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1/1 tachycardia, PR Logic, Wavelet - Amplia Quad CRTD

Patient

Male implanted with a triple-chamber defibrillator (Amplia Quad CRTD) for ischaemic cardiomyopathy.


Trace


1- What was the diagnosis made by the defibrillator for this episode?
This episode has been classified SVT-Wavelet by the device.

2- Which programmed zone appears on the graph?
A monitor zone is programmed from 390 ms.

3- What diagnosis does the interval plot suggest?
The graph shows a 1/1 tachycardia with abrupt acceleration recorded in the monitor zone; spontaneous termination after about 6 minutes.

4- How many discrimination parameters are programmed?
The discrimination parameters (PR Logic and Wavelet) are programmed with a SVT V. Limit of 260 ms; the other SVT 1:1 criterion is programmed ‘On’.

5- What information does the onset of arrhythmia give you?
The tachycardia starts with a rapid atrial rhythm, which is consistent with atrial tachycardia.

6- What are the possible diagnoses?
This is a 1/1 tachycardia; the possible diagnoses are therefore: atrial tachycardia with 1/1 conduction, junctional tachycardia, ventricular tachycardia with 1/1 retrograde conduction; the PR interval is relatively long with a VA interval shorter than the AV interval.

7- What information does the termination in arrhythmia give you?
The tachycardia stops spontaneously on a ventricular event, which is also in favour of atrial tachycardia.

8- What are the results of Wavelet?
Wavelet supports the diagnosis of SVT, with 7 of the 8 QRS complexes analysed similar to the reference template.

Take home message

  • This patient presented with episodes of atrial tachycardia detected in the monitor zone; the tachycardias began with an atrial extrasystole and ended spontaneously with a ventricular complex; these elements support the diagnosis of atrial tachycardia but are not part of the defibrillator analysis.
  • PR Logic gave a diagnosis of VT, but this was corrected by the Wavelet analysis.
  • The device highlights a 1/1 tachycardia that is not compatible with sinus tachycardia (sudden acceleration of atrial and ventricular rates); PR Logic analyses the position and succession of P waves between 3 consecutive R waves to differentiate VT, atrial tachycardia and junctional tachycardia; in this example, the atrial activity does not occur just before or just after the ventricular activity (in favour of junctional tachycardia) but is located in the first half of the RR interval (in favour of VT with retrograde conduction rather than atrial tachycardia); PR Logic concludes that the diagnosis is VT.
  • During a 1/1 tachycardia, if PR Logic concludes VT with retrograde conduction, Wavelet is integrated into the discrimination; if the morphology of the ventricular complexes in tachycardia is considered different from the reference, the device confirms the VT diagnosis; on the other hand, if the morphology is considered similar to the reference template, the device corrects the diagnosis and concludes supraventricular tachycardia; in this example, this avoids the delivery of inappropriate therapies.

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