Chapter 1 · Counters · Case 4

Spontaneous termination of a ventricular arrhythmia

Patient and episode

Patient

  • Patient with ischaemic cardiomyopathy implanted with a triple chamber defibrillator (Claria CRT-D).

The recording

Tap a number on the trace, or an entry in the list below

Rate / interval plot

Medtronic ICD electrogram, segment 1 of 1 — Spontaneous termination of a ventricular arrhythmia

EGM

Medtronic ICD electrogram, segment 1 of 1 — Spontaneous termination of a ventricular arrhythmia
  1. What diagnosis is suggested by the interval plot? The plot shows a sudden acceleration of the ventricular rate with cycles detected in the VF zone; the initial VF counter is filled (Detection) but no therapy is delivered following probable spontaneous reversion.
  2. What type of arrhythmia is it. This is probably a very rapid ventricular arrhythmia.
  3. How is the initial detection counter in the VF zone programmed? The initial counter is set to 30/40.
  4. What does aborted mean? Charging of the capacitors starts when the initial VF counter is filled; during charging, the arrhythmia stops spontaneously and after 4 consecutive cycles classified as BV, charging is interrupted (discontinuation of therapy).

Points to remember

  • This episode corresponds to polymorphic ventricular tachycardia which resolves spontaneously after about ten seconds.
  • This patient had multiple episodes of non-sustained ventricular tachycardia stored in the device’s memory; these are defined by at least 5 consecutive cycles in one of the detection zones without any counters being filled (VT or VF) and a few episodes, like this example, where the counters were filled but charging was interrupted.
  • Programming the number of cycles in the initial counter is crucial for the patient’s quality of life and prognosis; today, it is recommended that the initial counter in the VF zone is programmed for 30/40 cycles as a first-line treatment; results from a large number of patients have shown that this programming significantly reduces the number of inappropriate therapies (expected result) but also the number of appropriate but avoidable therapies, when the arrhythmia terminates spontaneously.

Practice out loud

Just describe the tracing. What do you think is going on? Describing the numbers can help.

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From Medtronic ICD — clinical cases by P. Bordachar, A. Thiyagarajah, L. Fontagne, M. Strik, S. Ploux. Published by Cardiocases. Every numbered marker on a recording is explained in the list beneath it; tap a marker on the trace or an entry in the list.

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