shows an appearance compatible with a ventricular arrhythmia (atrioventricular dissociation) accelerating after a Ramp + and terminating spontaneously.

4- How many discrimination parameters are programmed?
PR Logic and Wavelet are programmed with a SVT V.limit of 260 ms.

5- What is your diagnosis?
This is a ventricular arrhythmia that accelerates after a Ramp+ and terminates spontaneously.

6-What are the results of Wavelet?
Wavelet favours the diagnosis of SVT, with the majority of analysed QRS complexes judged to be similar to the reference template; Wavelet is not used however, as the ventricular rate is faster than the atrial rate.
Key messages

Take home message

  • In a dual or triple chamber defibrillator, international recommendations advise simultaneous programming of PR Logic and Wavelet.
  • It is important to understand the decision-making process when these 2 algorithms are programmed; when the ventricular rate is judged to be faster than the atrial rate, PR Logic concludes the arrhythmia is VT/VF and the device diagnoses VT without further analysis.
  • In this case (V > A), the device does not consult the Wavelet analysis, and therefore cannot modify the VT diagnosis made by PR Logic.
  • This example shows the advantage of prioritising PR Logic over Wavelet when the ventricular rate is faster than the atrial rate; in fact, the diagnosis is obvious with PR Logic whereas Wavelet would have concluded SVT and would have inhibited therapies.

X